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Sample records for correlated mimo channels

  1. Capacity Analysis of MIMO Rayleigh Channel with Spatial Fading Correlation

    NASA Astrophysics Data System (ADS)

    Trung, Ha Duyen; Benjapolakul, Watit; Araki, Kiyomichi

    MIMO (Multiple Input Multiple Output) communications systems equipped with array antennas at both the transmitter and receiver sides are a promising scheme to realize higher rate and/or reliable data transmission. In this paper, capacity analysis of MIMO Rayleigh channel with spatial correlation at the receiver of multipath taken into account is presented. In general, a model configuration of local scattering around a mobile station in MIMO environment is carried out by simulation to examine spatial correlation coefficients. Based on statistical properties of the eigenvalues of correlated complex random Wishart matrices, the exact closed-form expressions of distribution of the eigenvalues are investigated. Then, the general closed-form evaluation of integral form is proposed based on Meijer's G-function. The results demonstrate that the ergodic capacities are improved by increasing the number of the antennas and the SNR's. Compared with i. i. d. (independent identically distributed) Rayleigh channel, the incremental improvement of correlated Rayleigh channel is reduced by spatial fading correlation. The analytical results validated by Monte-Carlo simulations show a good agreement.

  2. Characteristic Analysis on UAV-MIMO Channel Based on Normalized Correlation Matrix

    PubMed Central

    Xi jun, Gao; Zi li, Chen; Yong Jiang, Hu

    2014-01-01

    Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition number of UAV-MIMO channel matrix, the channel capacity, and other characteristic parameters. The simulation results show that this channel correlation matrix can be applied to describe the changes of UAV-MIMO channel characteristics under different parameter settings comprehensively. This analysis method provides a theoretical basis for improving the transmission performance of UAV-MIMO channel. The development of MIMO technology shows practical application value in the field of UAV communication. PMID:24977185

  3. Characteristic analysis on UAV-MIMO channel based on normalized correlation matrix.

    PubMed

    Gao, Xi jun; Chen, Zi li; Hu, Yong Jiang

    2014-01-01

    Based on the three-dimensional GBSBCM (geometrically based double bounce cylinder model) channel model of MIMO for unmanned aerial vehicle (UAV), the simple form of UAV space-time-frequency channel correlation function which includes the LOS, SPE, and DIF components is presented. By the methods of channel matrix decomposition and coefficient normalization, the analytic formula of UAV-MIMO normalized correlation matrix is deduced. This formula can be used directly to analyze the condition number of UAV-MIMO channel matrix, the channel capacity, and other characteristic parameters. The simulation results show that this channel correlation matrix can be applied to describe the changes of UAV-MIMO channel characteristics under different parameter settings comprehensively. This analysis method provides a theoretical basis for improving the transmission performance of UAV-MIMO channel. The development of MIMO technology shows practical application value in the field of UAV communication.

  4. SER Analysis of MPPM-Coded MIMO-FSO System over Uncorrelated and Correlated Gamma-Gamma Atmospheric Turbulence Channels

    NASA Astrophysics Data System (ADS)

    Khallaf, Haitham S.; Garrido-Balsells, José M.; Shalaby, Hossam M. H.; Sampei, Seiichi

    2015-12-01

    The performance of multiple-input multiple-output free space optical (MIMO-FSO) communication systems, that adopt multipulse pulse position modulation (MPPM) techniques, is analyzed. Both exact and approximate symbol-error rates (SERs) are derived for both cases of uncorrelated and correlated channels. The effects of background noise, receiver shot-noise, and atmospheric turbulence are taken into consideration in our analysis. The random fluctuations of the received optical irradiance, produced by the atmospheric turbulence, is modeled by the widely used gamma-gamma statistical distribution. Uncorrelated MIMO channels are modeled by the α-μ distribution. A closed-form expression for the probability density function of the optical received irradiance is derived for the case of correlated MIMO channels. Using our analytical expressions, the degradation of the system performance with the increment of the correlation coefficients between MIMO channels is corroborated.

  5. An iterative detection method of MIMO over spatial correlated frequency selective channel: using list sphere decoding for simplification

    NASA Astrophysics Data System (ADS)

    Shi, Zhiping; Yan, Bing

    2010-08-01

    In multiple-input multiple-output(MIMO) wireless systems, combining good channel codes(e.g., Non-binary Repeat Accumulate codes) with adaptive turbo equalization is a good option to get better performance and lower complexity under Spatial Correlated Frequency Selective(SCFS) Channel. The key of this method is after joint antennas MMSE detection (JAD/MMSE) based on interruption cancelling using soft information, considering the detection result as an output of a Gaussian equivalent flat fading channel, and performing maximum likelihood detection(ML) to get more correct estimated result. But the using of ML brings great complexity increase, which is not allowed. In this paper, a low complexity method called list sphere decoding is introduced and applied to replace the ML in order to simplify the adaptive iterative turbo equalization system.

  6. Double Space Time Transmit Diversity OFDM System with Antenna Shuffling in Spatial Correlated Frequency Selective MIMO Channels

    NASA Astrophysics Data System (ADS)

    Zhou, Liang; Shimizu, Masahiko

    In this paper, we study low complexity transceiver for double space time transmit diversity (DSTTD) and orthogonal frequency division multiplexing (OFDM) system with antenna shuffling. Firstly, we propose a novel antenna shuffling method based on the criterion of minimizing the condition number of channel correlation matrix. The condition number is an indicator about the quality of the channel. By selecting the minimum of condition number which has better channel quality, consequently, a linear detector with respect to this new channel may achieve better performance results. A low complexity variant of the condition number calculation is also proposed, and it is shown that this criterion can be reduced to the minimum mean square error (MMSE) based criterion. Furthermore, the weighted soft decision Viterbi decoding is applied to mitigate noise enhancement inherent to zero forcing (ZF) and MMSE linear receivers and improve error rate performance. Next, we propose an algorithm to reduce the amount of feedback by exploiting the fact that the channel frequency responses across OFDM subcarriers are correlated. In the proposed algorithm, subcarriers are clustered in blocks, which are allocated the same shuffling pattern with the largest number of the shuffling patterns in the cluster. This way, the signaling overhead can be reduced in comparison with each subcarrier based feedback. Extensive simulations show that the proposed techniques for DSTTD-OFDM system outperform other existing techniques under both uncorrelated and highly spatial correlated frequency selective MIMO fading channels.

  7. Compressive Sensing With Prior Support Quality Information and Application to Massive MIMO Channel Estimation With Temporal Correlation

    NASA Astrophysics Data System (ADS)

    Rao, Xiongbin; Lau, Vincent K. N.

    2015-09-01

    In this paper, we consider the problem of compressive sensing (CS) recovery with a prior support and the prior support quality information available. Different from classical works which exploit prior support blindly, we shall propose novel CS recovery algorithms to exploit the prior support adaptively based on the quality information. We analyze the distortion bound of the recovered signal from the proposed algorithm and we show that a better quality prior support can lead to better CS recovery performance. We also show that the proposed algorithm would converge in $\\mathcal{O}\\left(\\log\\mbox{SNR}\\right)$ steps. To tolerate possible model mismatch, we further propose some robustness designs to combat incorrect prior support quality information. Finally, we apply the proposed framework to sparse channel estimation in massive MIMO systems with temporal correlation to further reduce the required pilot training overhead.

  8. Channel capacity of next generation large scale MIMO systems

    NASA Astrophysics Data System (ADS)

    Alshammari, A.; Albdran, S.; Matin, M.

    2016-09-01

    Information rate that can be transferred over a given bandwidth is limited by the information theory. Capacity depends on many factors such as the signal to noise ratio (SNR), channel state information (CSI) and the spatial correlation in the propagation environment. It is very important to increase spectral efficiency in order to meet the growing demand for wireless services. Thus, Multiple input multiple output (MIMO) technology has been developed and applied in most of the wireless standards and it has been very successful in increasing capacity and reliability. As the demand is still increasing, attention now is shifting towards large scale multiple input multiple output (MIMO) which has a potential of bringing orders of magnitude of improvement in spectral and energy efficiency. It has been shown that users channels decorrelate after increasing the number of antennas. As a result, inter-user interference can be avoided since energy can be focused on precise directions. This paper investigates the limits of channel capacity for large scale MIMO. We study the relation between spectral efficiency and the number of antenna N. We use time division duplex (TDD) system in order to obtain CSI using training sequence in the uplink. The same CSI is used for the downlink because the channel is reciprocal. Spectral efficiency is measured for channel model that account for small scale fading while ignoring the effect of large scale fading. It is shown the spectral efficiency can be improved significantly when compared to single antenna systems in ideal circumstances.

  9. Use Channel Reconfiguration Technique to Improve the Spatial Multiplexing Gain of MIMO Systems

    NASA Astrophysics Data System (ADS)

    Wang, Yung-Yi; Yang, Shih-Jen; Chen, Jiunn-Tsair

    Multiple-input-multiple-output (MIMO) wireless systems can not always have full spatial multiplexing gain due to the channel correlation problem caused by various factors such as the coupled antenna elements, and the key-hole effect of the propagation environment. In this paper, we proposed a channel reconfiguration technique to combat the rank deficiency problem of the involved MIMO wireless channels that can not afford high-order multiplexing gains. In the proposed approach, each mobile station can simultaneously receive several independent data streams from multiple base stations through a set of MMSE-based receive beamformers to suppress the multiple access interferences. Making use of the receive beamforming, which virtually produce the effect of a single antenna at each receive mobile, makes the transmit base station possible to reconfigure the MIMO downlink channel and then pre-cancel the co-channel interferences. The proposed signal processing mechanism that iteratively optimized the MMSE receive weights and the transmit precoders, which brings the reconfigured MIMO system about the high data throughput seen only with indoor MIMO systems having rich wireless channels. It is shown that as compared to the conventional MIMO system, the M4 system can achieve a significantly higher capacity which is proportional to the number of the linked base stations.

  10. Stable Transmission in the Time-Varying MIMO Broadcast Channel

    DTIC Science & Technology

    2008-01-01

    input multiple - output ( MIMO ) wireless channel promises significant gain in performance over that offered by conventional single-antenna systems [1...Jensen, “A low-cost open-hardware wideband multiple - input multiple - output ( MIMO ) wireless channel sounder,” to appear in IEEE Transactions on...the multiple - input single- output (MISO) broadcast channel. A similar study for erroneous CSIT was also performed for the computationally simpler zero

  11. Optimizing the wireless power transfer over MIMO Channels

    NASA Astrophysics Data System (ADS)

    Wiedmann, Karsten; Weber, Tobias

    2017-09-01

    In this paper, the optimization of the power transfer over wireless channels having multiple-inputs and multiple-outputs (MIMO) is studied. Therefore, the transmitter, the receiver and the MIMO channel are modeled as multiports. The power transfer efficiency is described by a Rayleigh quotient, which is a function of the channel's scattering parameters and the incident waves from both transmitter and receiver side. This way, the power transfer efficiency can be maximized analytically by solving a generalized eigenvalue problem, which is deduced from the Rayleigh quotient. As a result, the maximum power transfer efficiency achievable over a given MIMO channel is obtained. This maximum can be used as a performance bound in order to benchmark wireless power transfer systems. Furthermore, the optimal operating point which achieves this maximum will be obtained. The optimal operating point will be described by the complex amplitudes of the optimal incident and reflected waves of the MIMO channel. This supports the design of the optimal transmitter and receiver multiports. The proposed method applies for arbitrary MIMO channels, taking transmitter-side and/or receiver-side cross-couplings in both near- and farfield scenarios into consideration. Special cases are briefly discussed in this paper in order to illustrate the method.

  12. Evolution Trends of Wireless MIMO Channel Modeling towards IMT-Advanced

    NASA Astrophysics Data System (ADS)

    Chong, Chia-Chin; Watanabe, Fujio; Kitao, Koshiro; Imai, Tetsuro; Inamura, Hiroshi

    This paper describes an evolution and standardization trends of the wireless channel modeling activities towards IMT-Advanced. After a background survey on various channel modeling approaches is introduced, two well-known multiple-input-multiple-output (MIMO) channel models for cellular systems, namely, the 3GPP/3GPP2 Spatial Channel Model (SCM) and the IMT-Advanced MIMO Channel Model (IMT-Adv MCM) are compared, and their main similarities are pointed out. The performance of MIMO systems is greatly influenced by the spatial-temporal correlation properties of the underlying MIMO channels. Here, we investigate the spatial-temporal correlation characteristics of the 3GPP/3GPP2 SCM and the IMT-Adv MCM in term of their spatial multiplexing and spatial diversity gains. The main goals of this paper are to summarize the current state of the art, as well as to point out the gaps in the wireless channel modeling works, and thus hopefully to stimulate research in these areas.

  13. Uplink channel estimation error for large scale MIMO system

    NASA Astrophysics Data System (ADS)

    Albdran, Saleh; Alshammari, Ahmad; Matin, Mohammad

    2016-09-01

    The high demand on the wireless networks and the need for higher data rates are the motivation to develop new technologies. Recently, the idea of using large-scale MIMO systems has grabbed great attention from the researchers due to its high spectral and energy efficiency. In this paper, we analyze the UL channel estimation error using large number of antennas in the base station where the UL channel is based on predefined pilot signal. By making a comparison between the identified UL pilot signal and the received UL signal we can get the realization of the channel. We choose to deal with one cell scenario where the effect of inter-cell interference is eliminated for the sake of studying simple approach. While the number of antennas is very large in the base station side, we choose to have one antennal in the user terminal side. We choose to have two models to generate the channel covariance matrix includes one-ring model and exponential correlation model. Figures of channel estimation error are generated where the performance of the mean square error MSE per antenna is presented as a function signal to noise ratio SNR. The simulation results show that the higher the SNR the better the performance. Furthermore, the affect of the pilot length on the channel estimation error is studied where two different covariance models are used to see the impact of the two cases. In the two cases, the increase of the pilot length has improved the estimation accuracy.

  14. Sparse Recovery Algorithms for Pilot Assisted MIMO OFDM Channel Estimation

    NASA Astrophysics Data System (ADS)

    Qi, Chenhao; Wu, Lenan

    In this letter, the sparse recovery algorithm orthogonal matching pursuit (OMP) and subspace pursuit (SP) are applied for MIMO OFDM channel estimation. A new algorithm named SOMP is proposed, which combines the advantage of OMP and SP. Simulation results based on 3GPP spatial channel model (SCM) demonstrate that SOMP performs better than OMP and SP in terms of normalized mean square error (NMSE).

  15. Reduced Complexity in Antenna Selection for Polarized MIMO System with SVD for the Practical MIMO Communication Channel Environment

    NASA Astrophysics Data System (ADS)

    Sann Maw, Maung; Sasase, Iwao

    In the conventional multi-input multi-output (MIMO) communication systems, most of the antenna selection methods considered are suitable only for spatially separated uni-polarized system under Rayleigh fading channel in non-line of sight (NLOS) condition. There have a few antenna selection schemes for the cross-polarized system in LOS condition and Ricean fading channel, and no antenna selection scheme for the MIMO channel with both LOS and NLOS. In the practical MIMO channel case, influence of LOS and NLOS conditions in the channel can vary from time to time according to the channel parameters and user movement in the system. Based on these influences and channel condition, uni-polarized system may outperform a cross-polarized. Thus, we should consider this kind of practical MIMO channel environment when developing the antenna selection scheme. Moreover, no research work has been done on reducing the complexity of antenna selection for this kind of practical MIMO channel environment. In this paper, reduced complexity in antenna selection is proposed to give the higher throughput in the practical MIMO channel environment. In the proposed scheme, suitable polarized antennas are selected based on the calculation of singular value decomposition (SVD) of channel matrix and then adaptive bit loading is applied. Simulation results show that throughput of the system can be improved under the constraint of target BER and total transmit power of the MIMO system.

  16. Channel Acquisition for Massive MIMO-OFDM With Adjustable Phase Shift Pilots

    NASA Astrophysics Data System (ADS)

    You, Li; Gao, Xiqi; Swindlehurst, A. Lee; Zhong, Wen

    2016-03-01

    We propose adjustable phase shift pilots (APSPs) for channel acquisition in wideband massive multiple-input multiple-output (MIMO) systems employing orthogonal frequency division multiplexing (OFDM) to reduce the pilot overhead. Based on a physically motivated channel model, we first establish a relationship between channel space-frequency correlations and the channel power angle-delay spectrum in the massive antenna array regime, which reveals the channel sparsity in massive MIMO-OFDM. With this channel model, we then investigate channel acquisition, including channel estimation and channel prediction, for massive MIMO-OFDM with APSPs. We show that channel acquisition performance in terms of sum mean square error can be minimized if the user terminals' channel power distributions in the angle-delay domain can be made non-overlapping with proper phase shift scheduling. A simplified pilot phase shift scheduling algorithm is developed based on this optimal channel acquisition condition. The performance of APSPs is investigated for both one symbol and multiple symbol data models. Simulations demonstrate that the proposed APSP approach can provide substantial performance gains in terms of achievable spectral efficiency over the conventional phase shift orthogonal pilot approach in typical mobility scenarios.

  17. Power and Rate Adaptation Based on Imperfect Channel Estimation over MIMO Fading Channels

    NASA Astrophysics Data System (ADS)

    Kobravi, Alireza; Shikh-Bahaei, Mohammad

    We derive the optimum power and rate adaptation for maximizing the spectral efficiency of Multilevel Quadrature Amplitude Modulation (MQAM) over Multiple-Input Multiple-Output (MIMO) fading channels based on imperfect channel estimation. We use Pilot Symbol Assisted Modulation (PSAM)-based Minimum Mean Square Error (MMSE) channel estimator, and show that the optimum power adaptation on each sub-channel is a generalization of water-filling. We also show that the conventional water-filling (with bias) strategy for power adaptation is a suboptimum solution of the general optimization problem and it tends to the optimal solution as the correlation coefficients between eigenvalues of the true channel matrix and its estimate tend to one.

  18. Robust Linear Transmit/Receive Processing for Correlated MIMO Downlink with Imperfect CSI

    NASA Astrophysics Data System (ADS)

    Li, Hao; Xu, Changqing; Fan, Pingzhi

    In this paper we investigate designing optimal linear transmit/receive processing filters for multiuser MIMO downlinks with imperfect channel state information (CSI) and spatial fading correlation between antenna array at BS. A robust scheme is proposed to obtain the optimal linear transmit/receive filters in the sense of minimizing the average sum mean square error (SMSE) conditional on noisy channel estimates under a per-user transmit power constraint. Using an iterative procedure, the proposed scheme extends the existing optimization algorithm for uncorrelated single-user MIMO systems with perfect CSI to solve the problem of minimizing SMSE in spatially correlated MIMO downlinks with imperfect CSI. Comparing with non-robust scheme, we show that robust scheme efficiently mitigates the BER loss induced by imperfect CSI. In addition, the impact of fading correlation at BS on the performance of the proposed robust scheme is analyzed.

  19. A fast forward/backward semi-blind channel estimation for MIMO STC-OFDM systems

    NASA Astrophysics Data System (ADS)

    Chang, Lena; Cheng, Ching-Min; Tang, Zay-Shing

    2013-09-01

    In the study, we propose an efficient subspace-based semiblind channel estimation for multiple-input-multiple-output (MIMO) space-time code (STC) orthogonal frequency-division multiplexing (OFDM) systems. We first proposed a forward-backward estimation (FBE) method which can improve the channel estimation accuracy by using both the forward and backward receiving data. Then, based on the symmetric property of the forward and backward smoothed correlation matrix, we develop a fast forward-backward (FFB) estimation method which estimates the noise subspace by performing eigen-decomposition of two half dimensionality sub-matrices obtained from the forward and backward smoothed correlation matrix. FFB achieves the same performance as the FBE but only requires one-fourth computation complexity of FBE. Computer simulations demonstrate the effectiveness and accuracy in channel estimation of the proposed FFB for the MIMO STC-OFDM systems.

  20. A Portable MIMO Testbed and Selected Channel Measurements

    NASA Astrophysics Data System (ADS)

    Goud, Paul, Jr.; Hang, Robert; Truhachev, Dmitri; Schlegel, Christian

    2006-12-01

    A portable[InlineEquation not available: see fulltext.] multiple-input multiple-output (MIMO) testbed that is based on field programmable gate arrays (FPGAs) and which operates in the 902-928 MHz industrial, scientific, and medical (ISM) band has been developed by the High Capacity Digital Communications (HCDC) Laboratory at the University of Alberta. We present a description of the HCDC testbed along with MIMO channel capacities that were derived from measurements taken with the HCDC testbed for three special locations: a narrow corridor, an athletics field that is surrounded by a metal fence, and a parkade. These locations are special because the channel capacities are different from what is expected for a typical indoor or outdoor channel. For two of the cases, a ray-tracing analysis has been performed and the simulated channel capacity values closely match the values calculated from the measured data. A ray-tracing analysis, however, requires accurate geometrical measurements and sophisticated modeling for each specific location. A MIMO testbed is ideal for quickly obtaining accurate channel capacity information.

  1. Smoothing techniques for decision-directed MIMO OFDM channel estimation

    NASA Astrophysics Data System (ADS)

    Beinschob, P.; Zölzer, U.

    2011-07-01

    With the purpose of supplying the demand of faster and more reliable communication, multiple-input multiple-output (MIMO) systems in conjunction with Orthogonal Frequency Division Multiplexing (OFDM) are subject of extensive research. Successful Decoding requires an accurate channel estimate at the receiver, which is gained either by evaluation of reference symbols which requires designated resources in the transmit signal or decision-directed approaches. The latter offers a convenient way to maximize bandwidth efficiency, but it suffers from error propagation due to the dependency between the decoding of the current data symbol and the calculation of the next channel estimate. In our contribution we consider linear smoothing techniques to mitigate error propagation by the introduction of backward dependencies in the decision-based channel estimation. Designed as a post-processing step, frame repeat requests can be lowered by applying this technique if the data is insensitive to latency. The problem of high memory requirements of FIR smoothing in the context of MIMO-OFDM is addressed with an recursive approach that acquires minimal resources with virtual no performance loss. Channel estimate normalized mean square error and bit error rate (BER) performance evaluations are presented. For reference, a median filtering technique is presented that operates on the MIMO time-frequency grids of channel coefficients to reduce the peak-like outliers produced by wrong decisions due to unsuccessful decoding. Performance in terms of Bit Error Rate is compared to the proposed smoothing techniques.

  2. Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties

    NASA Astrophysics Data System (ADS)

    Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing

    This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

  3. Efficient Coordinated Recovery of Sparse Channels in Massive MIMO

    NASA Astrophysics Data System (ADS)

    Masood, Mudassir; Afify, Laila H.; Al-Naffouri, Tareq Y.

    2015-01-01

    This paper addresses the problem of estimating sparse channels in massive MIMO-OFDM systems. Most wireless channels are sparse in nature with large delay spread. In addition, these channels as observed by multiple antennas in a neighborhood have approximately common support. The sparsity and common support properties are attractive when it comes to the efficient estimation of large number of channels in massive MIMO systems. Moreover, to avoid pilot contamination and to achieve better spectral efficiency, it is important to use a small number of pilots. We present a novel channel estimation approach which utilizes the sparsity and common support properties to estimate sparse channels and require a small number of pilots. Two algorithms based on this approach have been developed which perform Bayesian estimates of sparse channels even when the prior is non-Gaussian or unknown. Neighboring antennas share among each other their beliefs about the locations of active channel taps to perform estimation. The coordinated approach improves channel estimates and also reduces the required number of pilots. Further improvement is achieved by the data-aided version of the algorithm. Extensive simulation results are provided to demonstrate the performance of the proposed algorithms.

  4. Channel Equalization for Single Carrier MIMO Underwater Acoustic Communications

    NASA Astrophysics Data System (ADS)

    Tao, Jun; Zheng, Yahong Rosa; Xiao, Chengshan; Yang, T. C.; Yang, Wen-Bin

    2010-12-01

    Multiple-input multiple-output (MIMO) underwater acoustic (UWA) channels introduce both space-time interference (STI) and time-varying phase distortion for transmitted signals. In such cases, the equalized symbols produced by conventional equalizer aiming for STI cancelation suffer phase rotation and thus cannot be reliably detected. In this paper, we propose a new equalization scheme for high data rate single carrier MIMO UWA channels. Different from existing methods employing joint equalization and symbolwise phase tracking technology, the proposed scheme decouples the interference cancelation (IC) operation and the phase compensation operation, leading to a generalized equalizer structure combining an IC equalizer with a phase compensator. The decoupling of the two functionalities leads to robust signal detection, which is most desirable in practical UWA applications. MIMO linear equalizer (LE) is adopted to remove space-time interference, and a groupwise phase estimation and correction method is used to compensate the phase rotation. In addition, the layered space-time processing technology is adopted to enhance the equalization performance. The proposed equalization scheme is tested to be very robust with extensive experimental data collected at Kauai, Hawaii, in September 2005, and Saint Margaret's Bay, Nova Scotia, Canada, in May 2006.

  5. MIMO Channel Matrix Condition Number Estimation and Threshold Selection for Combined K-Best Sphere Decoders

    NASA Astrophysics Data System (ADS)

    Roger, Sandra; Gonzalez, Alberto; Almenar, Vicenc; Vidal, Antonio M.

    It is known that MIMO channel matrix condition number influences detectors performance. Several authors have proposed combined decoders, mainly suboptimal, to cope with this fact. These combined algorithms require an estimation of the MIMO channel matrix condition number and a selection of a suitable threshold condition number. This letter presents practical algorithms to carry out the referred tasks and shows their performance in practice.

  6. Spatially Common Sparsity Based Adaptive Channel Estimation and Feedback for FDD Massive MIMO

    NASA Astrophysics Data System (ADS)

    Gao, Zhen; Dai, Linglong; Wang, Zhaocheng; Chen, Sheng

    2015-12-01

    This paper proposes a spatially common sparsity based adaptive channel estimation and feedback scheme for frequency division duplex based massive multi-input multi-output (MIMO) systems, which adapts training overhead and pilot design to reliably estimate and feed back the downlink channel state information (CSI) with significantly reduced overhead. Specifically, a non-orthogonal downlink pilot design is first proposed, which is very different from standard orthogonal pilots. By exploiting the spatially common sparsity of massive MIMO channels, a compressive sensing (CS) based adaptive CSI acquisition scheme is proposed, where the consumed time slot overhead only adaptively depends on the sparsity level of the channels. Additionally, a distributed sparsity adaptive matching pursuit algorithm is proposed to jointly estimate the channels of multiple subcarriers. Furthermore, by exploiting the temporal channel correlation, a closed-loop channel tracking scheme is provided, which adaptively designs the non-orthogonal pilot according to the previous channel estimation to achieve an enhanced CSI acquisition. Finally, we generalize the results of the multiple-measurement-vectors case in CS and derive the Cramer-Rao lower bound of the proposed scheme, which enlightens us to design the non-orthogonal pilot signals for the improved performance. Simulation results demonstrate that the proposed scheme outperforms its counterparts, and it is capable of approaching the performance bound.

  7. Inter-aperture correlation in MIMO free space optical systems

    NASA Astrophysics Data System (ADS)

    Özbilgin, Tuğba; Koca, Mutlu

    2015-10-01

    We present a unified framework for determining the inter-aperture separations in multiple-input-multiple-output (MIMO) free space optical (FSO) systems such that the transmitter-receiver paths are resolvable. The analysis framework is also useful in determining the amount of spatial correlation for a given set of system configuration parameters and aperture separations. It is applicable to both point apertures and also apertures with larger diameters and can be used at both transmit and receive arrays. We show that the results obtained via theoretical derivations are in good agreement with those in the literature obtained via measurements or simulations. The theoretical calculations reveal that even under strong turbulence conditions and very long link distances, aperture separations at the order of a few tens of centimeters are sufficient to have resolvable paths with independent fading gains. Furthermore, the channel correlations increase relatively slowly with decreasing inter-aperture separations which are below these values. We also provide design guidelines to obtain resolvable paths for several commonly used system configurations.

  8. Bidirectional MIMO Channel Tracking Based on PASTd and Performance Evaluation

    NASA Astrophysics Data System (ADS)

    Ehrenberg, Livnat; Gannot (Eurasipmember), Sharon; Shayevitz, Ofer; Leshem, Amir; Zehavi, Ephraim

    2010-12-01

    We consider a bidirectional time division duplex (TDD) multiple-input multiple-output (MIMO) communication system with time-varying channel and additive white Gaussian noise (AWGN). A blind bidirectional channel tracking algorithm, based on the projection approximation subspace tracking (PAST) algorithm, is applied in both terminals. The resulting singular value decomposition (SVD) of the channel matrix is then used to approximately diagonalize the channel. The proposed method is applied to an orthogonal frequency-division multiplexing-(OFDM-)MIMO setting with a typical indoor time-domain reflection model. The computational cost of the proposed algorithm, compared with other state-of-the-art algorithms, is relatively small. The Kalman filter is utilized for establishing a benchmark for the obtained performance of the proposed tracking algorithm. The performance degradation relative to a full channel state information (CSI) due to the application of the tracking algorithm is evaluated in terms of average effective rate and the outage probability and compared with alternative tracking algorithms. The obtained results are also compared with a benchmark obtained by the Kalman filter with known input signal and channel characteristics. It is shown that the expected degradation in performance of frequency-domain algorithms (which do not exploit the smooth frequency response of the channel) is only minor compared with time-domain algorithms in a range of reasonable signal-to-noise ratio (SNR) levels. The proposed bidirectional frequency-domain tracking algorithm, proposed in this paper, is shown to attain communication rates close to the benchmark and to outperform a competing algorithm. The paper is concluded by evaluating the proposed blind tracking method in terms of the outage probability and the symbol error rate (SER) versus. SNR for binary phase shift keying (BPSK) and 4-Quadrature amplitude modulation (QAM) constellations.

  9. Channel Estimation Using Cyclic Delay Pilot for SC-MIMO Multiplexing

    NASA Astrophysics Data System (ADS)

    Fujimori, Takafumi; Takeda, Kazuki; Ozaki, Kazuyuki; Nakajima, Akinori; Adachi, Fumiyuki

    In the next generation mobile communication systems, multiple-input multiple-output (MIMO) multiplexing is an indispensable technique to achieve very high-speed data transmission with a limited bandwidth. In MIMO multiplexing, it is necessary to estimate the channels between transmit and receive antennas for signal detection. In this paper, we propose a minimum mean square error (MMSE) channel estimation using cyclic delay pilot for single-carrier (SC)-MIMO multiplexing. In the proposed channel estimation, the same pilot block is altered through the addition of different cyclic delays and transmitted from different antennas at the same time for simultaneous estimation of all channels between transmit and receive antennas. We evaluate by computer simulation the bit error rate (BER) performance of MIMO multiplexing using the proposed channel estimation and compare it to those using time-multiplexed pilot based channel estimation (TMP-CE) and code-multiplexed pilot based channel estimation (CMP-CE).

  10. Precise SER Analysis and Performance Results of OSTBC MIMO-OFDM Systems over Uncorrelated Nakagami-m Fading Channels

    NASA Astrophysics Data System (ADS)

    Ahmad Ansari, Ejaz; Rajatheva, Nandana

    Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) over different fading channels is well investigated, its closed form symbol error rate (SER) expressions and performance results employing orthogonal space time block codes (OSTBCs) over uncorrelated frequency-selective Nakagami-m fading channels are still not available. The closed form expressions are extremely useful for evaluating system's performance without carrying out time consuming simulations. Similarly, the performance results are also quite beneficial for determining the system's performance in the sense that many practical wireless standards extensively employ MIMO-OFDM systems in conjunction with M-ary quadrature amplitude modulation (M-QAM) constellation. This paper thus, derives exact closed form expressions for the SER of M-ary Gray-coded one and two dimensional constellations when an OSTBC is employed and Nt transmit antennas are selected for transmission over frequency-selective Nakagami-m fading channels. For this purpose, first an exact closed-form of average SER expression of OSTBC based MIMO-OFDM system for M-ary phase shift keying (M-PSK) using traditional probability density function (PDF) approach is derived. We then compute exact closed form average SER expressions for M-ary pulse amplitude modulation (M-PAM) and M-QAM schemes by utilizing this generalized result. These expressions are valid over both frequency-flat and frequency-selective Nakagami-m fading MIMO channels and can easily be evaluated without using any numerical integration methods. We also show that average SER of MIMO-OFDM system using OSTBC in case of frequency-selective Rayleigh fading channels remains independent to the number of taps, L of that fading channel and the performance of the same system for two-tap un-correlated Rayleigh and Nakagami-m fading channels is better than that of the correlated one. Moreover, Monte Carlo simulation of MIMO-OFDM system

  11. A CORDIC based FFT processor for MIMO channel emulator

    NASA Astrophysics Data System (ADS)

    Xiong, Yanwei; Zhang, Jianhua; Zhang, Ping

    2013-03-01

    With the advent of Multi Input Multi Output (MIMO) systems, the system performance is highly dependent on the accurate representation of the channel condition that causes the wireless channel emulation to become increasingly important. The conventional Finite Impulse Response (FIR) based emulator has a high real-time but the complexity rapidly becomes impractical for larger array sizes. However, the frequency domain approach can avoid this problem and reduce the complexity for higher order arrays. The complexity comparison between in time domain and in frequency domain is made in this paper. The Fast Fourier Transform (FFT) as an important component of signal processing in frequency domain is briefly introduced and an FGPA system architecture based on CORDIC algorithm is proposed. The full design is implemented in Xilinx's Virtex-5.

  12. Joint Linear Processing for an Amplify-and-Forward MIMO Relay Channel with Imperfect Channel State Information

    NASA Astrophysics Data System (ADS)

    Chalise, Batu K.; Vandendorpe, Luc

    2010-12-01

    The problem of jointly optimizing the source precoder, relay transceiver, and destination equalizer has been considered in this paper for a multiple-input-multiple-output (MIMO) amplify-and-forward (AF) relay channel, where the channel estimates of all links are assumed to be imperfect. The considered joint optimization problem is nonconvex and does not offer closed-form solutions. However, it has been shown that the optimization of one variable when others are fixed is a convex optimization problem which can be efficiently solved using interior-point algorithms. In this context, an iterative technique with the guaranteed convergence has been proposed for the AF MIMO relay channel that includes the direct link. It has been also shown that, for the double-hop relay case without the receive-side antenna correlations in each hop, the global optimality can be confirmed since the structures of the source precoder, relay transceiver, and destination equalizer have closed forms and the remaining joint power allocation can be solved using Geometric Programming (GP) technique under high signal-to-noise ratio (SNR) approximation. In the latter case, the performance of the iterative technique and the GP method has been compared with simulations to ensure that the iterative approach gives reasonably good solutions with an acceptable complexity. Moreover, simulation results verify the robustness of the proposed design when compared to the nonrobust design that assumes estimated channels as actual channels.

  13. Studies on an Iterative Frequency Domain Channel Estimation Technique for MIMO-UWB Communications

    NASA Astrophysics Data System (ADS)

    Takanashi, Masaki; Ogawa, Yasutaka; Nishimura, Toshihiko; Ohgane, Takeo

    MIMO (Multiple-Input Multiple-Output) technologies have attracted much interest for high-rate and high-capacity wireless communications. MIMO technologies under frequency-selective fading environments (wideband MIMO technologies) have also been studied. A wideband MIMO system is affected by ISI (Inter Symbol Interference) and CCI (Co-Channel Interference). Hence, we need a MIMO signal detection technique that simultaneously suppresses ISI and CCI. The OFDM system and SC-FDE (Single Carrier-Frequency Domain Equalization) techniques are often used for suppressing ISI. By employing these techniques with the ZF (Zero Forcing) or the MMSE (Minimum Mean Square Error) spatial filtering technique, we can cancel both ISI and CCI. To use ZF or MMSE, we need channel state information for calculating the receive weights. Although an LS (Least Square) channel estimation technique has been proposed for MIMO-OFDM systems, it needs a large estimation matrix at the receiver side to obtain sufficient estimation performance in heavy multipath environments. However, the use of a large matrix increases computational complexity and the circuit size. We use frequency domain channel estimation to solve these problems and propose an iterative method for achieving better estimation performance. In this paper, we assume the use of a MIMO-UWB system that employs a UWB-IR (Ultra-Wideband Impulse Radio) scheme with the FDE technique as the wideband wireless transmission scheme for heavy multipath environments, and we evaluate the iterative frequency domain channel estimation through computer simulations and computational complexity calculations.

  14. Space-Time Power Schedule for Distributed MIMO Links Without Instantaneous Channel State Information at the Transmitting Nodes

    DTIC Science & Technology

    2008-02-01

    multiple distributed multiple - input multiple - output ( MIMO ) links without the knowledge of the instantaneous channel state information (CSI...Swindlehurst, Fellow, IEEE Abstract—A space–time optimal power schedule for multiple distributed multiple - input multiple - output ( MIMO ) links without the...and the optimality of different power scheduling approaches. Index Terms— Multiple - input multiple - output ( MIMO

  15. Performance analysis of MIMO-STBC systems with higher coding rate using adaptive semiblind channel estimation scheme.

    PubMed

    Kumar, Ravi; Saxena, Rajiv

    2014-01-01

    Semiblind channel estimation method provides the best trade-off in terms of bandwidth overhead, computational complexity and latency. The result after using multiple input multiple output (MIMO) systems shows higher data rate and longer transmit range without any requirement for additional bandwidth or transmit power. This paper presents the detailed analysis of diversity coding techniques using MIMO antenna systems. Different space time block codes (STBCs) schemes have been explored and analyzed with the proposed higher code rate. STBCs with higher code rates have been simulated for different modulation schemes using MATLAB environment and the simulated results have been compared in the semiblind environment which shows the improvement even in highly correlated antenna arrays and is found very close to the condition when channel state information (CSI) is known to the channel.

  16. Performance Analysis of MIMO-STBC Systems with Higher Coding Rate Using Adaptive Semiblind Channel Estimation Scheme

    PubMed Central

    Kumar, Ravi

    2014-01-01

    Semiblind channel estimation method provides the best trade-off in terms of bandwidth overhead, computational complexity and latency. The result after using multiple input multiple output (MIMO) systems shows higher data rate and longer transmit range without any requirement for additional bandwidth or transmit power. This paper presents the detailed analysis of diversity coding techniques using MIMO antenna systems. Different space time block codes (STBCs) schemes have been explored and analyzed with the proposed higher code rate. STBCs with higher code rates have been simulated for different modulation schemes using MATLAB environment and the simulated results have been compared in the semiblind environment which shows the improvement even in highly correlated antenna arrays and is found very close to the condition when channel state information (CSI) is known to the channel. PMID:24688379

  17. Improving MIMO-OFDM decision-directed channel estimation by utilizing error-correcting codes

    NASA Astrophysics Data System (ADS)

    Beinschob, P.; Lieberei, M.; Zölzer, U.

    2009-05-01

    In this paper a decision-directed Multiple-Input Multiple-Output (MIMO) channel tracking algorithm is enhanced to raise the channel estimate accuracy. While DDCE is prone to error propagation the enhancement employs channel decoding in the tracking process. Therefore, a quantized block of symbols is checked on consistency via the channel decoder, possibly corrected and then used. This yields a more robust tracking of the channel in terms of bit error rate and improves the channel estimate under certain conditions. Equalization is performed to prove the feasibility of the obtained channel estimate. Therefore a combined signal consisting of data and pilot symbols is sent. Adaptive filters are applied to exploit correlations in time, frequency and spatial domain. By using good error-correcting coding schemes like Turbo Codes or Low Density Parity Check (LDPC) codes, adequate channel estimates can be acquired even at low signal to noise ratios (SNR). The proposed algorithm among two others is applied for channel estimation and equalization and results are compared.

  18. Influence of the level of description of the indoor environment on the characteristic parameters of a MIMO channel

    NASA Astrophysics Data System (ADS)

    Pereira, Carlos; Chartois, Yannick; Pousset, Yannis; Vauzelle, Rodolphe

    2006-09-01

    Modelling of the environment is an important factor in electromagnetic wave propagation simulation, performed by a 3D ray-tracing method. The aim of this work is to study the effect of indoor environment modelling accuracy on MIMO (Multiple Input Multiple Output) channel characterisation. The first of the two environments investigated is the hall of our building, while the second one is a more confined environment and represents the floor of our laboratory. For these two indoor environments, three description levels are proposed in order to establish geometrical and electrical modelling impact on MIMO channel characterisation. Results are obtained by analysing the capacity and variation in correlation in relation to the polarisation, the presence of LOS (Line of sight) or NLOS configurations, the spacing between antennae and the number of transmitter and receiver antennae. To cite this article: C. Pereira et al., C. R. Physique 7 (2006).

  19. Channel estimation based on quantized MMP for FDD massive MIMO downlink

    NASA Astrophysics Data System (ADS)

    Guo, Yao-ting; Wang, Bing-he; Qu, Yi; Cai, Hua-jie

    2016-10-01

    In this paper, we consider channel estimation for Massive MIMO systems operating in frequency division duplexing mode. By exploiting the sparsity of propagation paths in Massive MIMO channel, we develop a compressed sensing(CS) based channel estimator which can reduce the pilot overhead. As compared with the conventional least squares (LS) and linear minimum mean square error(LMMSE) estimation, the proposed algorithm is based on the quantized multipath matching pursuit - MMP - reduced the pilot overhead and performs better than other CS algorithms. The simulation results demonstrate the advantage of the proposed algorithm over various existing methods including the LS, LMMSE, CoSaMP and conventional MMP estimators.

  20. Modeling of multi-channel MIMO-VLC systems in the indoor environment

    NASA Astrophysics Data System (ADS)

    Kowalczyk, Marcin

    2016-09-01

    The article presents a concept of simultaneous using multiple channels for data transmission (an approach MIMO- multiple input multiple output) in the visible light communication systems (VLC), which are considered here as their implementation inside buildings, in the aspect of their numerical modeling. There was presented both a mathematical description (a model) of such systems as well as obtained on this basis results in relation to the instances of MIMO-VLC system with two and four channels, respectively. The so-called non-imaging detectors were used at the receiver side . Obtained results allowed to gain a few valuable conclusions that were included in the last section of article.

  1. Joint Channel and Phase Noise Estimation in MIMO-OFDM Systems

    NASA Astrophysics Data System (ADS)

    Ngebani, I. M.; Chuma, J. M.; Zibani, I.; Matlotse, E.; Tsamaase, K.

    2017-05-01

    The combination of multiple-input multiple-output (MIMO) techniques with orthogonal frequency division multiplexing (OFDM), MIMO-OFDM, is a promising way of achieving high spectral efficiency in wireless communication systems. However, the performance of MIMO-ODFM systems is highly degraded by radio frequency (RF) impairments such as phase noise. Similar to the single-input single-output (SISO) case, phase noise in MIMO-OFDM systems results in a common phase error (CPE) and inter carrier interference (ICI). In this paper the problem of joint channel and phase noise estimation in a system with multiple transmit and receive antennas where each antenna is equipped with its own independent oscillator is tackled. The technique employed makes use of a novel placement of pilot carriers in the preamble and data portion of the MIMO-OFDM frame. Numerical results using a 16 and 64 quadrature amplitude modulation QAM schemes are provided to illustrate the effectiveness of the proposed scheme for MIMO-OFDM systems.

  2. Design and evaluation of an IDM-based MIMO FSO system over Gamma-Gamma turbulence channels

    NASA Astrophysics Data System (ADS)

    Zhang, Chenglei; Zhou, Xiaolin; Zheng, Xiaowei; Du, Jianhong

    2011-12-01

    In this paper, we design an interleave-division-multiplexing (IDM) based multiple-input multiple-output (MIMO) free-space optics (FSO) communication system. The system overcomes problems harassing conventional optical MIMO systems such as restrictions of antenna number and high complexity in receiver. An iterative on-off keying (OOK) modulated IDM MIMO detection algorithm is developed. Expression of an upper bound of frame-error-rate (FER) is derived. In addition, we evaluate the BER performance of the proposed optical MIMO scheme in various FSO scenarios. Simulations confirm that the proposed scheme can effectively increase the feasibility of FSO communications over Gamma-Gamma turbulence-induced fading channels.

  3. Statistical Space-Time-Frequency Characterization of MIMO Shallow Water Acoustic Channels

    DTIC Science & Technology

    2010-06-01

    multiple - input multiple - output ( MIMO ) SWA communication systems. By taking into account...20375 USA Abstract—This paper proposes a geometry-based statistical model for multiple - input multiple - output shallow water acous- tic multipath fading...statistical model for multiple - input multiple - output shallow water acoustic multipath fading channels. From the reference model, the corresponding

  4. Performance evaluation and channel modeling of MIMO free space optical communication system

    NASA Astrophysics Data System (ADS)

    Deng, Tianping; Lu, Yimin; Lu, Gang; Peng, Kai

    2005-11-01

    Free space optical communication systems represent one of the most promising approaches for addressing the emerging broadband access market, it can provide high bandwidth with no physical contact, but are hampered by signal fading effects due to particulate scattering caused by atmospheric turbulence. In this paper, we propose a new channel model of MIMO free space optical communication system. The physics meaning of this model is very clear, and its format is very simple. Mathematic results show that MIMO is a very effective way for intensity fluctuation reduction induced by turbulence, thus reduce the bit-error-rate of the system.

  5. A Chaos MIMO Transmission Scheme for Channel Coding and Physical-Layer Security

    NASA Astrophysics Data System (ADS)

    Okamoto, Eiji

    In recent wireless communication systems, security is ensured mainly in the upper-layer techniques such as a password or a cryptography processing. However, security needs not be restricted to the upper-layer and the addition of physical-layer security also would yield a much more robust system. Therefore, in this paper, we exploit chaos communication and propose a chaos multiple-input multiple-output (MIMO) transmission scheme which achieves physical-layer security and additional channel-coding gain. A chaotic modulation symbol is multiplied to the data to be transmitted at each MIMO antenna to exploit the MIMO antenna diversity, and at the receiver, the joint MIMO detection and chaos decoding is done by maximum likelihood decoding (MLD). The conventional chaos modulation suffers from bit error rate (BER) performance degradation, while the coding gain is obtained in the proposed scheme by the chaos modulation in MIMO. We evaluate the performances of the proposed scheme by an analysis and computer simulations.

  6. Measurement Based MIMO Channel Capacity in an Urban Canyon Environment at the 3.7GHz Band

    NASA Astrophysics Data System (ADS)

    Lim, Jae-Woo; Kwon, Se-Woong; Park, Youn-Hyun; Yoon, Hyun-Goo; Yook, Jong-Gwan; Yoon, Yong-Joong

    This paper describes the measurements made in an urban canyon environment of a relay network scenario to determine the capacity of the multiple-input-multiple-output (MIMO) channel. While varying antenna number and spacing, we measure the channel matrices in the 3.7GHz band using a 4×4 switching MIMO channel sounder. The results show that antenna spacing is shown to have less impact than signal-to-noise (SNR) on MIMO channel capacity in a line-of-sight (LOS) environment when physical antenna spacing is selected at four wavelengths. As a result, in an urban MIMO LOS scenario, a base station can provide sufficient data throughput to relay station because most links from base station to relay station have LOS environment and are free from restriction of antenna spacing.

  7. A Low-Complexity Transceiver Design in Sparse Multipath Massive MIMO Channels

    NASA Astrophysics Data System (ADS)

    Yu, Yuehua; Wang, Peng; Chen, He; Li, Yonghui; Vucetic, Branka

    2016-10-01

    In this letter, we develop a low-complexity transceiver design, referred to as semi-random beam pairing (SRBP), for sparse multipath massive MIMO channels. By exploring a sparse representation of the MIMO channel in the virtual angular domain, we generate a set of transmit-receive beam pairs in a semi-random way to support the simultaneous transmission of multiple data streams. These data streams can be easily separated at the receiver via a successive interference cancelation (SIC) technique, and the power allocation among them are optimized based on the classical waterfilling principle. The achieved degree of freedom (DoF) and capacity of the proposed approach are analyzed. Simulation results show that, compared to the conventional singular value decomposition (SVD)-based method, the proposed transceiver design can achieve near-optimal DoF and capacity with a significantly lower computational complexity.

  8. Maximizing Channel Capacity based on Antenna and MIMO Channel Characteristics and its Application to Multimedia Data Transmission

    NASA Astrophysics Data System (ADS)

    Pottkotter, Andrew

    Communication transmission between electronic devices is evolving at an ever faster pace. There are now more electronic handheld devices that we communicate with on a daily basis. The allotted bandwidth and speed for these devices are limited by hardware, software, handshaking capabilities between each electronic application. The demand for information at high data rates without the loss of reliability has evolved antenna technology and digital signal processing into more complex systems utilizing multiple processors and multiple antennas. This paper discusses the various techniques used to increase data speed, enhance channel capacity, and reliability of application specific devices with respect to the Multiple-Input-to-Multiple-Output (MIMO) based methods. MIMO based applications can improve the data speed, channel capacity, and reliability of the system with maximum limitations based on hardware, coding schemes, and handshaking abilities between devices.

  9. Analytical Derivation of 2×2 MIMO Channel Capacity in Terms of Multipath Angle Spread and Signal Strength

    NASA Astrophysics Data System (ADS)

    Yigit, Halil; Kavak, Adnan

    2012-03-01

    The capacity of multiple-input multiple-output (MIMO) wireless communication channels is affected by the multipath angle spread and relative multiple signal strength (RMSS) at both sides of the transmitter and the receiver. In this paper, we study analytically how these two factors emerge in the MIMO capacity equation when the channel state information (CSI) is unknown at the transmitter and perfectly known at the receiver. Mathematical expression for the channel capacity is carried out for 2×2 MIMO system and two propagation paths between the base station (BS) and the mobile terminal (MS) are considered. The proposed analytical model is verified through numerical results, which show that channel capacity increases with increasing angle spread. Also, as the relative strength of multipaths becomes larger, the better channel capacity is obtained.

  10. Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems-Part I: MIMO Case

    NASA Astrophysics Data System (ADS)

    Önen, Erol; Akan, Aydın; Chaparro, LuisF

    2010-12-01

    Multiple-input multiple-output (MIMO) systems hold the potential to drastically improve the spectral efficiency and link reliability in future wireless communications systems. A particularly promising candidate for next-generation fixed and mobile wireless systems is the combination of MIMO technology with Orthogonal Frequency Division Multiplexing (OFDM). OFDM has become the standard method because of its advantages over single carrier modulation schemes on multipath, frequency selective fading channels. Doppler frequency shifts are expected in fast-moving environments, causing the channel to vary in time, that degrades the performance of OFDM systems. In this paper, we present a time-varying channel modeling and estimation method based on the Discrete Evolutionary Transform to obtain a complete characterization of MIMO-OFDM channels. Performance of the proposed method is evaluated and compared on different levels of channel noise and Doppler frequency shifts.

  11. Efficiency of MIMO configuration and adaptive optics corrections in free space optical fading channels

    NASA Astrophysics Data System (ADS)

    Hajjarian, Zeinab; Kavehrad, Mohsen; Fadlullah, Jarir

    2010-01-01

    Free Space Optical (FSO) communications is the only practical candidate for realizing universal network coverage between ground and airborne nodes, satellites, and even moon and other nearby planets. When atmosphere (be it the earth or Mars) is a part of the optical channel, attributes of scattering and turbulence bring about amplitude attenuation, and scintillation, as well as beam wander and phase aberrations at the receiving aperture. Phase screens are usually used in order to simulate the atmospheric fading channel and phase fluctuations. In this paper, different methods of generating phase screens are compared based on their accuracy and computational complexity, as in most computer simulations, a large ensemble of phase screens are required for averaging purposes. To combat the focal plane intensity fading, caused by amplitude and phase variations in the received wave-front, it is possible to replace the Single Input-Single Output (SISO) communications system with its Multiple Input Multiple Output (MIMO) equivalent, which has the same total transmit power and receiving aperture area. Another alternative is to equip the receiver with a state of the art Adaptive Optics (AO) correction system. Using average Bit Error Rate (BER), as a performance metric, effectiveness of these two approaches are compared and it is shown that while a MIMO configuration outperforms a basic AO system capable of only tilt corrections, an ideal AO system, which is able to remove higher orders of Zernike modes can asymptotically perform as well as an equivalent MIMO configuration.

  12. Analysis of a Near Field MIMO Wireless Channel Using 5.6 GHz Dipole Antennas

    NASA Astrophysics Data System (ADS)

    Maricar, Mohamed Ismaeel; Gradoni, Gabriele; Greedy, Steve; Ivrlac, Michel T.; Nossek, Josef A.; Phang, Sendy; Creagh, Stephen C.; Tanner, Gregor; Thomas, David W. P.

    2016-05-01

    Understanding the impact of interference upon the performance of a multiple input multiple output (MIMO) based device is of paramount importance in ensuring a design is both resilient and robust. In this work the effect of element-element interference in the creation of multiple channels of a wireless link approaching the near-field regime is studied. The elements of the 2-antenna transmit- and receive-arrays are chosen to be identical folded dipole antennas operating at 5.6 GHz. We find that two equally strong channels can be created even if the antennas interact at sub-wavelength distances, thus confirming previous theoretical predictions.

  13. Achievable degrees of freedom of MIMO two-way relay interference channel with delayed CSIT

    NASA Astrophysics Data System (ADS)

    Li, Qingyun; Wu, Gang; Li, Shaoqian

    2016-10-01

    In this paper, assuming each node has delayed channel state information at the transmitter (CSIT), we investigate the achievable degrees of freedom (DOF) of MIMO two-way relay interference channel in frequency division duplex (FDD) systems, where there are K user pairs (i.e., 2K users) and each user in a user pair exchanges messages with the other user in the same user pair simultaneously via an intermediate relay. We propose a two-stage transmission scheme and derive the closed-form expressions for its achievable DOF.

  14. Performance Analysis of MIMO Schemes in Residential Home Environment via Wideband MIMO Propagation Measurement

    NASA Astrophysics Data System (ADS)

    Tran, Gia Khanh; Dao, Nguyen Dung; Sakaguchi, Kei; Araki, Kiyomichi; Iwai, Hiroshi; Sakata, Tsutomu; Ogawa, Koichi

    This paper illustrates a large-scale MIMO propagation channel measurement in a real life environment and evaluates throughput performance of various MIMO schemes in that environment. For that purpose, 4 × 4 MIMO transceivers and a novel spatial scanner are fabricated for wideband MIMO channel measurements in the 5GHz band. A total of more than 50, 000 spatial samples in an area of 150m2, which includes a bedroom, a Japanese room, a hallway, and the living and dining areas, are taken in a real residential home environment. Statistical properties of the propagation channel and throughput performance of various MIMO schemes are evaluated by using measured data. Propagation measurement results show large dynamic channel variations occurring in a real environment in which statistical properties of the channel, such as frequency correlation and spatial correlation are not stationary any more, and become functions of the SNR. Furthermore, evaluation of throughput shows that although MIMO schemes outperform the SISO system in most areas, open loop systems perform badly in the far areas with low SNR. Paying for the cost of CSI or partial CSI at Tx, closed loop and hybrid systems have superior performance compared to other schemes, especially in reasonable SNR areas ranging from 10dB to 30dB. Spatial correlation, which is common in Japanese wooden residences, is also found to be a dominant factor causing throughput degradation of the open loop MIMO schemes.

  15. Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

    NASA Astrophysics Data System (ADS)

    Wang, Huiqin; Wang, Xue; Cao, Minghua

    2017-02-01

    The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

  16. Power Scaling of Uplink Massive MIMO Systems With Arbitrary-Rank Channel Means

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Jin, Shi; Wong, Kai-Kit; Zhu, Hongbo; Matthaiou, Michail

    2014-10-01

    This paper investigates the uplink achievable rates of massive multiple-input multiple-output (MIMO) antenna systems in Ricean fading channels, using maximal-ratio combining (MRC) and zero-forcing (ZF) receivers, assuming perfect and imperfect channel state information (CSI). In contrast to previous relevant works, the fast fading MIMO channel matrix is assumed to have an arbitrary-rank deterministic component as well as a Rayleigh-distributed random component. We derive tractable expressions for the achievable uplink rate in the large-antenna limit, along with approximating results that hold for any finite number of antennas. Based on these analytical results, we obtain the scaling law that the users' transmit power should satisfy, while maintaining a desirable quality of service. In particular, it is found that regardless of the Ricean $K$-factor, in the case of perfect CSI, the approximations converge to the same constant value as the exact results, as the number of base station antennas, $M$, grows large, while the transmit power of each user can be scaled down proportionally to $1/M$. If CSI is estimated with uncertainty, the same result holds true but only when the Ricean $K$-factor is non-zero. Otherwise, if the channel experiences Rayleigh fading, we can only cut the transmit power of each user proportionally to $1/\\sqrt M$. In addition, we show that with an increasing Ricean $K$-factor, the uplink rates will converge to fixed values for both MRC and ZF receivers.

  17. Bayes-Optimal Joint Channel-and-Data Estimation for Massive MIMO With Low-Precision ADCs

    NASA Astrophysics Data System (ADS)

    Wen, Chao-Kai; Wang, Chang-Jen; Jin, Shi; Wong, Kai-Kit; Ting, Pangan

    2016-05-01

    This paper considers a multiple-input multiple-output (MIMO) receiver with very low-precision analog-to-digital convertors (ADCs) with the goal of developing massive MIMO antenna systems that require minimal cost and power. Previous studies demonstrated that the training duration should be {\\em relatively long} to obtain acceptable channel state information. To address this requirement, we adopt a joint channel-and-data (JCD) estimation method based on Bayes-optimal inference. This method yields minimal mean square errors with respect to the channels and payload data. We develop a Bayes-optimal JCD estimator using a recent technique based on approximate message passing. We then present an analytical framework to study the theoretical performance of the estimator in the large-system limit. Simulation results confirm our analytical results, which allow the efficient evaluation of the performance of quantized massive MIMO systems and provide insights into effective system design.

  18. Channel Equalization for Single Carrier MIMO Underwater Acoustic Communications

    DTIC Science & Technology

    2010-01-01

    packets. For each packet, the estimation was performed independently on each of the eight channels (hydrophones). Obviously, the Doppler shift is...www.eurasip.org). This year edition will take place in Barcelona, capital city of Catalonia (Spain), and will be jointly organized by the Centre Tecnològic de

  19. Rician MIMO Channel- and Jamming-Aware Decision Fusion

    NASA Astrophysics Data System (ADS)

    Ciuonzo, Domenico; Aubry, Augusto; Carotenuto, Vincenzo

    2017-08-01

    In this manuscript we study channel-aware decision fusion (DF) in a wireless sensor network (WSN) where: (i) the sensors transmit their decisions simultaneously for spectral efficiency purposes and the DF center (DFC) is equipped with multiple antennas; (ii) each sensor-DFC channel is described via a Rician model. As opposed to the existing literature, in order to account for stringent energy constraints in the WSN, only statistical channel information is assumed for the non-line-of sight (scattered) fading terms. For such a scenario, sub-optimal fusion rules are developed in order to deal with the exponential complexity of the likelihood ratio test (LRT) and impractical (complete) system knowledge. Furthermore, the considered model is extended to the case of (partially unknown) jamming-originated interference. Then the obtained fusion rules are modified with the use of composite hypothesis testing framework and generalized LRT. Coincidence and statistical equivalence among them are also investigated under some relevant simplified scenarios. Numerical results compare the proposed rules and highlight their jammingsuppression capability.

  20. An Application of Vector Coding with IBI Cancelling Demodulator and Code Elimination to Delay Spread MIMO Channels

    NASA Astrophysics Data System (ADS)

    Li, Zhao; Furukawa, Hiroshi

    Vector Coding (VC) is a novel vector modulation scheme that partitions a SISO (Single-Input Single-Output) channel into orthogonal subchannels by singular value decomposition (SVD). Because the orthogonal transmissions enabled by VC cannot cope with inter block interference (IBI) that is inevitable in delay spread channels, this paper proposes an IBI cancelling demodulator which can remove IBI by an iterative technique. We also show that code elimination in which insignificant eigencodes with lowermost eigenvalues are intentionally removed from transmission vectors greatly reduces BER (Bit Error Rate). The VC which utilizes the IBI cancelling demodulator and code elimination to reduce BER is compared with the original VC in not only delay spread SISO channels but also delay spread MIMO (Multi-Input Multi-Output) channels while emphasis is placed on the MIMO cases. Simulation results show that, under a predetermined BER, the enhanced MIMO-VC can improve effective transmission rate than the natural extension of VC to delay spread MIMO channels.

  1. Variable Is Better Than Invariable: Sparse VSS-NLMS Algorithms with Application to Adaptive MIMO Channel Estimation

    PubMed Central

    Gui, Guan; Chen, Zhang-xin; Xu, Li; Wan, Qun; Huang, Jiyan; Adachi, Fumiyuki

    2014-01-01

    Channel estimation problem is one of the key technical issues in sparse frequency-selective fading multiple-input multiple-output (MIMO) communication systems using orthogonal frequency division multiplexing (OFDM) scheme. To estimate sparse MIMO channels, sparse invariable step-size normalized least mean square (ISS-NLMS) algorithms were applied to adaptive sparse channel estimation (ACSE). It is well known that step-size is a critical parameter which controls three aspects: algorithm stability, estimation performance, and computational cost. However, traditional methods are vulnerable to cause estimation performance loss because ISS cannot balance the three aspects simultaneously. In this paper, we propose two stable sparse variable step-size NLMS (VSS-NLMS) algorithms to improve the accuracy of MIMO channel estimators. First, ASCE is formulated in MIMO-OFDM systems. Second, different sparse penalties are introduced to VSS-NLMS algorithm for ASCE. In addition, difference between sparse ISS-NLMS algorithms and sparse VSS-NLMS ones is explained and their lower bounds are also derived. At last, to verify the effectiveness of the proposed algorithms for ASCE, several selected simulation results are shown to prove that the proposed sparse VSS-NLMS algorithms can achieve better estimation performance than the conventional methods via mean square error (MSE) and bit error rate (BER) metrics. PMID:25089286

  2. Variable is better than invariable: sparse VSS-NLMS algorithms with application to adaptive MIMO channel estimation.

    PubMed

    Gui, Guan; Chen, Zhang-xin; Xu, Li; Wan, Qun; Huang, Jiyan; Adachi, Fumiyuki

    2014-01-01

    Channel estimation problem is one of the key technical issues in sparse frequency-selective fading multiple-input multiple-output (MIMO) communication systems using orthogonal frequency division multiplexing (OFDM) scheme. To estimate sparse MIMO channels, sparse invariable step-size normalized least mean square (ISS-NLMS) algorithms were applied to adaptive sparse channel estimation (ACSE). It is well known that step-size is a critical parameter which controls three aspects: algorithm stability, estimation performance, and computational cost. However, traditional methods are vulnerable to cause estimation performance loss because ISS cannot balance the three aspects simultaneously. In this paper, we propose two stable sparse variable step-size NLMS (VSS-NLMS) algorithms to improve the accuracy of MIMO channel estimators. First, ASCE is formulated in MIMO-OFDM systems. Second, different sparse penalties are introduced to VSS-NLMS algorithm for ASCE. In addition, difference between sparse ISS-NLMS algorithms and sparse VSS-NLMS ones is explained and their lower bounds are also derived. At last, to verify the effectiveness of the proposed algorithms for ASCE, several selected simulation results are shown to prove that the proposed sparse VSS-NLMS algorithms can achieve better estimation performance than the conventional methods via mean square error (MSE) and bit error rate (BER) metrics.

  3. Low-Complexity User Selection for Rate Maximization in MIMO Broadcast Channels with Downlink Beamforming

    PubMed Central

    Silva, Adão; Gameiro, Atílio

    2014-01-01

    We present in this work a low-complexity algorithm to solve the sum rate maximization problem in multiuser MIMO broadcast channels with downlink beamforming. Our approach decouples the user selection problem from the resource allocation problem and its main goal is to create a set of quasiorthogonal users. The proposed algorithm exploits physical metrics of the wireless channels that can be easily computed in such a way that a null space projection power can be approximated efficiently. Based on the derived metrics we present a mathematical model that describes the dynamics of the user selection process which renders the user selection problem into an integer linear program. Numerical results show that our approach is highly efficient to form groups of quasiorthogonal users when compared to previously proposed algorithms in the literature. Our user selection algorithm achieves a large portion of the optimum user selection sum rate (90%) for a moderate number of active users. PMID:24574928

  4. A Differential MIMO SC-FDE Transceiver Design over Multipath Fast Fading Channels

    NASA Astrophysics Data System (ADS)

    Deng, Juinn-Horng; Hwang, Jeng-Kuang

    In this paper, we propose a new differential MIMO single-carrier system with frequency-domain equalization (SC-FDE) aided by the insertion of cyclic prefix. This block transmission system not only inherits all the merits of the SISO SC-FDE system, but is also equipped with a differential space-time block coding (DSTBC) such as to combat the fast-changing frequency selective fading channels without the needs to estimate and then compensate the channel effects. Hence, for practical applications, it has the additional merits of decoding simplicity and robustness against high mobility transmission environments. Computer simulations show that the proposed system can provide diversity benefit as the non-differential system does, while greatly reducing the receiver complexity.

  5. Performance of MIMO E-SDM Systems Using Channel Prediction in Actual Time-Varying Indoor Fading Environments

    NASA Astrophysics Data System (ADS)

    Bui, Huu Phu; Nishimoto, Hiroshi; Nishimura, Toshihiko; Ohgane, Takeo; Ogawa, Yasutaka

    In time-varying fading environments, the performance of multiple-input multiple-output (MIMO) systems applying an eigenbeam-space division multiplexing (E-SDM) technique may be degraded due to a channel change during the time interval between the transmit weight matrix determination and the actual data transmission. To compensate for the channel change, we have proposed some channel prediction methods. Simulation results based on computer-generated channel data showed that better performance can be obtained when using the prediction methods in Rayleigh fading environments assuming the Jakes model with rich scatterers. However, actual MIMO systems may be used in line-of-sight (LOS) environments, and even in a non-LOS case, scatterers may not be uniformly distributed around a receiver and/or a transmitter. In addition, mutual coupling between antennas at both the transmitter and the receiver cannot be ignored as it affects the system performance in actual implementation. We conducted MIMO channel measurement campaigns at a 5.2GHz frequency band to evaluate the channel prediction techniques. In this paper, we present the experiment and simulation results using the measured channel data. The results show that robust bit-error rate performance is obtained when using the channel prediction methods and that the methods can be used in both Rayleigh and Rician fading environments, and do not need to know the maximum Doppler frequency.

  6. Approaching the MIMO Capacity with a Low-Rate Feedback Channel in V-BLAST

    NASA Astrophysics Data System (ADS)

    Chung, Seong Taek; Lozano, Angel; Huang, Howard C.; Sutivong, Arak; Cioffi, John M.

    2004-12-01

    This paper presents an extension of the vertical Bell Laboratories Layered Space-Time (V-BLAST) architecture in which the closed-loop multiple-input multiple-output (MIMO) capacity can be approached with conventional scalar coding, optimum successive decoding (OSD), and independent rate assignments for each transmit antenna. This theoretical framework is used as a basis for the proposed algorithms whereby rate and power information for each transmit antenna is acquired via a low-rate feedback channel. We propose the successive quantization with power control (SQPC) and successive rate and power quantization (SRPQ) algorithms. In SQPC, rate quantization is performed with continuous power control. This performs better than simply quantizing the rates without power control. A more practical implementation of SQPC is SRPQ, in which both rate and power levels are quantized. The performance loss due to power quantization is insignificant when 4-5 bits are used per antenna. Both SQPC and SRPQ show an average total rate close to the closed-loop MIMO capacity if a capacity-approaching scalar code is used per antenna.

  7. BER Analysis of Dual-Hop Amplify-and-Forward MIMO Relaying with Best Antenna Selection in Rayleigh Fading Channels

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Bin; Kim, Dongwoo

    Combining relaying and multi-input multi-output (MIMO) transmission is a generic way to overcome the channel-fading impairments. Best antenna selection is a simple but efficient MIMO method that achieves the full diversity and also serves as a lower bound reference of MIMO performance. For a dual-hop MIMO system with an ideal amplify-and-forward (AF) relaying gain and best antenna selection, we provide a probability density function (PDF) of received signal-to-noise ratio (SNR) and an analytic BER equation when using M-ary PSK in Rayleigh fading channels. The analytic result is shown to exactly match with simulated one. Furthermore, the effect of link unbalance between the first hop and the second hop, due to differences in the number of antennas deployed in both hops as well as in the average power of channel coefficients, on the BER performance is numerically investigated and the results show that the links with better balance give better performance.

  8. Experimental study on the statistic characteristics of a 3x3 RF MIMO channel over a single conventional multimode fiber.

    PubMed

    Lei, Yi; Li, Jianqiang; Wu, Rui; Fan, Yuting; Fu, Songnian; Yin, Feifei; Dai, Yitang; Xu, Kun

    2017-06-01

    Based on the observed random fluctuation phenomenon of speckle pattern across multimode fiber (MMF) facet and received optical power distribution across three output ports, we experimentally investigate the statistic characteristics of a 3×3 radio frequency multiple-input multiple-output (MIMO) channel enabled by mode division multiplexing in a conventional 50 µm MMF using non-mode-selective three-dimensional waveguide photonic lanterns as mode multiplexer and demultiplexer. The impacts of mode coupling on the MIMO channel coefficients, channel matrix, and channel capacity have been analyzed over different fiber lengths. The results indicate that spatial multiplexing benefits from the greater fiber length with stronger mode coupling, despite a higher optical loss.

  9. Topological Interference Management for K-User Downlink Massive MIMO Relay Network Channel

    PubMed Central

    Li, Jun; Lee, Moon Ho

    2017-01-01

    In this paper, we study the emergence of topological interference alignment and the characterizing features of a multi-user broadcast interference relay channel. We propose an alternative transmission strategy named the relay space-time interference alignment (R-STIA) technique, in which a K-user multiple-input-multiple-output (MIMO) interference channel has massive antennas at the transmitter and relay. Severe interference from unknown transmitters affects the downlink relay network channel and degrades the system performance. An additional (unintended) receiver is introduced in the proposed R-STIA technique to overcome the above problem, since it has the ability to decode the desired signals for the intended receiver by considering cooperation between the receivers. The additional receiver also helps in recovering and reconstructing the interference signals with limited channel state information at the relay (CSIR). The Alamouti space-time transmission technique and minimum mean square error (MMSE) linear precoder are also used in the proposed scheme to detect the presence of interference signals. Numerical results show that the proposed R-STIA technique achieves a better performance in terms of the bit error rate (BER) and sum-rate compared to the existing broadcast channel schemes. PMID:28817071

  10. Topological Interference Management for K-User Downlink Massive MIMO Relay Network Channel.

    PubMed

    Selvaprabhu, Poongundran; Chinnadurai, Sunil; Li, Jun; Lee, Moon Ho

    2017-08-17

    In this paper, we study the emergence of topological interference alignment and the characterizing features of a multi-user broadcast interference relay channel. We propose an alternative transmission strategy named the relay space-time interference alignment (R-STIA) technique, in which a K -user multiple-input-multiple-output (MIMO) interference channel has massive antennas at the transmitter and relay. Severe interference from unknown transmitters affects the downlink relay network channel and degrades the system performance. An additional (unintended) receiver is introduced in the proposed R-STIA technique to overcome the above problem, since it has the ability to decode the desired signals for the intended receiver by considering cooperation between the receivers. The additional receiver also helps in recovering and reconstructing the interference signals with limited channel state information at the relay (CSIR). The Alamouti space-time transmission technique and minimum mean square error (MMSE) linear precoder are also used in the proposed scheme to detect the presence of interference signals. Numerical results show that the proposed R-STIA technique achieves a better performance in terms of the bit error rate (BER) and sum-rate compared to the existing broadcast channel schemes.

  11. Channel Estimation and Performance Analysis of One-Bit Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Li, Yongzhi; Tao, Cheng; Seco-Granados, Gonzalo; Mezghani, Amine; Swindlehurst, A. Lee; Liu, Liu

    2017-08-01

    This paper considers channel estimation and system performance for the uplink of a single-cell massive multiple-input multiple-output (MIMO) system. Each receive antenna of the base station (BS) is assumed to be equipped with a pair of one-bit analog-to-digital converters (ADCs) to quantize the real and imaginary part of the received signal. We first propose an approach for channel estimation that is applicable for both flat and frequency-selective fading, based on the Bussgang decomposition that reformulates the nonlinear quantizer as a linear functionwith identical first- and second-order statistics. The resulting channel estimator outperforms previously proposed approaches across all SNRs. We then derive closed-form expressions for the achievable rate in flat fading channels assuming low SNR and a large number of users for the maximal ratio and zero forcing receivers that takes channel estimation error due to both noise and one-bit quantization into account. The closed-form expressions in turn allow us to obtain insight into important system design issues such as optimal resource allocation, maximal sum spectral efficiency, overall energy efficiency, and number of antennas. Numerical results are presented to verify our analytical results and demonstrate the benefit of optimizing system performance accordingly.

  12. Multiuser MIMO Systems

    DTIC Science & Technology

    2004-03-16

    Multiuser MIMO Systems H. Vincent Poor Princeton University phone: 609-258-1816 email: poor@prnceton.udu Abstract Communication systems with multiple ...This talk will discuss implications of using MIMO systems in multiple -access networks. The main focus of the talk will be on receiver signal processing... MIMO Systm Space-time Coded Systems Space-time Coded Systems - Single-user Channels: " Encoding of symbols across multiple transmit antennas. "* ST

  13. Three-dimensional model of hydro acoustic channel for research MIMO systems

    NASA Astrophysics Data System (ADS)

    Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.

    2017-05-01

    Currently, wireless hydroacoustic modems are actively being developed, which are used to provide efficient data transmission in the hydroacoustic channel. Such kind of developments are relevant for today, as they are used in various fields of science and fields of activity. An example is the connection with underwater vehicles for scientific, research, search and rescue purposes. Development of this kind of communication systems (modems) is a difficult task, as signal propagation is affected by various factors. As a result, the transfer characteristic changes with time, thereby imposing restrictions on the acoustic communication channel. In this regard, the researchers began the task of further study sonar environment and get a detailed mathematical description of the underwater channel. For this, a huge number of field tests were conducted, aimed at studying the underwater acoustic environment. However, the results of the research are always limited by the conditions in which the test took place. Therefore, it is not always possible to apply these results to the required conditions. All of the above features do not allow you to create some kind of a commonly accepted model for the acoustic channel, as studies based on experiments, collected in localized environments without generalizations. This paper presents, the three-dimensional model of the sonar channel for MIMO systems in the coastal zone, based on the acoustic signal propagation characteristics in the presence of multiple paths, the influence of the Doppler effect (as a result of mobile and / or base station traffic), in terms of signal attenuation, receiver characteristics influence and Transmitting antenna, etc.

  14. MIMO free-space optical communication employing coherent BPOLSK modulation in atmospheric optical turbulence channel with pointing errors

    NASA Astrophysics Data System (ADS)

    Prabu, K.; Kumar, D. Sriram

    2015-05-01

    An optical wireless communication system is an alternative to radio frequency communication, but atmospheric turbulence induced fading and misalignment fading are the main impairments affecting an optical signal when propagating through the turbulence channel. The resultant of misalignment fading is the pointing errors, it degrades the bit error rate (BER) performance of the free space optics (FSO) system. In this paper, we study the BER performance of the multiple-input multiple-output (MIMO) FSO system employing coherent binary polarization shift keying (BPOLSK) in gamma-gamma (G-G) channel with pointing errors. The BER performance of the BPOLSK based MIMO FSO system is compared with the single-input single-output (SISO) system. Also, the average BER performance of the systems is analyzed and compared with and without pointing errors. A novel closed form expressions of BER are derived for MIMO FSO system with maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques. The analytical results show that the pointing errors can severely degrade the performance of the system.

  15. Outage performance of MIMO FSO links over strong turbulence and misalignment fading channels.

    PubMed

    García-Zambrana, Antonio; Castillo-Vázquez, Carmen; Castillo-Vázquez, Beatriz

    2011-07-04

    Atmospheric turbulence produces fluctuations in the irradiance of the transmitted optical beam, which is known as atmospheric scintillation, severely degrading the performance over free-space optical (FSO) links. Additionally, since FSO systems are usually installed on high buildings, building sway causes vibrations in the transmitted beam, leading to an unsuitable alignment between transmitter and receiver and, hence, a greater deterioration in performance. In this paper, the outage probability as a performance measure for multiple-input/multiple-output (MIMO) FSO communication systems with intensity modulation and direct detection (IM/DD) over strong atmospheric turbulence channels with pointing errors is analyzed. Novel closed-form expressions for the outage probability as well as their corresponding asymptotic expressions are presented when the irradiance of the transmitted optical beam is susceptible to either strong turbulence conditions, following a negative exponential distribution, and pointing error effects, following a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. Obtained results show that the diversity order is independent of the pointing error when the equivalent beam radius at the receiver is at least twice the value of the pointing error displacement standard deviation at the receiver. Simulation results are further demonstrated to confirm the analytical results. Additionally, since proper FSO transmission requires transmitters with accurate control of their beamwidth, asymptotic expressions here obtained for different diversity techniques are used to find the optimum beamwidth that minimizes the outage performance.

  16. On the Degrees of Freedom of Interference Alignment for Multicell MIMO Interfering Broadcast Channels

    PubMed Central

    2014-01-01

    The interference alignment (IA) is a promising technique to efficiently mitigate interference and to enhance capacity of a wireless network. This paper proposes an interference alignment scheme for a cellular network with L cells and K users under a multiple-input multiple-output (MIMO) Gaussian interfering broadcast channel (IFBC) scenario. The proposed IA scheme aligns intercell interferences (ICI) into a small dimensional subspace through a cooperative receive beamforming and cancels both the ICI and interuser interferences (IUI) simultaneously through a transmit beamforming. We characterize the feasibility condition for the proposed IA to achieve a total number of degrees of freedom (DoF) of LK in terms of the numbers of transmit antennas and receive antennas. Then we derive the maximum number of DoF achieved by the proposed IA by finding an optimal dimension of ICI alignment subspace for a given antenna configuration. The numerical results show that the proposed IA scheme has a better DoF performance than the conventional schemes. PMID:24683362

  17. On the degrees of freedom of interference alignment for multicell MIMO interfering broadcast channels.

    PubMed

    Choi, Hyun-Ho

    2014-01-01

    The interference alignment (IA) is a promising technique to efficiently mitigate interference and to enhance capacity of a wireless network. This paper proposes an interference alignment scheme for a cellular network with L cells and K users under a multiple-input multiple-output (MIMO) Gaussian interfering broadcast channel (IFBC) scenario. The proposed IA scheme aligns intercell interferences (ICI) into a small dimensional subspace through a cooperative receive beamforming and cancels both the ICI and interuser interferences (IUI) simultaneously through a transmit beamforming. We characterize the feasibility condition for the proposed IA to achieve a total number of degrees of freedom (DoF) of LK in terms of the numbers of transmit antennas and receive antennas. Then we derive the maximum number of DoF achieved by the proposed IA by finding an optimal dimension of ICI alignment subspace for a given antenna configuration. The numerical results show that the proposed IA scheme has a better DoF performance than the conventional schemes.

  18. MIMO to LS-MIMO: A road to realization of 5G

    NASA Astrophysics Data System (ADS)

    Koppati, Naveena; Pavani, K.; Sharma, Dinesh; Sharma, Purnima K.

    2017-07-01

    MIMO means multiple inputs multiple outputs. As it refers MIMO is a RF technology used in many new technologies these days to increase link capacity and spectral efficiency. MIMO is used in Wi-Fi, LTE, 4G, 5G and other wireless technologies. This paper describes the earlier history of MIMO-OFDM and the antenna beam forming development in MIMO and types of MIMO. Also this treatise describes several decoding algorithms. The MIMO combined with OFDM increases the channel capacity. But the main problem is in estimating the transmitted signal from the received signal. So the channel knowledge is to be known in estimating the channel capacity. The advancement in MIMO-OFDM is Massive MIMO which is beneficial in providing additional data capacity in the increased traffic environment is described. In this memoir various application scenarios of LS-MIMO which increases the capacity are discussed.

  19. Plane-Wave and Vector-Rotation Approximation Technique for Reducing Computational Complexity to Simulate MIMO Propagation Channel Using Ray-Tracing

    NASA Astrophysics Data System (ADS)

    Yamada, Wataru; Kita, Naoki; Sugiyama, Takatoshi; Nojima, Toshio

    This paper proposes new techniques to simulate a MIMO propagation channel using the ray-tracing method for the purpose of decreasing the computational complexity. These techniques simulate a MIMO propagation channel by substituting the propagation path between a particular combination of transmitter and receiver antennas for all combinations of transmitter and receiver antennas. The estimation accuracy calculated using the proposed techniques is evaluated based on comparison to the results calculated using imaging algorithms. The results show that the proposed techniques simulate a MIMO propagation channel with low computational complexity, and a high level of estimation accuracy is achieved using the proposed Vector-Rotation Approximation technique compared to that for the imaging algorithm.

  20. Low complexity interference alignment algorithms for desired signal power maximization problem of MIMO channels

    NASA Astrophysics Data System (ADS)

    Sun, Cong; Yang, Yunchuan; Yuan, Yaxiang

    2012-12-01

    In this article, we investigate the interference alignment (IA) solution for a K-user MIMO interference channel. Proper users' precoders and decoders are designed through a desired signal power maximization model with IA conditions as constraints, which forms a complex matrix optimization problem. We propose two low complexity algorithms, both of which apply the Courant penalty function technique to combine the leakage interference and the desired signal power together as the new objective function. The first proposed algorithm is the modified alternating minimization algorithm (MAMA), where each subproblem has closed-form solution with an eigenvalue decomposition. To further reduce algorithm complexity, we propose a hybrid algorithm which consists of two parts. As the first part, the algorithm iterates with Householder transformation to preserve the orthogonality of precoders and decoders. In each iteration, the matrix optimization problem is considered in a sequence of 2D subspaces, which leads to one dimensional optimization subproblems. From any initial point, this algorithm obtains precoders and decoders with low leakage interference in short time. In the second part, to exploit the advantage of MAMA, it continues to iterate to perfectly align the interference from the output point of the first part. Analysis shows that in one iteration generally both proposed two algorithms have lower computational complexity than the existed maximum signal power (MSP) algorithm, and the hybrid algorithm enjoys lower complexity than MAMA. Simulations reveal that both proposed algorithms achieve similar performances as the MSP algorithm with less executing time, and show better performances than the existed alternating minimization algorithm in terms of sum rate. Besides, from the view of convergence rate, simulation results show that the MAMA enjoys fastest speed with respect to a certain sum rate value, while hybrid algorithm converges fastest to eliminate interference.

  1. Adaptive codebook selection schemes for image classification in correlated channels

    NASA Astrophysics Data System (ADS)

    Hu, Chia Chang; Liu, Xiang Lian; Liu, Kuan-Fu

    2015-09-01

    The multiple-input multiple-output (MIMO) system with the use of transmit and receive antenna arrays achieves diversity and array gains via transmit beamforming. Due to the absence of full channel state information (CSI) at the transmitter, the transmit beamforming vector can be quantized at the receiver and sent back to the transmitter by a low-rate feedback channel, called limited feedback beamforming. One of the key roles of Vector Quantization (VQ) is how to generate a good codebook such that the distortion between the original image and the reconstructed image is the minimized. In this paper, a novel adaptive codebook selection scheme for image classification is proposed with taking both spatial and temporal correlation inherent in the channel into consideration. The new codebook selection algorithm is developed to select two codebooks from the discrete Fourier transform (DFT) codebook, the generalized Lloyd algorithm (GLA) codebook and the Grassmannian codebook to be combined and used as candidates of the original image and the reconstructed image for image transmission. The channel is estimated and divided into four regions based on the spatial and temporal correlation of the channel and an appropriate codebook is assigned to each region. The proposed method can efficiently reduce the required information of feedback under the spatially and temporally correlated channels, where each region is adaptively. Simulation results show that in the case of temporally and spatially correlated channels, the bit-error-rate (BER) performance can be improved substantially by the proposed algorithm compared to the one with only single codebook.

  2. Effective capacity of MIMO free-space optical systems over gamma-gamma turbulence channels

    NASA Astrophysics Data System (ADS)

    Chen, Li; Wang, Weidong

    2017-01-01

    In this paper, we provide the capacity limits of multiple-input multiple-output (MIMO) free-space optical communication (FSO) system in the presence of quality of service (QoS) requirements. Closed-form expression for the effective capacity of MIMO FSO system with equal gain combining (EGC) is derived. In order to provide insights into the impact of various system parameters, asymptotic expressions are further analyzed in the high signal-to-noise ratio (SNR) regime. Special cases are provided according to the derived results at the same time. Numerical results are given to validate all the analytical results, and the influences of QoS requirements and MIMO configurations are also illustrated.

  3. Pilot Beam Pattern Design for Channel Estimation in Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Noh, Song; Zoltowski, Michael D.; Sung, Youngchul; Love, David J.

    2014-10-01

    In this paper, the problem of pilot beam pattern design for channel estimation in massive multiple-input multiple-output systems with a large number of transmit antennas at the base station is considered, and a new algorithm for pilot beam pattern design for optimal channel estimation is proposed under the assumption that the channel is a stationary Gauss-Markov random process. The proposed algorithm designs the pilot beam pattern sequentially by exploiting the properties of Kalman filtering and the associated prediction error covariance matrices and also the channel statistics such as spatial and temporal channel correlation. The resulting design generates a sequentially-optimal sequence of pilot beam patterns with low complexity for a given set of system parameters. Numerical results show the effectiveness of the proposed algorithm.

  4. Open area 2 × 2 MIMO channel model for 2 GHz low-elevation links with diversity and capacity applications

    NASA Astrophysics Data System (ADS)

    Zelený, J.; Pérez-Fontán, F.; Pechac, P.; Mariño-Espiñeira, P.

    2017-05-01

    In civil surveillance applications, unmanned aerial vehicles (UAV) are being increasingly used in floods, fires, and law enforcement scenarios. In order to transfer large amounts of information from UAV-mounted cameras, relays, or sensors, large bandwidths are needed in comparison to those required for remotely commanding the UAV. This demands the use of higher-frequency bands, in all probability in the vicinity of 2 or 5 GHz. Novel hardware developments need propagation channel models for the ample range of operational scenarios envisaged, including multiple-input, multiple-output (MIMO) deployments. These configurations may enable a more robust transmission by increasing either the carrier-to-noise ratio statistics or the achievable capacity. In this paper, a 2 × 2 MIMO propagation channel model for an open-field environment capable of synthesizing a narrowband time series at 2 GHz is described. Maximal ratio combining diversity and capacity improvements are also evaluated through synthetic series and compared with measurement results. A simple flat, open scenario was evaluated based on which other, more complex environments can be modeled.

  5. A Broadcast Scheme for MIMO Systems with Channel State Information at the Transmitter

    NASA Astrophysics Data System (ADS)

    Hwang, Insoo; You, Cheolwoo; Kim, Dongho; Kim, Yungsoo; Tarokh, Vahid

    We propose a new broadcast strategy for a multiple-input multiple-output (MIMO) system with N transmit antennas at the transmitter and M≤N single antenna receivers. The proposed method, based on dirty-paper coding (DPC), spatially separates the M users but does not suffer from the power loss of classical spatial division multiple access (SDMA). For the special case of M=N=2 and when the two single antenna receivers are assumed to be co-located, the proposed scheme produces a 2 transmit, 2 receiver antenna MIMO transmission system that doubles the symbol rate of MIMO space-time block code (STBC) systems from one to two symbol per transmission time. It is proved theoretically and experimentally that the proposed scheme provides the same performance level as that of MIMO STBC systems (i. e., the Alamouti scheme) for the first symbol, and the same performance as the Bell labs layered space-time (BLAST) system for the second symbol. When compared to the BLAST system, the proposed scheme has the same symbol rate, but achieves significantly better performance, since it provides 2 level diversity per symbol on the first symbol while the BLAST system does not provide any diversity.

  6. Wideband MIMO channel characterization in TV studios and inside buildings in the 2.2-2.5 GHz frequency band

    NASA Astrophysics Data System (ADS)

    Razavi-Ghods, N.; Salous, S.

    2009-10-01

    Multiple input multiple output (MIMO) measurements were performed with a chirp sounder with a switched antenna array at the transmitter and eight parallel receiver channels with 96-MHz bandwidth at 2.25 GHz in TV studios and 240-MHz bandwidth at 2.38 GHz inside buildings. MIMO capacity was estimated from the data with linear and circular arrays with array sizes 2 by 2, 4 by 4, and 6 by 8. Mean capacity estimates for 30-dB signal-to-noise ratio for both line of sight and obstructed line of sight were on the order of 11-31 b/s/Hz for the 2 by 2 to 4 by 4 antenna configurations and for the 6 by 8 directional antenna measurements a median capacity of 50 b/s/Hz. This is an increase of 20 b/s/Hz from the 4 by 4 omnidirectional antenna array indicating diversity gain as well as an increase due to the number of antennas.

  7. Analysis of the method of division of spatial channels with successive interference cancellation in modern MIMO-OFDM cellular systems

    NASA Astrophysics Data System (ADS)

    Davydov, A. V.; Mal'Tsev, A. A.

    2011-10-01

    We consider the problem of parallel data transmission via several spatial channels in modern high-throughput cellular systems employing the OFDM (Orthogonal Frequency Division Multiplexing) and antenna arrays at both ends of the communication system. Parallel data transmission in such MIMO (Multiple Input Multiple Output) systems is achieved by using the beamforming schemes in the transmitter and the special methods of the spatial-channel division in the receiver. Interference immunity of the scheme of the spatial-channel division by the maximum-likelihood criterion using the method of successive interference cancellation is analyzed. Probability of implementation of the stage of successive interference cancellation for the case of two spatial channels and various combinations of the coding schemes and modulations is obtained. We analyze the efficiency of a cellular communication system using horizontal coding and successive interference cancellation. Practical recommendations on choosing modulation and the code speed for each spatial channel, which ensure maximum interference immunity of a receiver with successive interference cancellation, are made.

  8. Single-Tap Precoders and Decoders for Multiuser MIMO FBMC-OQAM Under Strong Channel Frequency Selectivity

    NASA Astrophysics Data System (ADS)

    Rottenberg, Francois; Mestre, Xavier; Horlin, Francois; Louveaux, Jerome

    2017-02-01

    The design of linear precoders or decoders for multiuser (MU) multiple-input multiple-output (MIMO) filterbank multicarrier (FBMC) modulations in the case of strong channel frequency selectivity is presented. The users and the base station (BS) communicate using space division multiple access (SDMA). The low complexity proposed solution is based on a single tap per-subcarrier precoding/decoding matrix at the base station (BS) in the downlink/uplink. As opposed to classical approaches that assume flat channel frequency selectivity at the subcarrier level, the BS does not make this assumption and takes into account the distortion caused by channel frequency selectivity. The expression of the FBMC asymptotic mean squared error (MSE) in the case of strong channel selectivity derived in earlier works is developed and extended. The linear precoders and decoders are found by optimizing the MSE formula under two design criteria, namely zero forcing (ZF) or minimum mean squared error (MMSE). Finally, simulation results demonstrate the performance of the optimized design. As long as the number of BS antennas is larger than the number of users, it is shown that those extra degrees of freedom can be used to compensate for the channel frequency selectivity.

  9. An ICA based MIMO-OFDM VLC scheme

    NASA Astrophysics Data System (ADS)

    Jiang, Fangqing; Deng, Honggui; Xiao, Wei; Tao, Shaohua; Zhu, Kaicheng

    2015-07-01

    In this paper, we propose a novel ICA based MIMO-OFDM VLC scheme, where ICA is applied to convert the MIMO-OFDM channel into several SISO-OFDM channels to reduce computational complexity in channel estimation, without any spectral overhead. Besides, the FM is first investigated to further modulate the OFDM symbols to eliminate the correlation of the signals, so as to improve the separation performance of the ICA algorithm. In the 4×4MIMO-OFDM VLC simulation experiment, LOS path and NLOS paths are both considered, each transmitting signal at 100 Mb/s. Simulation results show that the BER of the proposed scheme reaches the 10-5 level at SNR=20 dB, which is a large improvement compared to the traditional schemes.

  10. Optical fibre sensors based on multi-mode fibres and MIMO signal processing: an experimental approach

    NASA Astrophysics Data System (ADS)

    Ahrens, Andreas; Sandmann, Andre; Bremer, Kort; Roth, Bernhard; Lochmann, Steffen

    2015-09-01

    In this paper multiple-input multiple-output (MIMO) signal processing is investigated for fibre optic sensor applications. A (2 × 2) MIMO implementation is realized by using lower-order and higher-order mode groups of a graded-index (GI) multi-mode fibre (MMF) as separate transmission channels. A micro-bending pressure sensor changes these separate transmission characteristics and introduces additional crosstalk. By observing the weight-factors of the MIMO system the amount of load applied was determined. Experiments verified a good correlation between the change of the MIMO weight coefficients and the load applied to the sensor and thus verified that MIMO signal processing can beneficially be used for fibre optic sensor applications.

  11. MIMO decorrelation for visible light communication based on angle optimization

    NASA Astrophysics Data System (ADS)

    Zhang, Haiyong; Zhu, Yijun

    2017-03-01

    Recently, many researchers have used the normal vector tilting to solve the problems about low rate of multiplexing and channel strong correlation in Visible Light Communication Multiple-Input Multiple-Output (VLC-MIMO) system, but they all lack of the theoretical support. In this paper, we establish a channel model about 2×2 VLC-MIMO, then translate the communication problem about vector tilting optimal angle in a certain range into a mathematical problem about seeking the minimum value of function. Finally, we deduced the mathematic expressions about the optimal tilting angles of corresponding LEDs and PDs, and these expressions will provide a theoretical basis for the further study.

  12. Spatial correlation for transmitters in spatial MIMO optical wireless links with Gaussian-beam waves and aperture effects

    NASA Astrophysics Data System (ADS)

    Chen, Zhixiao; Yu, Song; Wang, Tianyi; Wu, Guohua; Guo, Hong; Gu, Wanyi

    2013-01-01

    The spatial correlation between signals arising from a pair of constituent transmitters in a spatial multiple-input-multiple-output (MIMO) system is investigated. General formulations for the spatial correlation functions considering Gaussian-beam waves and receiver aperture effects are given under weak turbulence condition. Based on the analytical expressions, we find that spatial correlation decreases with separation distance, but increases with receiver aperture sizes, turbulence strength and wavelengths. In particular, receiver aperture averaging effects can evidently increase the correlation. It is also shown that decreasing the beam widths can generally reduce the spatial correlation, and convergent beams have lower spatial correlation than their collimated counterparts. It is found that Gaussian beams with the Fresnel ratios larger than 1 have advantages in reducing both the spatial correlation and the beam scintillations.

  13. Performance Improvement in Spatially Multiplexed MIMO Systems over Weibull-Gamma Fading Channel

    NASA Astrophysics Data System (ADS)

    Tiwari, Keerti; Saini, Davinder S.; Bhooshan, Sunil V.

    2016-11-01

    In multiple-input multiple-output (MIMO) systems, spatial demultiplexing at the receiver has its own significance. Thus, several detection techniques have been investigated. There is a tradeoff between computational complexity and optimal performance in most of the detection techniques. One of the detection techniques which gives improved performance and acceptable level of complexity is ordered successive interference cancellation (OSIC) with minimum mean square error (MMSE). However, optimal performance can be achieved by maximum likelihood (ML) detection but at a higher complexity level. Therefore, MMSE-OSIC with candidates (OSIC2) detection is recommended as a solution. In this paper, spatial multiplexed (SM) MIMO systems are considered to evaluate error performance with different detection techniques such as MMSE-OSIC, ML and MMSE-OSIC2 in a composite fading i. e. Weibull-gamma (WG) fading environment. In WG distribution, Weibull and gamma distribution represent multipath and shadowing effects, respectively. Simulation results illustrate that MMSE-OSIC2 detection technique gives the improved symbol error rate (SER) performance which is similar to ML performance and its complexity level approaches to MMSE-OSIC.

  14. Performance Limits and Design of MIMO for Sensor and Ad Hoc Wireless and Networks

    DTIC Science & Technology

    2009-01-05

    Multiple - input multiple output ( MIMO ) systems, MIMO Radar, Sensor networks, Energy... multiple - input multiple - output ( MIMO ) channels, provided at least as many transmit as receive antennas are used, recent research shows that...research. Multiple - input multiple - output ( MIMO ) channels formed by using multiple transmit and receive antennas have lead to a revolution

  15. Remote sensing using MIMO systems

    DOEpatents

    Bikhazi, Nicolas; Young, William F; Nguyen, Hung D

    2015-04-28

    A technique for sensing a moving object within a physical environment using a MIMO communication link includes generating a channel matrix based upon channel state information of the MIMO communication link. The physical environment operates as a communication medium through which communication signals of the MIMO communication link propagate between a transmitter and a receiver. A spatial information variable is generated for the MIMO communication link based on the channel matrix. The spatial information variable includes spatial information about the moving object within the physical environment. A signature for the moving object is generated based on values of the spatial information variable accumulated over time. The moving object is identified based upon the signature.

  16. Teleportation-induced correlated quantum channels.

    PubMed

    Caruso, F; Giovannetti, V; Palma, G M

    2010-01-15

    Quantum teleportation of an n-qubit state performed using as an entangled resource a general bipartite state of 2n qubits instead of n Bell states is equivalent to a correlated Pauli channel. This yields a new characterization of such channels in terms of many-body correlation functions of the teleporting media. It provides a relatively simple method for determining whether a correlated quantum channel is able to reliably convey quantum messages by studying the entanglement properties of the teleportation mediating system. Our model is then generalized to the continuous-variable case.

  17. Millimeter Wave MIMO Channel Estimation Using Overlapped Beam Patterns and Rate Adaptation

    NASA Astrophysics Data System (ADS)

    Kokshoorn, Matthew; Chen, He; Wang, Peng; Li, Yonghui; Vucetic, Branka

    2017-02-01

    This paper is concerned with the channel estimation problem in Millimeter wave (mmWave) wireless systems with large antenna arrays. By exploiting the inherent sparse nature of the mmWave channel, we first propose a fast channel estimation (FCE) algorithm based on a novel overlapped beam pattern design, which can increase the amount of information carried by each channel measurement and thus reduce the required channel estimation time compared to the existing non-overlapped designs. We develop a maximum likelihood (ML) estimator to optimally extract the path information from the channel measurements. Then, we propose a novel rate-adaptive channel estimation (RACE) algorithm, which can dynamically adjust the number of channel measurements based on the expected probability of estimation error (PEE). The performance of both proposed algorithms is analyzed. For the FCE algorithm, an approximate closed-form expression for the PEE is derived. For the RACE algorithm, a lower bound for the minimum signal energy-to-noise ratio required for a given number of channel measurements is developed based on the Shannon-Hartley theorem. Simulation results show that the FCE algorithm significantly reduces the number of channel estimation measurements compared to the existing algorithms using non-overlapped beam patterns. By adopting the RACE algorithm, we can achieve up to a 6dB gain in signal energy-to-noise ratio for the same PEE compared to the existing algorithms.

  18. Optimal DoF Region for the Asymmetric Two-Pair MIMO Two-Way Relay Channel

    NASA Astrophysics Data System (ADS)

    Liu, Kangqi; Tao, Meixia; Yuan, Xiaojun

    2017-04-01

    In this paper, we study the optimal degrees of freedom (DoF) region for the two-pair MIMO two-way relay channel (TWRC) with asymmetric antenna setting, where two pairs of users exchange information with the help of a common relay. Each user $i$ is equipped with $M_i$ antennas, for $i=1,2,3,4$, and the relay is equipped with $N$ antennas. First, we derive an outer bound of the DoF region by using the cut-set theorem and the genie-message approach. Then, we propose a new transmission scheme to achieve the outer bound of the DoF region. Due to the asymmetric data exchange, where the two users in each pair can communicate a different number of data streams, we not only need to form the network-coded symbols but also need to process the additional asymmetric data streams at the relay. This is realized through the joint design of relay compression matrix and source precoding matrices. After obtaining the optimal DoF region, we study the optimal sum DoF by solving a linear programming problem. From the optimal DoF region of this channel, we show that in the asymmetric antenna setting, some antennas at certain source nodes are redundant and cannot contribute to enlarge the DoF region. We also show that there is no loss of optimality in terms of the sum DoF by enforcing symmetric data exchange, where the two users in each pair are restricted to communicate the same number of data streams.

  19. First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands

    PubMed Central

    Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

    2016-01-01

    Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity. PMID:27399715

  20. First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

    PubMed

    Maruta, Kazuki; Iwakuni, Tatsuhiko; Ohta, Atsushi; Arai, Takuto; Shirato, Yushi; Kurosaki, Satoshi; Iizuka, Masataka

    2016-07-08

    Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity.

  1. Quantum Correlations Evolution Asymmetry in Quantum Channels

    NASA Astrophysics Data System (ADS)

    Li, Meng; Huang, Yun-Feng; Guo, Guang-Can

    2017-03-01

    It was demonstrated that the entanglement evolution of a specially designed quantum state in the bistochastic channel is asymmetric. In this work, we generalize the study of the quantum correlations, including entanglement and quantum discord, evolution asymmetry to various quantum channels. We found that the asymmetry of entanglement and quantum discord only occurs in some special quantum channels, and the behavior of the entanglement evolution may be quite different from the behavior of the quantum discord evolution. To quantum entanglement, in some channels it decreases monotonously with the increase of the quantum channel intensity. In some other channels, when we increase the intensity of the quantum channel, it decreases at first, then keeps zero for some time, and then rises up. To quantum discord, the evolution becomes more complex and you may find that it evolutes unsmoothly at some points. These results illustrate the strong dependence of the quantum correlations evolution on the property of the quantum channels. Supported by the National Natural Science Foundation of China under Grant Nos. 61327901, 61490711, 61225025, 11474268, and the Fundamental Research Funds for the Central Universities under Grant No. WK2470000018

  2. Protecting Quantum Correlation from Correlated Amplitude Damping Channel

    NASA Astrophysics Data System (ADS)

    Huang, Zhiming; Zhang, Cai

    2017-08-01

    In this work, we investigate the dynamics of quantum correlation measured by measurement-induced nonlocality (MIN) and local quantum uncertainty (LQU) in correlated amplitude damping (CAD) channel. We find that the memory parameter brings different influences on MIN and LQU. In addition, we propose a scheme to protect quantum correlation by executing prior weak measurement (WM) and post-measurement reversal (MR). However, better protection of quantum correlation by the scheme implies a lower success probability (SP).

  3. Adaptive Multi-Node Multiple Input and Multiple Output (MIMO) Transmission for Mobile Wireless Multimedia Sensor Networks

    PubMed Central

    Cho, Sunghyun; Choi, Ji-Woong; You, Cheolwoo

    2013-01-01

    Mobile wireless multimedia sensor networks (WMSNs), which consist of mobile sink or sensor nodes and use rich sensing information, require much faster and more reliable wireless links than static wireless sensor networks (WSNs). This paper proposes an adaptive multi-node (MN) multiple input and multiple output (MIMO) transmission to improve the transmission reliability and capacity of mobile sink nodes when they experience spatial correlation. Unlike conventional single-node (SN) MIMO transmission, the proposed scheme considers the use of transmission antennas from more than two sensor nodes. To find an optimal antenna set and a MIMO transmission scheme, a MN MIMO channel model is introduced first, followed by derivation of closed-form ergodic capacity expressions with different MIMO transmission schemes, such as space-time transmit diversity coding and spatial multiplexing. The capacity varies according to the antenna correlation and the path gain from multiple sensor nodes. Based on these statistical results, we propose an adaptive MIMO mode and antenna set switching algorithm that maximizes the ergodic capacity of mobile sink nodes. The ergodic capacity of the proposed scheme is compared with conventional SN MIMO schemes, where the gain increases as the antenna correlation and path gain ratio increase. PMID:24152920

  4. Application of MIMO technology in ultraviolet communication

    NASA Astrophysics Data System (ADS)

    Huang, Gang; Tang, Yi; Ni, Guoqiang; Huang, Heqing; Zhang, Xuan

    2013-12-01

    Affected by atmospheric turbulence and multipath transmission, inter-symbol interference (ISI) is generated, and communication speed is limited in the channel of non-line-of-sight ultraviolet (NLOS UV) communication. Thus, MIMO space division multiplexing (MIMO-SDM) technology has a significant effect to reduce co-channel interference, fading and improve the transmission rate. Combined with characteristics of UV channel and noise, model of UV communication MIMO channel and channel capacity is developed, and the application of SDM technology based on vertical bell laboratories layered space-time coding (V-BLAST) is investigated. Also bit error rate (BER) performances with zero-forcing (ZF), minimum mean square error (MMSE) detection algorithm are obtained. Simulation results show that the capacity of UV communication MIMO channel is related to the number of transmit and received antennas , and channel SNR. And the BER performance with MMSE detection algorithm is better than ZF detection algorithm.

  5. Designing Waveform Sets with Good Correlation and Stopband Properties for MIMO Radar via the Gradient-Based Method

    PubMed Central

    Tang, Liang; Zhu, Yongfeng; Fu, Qiang

    2017-01-01

    Waveform sets with good correlation and/or stopband properties have received extensive attention and been widely used in multiple-input multiple-output (MIMO) radar. In this paper, we aim at designing unimodular waveform sets with good correlation and stopband properties. To formulate the problem, we construct two criteria to measure the correlation and stopband properties and then establish an unconstrained problem in the frequency domain. After deducing the phase gradient and the step size, an efficient gradient-based algorithm with monotonicity is proposed to minimize the objective function directly. For the design problem without considering the correlation weights, we develop a simplified algorithm, which only requires a few fast Fourier transform (FFT) operations and is more efficient. Because both of the algorithms can be implemented via the FFT operations and the Hadamard product, they are computationally efficient and can be used to design waveform sets with a large waveform number and waveform length. Numerical experiments show that the proposed algorithms can provide better performance than the state-of-the-art algorithms in terms of the computational complexity. PMID:28468308

  6. Designing Waveform Sets with Good Correlation and Stopband Properties for MIMO Radar via the Gradient-Based Method.

    PubMed

    Tang, Liang; Zhu, Yongfeng; Fu, Qiang

    2017-05-01

    Waveform sets with good correlation and/or stopband properties have received extensive attention and been widely used in multiple-input multiple-output (MIMO) radar. In this paper, we aim at designing unimodular waveform sets with good correlation and stopband properties. To formulate the problem, we construct two criteria to measure the correlation and stopband properties and then establish an unconstrained problem in the frequency domain. After deducing the phase gradient and the step size, an efficient gradient-based algorithm with monotonicity is proposed to minimize the objective function directly. For the design problem without considering the correlation weights, we develop a simplified algorithm, which only requires a few fast Fourier transform (FFT) operations and is more efficient. Because both of the algorithms can be implemented via the FFT operations and the Hadamard product, they are computationally efficient and can be used to design waveform sets with a large waveform number and waveform length. Numerical experiments show that the proposed algorithms can provide better performance than the state-of-the-art algorithms in terms of the computational complexity.

  7. Upper and lower bounds for the ergodic capacity of MIMO Jacobi fading channels.

    PubMed

    Nafkha, Amor; Bonnefoi, Rémi

    2017-05-29

    In multi-(core/mode) optical fiber communication, the transmission channel can be modeled as a complex sub-matrix of the Haar-distributed unitary matrix (complex Jacobi unitary ensemble). In this letter, we present new analytical expressions of the upper and lower bounds for the ergodic capacity of multiple-input multiple-output Jacobi-fading channels. Recent results on the determinant of the Jacobi unitary ensemble are employed to derive a tight lower bound on the ergodic capacity. We use Jensen's inequality to provide an analytical closed-form upper bound to the ergodic capacity at any signal-to-noise ratio (SNR). Closed-form expressions of the ergodic capacity, at low and high SNR regimes, are also derived. Simulation results are presented to validate the accuracy of the derived expressions.

  8. Massive MIMO for Wireless Sensing With a Coherent Multiple Access Channel

    NASA Astrophysics Data System (ADS)

    Jiang, Feng; Chen, Jie; Swindlehurst, A. Lee; Lopez-Salcedo, Jose A.

    2015-06-01

    We consider the detection and estimation of a zero-mean Gaussian signal in a wireless sensor network with a coherent multiple access channel, when the fusion center (FC) is configured with a large number of antennas and the wireless channels between the sensor nodes and FC experience Rayleigh fading. For the detection problem, we study the Neyman-Pearson (NP) Detector and Energy Detector (ED), and find optimal values for the sensor transmission gains. For the NP detector which requires channel state information (CSI), we show that detection performance remains asymptotically constant with the number of FC antennas if the sensor transmit power decreases proportionally with the increase in the number of antennas. Performance bounds show that the benefit of multiple antennas at the FC disappears as the transmit power grows. The results of the NP detector are also generalized to the linear minimum mean squared error estimator. For the ED which does not require CSI, we derive optimal gains that maximize the deflection coefficient of the detector, and we show that a constant deflection can be asymptotically achieved if the sensor transmit power scales as the inverse square root of the number of FC antennas. Unlike the NP detector, for high sensor power the multi-antenna ED is observed to empirically have significantly better performance than the single-antenna implementation. A number of simulation results are included to validate the analysis.

  9. Adaptive multiregression in reproducing kernel Hilbert spaces: the multiaccess MIMO channel case.

    PubMed

    Slavakis, Konstantinos; Bouboulis, Pantelis; Theodoridis, Sergios

    2012-02-01

    This paper introduces a wide framework for online, i.e., time-adaptive, supervised multiregression tasks. The problem is formulated in a general infinite-dimensional reproducing kernel Hilbert space (RKHS). In this context, a fairly large number of nonlinear multiregression models fall as special cases, including the linear case. Any convex, continuous, and not necessarily differentiable function can be used as a loss function in order to quantify the disagreement between the output of the system and the desired response. The only requirement is the subgradient of the adopted loss function to be available in an analytic form. To this end, we demonstrate a way to calculate the subgradients of robust loss functions, suitable for the multiregression task. As it is by now well documented, when dealing with online schemes in RKHS, the memory keeps increasing with each iteration step. To attack this problem, a simple sparsification strategy is utilized, which leads to an algorithmic scheme of linear complexity with respect to the number of unknown parameters. A convergence analysis of the technique, based on arguments of convex analysis, is also provided. To demonstrate the capacity of the proposed method, the multiregressor is applied to the multiaccess multiple-input multiple-output channel equalization task for a setting with poor resources and nonavailable channel information. Numerical results verify the potential of the method, when its performance is compared with those of the state-of-the-art linear techniques, which, in contrast, use space-time coding, more antenna elements, as well as full channel information.

  10. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    NASA Astrophysics Data System (ADS)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  11. Secure quantum communication using classical correlated channel

    NASA Astrophysics Data System (ADS)

    Costa, D.; de Almeida, N. G.; Villas-Boas, C. J.

    2016-10-01

    We propose a secure protocol to send quantum information from one part to another without a quantum channel. In our protocol, which resembles quantum teleportation, a sender (Alice) and a receiver (Bob) share classical correlated states instead of EPR ones, with Alice performing measurements in two different bases and then communicating her results to Bob through a classical channel. Our secure quantum communication protocol requires the same amount of classical bits as the standard quantum teleportation protocol. In our scheme, as in the usual quantum teleportation protocol, once the classical channel is established in a secure way, a spy (Eve) will never be able to recover the information of the unknown quantum state, even if she is aware of Alice's measurement results. Security, advantages, and limitations of our protocol are discussed and compared with the standard quantum teleportation protocol.

  12. MIMO Precoding for Networked Control Systems with Energy Harvesting Sensors

    NASA Astrophysics Data System (ADS)

    Cai, Songfu; Lau, Vincent K. N.

    2016-09-01

    In this paper, we consider a MIMO networked control system with an energy harvesting sensor, where an unstable MIMO dynamic system is connected to a controller via a MIMO fading channel. We focus on the energy harvesting and MIMO precoding design at the sensor so as to stabilize the unstable MIMO dynamic plant subject to the energy availability constraint at the sensor. Using the Lyapunov optimization approach, we propose a closed-form dynamic energy harvesting and dynamic MIMO precoding solution, which has an event-driven control structure. Furthermore, the MIMO precoding solution is shown to have an eigenvalue water-filling structure, where the water level depends on the state estimation covariance, energy queue and the channel state, and the sea bed level depends on the state estimation covariance. The proposed scheme is also compared with various baselines and we show that significant performance gains can be achieved.

  13. Performance Analysis of Dual-hop MIMO Relay Systems with MRT&RAS in the Presence of Co-channel Interference

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoming; Cai, Yueming; Yang, Weiwei

    2013-09-01

    This paper focuses on the downlink dual-hop multiple-input multiple-output (MIMO) amplify-and-forward (AF) relay systems that employ the maximal-ratio transmission and receive antenna selection scheme (MRT&RAS) for use in each hop. The system under consideration is equipped with arbitrary NS, NR, and ND antennas at the base station (BS), relay station (RS), and mobile station (MS), respectively. The system performance has been investigated over Nakagami-m fading in presence of independent but not necessarily identically distributed co-channel interferences (CCIs) at both the RS and MS. First, we derive an accurate closed-form approximate expression for the outage probability and a single-integral expression for the average symbol error rate (SER), respectively. Besides, to render direct insights into the combined effect of multiple-antenna and interference on the system performance, the asymptotic expressions for the outage probability and the average SER are also presented. Furthermore, we determine the optimal power allocation (OPA) by using the exact and asymptotic methods, respectively, such that the outage probability is minimized. Finally, numerical results validate the correctness of the derived expressions and show that OPA offers superior performance over uniform power allocation. Our analysis and results provide insights on investigating and optimizing the performance of the downlink MIMO relay transmission in practical interference-limited wireless networks.

  14. GPUbased, Microsecond Latency, HectoChannel MIMO Feedback Control of Magnetically Confined Plasmas

    NASA Astrophysics Data System (ADS)

    Rath, Nikolaus

    Feedback control has become a crucial tool in the research on magnetic confinement of plasmas for achieving controlled nuclear fusion. This thesis presents a novel plasma feedback control system that, for the first time, employs a Graphics Processing Unit (GPU) for microsecond-latency, real-time control computations. This novel application area for GPU computing is opened up by a new system architecture that is optimized for low-latency computations on less than kilobyte sized data samples as they occur in typical plasma control algorithms. In contrast to traditional GPU computing approaches that target complex, high-throughput computations with massive amounts of data, the architecture presented in this thesis uses the GPU as the primary processing unit rather than as an auxiliary of the CPU, and data is transferred from A-D/D-A converters directly into GPU memory using peer-to-peer PCI Express transfers. The described design has been implemented in a new, GPU-based control system for the High-Beta Tokamak - Extended Pulse (HBT-EP) device. The system is built from commodity hardware and uses an NVIDIA GeForce GPU and D-TACQ A-D/D-A converters providing a total of 96 input and 64 output channels. The system is able to run with sampling periods down to 4 μs and latencies down to 8 μs. The GPU provides a total processing power of 1.5 x 1012 floating point operations per second. To illustrate the performance and versatility of both the general architecture and concrete implementation, a new control algorithm has been developed. The algorithm is designed for the control of multiple rotating magnetic perturbations in situations where the plasma equilibrium is not known exactly and features an adaptive system model: instead of requiring the rotation frequencies and growth rates embedded in the system model to be set a priori, the adaptive algorithm derives these parameters from the evolution of the perturbation amplitudes themselves. This results in non-linear control

  15. Spatial variability of correlated color temperature of lightning channels

    NASA Astrophysics Data System (ADS)

    Shimoji, Nobuaki; Aoyama, Ryoma; Hasegawa, Wataru

    In this paper, we present the spatial variability of the correlated color temperature of lightning channel shown in a digital still image. In order to analyze the correlated color temperature, we calculated chromaticity coordinates of the lightning channels in the digital still image. From results, the spatial variation of the correlated color temperature of the lightning channel was confirmed. Moreover, the results suggest that the correlated color temperature and peak current of the lightning channels are related to each other.

  16. Performance Evaluation of MIMO-UWB Systems Using Measured Propagation Data and Proposal of Timing Control Scheme in LOS Environments

    NASA Astrophysics Data System (ADS)

    Takanashi, Masaki; Nishimura, Toshihiko; Ogawa, Yasutaka; Ohgane, Takeo

    Ultrawide-band impulse radio (UWB-IR) technology and multiple-input multiple-output (MIMO) systems have attracted interest regarding their use in next-generation high-speed radio communication. We have studied the use of MIMO ultrawide-band (MIMO-UWB) systems to enable higher-speed radio communication. We used frequency-domain equalization based on the minimum mean square error criterion (MMSE-FDE) to reduce intersymbol interference (ISI) and co-channel interference (CCI) in MIMO-UWB systems. Because UWB systems are expected to be used for short-range wireless communication, MIMO-UWB systems will usually operate in line-of-sight (LOS) environments and direct waves will be received at the receiver side. Direct waves have high power and cause high correlations between antennas in such environments. Thus, it is thought that direct waves will adversely affect the performance of spatial filtering and equalization techniques used to enhance signal detection. To examine the feasibility of MIMO-UWB systems, we conducted MIMO-UWB system propagation measurements in LOS environments. From the measurements, we found that the arrival time of direct waves from different transmitting antennas depends on the MIMO configuration. Because we can obtain high power from the direct waves, direct wave reception is critical for maximizing transmission performance. In this paper, we present our measurement results, and propose a way to improve performance using a method of transmit (Tx) and receive (Rx) timing control. We evaluate the bit error rate (BER) performance for this form of timing control using measured channel data.

  17. FPGA implemented testbed in 8-by-8 and 2-by-2 OFDM-MIMO channel estimation and design of baseband transceiver.

    PubMed

    Ramesh, S; Seshasayanan, R

    2016-01-01

    In this study, a baseband OFDM-MIMO framework with channel timing and estimation synchronization is composed and executed utilizing the FPGA innovation. The framework is prototyped in light of the IEEE 802.11a standard and the signals transmitted and received utilizing a data transmission of 20 MHz. With the assistance of the QPSK tweak, the framework can accomplish a throughput of 24 Mbps. Besides, the LS formula is executed and the estimation of a frequency-specific fading channel is illustrated. For the rough estimation of timing, MNC plan is examined and actualized. Above all else, the whole framework is demonstrated in MATLAB and a drifting point model is set up. At that point, the altered point model is made with the assistance of Simulink and Xilinx's System Generator for DSP. In this way, the framework is incorporated and actualized inside of Xilinx's ISE tools and focused to Xilinx Virtex 5 board. In addition, an equipment co-simulation is contrived to decrease the preparing time while figuring the BER of the fixed point model. The work concentrates on above all else venture for further examination of planning creative channel estimation strategies towards applications in the fourth era (4G) mobile correspondence frameworks.

  18. 16 × 16 MIMO Testbed for MU-MIMO Downlink Transmission

    NASA Astrophysics Data System (ADS)

    Nishimori, Kentaro; Kudo, Riichi; Honma, Naoki; Takatori, Yasushi; Mizoguchi, Masato

    Multi-user multiple input multiple output (MU-MIMO) systems have attracted much attention as a technology that enhances the total system capacity by generating a virtual MIMO channel between a base station and multiple terminal stations. Extensive evaluations are still needed because there are many more system parameters in MU-MIMO than in single user (SU)-MIMO and the MU-MIMO performance in actual environments is still not well understood. This paper describes the features and effectiveness of a 16 × 16 MU-MIMO testbed in an actual indoor environment. Moreover, we propose a simple adaptive modulation scheme for MU-MIMO-OFDM transmission that employs a bit interleaver in the frequency and space domains. We evaluate the frequency efficiency by obtaining the bit error rate of this testbed in an actual indoor environment. We show that 16 × 4 × 4-user MU-MIMO transmission using the proposed modulation scheme achieves the frequency utilization of 870Mbps and 1Gbps (respective SNRs: 31 and 36dB) with a 20-MHz bandwidth.

  19. MIMO System with Relative Phase Difference Time-Shift Modulation for Rician Fading Environment

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kenichi; Someya, Takao; Ohtsuki, Tomoaki; Jarot, Sigit P. W.; Kashima, Tsuyoshi

    Multiple-Input Multiple-Output (MIMO) systems that realize high-speed data transmission with multiple antennas at both transmitter and receiver are drawing much attention. In line-of sight (LOS) environments, the performance of MIMO systems depends largely on the difference of the phase difference of direct paths from transmit antennas to each receive antenna. When the phase difference of direct paths are close to each other, the spatial division multiplexing (SDM) channels are not orthogonal to each other so signal detection becomes difficult. In this paper, we propose a MIMO system with relative phase difference time-shift modulation (RPDTM) in Rician fading environments. The proposed scheme transmits independent signals from each antenna at each time slot where the relative phase difference between signal constellations used by transmit antennas varies in a pre-determined pattern. This transmission virtually changes the phase difference of direct paths from transmit antennas to each receive antenna without lowering data rate and without knowledge of the channels. In addition, forward error correction coding (ECC) is applied to exploit the time slots where the receiver can detect the signals easily to improve the detection performance. If there are time slots where the receiver can separate the received signal, the receiver can decode the data by using the time slots and the correlation between data. From the results of computer simulation, we show that MIMO system with RPDTM can achieve the better bit error rate (BER) than the conventional MIMO system. We also show that the MIMO system with RPDTM is effective by about Rician factor K=10dB.

  20. Space-time adaptive processing algorithm for airborne MIMO radar with nonside-looking array using temporally correlated multiple sparse Bayesian learning

    NASA Astrophysics Data System (ADS)

    Liu, Hanwei; Zhang, Yongshun; Guo, Yiduo; Wang, Qiang

    2017-01-01

    The near-range clutter of airborne nonside-looking array greatly depends on range. Conventional phased-array space-time adaptive processing (STAP) radar suffers severe performance degradation in the presence of a near-range clutter scenario. To efficiently suppress no-stationary clutter with only one snapshot, an STAP algorithm for airborne multiple-input multiple-output (MIMO) radar with nonside-looking array based on sparse representation is first presented, which is referred to as MIMOSR-STAP in this paper. By exploiting the waveform diversity of MIMO radar, each snapshot of a tested range-cell is transformed into the multisnapshots of phased array radar, which are used to estimate the high-resolution space-time spectrum with multiple measurement vectors technique. The proposed approach is effective in estimating the spectrum by utilizing temporally correlated multiple sparse Bayesian learning. In the sequel, the clutter covariance matrix and corresponding adaptive weight vector are efficiently obtained. MIMOSR-STAP enjoys high accuracy and robustness so that it achieves better performance of output signal-to-clutter-plus-noise-ratio and minimum detectable velocity than the single measurement vector sparse representation methods in the literature. Thus, MIMOSR-STAP performs well in a serious nonstationary clutter scenario and is suitable for an insufficient independent and identically distributed samples environment.

  1. Performance Analysis of Adaptive Interleaving for MIMO-OFDM Systems

    DTIC Science & Technology

    2005-01-01

    multiple - input and multiple - output orthogonal frequency division multiplexing ( MIMO -OFDM) systems is proposed... multiple transmit-and-receive antennas are used to form a multiple - input and multiple - output ( MIMO ) system. The orthogonal frequency division multiple xing...transmit and receive antennas compared with a single - input single- output (SISO) system with flat Rayleigh fading or narrowband channels

  2. Error Rate Improvement in Underwater MIMO Communications Using Sparse Partial Response Equalization

    DTIC Science & Technology

    2006-09-01

    multiple transmitters and receivers or MIMO ( multiple input , multiple output ) configura- tions and associated signal processing at the... input multiple output ( MIMO ) ISI channels has been proposed in [2], where the authors have designed a MIMO PRE based on the MMSE criterion. The target...soft input , soft output channel detector (usually the maximum a-posteriori probability (MAP) detector) is used to detect the channel symbols which

  3. Enhancing Connectivity of Unmanned Vehicles Through MIMO Communications

    DTIC Science & Technology

    2013-09-01

    information at the transmitter . A variable rate MIMO scheme is proposed to overcome these challenges in order to realize the promising throughput gain...lead to rank deficient channel matrices, which are exacerbated due to the absence of channel state information at the transmitter . A variable rate MIMO...pair. This is further exacerbated by the lack of channel state information at the transmitter - RPAs are not only of high mobility but they may maneuver

  4. Transmission of Correlated Messages over Interference Channels with Strong Interference

    NASA Astrophysics Data System (ADS)

    Choi, Suhan; Yoon, Eunchul; Moon, Hichan

    Transmission of correlated messages over interference channels with strong interference is considered. As a result, an achievable rate region is presented. It is shown that if the messages are correlated, the achievable rate region can be larger than the capacity region given by Costa and El Gamal. As an example, the Gaussian interference channel is considered.

  5. Quantum channels with correlated noise and entanglement teleportation

    SciTech Connect

    Yeo Ye

    2003-05-01

    Motivated by the results of Macchiavello and Palma on entanglement-enhanced information transmission over a quantum channel with correlated noise, we demonstrate how the entanglement teleportation scheme of Lee and Kim gives rise to two uncorrelated generalized depolarizing channels. In an attempt to find a teleportation scheme that yields two correlated generalized depolarizing channels, we discover a teleportation scheme that allows one to learn about the entanglement in an entangled pure input state, without decreasing the amount of entanglement associated with it.

  6. Shannon information capacity of time reversal wideband multiple-input multiple-output system based on correlated statistical channels

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Bing-Zhong, Wang; Shuai, Ding

    2016-05-01

    Utilizing channel reciprocity, time reversal (TR) technique increases the signal-to-noise ratio (SNR) at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output (MIMO) communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331007, 61361166008, and 61401065) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120185130001).

  7. Removing correlations in signals transmitted over a quantum memory channel

    NASA Astrophysics Data System (ADS)

    Lupo, Cosmo; Memarzadeh, Laleh; Mancini, Stefano

    2012-01-01

    We consider a model of a bosonic memory channel, which induces correlations among the transmitted signals. The application of suitable unitary transformations at the encoding and decoding stages allows the complete removal of correlations, thereby mapping the memory channel into a memoryless one. However, such transformations, being global over an arbitrarily large number of bosonic modes, are not realistically implementable. We then introduce a family of efficiently realizable transformations, which can be used to partially remove correlations among errors, and we quantify the reduction of the gap with memoryless channels.

  8. Optimal Performance Monitoring of Hybrid Mid-Infrared Wavelength MIMO Free Space Optical and RF Wireless Networks in Fading Channels

    NASA Astrophysics Data System (ADS)

    Schmidt, Barnet Michael

    An optimal performance monitoring metric for a hybrid free space optical and radio-frequency (RF) wireless network, the Outage Capacity Objective Function, is analytically developed and studied. Current and traditional methods of performance monitoring of both optical and RF wireless networks are centered on measurement of physical layer parameters, the most common being signal-to-noise ratio, error rate, Q factor, and eye diagrams, occasionally combined with link-layer measurements such as data throughput, retransmission rate, and/or lost packet rate. Network management systems frequently attempt to predict or forestall network failures by observing degradations of these parameters and to attempt mitigation (such as offloading traffic, increasing transmitter power, reducing the data rate, or combinations thereof) prior to the failure. These methods are limited by the frequent low sensitivity of the physical layer parameters to the atmospheric optical conditions (measured by optical signal-to-noise ratio) and the radio frequency fading channel conditions (measured by signal-to-interference ratio). As a result of low sensitivity, measurements of this type frequently are unable to predict impending failures sufficiently in advance for the network management system to take corrective action prior to the failure. We derive and apply an optimal measure of hybrid network performance based on the outage capacity of the hybrid optical and RF channel, the outage capacity objective function. The objective function provides high sensitivity and reliable failure prediction, and considers both the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The radio frequency segment analysis considers the three most common RF channel fading statistics: Rayleigh, Ricean, and Nakagami-m. The novel application of information theory to the underlying physics of the

  9. On the Performance of Code Acquisition in MIMO CDMA Systems

    NASA Astrophysics Data System (ADS)

    Kim, Sangchoon; An, Jinyoung

    This letter investigates the effects of using multiple transmit antennas on code acquisition for preamble search in the CDMA uplink when MIMO is used for signal transmission and reception. The performance of a ML code acquisition technique in the presence of MIMO channel is analyzed by considering the detection and miss probabilities. The acquisition performance is numerically evaluated on a frequency selective fading channel. It is found that the performance of code acquisition scheme for a SIMO system is better than that for the case of MIMO on the low thresholds in terms of detection performance and MAT.

  10. A Simple Expression for the Matrix Gradient of a Diagonal Element of R in QR Decomposition for Use in MIMO Communications and Signal Processing

    DTIC Science & Technology

    2010-12-01

    multiple - input multiple - output ( MIMO ) channels. When QRD is used in signal... multiple - input multiple - output ( MIMO ) channels. In signal processing and communications, it is of interest to know how noise perturbation ofA affects the...include adaptive equalization [2] (chapter 15.9) and transceiver design for multiple - input multiple - output ( MIMO ) communications [5] [6] [7]. In the

  11. Ion channel noise can explain firing correlation in auditory nerves.

    PubMed

    Moezzi, Bahar; Iannella, Nicolangelo; McDonnell, Mark D

    2016-10-01

    Neural spike trains are commonly characterized as a Poisson point process. However, the Poisson assumption is a poor model for spiking in auditory nerve fibres because it is known that interspike intervals display positive correlation over long time scales and negative correlation over shorter time scales. We have therefore developed a biophysical model based on the well-known Meddis model of the peripheral auditory system, to produce simulated auditory nerve fibre spiking statistics that more closely match the firing correlations observed in empirical data. We achieve this by introducing biophysically realistic ion channel noise to an inner hair cell membrane potential model that includes fractal fast potassium channels and deterministic slow potassium channels. We succeed in producing simulated spike train statistics that match empirically observed firing correlations. Our model thus replicates macro-scale stochastic spiking statistics in the auditory nerve fibres due to modeling stochasticity at the micro-scale of potassium channels.

  12. The dynamic behaviors of complementary correlations under decoherence channels

    NASA Astrophysics Data System (ADS)

    Du, Ming-Ming; Wang, Dong; Ye, Liu

    2017-01-01

    Complementary correlations can reveal the genuine quantum correlations present in a composite quantum system. Here, we explore an effective method to identify the entangled Bell diagonal states by means of Pearson correlation, one of the complementary correlations. Then, we extend this method to expose the dynamic behavior of complementary correlations under various kinds of decoherence channels. The sudden death and revival of entanglement can be explained by the idea of Pearson correlation. The threshold that is used to identify entanglement is proposed. Furthermore, we put forward a new method to expound the underlying physical mechanisms for which classical and quantum correlations suffer a sudden change in the decoherence process.

  13. The dynamic behaviors of complementary correlations under decoherence channels

    PubMed Central

    Du, Ming-Ming; Wang, Dong; Ye, Liu

    2017-01-01

    Complementary correlations can reveal the genuine quantum correlations present in a composite quantum system. Here, we explore an effective method to identify the entangled Bell diagonal states by means of Pearson correlation, one of the complementary correlations. Then, we extend this method to expose the dynamic behavior of complementary correlations under various kinds of decoherence channels. The sudden death and revival of entanglement can be explained by the idea of Pearson correlation. The threshold that is used to identify entanglement is proposed. Furthermore, we put forward a new method to expound the underlying physical mechanisms for which classical and quantum correlations suffer a sudden change in the decoherence process. PMID:28134291

  14. An improved MIMO-SAR simulator strategy with ray tracing

    NASA Astrophysics Data System (ADS)

    Xiang, Xingyu; Mo, Zijian; Wang, Zhonghai; Chen, Genshe; Pham, Khanh; Blasch, Erik

    2016-05-01

    High resolution and wide-swath imaging can be obtained by Multiple-Input Multiple-Output (MIMO) synthetic aperture radar (SAR) with the state of the art technologies. The time division multiple access (TDMA) MIMO SAR mimics the motion of the antenna of SAR systems by switching the array channels to transmit the radar signals at different time slots. In this paper, we develop a simulation tool with ray tracing techniques to retrieve high resolution and accurate SAR images for development of MIMO SAR imaging methods. Without loss of generality, in the proposed simulator, we apply a TDMA MIMO SAR system with 13 transmitting antennas and 8 receiving antennas, where all transmitting antennas share a single transmitter and the receiving antennas share a single receiver. By comparing with the normal simulation MIMO SAR strategies, the simulation image using ray tracing results validate that the proposed method provides more accurate and higher resolution SAR images.

  15. Digital correlator for the portable channel prober measurement instrument

    NASA Astrophysics Data System (ADS)

    Peo, George E., Jr.

    1987-12-01

    This document describes a Digital Correlator for the Portable Channel Prober Measurement Instrument being developed by the Naval Research Laboratory for use in experiments designed to characterize high frequency (HF) radio channels. This Digital Correlator is a digital signal processor designed and constructed by Stow Computer, 111 old Bolton Road, Stow, MA 01775, (617/508) 897-6838. Two Digital Correlators are integrated into the existing Digital Pre-processor to make a Portable Wideband HF Channel Analyzer. The Portable Wideband HF Channel Analyzer will be located at the receiving site of the channel probing experiment and is situated between the coherent radio receiver and the microcomputer used for data recording and analysis. The Portable Wideband HF Channel Analyzer computes the delay power spectrum of the received waveform. The in-phase and quadrature outputs of the receiver are sampled and converted to digital values by the Analog to Digital Converter, integrated by the Integrator, and correlated with a stored replica of the transmitted waveform by two Digital Correlators. The resulting tap gains are then read by the system microcomputer using the microcomputer interface.

  16. Volume holographic wavelet correlators with multi-input channels

    NASA Astrophysics Data System (ADS)

    Feng, Wenyi; Yan, Yingbai; Jin, Guofan; Wu, Minxian; He, Qingsheng

    1999-10-01

    Optical correlators based on volume holographic associative storage and wavelet matched filtering generally have single input channel. In other words, they can only process one input image at a same time. Based on the fact that a volume holographic correlator is not a shift invariance system, novel volume holographic wavelet correlators with multi- input channels are proposed and constructed in this paper to improve the parallelism of processing. Without adding any component, the method of input plane shifting and the technique of angle multiplexing are combined besides the introduction of wavelet transform. With the correlators, several input images can be recognized simultaneously according to a same system output. Conditions of realizing multi-input channel processing are studied in this paper. The mechanism and prototype of the system are described in detail. The performance of the system in human face recognition is testified by experiment. Promising results are given.

  17. Design of Massive-MIMO-NOMA With Limited Feedback

    NASA Astrophysics Data System (ADS)

    Ding, Zhiguo; Poor, H. Vincent

    2016-05-01

    In this letter, a low-feedback non-orthogonal multiple access (NOMA) scheme using massive multiple-input multiple-output (MIMO) transmission is proposed. In particular, the proposed scheme can decompose a massive-MIMO-NOMA system into multiple separated single-input single-output NOMA channels, and analytical results are developed to evaluate the performance of the proposed scheme for two scenarios, with perfect user ordering and with one-bit feedback, respectively.

  18. Downlink Training Techniques for FDD Massive MIMO Systems: Open-Loop and Closed-Loop Training With Memory

    NASA Astrophysics Data System (ADS)

    Choi, Junil; Love, David J.; Bidigare, Patrick

    2014-10-01

    The concept of deploying a large number of antennas at the base station, often called massive multiple-input multiple-output (MIMO), has drawn considerable interest because of its potential ability to revolutionize current wireless communication systems. Most literature on massive MIMO systems assumes time division duplexing (TDD), although frequency division duplexing (FDD) dominates current cellular systems. Due to the large number of transmit antennas at the base station, currently standardized approaches would require a large percentage of the precious downlink and uplink resources in FDD massive MIMO be used for training signal transmissions and channel state information (CSI) feedback. To reduce the overhead of the downlink training phase, we propose practical open-loop and closed-loop training frameworks in this paper. We assume the base station and the user share a common set of training signals in advance. In open-loop training, the base station transmits training signals in a round-robin manner, and the user successively estimates the current channel using long-term channel statistics such as temporal and spatial correlations and previous channel estimates. In closed-loop training, the user feeds back the best training signal to be sent in the future based on channel prediction and the previously received training signals. With a small amount of feedback from the user to the base station, closed-loop training offers better performance in the data communication phase, especially when the signal-to-noise ratio is low, the number of transmit antennas is large, or prior channel estimates are not accurate at the beginning of the communication setup, all of which would be mostly beneficial for massive MIMO systems.

  19. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System

    PubMed Central

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system. PMID:26421311

  20. Computer Simulation and Field Experiment for Downlink Multiuser MIMO in Mobile WiMAX System.

    PubMed

    Yamaguchi, Kazuhiro; Nagahashi, Takaharu; Akiyama, Takuya; Matsue, Hideaki; Uekado, Kunio; Namera, Takakazu; Fukui, Hiroshi; Nanamatsu, Satoshi

    2015-01-01

    The transmission performance for a downlink mobile WiMAX system with multiuser multiple-input multiple-output (MU-MIMO) systems in a computer simulation and field experiment is described. In computer simulation, a MU-MIMO transmission system can be realized by using the block diagonalization (BD) algorithm, and each user can receive signals without any signal interference from other users. The bit error rate (BER) performance and channel capacity in accordance with modulation schemes and the number of streams were simulated in a spatially correlated multipath fading environment. Furthermore, we propose a method for evaluating the transmission performance for this downlink mobile WiMAX system in this environment by using the computer simulation. In the field experiment, the received power and downlink throughput in the UDP layer were measured on an experimental mobile WiMAX system developed in Azumino City in Japan. In comparison with the simulated and experimented results, the measured maximum throughput performance in the downlink had almost the same performance as the simulated throughput. It was confirmed that the experimental mobile WiMAX system for MU-MIMO transmission successfully increased the total channel capacity of the system.

  1. Statistical MIMO Radar

    DTIC Science & Technology

    2004-12-20

    improve the radar’s performance. MIMO radar utilizes multiple antennas at both the transmitter and receiver. It can be applied in monostatic or bistatic...signal at the output of the beamformer equals , , HE t x y x y t t M E y t x y x M r a b s n a b        20y s t n t S- MIMO Radar

  2. Analysis on the Diversity and Multiplexing Tradeoff of Antenna Selected MIMO System

    NASA Astrophysics Data System (ADS)

    Feng, Zhenjie; Zhang, Taiyi

    Antenna selection is a practical way to decrease system complexity and the hardware cost of radio frequency (RF) chains in multiple input multiple output (MIMO) system. In this study, we give a simple characterization of the optimal diversity and multiplexing tradeoff (DMT) curve of the MIMO system with antenna subset selection at both the transmitter and the receiver for Rayleigh fading channel.

  3. LTE-advanced MIMO uplink for mobile system

    NASA Astrophysics Data System (ADS)

    Alhasson, Bader; Li, Xin; Bloul, Albe M.; Matin, M.

    2010-08-01

    By increasing multimedia communications, mobile communications are expected to reliably support high data rate transmissions. To provide higher peak rate at a better system efficiency, which is necessary to support broadband data services over Wireless links, we need to employ long term evolution Advanced (LTE-A) Multiple-input multiple-output MIMO uplink. The outline of this paper is to investigate and discuss the Long Term Evolution (LTE) for broadband wireless technologies and to discuss its functionality. We explore how LTE uses the inter-technology mobility to support a variety of access technology. This paper investigates the channel capacity and bit error rate of MIMO-OFDM system. In addition, it introduces various MIMO technologies employed in LTE and provide a brief overview on the MIMO technologies currently discussed in the LTE-Advanced forum.

  4. Multipartite correlation degradation in amplitude-damping quantum channels

    NASA Astrophysics Data System (ADS)

    Batle, J.; Farouk, A.; Alkhambashi, M.; Abdalla, S.

    2017-04-01

    Multipartite correlations, such as entanglement and non-locality, are considered when particles pass through a generalized amplitude-damping channel. Results for pure and mixed states for two qubits suggest that initial mixed states can still be considered provided that their degree of mixture is low enough. Also, the ensuing small values for non-locality suggest that instances involving more than three parties cannot easily be considered for practical purposes.

  5. A correlation for nucleate flow boiling in small channels

    SciTech Connect

    Tran, T.N. |; Wambsganss, M.W.; Chyu, M.C.; France, D.M.

    1997-08-01

    Compact heat exchangers are becoming more attractive for applications in which energy conservation, space saving, and cost are important considerations. Applications exist in the process industries where phase-change heat transfer realizes more compact designs and improved performance compared to single-phase heat transfer. However, there have been only a few studies in the literature reporting on phase-change heat transfer and two-phase flow in compact heat exchangers, and validated design correlations are lacking. Recent data from experiments on flow boiling of refrigerants in small channels have led researchers to conclude that nucleation is the dominant heat transfer mechanism over a broad range of heat flux and wall superheats. Local heat transfer coefficients and overall two-phase pressure drops were measured for three different refrigerants with circular and non-circular channels in a range of pressures. This data base supports the nucleate boiling mechanism, and it was used to develop a new correlation for heat transfer in nucleate flow boiling. The correlation is based on the Rohsenow boiling model, introducing a confinement number defined by Kew and Cornwell. The new correlation predicts the experimental data for nucleate flow boiling of three refrigerants within {+-}15%.

  6. Max–Min Multicell-Aware Precoding and Power Allocation for Downlink Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Zarei, Shahram; Aulin, Jocelyn; Gerstacker, Wolfgang; Schober, Robert

    2017-10-01

    We propose a max-min multi-cell aware regularized zero-forcing (Max-Min MCA-RZF) precoding and power allocation scheme for downlink multi-cell massive multiple-input multiple-output (MIMO) systems. A general correlated channel model is considered, and the adopted channel state information (CSI) acquisition model includes the effects of estimation errors and pilot contamination. We use results from random matrix theory to derive deterministic equivalents for the proposed Max-Min power allocation in the large system limit which solely depend on statistical CSI, but not on individual channel realizations. Our numerical results show that the proposed Max-Min MCA-RZF precoder achieves a substantially higher network-wide minimum rate than the MCA-RZF and the conventional RZF precoders with uniform power allocation, respectively, as well as the conventional RZF precoder with Max-Min power allocation.

  7. MIMO Transceiver Systems on AUVs

    DTIC Science & Technology

    2008-09-30

    MIMO Transceiver Systems on AUVs Mohsen Badiey 107 Robinson Hall College of Marine and Earth Studies, University of Delaware phone...acoustic MIMO communication testbed on a small AUV at the frequency band of 8-50 kHz for data communication studies, and 2) Make this system capable...environments. The MIMO transceiver system on the AUV is designed for ease of use and low-cost deployment during at-sea experiments. The system under

  8. A MIMO-OFDM Testbed for Wireless Local Area Networks

    NASA Astrophysics Data System (ADS)

    Fàbregas, Albert Guilléni; Guillaud, Maxime; Slock, Dirk TM; Caire, Giuseppe; Gosse, Karine; Rouquette, Stéphanie; Dias, Alexandre Ribeiro; Bernardin, Philippe; Miet, Xavier; Conrat, Jean-Marc; Toutain, Yann; Peden, Alain; Li, Zaiqing

    2006-12-01

    We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally, we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system.

  9. Power amplifier linearization technique with IQ imbalance and crosstalk compensation for broadband MIMO-OFDM transmitters

    NASA Astrophysics Data System (ADS)

    Gregorio, Fernando; Cousseau, Juan; Werner, Stefan; Riihonen, Taneli; Wichman, Risto

    2011-12-01

    The design of predistortion techniques for broadband multiple input multiple output-OFDM (MIMO-OFDM) systems raises several implementation challenges. First, the large bandwidth of the OFDM signal requires the introduction of memory effects in the PD model. In addition, it is usual to consider an imbalanced in-phase and quadrature (IQ) modulator to translate the predistorted baseband signal to RF. Furthermore, the coupling effects, which occur when the MIMO paths are implemented in the same reduced size chipset, cannot be avoided in MIMO transceivers structures. This study proposes a MIMO-PD system that linearizes the power amplifier response and compensates nonlinear crosstalk and IQ imbalance effects for each branch of the multiantenna system. Efficient recursive algorithms are presented to estimate the complete MIMO-PD coefficients. The algorithms avoid the high computational complexity in previous solutions based on least squares estimation. The performance of the proposed MIMO-PD structure is validated by simulations using a two-transmitter antenna MIMO system. Error vector magnitude and adjacent channel power ratio are evaluated showing significant improvement compared with conventional MIMO-PD systems.

  10. Multiuser Detectors for MIMO DS/CDMA Systems

    DTIC Science & Technology

    2005-01-01

    input vector x̃ to yield the output b̂. The weight matrix W̃ is chosen to minimize the cost function JLMS = E ·°°°CHW̃H (n) x̃ (n)ÁL− b (n)°°°2¸ = E...Multiuser Detectors for MIMO DS/CDMA Systems Fang-Biau Ueng, Shang-Chun Tsai and Jun-Da Chen EE, NCHU, Taichung, Taiwan. E-mail: fbueng...cK is the spreading sequence of each user, respectively. We consider a MIMO channel with N transmitted and M received antennas. Assuming that

  11. Capacity Optimization of MIMO Links with Interference

    DTIC Science & Technology

    2011-06-01

    Multiple - Input Multiple - Output ( MIMO ) systems have shown great promise in providing high spectral efficiency for single user...the case of strong interference. 15. SUBJECT TERMS Multiple - input multiple - output systems, capacity optimization, cochannel interference. 16...wireless link without interference [3], [4]. There has also much work on the MIMO -based cellular networks, which include MIMO multiple access ( MIMO

  12. Advanced Techniques for MIMO Broadband Communications

    DTIC Science & Technology

    2005-12-01

    Multiple input multiple output ( MIMO ) systems can provide high...Approved for Public Release Distribution Unlimited 20060614025 Abstract Multiple input multiple output ( MIMO ) systems can provide high diversity, high... multiple transmit/receive antennas are referred to as multiple input multiple output ( MIMO ) systems. As studies advance, it is shown that MIMO

  13. Precoded spatial multiplexing MIMO system with spatial component interleaver.

    PubMed

    Gao, Xiang; Wu, Zhanji

    In this paper, the performance of precoded bit-interleaved coded modulation (BICM) spatial multiplexing multiple-input multiple-output (MIMO) system with spatial component interleaver is investigated. For the ideal precoded spatial multiplexing MIMO system with spatial component interleaver based on singular value decomposition (SVD) of the MIMO channel, the average pairwise error probability (PEP) of coded bits is derived. Based on the PEP analysis, the optimum spatial Q-component interleaver design criterion is provided to achieve the minimum error probability. For the limited feedback precoded proposed scheme with linear zero forcing (ZF) receiver, in order to minimize a bound on the average probability of a symbol vector error, a novel effective signal-to-noise ratio (SNR)-based precoding matrix selection criterion and a simplified criterion are proposed. Based on the average mutual information (AMI)-maximization criterion, the optimal constellation rotation angles are investigated. Simulation results indicate that the optimized spatial multiplexing MIMO system with spatial component interleaver can achieve significant performance advantages compared to the conventional spatial multiplexing MIMO system.

  14. Airborne MIMO GMTI Radar

    DTIC Science & Technology

    2011-03-31

    applications [1], [2], [3], [4]. [5]. [6]. [7]. [8]. [9]. [10]. [11]. [12]. Conventional phased array radars form a single coherent transmit beam and...intentionally left blank. 1. INTRODUCTION Conventional phased - array radars form a single coherent transmit beam and measure the backscattered response... steering vector for a SI MO array with nr"/? receiver phase centers located at positions xm + y„. This is how the MIMO virtual array arises. The waveforms

  15. Studies of Hybrid MIMO

    DTIC Science & Technology

    2008-08-01

    beamforming approaches to improve radar target detection, tracking and classification. 15. SUBJECT TERMS EOARD, target ...Sammartino, C.J. Baker, H.D. Griffiths – “ Target Model Effects On MIMO Radar Performance” – 2006 IEEE ICASSP, International Confer- ence on Acoustic...2007, St. Thomas, US Virgin Islands, 12th-14th Dec 2007. 11. P.F. Sammartino, C.J. Baker, M. Rangaswamy – “Moving target localization with multistatic

  16. The relative degree enhancement problem for MIMO nonlinear systems

    SciTech Connect

    Schoenwald, D.A.; Oezguener, Ue.

    1995-07-01

    The authors present a result for linearizing a nonlinear MIMO system by employing partial feedback - feedback at all but one input-output channel such that the SISO feedback linearization problem is solvable at the remaining input-output channel. The partial feedback effectively enhances the relative degree at the open input-output channel provided the feedback functions are chosen to satisfy relative degree requirements. The method is useful for nonlinear systems that are not feedback linearizable in a MIMO sense. Several examples are presented to show how these feedback functions can be computed. This strategy can be combined with decentralized observers for a completely decentralized feedback linearization result for at least one input-output channel.

  17. MIMO Radar - Diversity Means Superiority

    DTIC Science & Technology

    2007-10-01

    MIMO radar than wit ,11 its plascd- array counterpart. In [9], a MIMO radar technique is suggested to improve the radar tesoilluOll. The idea is to...AB - XSH(SSH)-]H +Iq = QI I+±l 7 - [ AnB -XSH(SSH)-] (SSH)[An-XSH(SSH)-I] 1 Q - IQI I XssHH[ABxsH(ssH)

  18. Sievenpiper HIS and its influence on antenna correlation

    NASA Astrophysics Data System (ADS)

    Hampel, S. K.; Schmitz, O.; Rolfes, I.

    2008-05-01

    ⪉bel{sec:abstract} This paper deals with the influence of artificial magnetic conductors (AMC), so-called Sievenpiper High Impedance Surfaces (HIS), on the MIMO and Diversity performance of a planar linear-polarized 2×2 dipole array in the ISM-band at 2.45 GHz. The characteristic performance criteria such as envelope correlation coefficient, spectral efficiency, Mean Effective Gain (MEG) and Diversity gain of a coupled 2×2 dipole array are investigated. By means of full-wave electromagnetic analysis as well as Monte-Carlo simulations applying statistical channel models the characteristic antenna pattern just as the MIMO and Diversity analysis is performed, respectively. The obtained results show that the application of Sievenpiper High Impedance Surfaces to planar antenna arrays enables good MIMO and Diversity performance compared to ideal configurations in free-space while offering the design of low profile antennas with simultaneously enhanced characteristics.

  19. Massive MIMO-OFDM indoor visible light communication system downlink architecture design

    NASA Astrophysics Data System (ADS)

    Lang, Tian; Li, Zening; Chen, Gang

    2014-10-01

    Multiple-input multiple-output (MIMO) technique is now used in most new broadband communication system, and orthogonal frequency division multiplexing (OFDM) is also utilized within current 4th generation (4G) of mobile telecommunication technology. With MIMO and OFDM combined, visible light communication (VLC) system's diversity gain is increase, yet system capacity for dispersive channels is also enhanced. Moreover, with the emerging massive MIMO-OFDM VLC system, there are significant advantages than smaller systems' such as channel hardening, further increasing of energy efficiency (EE) and spectral efficiency (SE) based on law of large number. This paper addresses one of the major technological challenges, system architecture design, which was solved by semispherical beehive structure (SBS) receiver and so that diversity gain can be identified and applied in Massive MIMO VLC system. Simulation results shows that the proposed design clearly presents a spatial diversity over conventional VLC systems.

  20. Spatial Modulation in the Underwater Acoustic Channel

    DTIC Science & Technology

    2004-12-20

    input multiple - output ( MIMO ) communication channels are an active area of research for terrestrial wireless applications. The natural bandwidth...band phone can expect coherence times of ABSTRACT nearly 10000/B. These conditions demand sophisticated Multiple - input / multiple - output ( MIMO ...Spatial Modulation in the Underwater Acoustic Channel Daniel Kilfoyle SAIC phone: 508-274-1197 email: daniel.b.kilfoyle@saic.com Abstract Multiple

  1. Single Front-End MIMO Architecture with Parasitic Antenna Elements

    NASA Astrophysics Data System (ADS)

    Yoshida, Mitsuteru; Sakaguchi, Kei; Araki, Kiyomichi

    In recent years, wireless communication technology has been studied intensively. In particular, MIMO which employs several transmit and receive antennas is a key technology for enhancing spectral efficiency. However, conventional MIMO architectures require some transceiver circuits for the sake of transmitting and receiving separate signals, which incurs the cost of one RF front-end per antenna. In addition to that, MIMO systems are assumed to be used in low spatial correlation environment between antennas. Since a short distance between each antenna causes high spatial correlation and coupling effect, it is difficult to miniaturize wireless terminals for mobile use. This paper shows a novel architecture which enables mobile terminals to be miniaturized and to work with a single RF front-end by means of adaptive analog beam-forming with parasitic antenna elements and antenna switching for spatial multiplexing. Furthermore, statistical analysis of the proposed architecture is also discussed in this paper.

  2. Multi-channel digital correlator and hardware simulator for fluorescence correlation spectroscopy, dynamic light scattering and multichannel photon time stamping

    NASA Astrophysics Data System (ADS)

    Lescano, Isaac; Davis, Lloyd

    2007-11-01

    In fluorescence correlation spectroscopy and dynamic light scattering, digital correlators acquire the autocorrelation function of detected photons to measure diffusional dynamics of biomolecules and small particles. Multi-channel data from different wavelengths or scattering angles provides increased information for resolving multiple species. Similarly, in single-molecule spectroscopy and in experiments on photon entanglement, there is a need to acquire time stamps of photons from multiple detectors. To enable such advances, we have developed a cost-effective 16-channel correlator, and also a hardware simulator for a 16-channel photon detector for testing digital correlators, each based on a National Instruments R-series reconfigurable digital i/o card. The correlator scans 16 digital inputs each 6.25 ns for photon detector pulses and sends the photon time stamp and channel data to the host PC via a FIFO and 3 DMA channels, allowing >10^7 counts/s among the 16 channels. The PC calculates all autocorrelation and cross-correlations for logarithmically spaced delays in a real-time algorithm. The hardware simulator works in reverse: Simulated time stamp and channel data are sent by DMA to the card, which generates TTL pulses for the 16 digital outputs as though they came from 16 real photon detectors.

  3. Design and implementation of a MIMO MAC protocol for ad hoc networking

    NASA Astrophysics Data System (ADS)

    Redi, Jason; Watson, Bill; Ramanathan, Ram; Basu, Prithwish; Tchakountio, Fabrice; Girone, Michael; Steenstrup, Martha

    2006-05-01

    Multiple Input Multiple Output (MIMO) provides the potential for significant gains in channel capacity and spectral efficiency through its use of multiple element antenna systems and space-time coding. There are numerous published accounts of experimental MIMO communications links with high numbers of transmit and receive antennas, as well as commercial products exploiting MIMO with smaller antenna configurations. However, the use of MIMO as a modulation scheme for mobile ad hoc networking has so far only been explored as part of a theoretic or simulation exercise. In this paper we describe the design and implementation of a MAC protocol for a MIMO system which is designed to exploit the capability of 8x10 MIMO for ad hoc networks. This work is unique in that from the start our design considered the specific capabilities and parameters of an existing 8x10 MIMO physical layer, including nonnegligible decoding delays, variable array size and coding schemes, as well as fixed frame sizes. Furthermore, given the bandwidths and antenna array sizes available, the physical layer design could achieve hundreds of megabits in link capacity, and our MAC protocol therefore needed to be designed and implemented in such a way as to maximize this capacity, particularly in a network multi-hop environment. Our MIMO-MAC protocol provides this capability while supporting multi-hop ad hoc networks through novel schemes for channel access, segmentation/reassembly, ARQ and link adaptation. This paper discusses the challenges and tradeoffs involved in developing a MAC for real MIMO hardware, and briefly describes a subset of our solutions to them.

  4. Feedback Reduction in Uplink MIMO OFDM Systems by Chunk Optimization

    NASA Astrophysics Data System (ADS)

    Jorswieck, Eduard; Sezgin, Aydin; Ottersten, Björn; Paulraj, Arogyaswami

    2007-12-01

    The performance of multiuser MIMO systems can be significantly increased by channel-aware scheduling and signal processing at the transmitters based on channel state information. In the multipleantenna uplink multicarrier scenario, the base station decides centrally on the optimal signal processing and spectral power allocation as well as scheduling. An interesting challenge is the reduction of the overhead in order to inform the mobiles about their transmit strategies. In this work, we propose to reduce the feedback by chunk processing and quantization. We maximize the weighted sum rate of a MIMO OFDM MAC under individual power constraints and chunk size constraints. An efficient iterative algorithm is developed and convergence is proved. The feedback overhead as a function of the chunk size is considered in the rate computation and the optimal chunk size is determined by numerical simulations for various channel models. Finally, the issues of finite modulation and coding schemes as well as quantization of the precoding matrices are addressed.

  5. Time-Domain Receiver Design for MIMO Underwater Acoustic Communications

    DTIC Science & Technology

    2008-09-01

    is also estimated with LFM signal by measuring the span of the LFM correlation main ridge [20]. It’s shown that for all MIMO subchannels , most of the...Obviously, over the de- picted delay spread of 15 ms, each of the subchannels contains two CIR peaks located at 2 ms and 6 ms, respectively, and we chose 10

  6. Structural correlates of selectivity and inactivation in potassium channels

    PubMed Central

    McCoy, Jason G.; Nimigean, Crina M.

    2011-01-01

    Potassium channels are involved in a tremendously diverse range of physiological applications requiring distinctly different functional properties. Not surprisingly, the amino acid sequences for these proteins are diverse as well, except for the region that has been ordained the “selectivity filter”. The goal of this review is to examine our current understanding of the role of the selectivity filter and regions adjacent to it in specifying selectivity as well as its role in gating/inactivation and possible mechanisms by which these processes are coupled. Our working hypothesis is that an amino acid network behind the filter modulates selectivity in channels with the same signature sequence while at the same time affecting channel inactivation properties. PMID:21958666

  7. Zero-forcing pre-coding for MIMO WiMAX transceivers: Performance analysis and implementation issues

    NASA Astrophysics Data System (ADS)

    Cattoni, A. F.; Le Moullec, Y.; Sacchi, C.

    Next generation wireless communication networks are expected to achieve ever increasing data rates. Multi-User Multiple-Input-Multiple-Output (MU-MIMO) is a key technique to obtain the expected performance, because such a technique combines the high capacity achievable using MIMO channel with the benefits of space division multiple access. In MU-MIMO systems, the base stations transmit signals to two or more users over the same channel, for this reason every user can experience inter-user interference. This paper provides a capacity analysis of an online, interference-based pre-coding algorithm able to mitigate the multi-user interference of the MU-MIMO systems in the context of a realistic WiMAX application scenario. Simulation results show that pre-coding can significantly increase the channel capacity. Furthermore, the paper presents several feasibility considerations for implementation of the analyzed technique in a possible FPGA-based software defined radio.

  8. Color-Space-Based Visual-MIMO for V2X Communication †

    PubMed Central

    Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

    2016-01-01

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance. PMID:27120603

  9. Color-Space-Based Visual-MIMO for V2X Communication.

    PubMed

    Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

    2016-04-23

    In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.

  10. Multi-pair two-way massive MIMO AF relaying with ZFR/ZFT beamforming and imperfect CSI over ricean fading channels

    NASA Astrophysics Data System (ADS)

    Xu, Kui; Sun, Xiaoli; Zhang, Dongmei

    2016-10-01

    This paper investigates the spectral and energy efficiencies of a multi-pair two-way amplify-and-forward (AF) relay system over Ricean fading channels, where multiple user-pairs exchange information within pair through a relay with very large number of antennas, while each user equipped with a single antenna. Firstly, beamforming matrixe of zero-forcing reception/zero-forcing transmission (ZFR/ZFT) with imperfect channel state information (CSI) at the relay is given. Then, the unified asymptotic signal-to-interference-plus-noise ratio (SINR) expressions with imperfect CSI are obtained analytically. Finally, two power scaling schemes are proposed and the asymptotic spectral and energy efficiencies based on the proposed power scaling schemes are derived and verified by the Monte-Carlo simulations. Theoretical analyses and simulation results show that with imperfect CSI, if the number of relay antennas grows asymptotically large, we need cut down the transmit power of each user and relay to different proportion when the Ricean K-factor is non-zero and zero (Rayleigh fading) in order to maintain a desirable rate.

  11. Improved Stack Algorithm for MIMO Wireless Communication Systems

    NASA Astrophysics Data System (ADS)

    Liu, Li; Wang, Jinkuan; Yan, Dongmei; Du, Ruiyan; Wang, Bin

    The use of multiple antennas at both transmitter and receiver can increase wireless communication system capacity enormously. The optimal detection algorithm for MIMO system is Maximum likelihood detection (MLD) algorithm, which provides the best bit error rate (BER) performance for MIMO system. However, the computational complexity of MLD algorithm grows exponentially with the number of transmit antennas and the order of modulation. An improved MIMO detection algorithm which combined M-algorithm with stack algorithm was presented in this paper. The proposed algorithm was a multistage detection which was consisted with three parts: MLD, M-algorithm and stack algorithm. In MIMO communication system with m transmit antennas, after performing QR decomposition of the channel matrix, the MLD with length L was done firstly. The partial accumulated metrics were calculated and sorted, which produced an ordered set. Then selecting the first M partial symbol vectors to form a new ordered set. Based on the new ordered set, stack algorithm was performed to search for the symbols with the minimum accumulated metrics. The proposed algorithm combining M algorithm and stack algorithm reduced numbers of ordering with the original stack algorithm, the probability of look back and improving the detection performance.

  12. Optimal Power Schedule for Distributed MIMO Links

    DTIC Science & Technology

    2006-11-01

    INTRODUCTION A multiple - input multiple - output ( MIMO ) wireless link is well known to provide a much higher capacity than a single- input single- output ...However, for a wireless network of multiple distributed MIMO links, such as a network in the future combat sys- tems, there are new issues of research...The existing MIMO theory is not sufficient for such a wireless network where multiple MIMO links cause mutual interferences to each other. This

  13. A 32-channel photon counting module with embedded auto/cross-correlators for real-time parallel fluorescence correlation spectroscopy

    SciTech Connect

    Gong, S.; Labanca, I.; Rech, I.; Ghioni, M.

    2014-10-15

    Fluorescence correlation spectroscopy (FCS) is a well-established technique to study binding interactions or the diffusion of fluorescently labeled biomolecules in vitro and in vivo. Fast FCS experiments require parallel data acquisition and analysis which can be achieved by exploiting a multi-channel Single Photon Avalanche Diode (SPAD) array and a corresponding multi-input correlator. This paper reports a 32-channel FPGA based correlator able to perform 32 auto/cross-correlations simultaneously over a lag-time ranging from 10 ns up to 150 ms. The correlator is included in a 32 × 1 SPAD array module, providing a compact and flexible instrument for high throughput FCS experiments. However, some inherent features of SPAD arrays, namely afterpulsing and optical crosstalk effects, may introduce distortions in the measurement of auto- and cross-correlation functions. We investigated these limitations to assess their impact on the module and evaluate possible workarounds.

  14. A 32-channel photon counting module with embedded auto/cross-correlators for real-time parallel fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Gong, S.; Labanca, I.; Rech, I.; Ghioni, M.

    2014-10-01

    Fluorescence correlation spectroscopy (FCS) is a well-established technique to study binding interactions or the diffusion of fluorescently labeled biomolecules in vitro and in vivo. Fast FCS experiments require parallel data acquisition and analysis which can be achieved by exploiting a multi-channel Single Photon Avalanche Diode (SPAD) array and a corresponding multi-input correlator. This paper reports a 32-channel FPGA based correlator able to perform 32 auto/cross-correlations simultaneously over a lag-time ranging from 10 ns up to 150 ms. The correlator is included in a 32 × 1 SPAD array module, providing a compact and flexible instrument for high throughput FCS experiments. However, some inherent features of SPAD arrays, namely afterpulsing and optical crosstalk effects, may introduce distortions in the measurement of auto- and cross-correlation functions. We investigated these limitations to assess their impact on the module and evaluate possible workarounds.

  15. A 32-channel photon counting module with embedded auto/cross-correlators for real-time parallel fluorescence correlation spectroscopy

    PubMed Central

    Gong, S.; Labanca, I.; Rech, I.; Ghioni, M.

    2014-01-01

    Fluorescence correlation spectroscopy (FCS) is a well-established technique to study binding interactions or the diffusion of fluorescently labeled biomolecules in vitro and in vivo. Fast FCS experiments require parallel data acquisition and analysis which can be achieved by exploiting a multi-channel Single Photon Avalanche Diode (SPAD) array and a corresponding multi-input correlator. This paper reports a 32-channel FPGA based correlator able to perform 32 auto/cross-correlations simultaneously over a lag-time ranging from 10 ns up to 150 ms. The correlator is included in a 32 × 1 SPAD array module, providing a compact and flexible instrument for high throughput FCS experiments. However, some inherent features of SPAD arrays, namely afterpulsing and optical crosstalk effects, may introduce distortions in the measurement of auto- and cross-correlation functions. We investigated these limitations to assess their impact on the module and evaluate possible workarounds. PMID:25362365

  16. Neuromodulation independently determines correlated channel expression and conductance levels in motor neurons of the stomatogastric ganglion.

    PubMed

    Temporal, Simone; Desai, Mohati; Khorkova, Olga; Varghese, Gladis; Dai, Aihua; Schulz, David J; Golowasch, Jorge

    2012-01-01

    Neuronal identity depends on the regulated expression of numerous molecular components, especially ionic channels, which determine the electrical signature of a neuron. Such regulation depends on at least two key factors, activity itself and neuromodulatory input. Neuronal electrical activity can modify the expression of ionic currents in homeostatic or nonhomeostatic fashion. Neuromodulators typically modify activity by regulating the properties or expression levels of subsets of ionic channels. In the stomatogastric system of crustaceans, both types of regulation have been demonstrated. Furthermore, the regulation of the coordinated expression of ionic currents and the channels that carry these currents has been recently reported in diverse neuronal systems, with neuromodulators not only controlling the absolute levels of ionic current expression but also, over long periods of time, appearing to modify their correlated expression. We hypothesize that neuromodulators may regulate the correlated expression of ion channels at multiple levels and in a cell-type-dependent fashion. We report that in two identified neuronal types, three ionic currents are linearly correlated in a pairwise manner, suggesting their coexpression or direct interactions, under normal neuromodulatory conditions. In each cell, some currents remain correlated after neuromodulatory input is removed, whereas the correlations between the other pairs are either lost or altered. Interestingly, in each cell, a different suite of currents change their correlation. At the transcript level we observe distinct alterations in correlations between channel mRNA amounts, including one of the cell types lacking a correlation under normal neuromodulatory conditions and then gaining the correlation when neuromodulators are removed. Synaptic activity does not appear to contribute, with one possible exception, to the correlated expression of either ionic currents or of the transcripts that code for the respective

  17. Performance Analysis of Beamforming in Fixed-gain AF Relay Networks with Asymmetric Correlated Fading Channels

    NASA Astrophysics Data System (ADS)

    Li, Min

    2014-07-01

    In this paper, the performance of beamforming (BF) for a dual-hop amplify-and-forward (AF) relay network, where the source and destination are each equipped with multiple antennas, is investigated. It is assumed that the source-relay and relay-destination channels experience mixed fading distributions, namely, correlated Nakagami-m/Rician and correlated Rician/Nakagami-m, respectively. By considering fixed-gain relaying, analytical expressions for outage probability (OP) and average symbol error rate (ASER) are derived in closed-form. Numerical results are presented to demonstrate the efficacy of our performance analysis, also illustrate the impact of channel correlation, fading severity, Rician factor and antenna configuration on the performance of the system. It is shown that the correlated Nakagami-m/Rician fading channel can achieve better performance than the correlated Rician/Nakagami-m fading channel with the increase of fading severity parameter, and the correlated Rician/Nakagami-m fading channel may outperform the correlated Nakagami-m/Rician fading channel by enlarging the Rician factor.

  18. Generation and protection of steady-state quantum correlations due to quantum channels with memory

    NASA Astrophysics Data System (ADS)

    Guo, You-neng; Fang, Mao-fa; Wang, Guo-you; Zeng, Ke

    2016-12-01

    We have proposed a scheme of the generation and preservation of two-qubit steady-state quantum correlations through quantum channels where successive uses of the channels are correlated. Different types of noisy channels with memory, such as amplitude damping, phase damping, and depolarizing channels, have been taken into account. Some analytical or numerical results are presented. The effect of channels with memory on dynamics of quantum correlations has been discussed in detail. The results show that steady-state entanglement between two initial qubits whose initial states are prepared in a specific family states without entanglement subject to amplitude damping channel with memory can be generated. The entanglement creation is related to the memory coefficient of channel μ . The stronger the memory coefficient of channel μ is, the more the entanglement creation is, and the earlier the separable state becomes the entangled state. Besides, we compare the dynamics of entanglement with that of quantum discord when a two-qubit system is initially prepared in an entangled state. We show that entanglement dynamics suddenly disappears, while quantum discord dynamics displays only in the asymptotic limit. Furthermore, two-qubit quantum correlations can be preserved at a long time in the limit of μ → 1.

  19. Evaluation of Correlations of Flow Boiling Heat Transfer of R22 in Horizontal Channels

    PubMed Central

    Fang, Xiande; Li, Dingkun

    2013-01-01

    The calculation of two-phase flow boiling heat transfer of R22 in channels is required in a variety of applications, such as chemical process cooling systems, refrigeration, and air conditioning. A number of correlations for flow boiling heat transfer in channels have been proposed. This work evaluates the existing correlations for flow boiling heat transfer coefficient with 1669 experimental data points of flow boiling heat transfer of R22 collected from 18 published papers. The top two correlations for R22 are those of Liu and Winterton (1991) and Fang (2013), with the mean absolute deviation of 32.7% and 32.8%, respectively. More studies should be carried out to develop better ones. Effects of channel dimension and vapor quality on heat transfer are analyzed, and the results provide valuable information for further research in the correlation of two-phase flow boiling heat transfer of R22 in channels. PMID:23956695

  20. Evaluation of correlations of flow boiling heat transfer of R22 in horizontal channels.

    PubMed

    Zhou, Zhanru; Fang, Xiande; Li, Dingkun

    2013-01-01

    The calculation of two-phase flow boiling heat transfer of R22 in channels is required in a variety of applications, such as chemical process cooling systems, refrigeration, and air conditioning. A number of correlations for flow boiling heat transfer in channels have been proposed. This work evaluates the existing correlations for flow boiling heat transfer coefficient with 1669 experimental data points of flow boiling heat transfer of R22 collected from 18 published papers. The top two correlations for R22 are those of Liu and Winterton (1991) and Fang (2013), with the mean absolute deviation of 32.7% and 32.8%, respectively. More studies should be carried out to develop better ones. Effects of channel dimension and vapor quality on heat transfer are analyzed, and the results provide valuable information for further research in the correlation of two-phase flow boiling heat transfer of R22 in channels.

  1. A 1 GHz sample rate, 256-channel, 1-bit quantization, CMOS, digital correlator chip

    NASA Technical Reports Server (NTRS)

    Timoc, C.; Tran, T.; Wongso, J.

    1992-01-01

    This paper describes the development of a digital correlator chip with the following features: 1 Giga-sample/second; 256 channels; 1-bit quantization; 32-bit counters providing up to 4 seconds integration time at 1 GHz; and very low power dissipation per channel. The improvements in the performance-to-cost ratio of the digital correlator chip are achieved with a combination of systolic architecture, novel pipelined differential logic circuits, and standard 1.0 micron CMOS process.

  2. Automatic detection of noisy channels in fNIRS signal based on correlation analysis.

    PubMed

    Guerrero-Mosquera, Carlos; Borragán, Guillermo; Peigneux, Philippe

    2016-09-15

    fNIRS signals can be contaminated by distinct sources of noise. While most of the noise can be corrected using digital filters, optimized experimental paradigms or pre-processing methods, few approaches focus on the automatic detection of noisy channels. In the present study, we propose a new method that detect automatically noisy fNIRS channels by combining the global correlations of the signal obtained from sliding windows (Cui et al., 2010) with correlation coefficients extracted experimental conditions defined by triggers. The validity of the method was evaluated on test data from 17 participants, for a total of 16 NIRS channels per subject, positioned over frontal, dorsolateral prefrontal, parietal and occipital areas. Additionally, the detection of noisy channels was tested in the context of different levels of cognitive requirement in a working memory N-back paradigm. Bad channels detection accuracy, defined as the proportion of bad NIRS channels correctly detected among the total number of channels examined, was close to 91%. Under different cognitive conditions the area under the Receiver Operating Curve (AUC) increased from 60.5% (global correlations) to 91.2% (local correlations). Our results show that global correlations are insufficient for detecting potentially noisy channels when the whole data signal is included in the analysis. In contrast, adding specific local information inherent to the experimental paradigm (e.g., cognitive conditions in a block or event-related design), improved detection performance for noisy channels. Also, we show that automated fNIRS channel detection can be achieved with high accuracy at low computational cost. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Leakage-based precoding for MU-MIMO VLC systems under optical power constraint

    NASA Astrophysics Data System (ADS)

    Chen, Jiaxuan; Wang, Qi; Wang, Zhaocheng

    2017-01-01

    In this paper, we investigate a multiuser multiple-input multiple-output (MU-MIMO) system for indoor visible light communication (VLC), in which precoding is conducted under optical power constraint rather than electrical power constraint. Leakage-based precoding designed by maximizing signal-to-leakage-plus-noise ratio (SLNR) is adopted to suppress the multiuser interference under optical power constraint and power allocation is proposed to maximize the throughput of the system. Simulations demonstrate the performance gain of optimal power allocation and indicate that the leakage-based precoding scheme outperforms zero forcing counterpart when the channel is highly correlated and still works well when the number of transmitters is less than that of receivers.

  4. Free-space optical communications using orbital-angular-momentum multiplexing combined with MIMO-based spatial multiplexing.

    PubMed

    Ren, Yongxiong; Wang, Zhe; Xie, Guodong; Li, Long; Cao, Yinwen; Liu, Cong; Liao, Peicheng; Yan, Yan; Ahmed, Nisar; Zhao, Zhe; Willner, Asher; Ashrafi, Nima; Ashrafi, Solyman; Linquist, Roger D; Bock, Robert; Tur, Moshe; Molisch, Andreas F; Willner, Alan E

    2015-09-15

    We explore the potential of combining the advantages of multiple-input multiple-output (MIMO)-based spatial multiplexing with those of orbital angular momentum (OAM) multiplexing to increase the capacity of free-space optical (FSO) communications. We experimentally demonstrate an 80 Gbit/s FSO system with a 2×2 aperture architecture, in which each transmitter aperture contains two multiplexed data-carrying OAM modes. Inter-channel crosstalk effects are minimized by the OAM beams' inherent orthogonality and by the use of 4×4 MIMO signal processing. Our experimental results show that the bit-error rates can reach below the forward error correction limit of 3.8×10(-3) and the power penalties are less than 3.6 dB for all channels after MIMO processing. This indicates that OAM and MIMO-based spatial multiplexing could be simultaneously utilized, thereby providing the potential to enhance system performance.

  5. Adaptive reconfigurable V-BLAST type equalizer for cognitive MIMO-OFDM radios

    NASA Astrophysics Data System (ADS)

    Ozden, Mehmet Tahir

    2015-12-01

    An adaptive channel shortening equalizer design for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) radio receivers is considered in this presentation. The proposed receiver has desirable features for cognitive and software defined radio implementations. It consists of two sections: MIMO decision feedback equalizer (MIMO-DFE) and adaptive multiple Viterbi detection. In MIMO-DFE section, a complete modified Gram-Schmidt orthogonalization of multichannel input data is accomplished using sequential processing multichannel Givens lattice stages, so that a Vertical Bell Laboratories Layered Space Time (V-BLAST) type MIMO-DFE is realized at the front-end section of the channel shortening equalizer. Matrix operations, a major bottleneck for receiver operations, are accordingly avoided, and only scalar operations are used. A highly modular and regular radio receiver architecture that has a suitable structure for digital signal processing (DSP) chip and field programable gate array (FPGA) implementations, which are important for software defined radio realizations, is achieved. The MIMO-DFE section of the proposed receiver can also be reconfigured for spectrum sensing and positioning functions, which are important tasks for cognitive radio applications. In connection with adaptive multiple Viterbi detection section, a systolic array implementation for each channel is performed so that a receiver architecture with high computational concurrency is attained. The total computational complexity is given in terms of equalizer and desired response filter lengths, alphabet size, and number of antennas. The performance of the proposed receiver is presented for two-channel case by means of mean squared error (MSE) and probability of error evaluations, which are conducted for time-invariant and time-variant channel conditions, orthogonal and nonorthogonal transmissions, and two different modulation schemes.

  6. Time-correlation analysis of simulated water motion in flexible and rigid gramicidin channels.

    PubMed Central

    Chiu, S W; Jakobsson, E; Subramaniam, S; McCammon, J A

    1991-01-01

    Molecular dynamics simulations have been done on a system consisting of the polypeptide membrane channel former gramicidin, plus water molecules in the channel and caps of waters at the two ends of the channel. In the absence of explicit simulation of the surrounding membrane, the helical form of the channel was maintained by artificial restraints on the peptide motion. The characteristic time constant of the artificial restraint was varied to assess the effect of the restraints on the channel structure and water motions. Time-correlation analysis was done on the motions of individual channel waters and on the motions of the center of mass of the channel waters. It is found that individual water molecules confined in the channel execute higher frequency motions than bulk water, for all degrees of channel peptide restraint. The center-of-mass motion of the chain of channel waters (which is the motion that is critical for transmembrane transport, due to the mandatory single filing of water in the channel) does not exhibit these higher frequency motions. The mobility of the water chain is dramatically reduced by holding the channel rigid. Thus permeation through the channel is not like flow through a rigid pipe; rather permeation is facilitated by peptide motion. For the looser restraints we used, the mobility of the water chain was not very much affected by the degree of restraint. Depending on which set of experiments is considered, the computed mobility of our water chain in the flexible channel is four to twenty times too high to account for the experimentally measured resistance of the gramicidin channel to water flow. From this result it appears likely that the peptide motions of an actual gramicidin channel embedded in a lipid membrane may be more restrained than in our flexible channel model, and that these restraints may be a significant modulator of channel permeability. For the completely rigid channel model the "trapping" of the water molecules in

  7. Denoising Algorithm for CFA Image Sensors Considering Inter-Channel Correlation.

    PubMed

    Lee, Min Seok; Park, Sang Wook; Kang, Moon Gi

    2017-05-28

    In this paper, a spatio-spectral-temporal filter considering an inter-channel correlation is proposed for the denoising of a color filter array (CFA) sequence acquired by CCD/CMOS image sensors. Owing to the alternating under-sampled grid of the CFA pattern, the inter-channel correlation must be considered in the direct denoising process. The proposed filter is applied in the spatial, spectral, and temporal domain, considering the spatio-tempo-spectral correlation. First, nonlocal means (NLM) spatial filtering with patch-based difference (PBD) refinement is performed by considering both the intra-channel correlation and inter-channel correlation to overcome the spatial resolution degradation occurring with the alternating under-sampled pattern. Second, a motion-compensated temporal filter that employs inter-channel correlated motion estimation and compensation is proposed to remove the noise in the temporal domain. Then, a motion adaptive detection value controls the ratio of the spatial filter and the temporal filter. The denoised CFA sequence can thus be obtained without motion artifacts. Experimental results for both simulated and real CFA sequences are presented with visual and numerical comparisons to several state-of-the-art denoising methods combined with a demosaicing method. Experimental results confirmed that the proposed frameworks outperformed the other techniques in terms of the objective criteria and subjective visual perception in CFA sequences.

  8. Denoising Algorithm for CFA Image Sensors Considering Inter-Channel Correlation

    PubMed Central

    Lee, Min Seok; Park, Sang Wook; Kang, Moon Gi

    2017-01-01

    In this paper, a spatio-spectral-temporal filter considering an inter-channel correlation is proposed for the denoising of a color filter array (CFA) sequence acquired by CCD/CMOS image sensors. Owing to the alternating under-sampled grid of the CFA pattern, the inter-channel correlation must be considered in the direct denoising process. The proposed filter is applied in the spatial, spectral, and temporal domain, considering the spatio-tempo-spectral correlation. First, nonlocal means (NLM) spatial filtering with patch-based difference (PBD) refinement is performed by considering both the intra-channel correlation and inter-channel correlation to overcome the spatial resolution degradation occurring with the alternating under-sampled pattern. Second, a motion-compensated temporal filter that employs inter-channel correlated motion estimation and compensation is proposed to remove the noise in the temporal domain. Then, a motion adaptive detection value controls the ratio of the spatial filter and the temporal filter. The denoised CFA sequence can thus be obtained without motion artifacts. Experimental results for both simulated and real CFA sequences are presented with visual and numerical comparisons to several state-of-the-art denoising methods combined with a demosaicing method. Experimental results confirmed that the proposed frameworks outperformed the other techniques in terms of the objective criteria and subjective visual perception in CFA sequences. PMID:28555044

  9. The Sum-Rate Capacity of Strong Interference Channels with Correlated Messages

    NASA Astrophysics Data System (ADS)

    Choi, Suhan

    The transmission of correlated messages over strong interference channels is examined. The result is the proposal of a single-letter characterization of the sum-rate capacity of strong interference channels with correlated messages. It is shown that if the messages are independent, the sum-rate capacity is equal to that of [1] obtained by Costa and El Gamal. However, it can be larger than that of [1] if the messages are correlated. It is also shown that, in terms of the sum-rate, the achievable rate region in [2] is indeed the sum-rate capacity.

  10. Broadbeam for Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Qiao, Deli; Qian, Haifeng; Li, Geoffrey Ye

    2016-05-01

    Massive MIMO has been identified as one of the promising disruptive air interface techniques to address the huge capacity requirement demanded by 5G wireless communications. For practical deployment of such systems, the control message need to be broadcast to all users reliably in the cell using broadbeam. A broadbeam is expected to have the same radiated power in all directions to cover users in any place in a cell. In this paper, we will show that there is no perfect broadbeam. Therefore, we develop a method for generating broadbeam that can allow tiny fluctuations in radiated power. Overall, this can serve as an ingredient for practical deployment of the massive MIMO systems.

  11. Distributed MIMO-OFDM in imperfectly synchronized cooperative network

    NASA Astrophysics Data System (ADS)

    Zhang, Yimin; Wang, Genyuan; Amin, Moeness G.

    2006-05-01

    Coded space-time cooperation is an efficient approach in delivering information over a relay network. Multiple cooperative terminals (nodes) form a distributed multiple-input-multiple-output (MIMO) systems, thus providing high data rates and high diversity gains. However, unlike conventional co-located MIMO systems, it is impractical for distributed MIMO networks to maintain perfect timing synchronization between different transmit terminals. In particular, the presence of a fractional-symbol delay difference between the signals transmitted from different terminals can cause erroneous sampling positions and yield highly dispersive channels even at a memoryless channel environment. Existing methods solve such problem based on time-domain approaches where adaptive equalization is required at the receivers for combining the information transmitted from distributed sources. In this paper, we propose the use of OFDM-based approaches using distributed space-frequency codes. The proposed schemes are insensitive to fractional-symbol delays and lead to higher data rate transmission and simplified implementation. In addition, the proposed schemes permit the use of relatively simple amplify-and-forward algorithm in multi-hop wireless networks without delay accumulations. The time delay in each relaying hop by reconstructing the cyclic prefix and, as such, improve the spectral efficiency, while keeping a simple relaying structure.

  12. Hierarchical Interference Mitigation for Massive MIMO Cellular Networks

    NASA Astrophysics Data System (ADS)

    Liu, An; Lau, Vincent

    2014-09-01

    We propose a hierarchical interference mitigation scheme for massive MIMO cellular networks. The MIMO precoder at each base station (BS) is partitioned into an inner precoder and an outer precoder. The inner precoder controls the intra-cell interference and is adaptive to local channel state information (CSI) at each BS (CSIT). The outer precoder controls the inter-cell interference and is adaptive to channel statistics. Such hierarchical precoding structure reduces the number of pilot symbols required for CSI estimation in massive MIMO downlink and is robust to the backhaul latency. We study joint optimization of the outer precoders, the user selection, and the power allocation to maximize a general concave utility which has no closed-form expression. We first apply random matrix theory to obtain an approximated problem with closed-form objective. We show that the solution of the approximated problem is asymptotically optimal with respect to the original problem as the number of antennas per BS grows large. Then using the hidden convexity of the problem, we propose an iterative algorithm to find the optimal solution for the approximated problem. We also obtain a low complexity algorithm with provable convergence. Simulations show that the proposed design has significant gain over various state-of-the-art baselines.

  13. 2 × 2 MIMO radio-over-fiber system at 60 GHz employing frequency domain equalization.

    PubMed

    Lin, Chun-Ting; Ng'oma, Anthony; Lee, Wei-Yuan; Wei, Chia-Chien; Wang, Chih-Yun; Lu, Tsung-Hung; Chen, Jyehong; Jiang, Wen-Jr; Ho, Chun-Hung

    2012-01-02

    This work experimentally demonstrates the efficacy of the 2 × 2 multiple-input multiple-output (MIMO) technique for capacity improvement of a 60-GHz radio-over-fiber (RoF) system employing single-carrier modulation format. We employ frequency domain equalization (FDE) to estimate the channel response, including frequency response of the 60 GHz RoF system and the MIMO wireless channel. Using FDE and MIMO techniques, we experimentally demonstrate the doubling the of wireless data capacity of a 60 GHz RoF system to 27.15 Gb/s using 16-QAM modulation format, with transmission over 25 km of standard single-mode fiber and 3 m wireless distance.

  14. Atmospheric turbulence mitigation in an OAM-based MIMO free-space optical link using spatial diversity combined with MIMO equalization.

    PubMed

    Ren, Yongxiong; Wang, Zhe; Xie, Guodong; Li, Long; Willner, Asher J; Cao, Yinwen; Zhao, Zhe; Yan, Yan; Ahmed, Nisar; Ashrafi, Nima; Ashrafi, Solyman; Bock, Robert; Tur, Moshe; Willner, Alan E

    2016-06-01

    We explore the mitigation of atmospheric turbulence effects for orbital angular momentum (OAM)-based free-space optical (FSO) communications with multiple-input multiple-output (MIMO) architecture. Such a system employs multiple spatially separated aperture elements at the transmitter/receiver, and each transmitter aperture contains multiplexed data-carrying OAM beams. We propose to use spatial diversity combined with MIMO equalization to mitigate both weak and strong turbulence distortions. In a 2×2 FSO link with each transmitter aperture containing two multiplexed OAM modes of ℓ=+1 and ℓ=+3, we experimentally show that at least two OAM data channels could be recovered under both weak and strong turbulence distortions using selection diversity assisted with MIMO equalization.

  15. Magnetic MIMO Signal Processing and Optimization for Wireless Power Transfer

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Moghadam, Mohammad R. Vedady; Zhang, Rui

    2017-06-01

    In magnetic resonant coupling (MRC) enabled multiple-input multiple-output (MIMO) wireless power transfer (WPT) systems, multiple transmitters (TXs) each with one single coil are used to enhance the efficiency of simultaneous power transfer to multiple single-coil receivers (RXs) by constructively combining their induced magnetic fields at the RXs, a technique termed "magnetic beamforming". In this paper, we study the optimal magnetic beamforming design in a multi-user MIMO MRC-WPT system. We introduce the multi-user power region that constitutes all the achievable power tuples for all RXs, subject to the given total power constraint over all TXs as well as their individual peak voltage and current constraints. We characterize each boundary point of the power region by maximizing the sum-power deliverable to all RXs subject to their minimum harvested power constraints. For the special case without the TX peak voltage and current constraints, we derive the optimal TX current allocation for the single-RX setup in closed-form as well as that for the multi-RX setup. In general, the problem is a non-convex quadratically constrained quadratic programming (QCQP), which is difficult to solve. For the case of one single RX, we show that the semidefinite relaxation (SDR) of the problem is tight. For the general case with multiple RXs, based on SDR we obtain two approximate solutions by applying time-sharing and randomization, respectively. Moreover, for practical implementation of magnetic beamforming, we propose a novel signal processing method to estimate the magnetic MIMO channel due to the mutual inductances between TXs and RXs. Numerical results show that our proposed magnetic channel estimation and adaptive beamforming schemes are practically effective, and can significantly improve the power transfer efficiency and multi-user performance trade-off in MIMO MRC-WPT systems.

  16. Cystic fibrosis gene expression is not correlated with rectifying Cl sup minus channels

    SciTech Connect

    Ward, C.L.; Krouse, M.E.; Kopito, R.R.; Wine, J.J. ); Gruenert, D.C. )

    1991-06-15

    Cystic fibrosis (CF) involves a profound reduction of Cl{sup {minus}} permeability in several exocrine tissues. A distinctive, outwardly rectifying, depolarization-induced Cl{sup {minus}} channel (ORDIC channel) has been proposed to account for the Cl{sup {minus}} conductance that is defective in CF. The recently identified CF gene is predicted to code for a 1480-amino acid integral membrane protein termed the CF transmembrane conductance regulator (CFTR). The CFTR shares sequence similarity with a superfamily of ATP-binding membrane transport proteins such as P-glycoprotein and STE6, but it also has features consistent with an ion channel function. It has been proposed that the CFTR might be an ORDIC channel. To determine if CFTR and ORDIC channel expression are correlated, the authors surveyed various cell lines for natural variation in CFTR and ORDIC channel expression. In four human epithelial cell lines (T84, CaCo2, PANC-1, and 9HTEo-/S) that encompass the full observed range of CFTR mRNA levels and ORDIC channel density the authors found no correlation.

  17. A New User Selection Measure in Block Diagonalization Algorithm for Multiuser MIMO Systems

    NASA Astrophysics Data System (ADS)

    Kudo, Riichi; Takatori, Yasushi; Nishimori, Kentaro; Ohta, Atsushi; Kubota, Shuji; Mizoguchi, Masato

    Multiuser — Multiple Input Multiple Output (MU-MIMO) techniques were proposed to increase spectrum efficiency; a key assumption was that the Mobile Terminals (MTs) were simple with only a few antennas. This paper focuses on the Block Diagonalization algorithm (BD) based on the equal power allocation strategy as a practical MU-MIMO technique. When there are many MTs inside the service area of the access point (AP), the AP must determine, at each time slot, the subset of the MTs to be spatially multiplexed. Since the transmission performance depends on the subsets of MTs, the user selection method needs to use the Channel State Information (CSI) obtained in the physical layer to maximize the Achievable Transmission Rate (ATR). In this paper, we clarify the relationship between ATR with SU-MIMO and that with MU-MIMO in a high eigenvalue channel. Based on the derived relationship, we propose a new measure for user selection. The new measure, the eigenvalue decay factor, represents the degradation of the eigenvalues in null space compared to those in SU-MIMO; it is obtained from the signal space vectors of the MTs. A user selection method based on the proposed measure identifies the combination of MTs that yields the highest ATR; our approach also reduces the computational load of user selection. We evaluate the effectiveness of user selection with the new measure using numerical formulations and computer simulations.

  18. Optimal Data Transmission on MIMO OFDM Channels

    DTIC Science & Technology

    2008-12-01

    ter facultado a possibilidade de enriquecer o meu conhecimento académico. Quando il mio maestro e mentore di tesi Roberto Cristi la ringrazio per la...Convolution Encoder [171,133] RSn puncture RSn2 CC RS r nn = ]0,1,1,0,0,1,1,0,1,1[,6/5 ]0,1,1,0,1,1[,4/3 ]1,0,1,1[,3/2 ]1,1[,2/1 == == == == Pr Pr Pr Pr CC

  19. Hidden Markov modeling for single channel kinetics with filtering and correlated noise.

    PubMed Central

    Qin, F; Auerbach, A; Sachs, F

    2000-01-01

    Hidden Markov modeling (HMM) can be applied to extract single channel kinetics at signal-to-noise ratios that are too low for conventional analysis. There are two general HMM approaches: traditional Baum's reestimation and direct optimization. The optimization approach has the advantage that it optimizes the rate constants directly. This allows setting constraints on the rate constants, fitting multiple data sets across different experimental conditions, and handling nonstationary channels where the starting probability of the channel depends on the unknown kinetics. We present here an extension of this approach that addresses the additional issues of low-pass filtering and correlated noise. The filtering is modeled using a finite impulse response (FIR) filter applied to the underlying signal, and the noise correlation is accounted for using an autoregressive (AR) process. In addition to correlated background noise, the algorithm allows for excess open channel noise that can be white or correlated. To maximize the efficiency of the algorithm, we derive the analytical derivatives of the likelihood function with respect to all unknown model parameters. The search of the likelihood space is performed using a variable metric method. Extension of the algorithm to data containing multiple channels is described. Examples are presented that demonstrate the applicability and effectiveness of the algorithm. Practical issues such as the selection of appropriate noise AR orders are also discussed through examples. PMID:11023898

  20. Uplink transmit beamforming design for SINR maximization with full multiuser channel state information

    NASA Astrophysics Data System (ADS)

    Xi, Songnan; Zoltowski, Michael D.

    2008-04-01

    Multiuser multiple-input multiple-output (MIMO) systems are considered in this paper. We continue our research on uplink transmit beamforming design for multiple users under the assumption that the full multiuser channel state information, which is the collection of the channel state information between each of the users and the base station, is known not only to the receiver but also to all the transmitters. We propose an algorithm for designing optimal beamforming weights in terms of maximizing the signal-to-interference-plus-noise ratio (SINR). Through statistical modeling, we decouple the original mathematically intractable optimization problem and achieved a closed-form solution. As in our previous work, the minimum mean-squared error (MMSE) receiver with successive interference cancellation (SIC) is adopted for multiuser detection. The proposed scheme is compared with an existing jointly optimized transceiver design, referred to as the joint transceiver in this paper, and our previously proposed eigen-beamforming algorithm. Simulation results demonstrate that our algorithm, with much less computational burden, accomplishes almost the same performance as the joint transceiver for spatially independent MIMO channel and even better performance for spatially correlated MIMO channels. And it always works better than our previously proposed eigen beamforming algorithm.

  1. Distributed Compressive CSIT Estimation and Feedback for FDD Multi-User Massive MIMO Systems

    NASA Astrophysics Data System (ADS)

    Rao, Xiongbin; Lau, Vincent K. N.

    2014-06-01

    To fully utilize the spatial multiplexing gains or array gains of massive MIMO, the channel state information must be obtained at the transmitter side (CSIT). However, conventional CSIT estimation approaches are not suitable for FDD massive MIMO systems because of the overwhelming training and feedback overhead. In this paper, we consider multi-user massive MIMO systems and deploy the compressive sensing (CS) technique to reduce the training as well as the feedback overhead in the CSIT estimation. The multi-user massive MIMO systems exhibits a hidden joint sparsity structure in the user channel matrices due to the shared local scatterers in the physical propagation environment. As such, instead of naively applying the conventional CS to the CSIT estimation, we propose a distributed compressive CSIT estimation scheme so that the compressed measurements are observed at the users locally, while the CSIT recovery is performed at the base station jointly. A joint orthogonal matching pursuit recovery algorithm is proposed to perform the CSIT recovery, with the capability of exploiting the hidden joint sparsity in the user channel matrices. We analyze the obtained CSIT quality in terms of the normalized mean absolute error, and through the closed-form expressions, we obtain simple insights into how the joint channel sparsity can be exploited to improve the CSIT recovery performance.

  2. Avoiding disentanglement of multipartite entangled optical beams with a correlated noisy channel

    PubMed Central

    Deng, Xiaowei; Tian, Caixing; Su, Xiaolong; Xie, Changde

    2017-01-01

    A quantum communication network can be constructed by distributing a multipartite entangled state to space-separated nodes. Entangled optical beams with highest flying speed and measurable brightness can be used as carriers to convey information in quantum communication networks. Losses and noises existing in real communication channels will reduce or even totally destroy entanglement. The phenomenon of disentanglement will result in the complete failure of quantum communication. Here, we present the experimental demonstrations on the disentanglement and the entanglement revival of tripartite entangled optical beams used in a quantum network. We experimentally demonstrate that symmetric tripartite entangled optical beams are robust in pure lossy but noiseless channels. In a noisy channel, the excess noise will lead to the disentanglement and the destroyed entanglement can be revived by the use of a correlated noisy channel (non-Markovian environment). The presented results provide useful technical references for establishing quantum networks. PMID:28295024

  3. Avoiding disentanglement of multipartite entangled optical beams with a correlated noisy channel

    NASA Astrophysics Data System (ADS)

    Deng, Xiaowei; Tian, Caixing; Su, Xiaolong; Xie, Changde

    2017-03-01

    A quantum communication network can be constructed by distributing a multipartite entangled state to space-separated nodes. Entangled optical beams with highest flying speed and measurable brightness can be used as carriers to convey information in quantum communication networks. Losses and noises existing in real communication channels will reduce or even totally destroy entanglement. The phenomenon of disentanglement will result in the complete failure of quantum communication. Here, we present the experimental demonstrations on the disentanglement and the entanglement revival of tripartite entangled optical beams used in a quantum network. We experimentally demonstrate that symmetric tripartite entangled optical beams are robust in pure lossy but noiseless channels. In a noisy channel, the excess noise will lead to the disentanglement and the destroyed entanglement can be revived by the use of a correlated noisy channel (non-Markovian environment). The presented results provide useful technical references for establishing quantum networks.

  4. On the reliable decentralised stabilisation of n MIMO systems

    NASA Astrophysics Data System (ADS)

    Befekadu, Getachew K.; Gupta, Vijay; Antsaklis, Panos J.

    2014-08-01

    In this paper, we consider the problem of reliable decentralised stabilisation for n multi-input multi-output (MIMO) systems when some of the shared controllers among these systems are faulty, in the sense that they fail to operate properly due to subsystem (module) failures that may occur in actuators, sensors or controllers. Specifically, we present a design framework using a dilated linear matrix inequalities (LMIs) technique for deriving reliable stabilising state-feedback gains for all n MIMO systems; while a set of decentralised unknown disturbance observers (UDOs) that are shared by all n MIMO systems is used for extending the result to the output-feedback case. Moreover, a sufficient condition for the solvability of the set of decentralised UDOs is given in terms of a minimum-phase condition of each subsystem and a lower-bounding condition on the number of outputs of each channel. We also present a numerical example that illustrates the applicability of the proposed technique.

  5. Multiple-Optimizing Dynamic Sensor Networks with MIMO Technology (PREPRINT)

    DTIC Science & Technology

    2010-06-01

    Multiple - Input Multiple - Output ( MIMO ) transceiver...wchen@tnstate.edu, hmiao@tnstate.edu, havokjinx@gmial.com) Abstract: A Multiple - Input Multiple - Output ( MIMO ) transceiver provides extremely high...After comparing the simulation results in SISO (Single Input Single Output ), 2×2 MIMO and 4×4 MIMO WSNs for different filed size,

  6. Energy-efficient constellations design and fast decoding for space-collaborative MIMO visible light communications

    NASA Astrophysics Data System (ADS)

    Zhu, Yi-Jun; Liang, Wang-Feng; Wang, Chao; Wang, Wen-Ya

    2017-01-01

    In this paper, space-collaborative constellations (SCCs) for indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems are considered. Compared with traditional VLC MIMO techniques, such as repetition coding (RC), spatial modulation (SM) and spatial multiplexing (SMP), SCC achieves the minimum average optical power for a fixed minimum Euclidean distance. We have presented a unified SCC structure for 2×2 MIMO VLC systems and extended it to larger MIMO VLC systems with more transceivers. Specifically for 2×2 MIMO VLC, a fast decoding algorithm is developed with decoding complexity almost linear in terms of the square root of the cardinality of SCC, and the expressions of symbol error rate of SCC are presented. In addition, bit mappings similar to Gray mapping are proposed for SCC. Computer simulations are performed to verify the fast decoding algorithm and the performance of SCC, and the results demonstrate that the performance of SCC is better than those of RC, SM and SMP for indoor channels in general.

  7. Unified tensor model for space-frequency spreading-multiplexing (SFSM) MIMO communication systems

    NASA Astrophysics Data System (ADS)

    de Almeida, André LF; Favier, Gérard

    2013-12-01

    This paper presents a unified tensor model for space-frequency spreading-multiplexing (SFSM) multiple-input multiple-output (MIMO) wireless communication systems that combine space- and frequency-domain spreadings, followed by a space-frequency multiplexing. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades and provides space and frequency diversities, while orthogonal space-frequency multiplexing enables multi-stream transmission. We adopt a tensor-based formulation for the proposed SFSM MIMO system that incorporates space, frequency, time, and code dimensions by means of the parallel factor model. The developed SFSM tensor model unifies the tensorial formulation of some existing multiple-access/multicarrier MIMO signaling schemes as special cases, while revealing interesting tradeoffs due to combined space, frequency, and time diversities which are of practical relevance for joint symbol-channel-code estimation. The performance of the proposed SFSM MIMO system using either a zero forcing receiver or a semi-blind tensor-based receiver is illustrated by means of computer simulation results under realistic channel and system parameters.

  8. Joint Antenna Selection for Achieving Diversity in a Two-Way Relaying Channel

    NASA Astrophysics Data System (ADS)

    Xu, Kun; Gao, Yuanyuan; Yi, Xiaoxin; Yang, Weiwei

    Joint transmit and receive antenna selection (JTRAS) is proposed for the multiple-input multiple-output (MIMO) two-way relaying channel. A simple and closed-form lower bound on the outage probability of JTRAS is derived. Furthermore, asymptotic analysis reveals that JTRAS can attain the maximum achievable diversity order of the MIMO dual-hop relaying channel.

  9. Transmission Subspace Tracing for MIMO Communications Systems

    DTIC Science & Technology

    2001-11-01

    multiple - input multiple - output ( MIMO ...3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE TRANSMISSION SUBSPACE TRACKING FOR MULTIPLE - INPUT MULTIPLE - OUPUT ( MIMO ) COMMUNICATIONS SYSTEMS...publications/pubs/index.html 14. ABSTRACT This paper describes the benefits of transmission subspace tracking for multiple input multiple output

  10. Gaussian capacity of the quantum bosonic memory channel with additive correlated Gaussian noise

    SciTech Connect

    Schaefer, Joachim; Karpov, Evgueni; Cerf, Nicolas J.

    2011-09-15

    We present an algorithm for calculation of the Gaussian classical capacity of a quantum bosonic memory channel with additive Gaussian noise. The algorithm, restricted to Gaussian input states, is applicable to all channels with noise correlations obeying certain conditions and works in the full input energy domain, beyond previous treatments of this problem. As an illustration, we study the optimal input states and capacity of a quantum memory channel with Gauss-Markov noise [J. Schaefer, Phys. Rev. A 80, 062313 (2009)]. We evaluate the enhancement of the transmission rate when using these optimal entangled input states by comparison with a product coherent-state encoding and find out that such a simple coherent-state encoding achieves not less than 90% of the capacity.

  11. Correlation among Channeling, Morphological and Micro-structural Properties in Epitaxial CeO2 Films

    SciTech Connect

    Saraf, Laxmikant V.; McCready, David E.; Shutthanandan, V.; Wang, Chong M.; Engelhard, Mark H.; Thevuthasan, Suntharampillai

    2006-03-20

    We report an evidence of a critical thickness at ~ 64 nm in epitaxial CeO2 films grown at 750 0C on YSZ substrates by dc magnetron sputtering where optimum ion channeling can be correlated with overall strain relaxation and film surface roughness. The occurrence of saturation in ion channeling yield, enhancement in the average surface roughness and relaxation in c-axis strain is clearly evident in thicker films beyond the critical thickness. Despite excellent surface smoothness and overall epitaxial growth, CeO2 films grown at 650 0C did not show optimum ion channeling properties due to high misfit dislocation and defect density. These results are discussed from a viewpoint of the need for such an optimum thickness to develop multilayers with smooth interfaces with relative overall lattice relaxation.

  12. [TRP calcium channel and breast cancer: expression, role and correlation with clinical parameters].

    PubMed

    Ouadid-Ahidouch, Halima; Dhennin-Duthille, Isabelle; Gautier, Mathieu; Sevestre, Henri; Ahidouch, Ahmed

    2012-06-01

    Breast cancer (BC) has the highest incidence rate in women in industrialized countries. Statistically, it is estimated that one out of 10 women will develop BC during her life. Evidence is accumulating for the role of ion channels in the development of cancer. Most studied ion channels in BC are K(+) channels, which are involved in cell proliferation, cell cycle progression and cell migration, and Na(+) channels, which correlate with invasiveness. Emerging studies demonstrated the role of Ca(2+) signaling in cancer cell proliferation, survival and migration. Recent findings demonstrated that the expression and/or activity of the transient receptor potential (TRP) channels are altered in several cancers. Among the TRP families, TRPC (canonical or classical), TRPM (melastatin) and TRPV (vanilloid) are related to malignant growth and cancer progression. Although these channels are frequently and abundantly expressed in many tumors, their specific expression, activity and roles in BC are still poorly understood. The expression of TRP channels has also been proposed as a tool for diagnosis, prognosis and/or therapeutic issues of several diseases. In cancer, TRPV6 and TRPM8 have been proposed as tumor progression markers of prostate cancer outcome and TRPC6 as a novel therapeutic target for esophageal carcinoma. Interestingly high levels of TRPC3 expression correlate with a favorable prognosis in patients with lung adenocarcinoma. Our team has recently reported the expression and role of TRPC1, TRPC6, TRPM7, TRPM8 and TRPV6 in BC cell lines and primary cultures. We have also investigated TRP expression and their clinical significance in human breast adenocarcinoma and we suggest that TRP channels are new potential BC markers. Indeed TRPC1 and TRPM8 may be considered as good prognosis markers of well-differentiated tumors, TRPM7 as a proliferative marker of poorly differentiated tumors and TRPV6 as a prognosis marker of aggressive cancers. In this review, we summarize the

  13. Channels

    NASA Image and Video Library

    2014-04-29

    Two channels are visible in this image from NASA 2001 Mars Odyssey spacecraft . The smaller one near the bottom did not carve as deeply as the larger channel at the top. The channel near the top of the image is near the origin of Mamers Valles.

  14. Quantum-correlation breaking channels, broadcasting scenarios, and finite Markov chains

    NASA Astrophysics Data System (ADS)

    Korbicz, J. K.; Horodecki, P.; Horodecki, R.

    2012-10-01

    One of the classical results concerning quantum channels is the characterization of entanglement-breaking channels [M. Horodecki, P. W. Shor, and M. B. Ruskai, Rev. Math. Phys.RMPHEX0129-055X10.1142/S0129055X03001709 15, 629 (2003)]. We address the question whether there exists a similar characterization on the level of quantum correlations which may go beyond entanglement. The answer is fully affirmative in the case of breaking quantum correlations down to the, so-called, QC (quantum-classical) type, while it is no longer true in the CC (classical-classical) case. The corresponding channels turn out to be measurement maps. Our study also reveals an unexpected link between quantum state and local correlation broadcasting and finite Markov chains. We present a possibility of broadcasting via non von Neumann measurements, which relies on the Perron-Frobenius theorem. Surprisingly, this is not the typical generalized controlled-not (c-not) gate scenario appearing naturally in this context.

  15. Quantum correlations in Gaussian states via Gaussian channels: steering, entanglement, and discord

    NASA Astrophysics Data System (ADS)

    Wang, Zhong-Xiao; Wang, Shuhao; Li, Qiting; Wang, Tie-Jun; Wang, Chuan

    2016-06-01

    Here we study the quantum steering, quantum entanglement, and quantum discord for Gaussian Einstein-Podolsky-Rosen states via Gaussian channels. And the sudden death phenomena for Gaussian steering and Gaussian entanglement are theoretically observed. We find that some Gaussian states have only one-way steering, which confirms the asymmetry of quantum steering. Also we investigate that the entangled Gaussian states without Gaussian steering and correlated Gaussian states own no Gaussian entanglement. Meanwhile, our results support the assumption that quantum entanglement is intermediate between quantum discord and quantum steering. Furthermore, we give experimental recipes for preparing quantum states with desired types of quantum correlations.

  16. A revised correlation based on heat transfer model of slug flow in mini/micro-channels

    NASA Astrophysics Data System (ADS)

    Li, Xuejiao; Jia, Li; Yin, Liaofei; An, Zhoujian

    2017-07-01

    As flow boiling in mini/micro-channel, slug flow was corresponding to the optimal heat transfer ability owing to the evaporation of thin liquid film. Based on the heat transfer mechanism of liquid film evaporation, a simplified heat transfer model of slug flow was proposed. Li-Wu heat transfer correlation (Int J Heat Mass Transf 53(9): 1778-1787, 2010) was revised by introducing evaporation parameter, C e . With the evaporation parameter, C e , the revised correlation predicted the slug flow database with MAE (Mean Absolute Error) 25.14%, which improved the prediction accuracy remarkably.

  17. Application of MIMO Techniques in sky-surface wave hybrid networking sea-state radar system

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Wu, X.; Yue, X.; Liu, J.; Li, C.

    2016-12-01

    The sky-surface wave hybrid networking sea-state radar system contains of the sky wave transmission stations at different sites and several surface wave radar stations. The subject comes from the national 863 High-tech Project of China. The hybrid sky-surface wave system and the HF surface wave system work simultaneously and the HF surface wave radar (HFSWR) can work in multi-static and surface-wave networking mode. Compared with the single mode radar system, this system has advantages of better detection performance at the far ranges in ocean dynamics parameters inversion. We have applied multiple-input multiple-output(MIMO) techniques in this sea-state radar system. Based on the multiple channel and non-causal transmit beam-forming techniques, the MIMO radar architecture can reduce the size of the receiving antennas and simplify antenna installation. Besides, by efficiently utilizing the system's available degrees of freedom, it can provide a feasible approach for mitigating multipath effect and Doppler-spread clutter in Over-the-horizon Radar. In this radar, slow-time phase-coded MIMO method is used. The transmitting waveforms are phase-coded in slow-time so as to be orthogonal after Doppler processing at the receiver. So the MIMO method can be easily implemented without the need to modify the receiver hardware. After the radar system design, the MIMO experiments of this system have been completed by Wuhan University during 2015 and 2016. The experiment used Wuhan multi-channel ionospheric sounding system(WMISS) as sky-wave transmitting source and three dual-frequency HFSWR developed by the Oceanography Laboratory of Wuhan University. The transmitter system located at Chongyang with five element linear equi-spaced antenna array and Wuhan with one log-periodic antenna. The RF signals are generated by synchronized, but independent digital waveform generators - providing complete flexibility in element phase and amplitude control, and waveform type and parameters

  18. Particle swarm optimization for pilot tones design in MIMO-OFDM systems

    NASA Astrophysics Data System (ADS)

    Nuri Seyman, Muhammet; Taşpinar, Necmi

    2011-12-01

    Channel estimation is an essential task in MIMO-OFDM systems for coherent demodulation and data detection. Also designing pilot tones that affect the channel estimation performance is an important issue for these systems. For this reason, in this article we propose particle swarm optimization (PSO) to optimize placement and power of the comb-type pilot tones that are used for least square (LS) channel estimation in MIMO-OFDM systems. To optimize the pilot tones, upper bound of MSE is used as the objective function of PSO. The effects of Doppler shifts on designing pilot tones are also investigated. According to the simulation results, PSO is an effective solution for designing pilot tones.

  19. Ultra-compact 32-channel system for time-correlated single-photon counting measurements

    NASA Astrophysics Data System (ADS)

    Antonioli, S.; Cuccato, A.; Miari, L.; Labanca, I.; Rech, I.; Ghioni, M.

    2013-05-01

    Modern Time-Correlated Single-Photon Counting applications require to detect spectral and temporal fluorescence data simultaneously and from different areas of the analyzed sample. These rising quests have led the development of multichannel systems able to perform high count rate and high performance analysis. In this work we describe a new 32-channel TCSPC system designed to be used in modern setups. The presented module consists of four independent 8-channel TCSPC boards, each of them including two 4-channel Time-Amplitude Converter arrays. These TAC arrays are built-in 0.35 μm Si-Ge BiCMOS technology and are characterized by low crosstalk, high resolution, high conversion rate and variable full-scale range. The 8-channel TCSPC board implements an 8-channel ADC to sample the TAC outputs, an FPGA to record and organize the measurement results and a USB 2.0 interface to enable real-time data transmission to and from an external PC. Experimental results demonstrate that the acquisition system ensures high performance TCSPC measurements, in particular: high conversion rate (5 MHz), good time resolution (down to 30 psFWHM with the full scale range set to 11 ns) and low differential non-linearity (rms value lower than 0.15% of the time bin width). We design the module to be very compact and, thanks to the reduced dimensions of the 8-channel TCSPC board (95×40 mm), the whole system can be enclosed in a small aluminum case (160×125×30 mm).

  20. A Minimized MIMO-UWB Antenna with High Isolation and Triple Band-Notched Functions

    NASA Astrophysics Data System (ADS)

    Kong, Yuanyuan; Li, Yingsong; Yu, Kai

    2016-11-01

    A compact high isolation MIMO-UWB antenna with triple frequency rejection bands is proposed for UWB communication applications. The proposed MIMO-UWB antenna consists of two identical UWB antennas and each antenna element has a semicircle ring shaped radiation patch fed by a bend microstrip feeding line for covering the UWB band, which operates from 2.85 GHz to 11.79 GHz with an impedance bandwidth of 122.1 %. By etching a L-shaped slot on the ground plane, and embedding an "anchor" shaped stub into the patch and integrating an open ring under the semicircle shaped radiation patch, three notch bands are realized to suppress WiMAX (3.3-3.6 GHz), WLAN(5.725-5.825 GHz) and uplink of X-band satellite (7.9-8.4 GHz) signals. The high isolation with S21<-20 dB in most UWB band is obtained by adding a protruded decoupling structure. The design procedure of the MIMO-UWB antenna is given in detail. The proposed MIMO-UWB antenna is simulated, fabricated and measured. Experimental results demonstrate that the proposed MIMO-UWB antenna has a stable gain, good impedance match, high isolation, low envelope correlation coefficient and good radiation pattern at the UWB operating band and it can provide three designated notch bands.

  1. Correlation between human ether‐a‐go‐go‐related gene channel inhibition and action potential prolongation

    PubMed Central

    Saxena, P; Hortigon‐Vinagre, M P; Beyl, S; Baburin, I; Andranovits, S; Iqbal, S M; Costa, A; IJzerman, A P; Kügler, P; Timin, E

    2017-01-01

    Background and Purpose Human ether‐a‐go‐go‐related gene (hERG; Kv11.1) channel inhibition is a widely accepted predictor of cardiac arrhythmia. hERG channel inhibition alone is often insufficient to predict pro‐arrhythmic drug effects. This study used a library of dofetilide derivatives to investigate the relationship between standard measures of hERG current block in an expression system and changes in action potential duration (APD) in human‐induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs). The interference from accompanying block of Cav1.2 and Nav1.5 channels was investigated along with an in silico AP model. Experimental Approach Drug‐induced changes in APD were assessed in hiPSC‐CMs using voltage‐sensitive dyes. The IC50 values for dofetilide and 13 derivatives on hERG current were estimated in an HEK293 expression system. The relative potency of each drug on APD was estimated by calculating the dose (D150) required to prolong the APD at 90% (APD90) repolarization by 50%. Key Results The D150 in hiPSC‐CMs was linearly correlated with IC50 of hERG current. In silico simulations supported this finding. Three derivatives inhibited hERG without prolonging APD, and these compounds also inhibited Cav1.2 and/or Nav1.5 in a channel state‐dependent manner. Adding Cav1.2 and Nav1.2 block to the in silico model recapitulated the direction but not the extent of the APD change. Conclusions and Implications Potency of hERG current inhibition correlates linearly with an index of APD in hiPSC‐CMs. The compounds that do not correlate have additional effects including concomitant block of Cav1.2 and/or Nav1.5 channels. In silico simulations of hiPSC‐CMs APs confirm the principle of the multiple ion channel effects. PMID:28681507

  2. Correlation between human ether-a-go-go-related gene channel inhibition and action potential prolongation.

    PubMed

    Saxena, P; Hortigon-Vinagre, M P; Beyl, S; Baburin, I; Andranovits, S; Iqbal, S M; Costa, A; IJzerman, A P; Kügler, P; Timin, E; Smith, G L; Hering, S

    2017-09-01

    Human ether-a-go-go-related gene (hERG; Kv 11.1) channel inhibition is a widely accepted predictor of cardiac arrhythmia. hERG channel inhibition alone is often insufficient to predict pro-arrhythmic drug effects. This study used a library of dofetilide derivatives to investigate the relationship between standard measures of hERG current block in an expression system and changes in action potential duration (APD) in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The interference from accompanying block of Cav 1.2 and Nav 1.5 channels was investigated along with an in silico AP model. Drug-induced changes in APD were assessed in hiPSC-CMs using voltage-sensitive dyes. The IC50 values for dofetilide and 13 derivatives on hERG current were estimated in an HEK293 expression system. The relative potency of each drug on APD was estimated by calculating the dose (D150 ) required to prolong the APD at 90% (APD90 ) repolarization by 50%. The D150 in hiPSC-CMs was linearly correlated with IC50 of hERG current. In silico simulations supported this finding. Three derivatives inhibited hERG without prolonging APD, and these compounds also inhibited Cav 1.2 and/or Nav 1.5 in a channel state-dependent manner. Adding Cav 1.2 and Nav 1.2 block to the in silico model recapitulated the direction but not the extent of the APD change. Potency of hERG current inhibition correlates linearly with an index of APD in hiPSC-CMs. The compounds that do not correlate have additional effects including concomitant block of Cav 1.2 and/or Nav 1.5 channels. In silico simulations of hiPSC-CMs APs confirm the principle of the multiple ion channel effects. © 2017 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

  3. The Modulus of the Complex Correlation Coefficient Between Co-Polarized Channels for Oil Spill Observation

    NASA Astrophysics Data System (ADS)

    Khenouchi, H.; Smara, Y.; Migliaccio, M.; Nunziata, F.; Buono, A.

    2016-08-01

    Sea oil pollution is a matter of great concern since it affects both the environment and human health. Recent studies demonstrated that synthetic aperture radar (SAR) polarimetry is able to provide additional information useful for environmental applications, i. e., oil spill observation. In this context, different approaches based on polarimetric SARs were developed. In this study, a dual-polarimetric feature, namely the modulus of the complex correlation coefficient between the co-polarized channels, is used to discriminate between sea oil spill and weak-damping look-alikes.The proposed approach relies on the fact that high correlation between co-polarized channels is expected over sea surface and weak-damping look- alikes due to the dominant Bragg scattering, while significantly lower correlation is expected over strong-damping oil spills since they are characterized by a no-Bragg scattering behaviour. Experimental results show that the modulus of the complex correlation between the co-polarized chan- nels can be successfully exploited for both the observation of sea oil slicks and their discrimination from weak-damping look-alikes.

  4. Structure-correlated diffusion anisotropy in nanoporous channel networks by Monte Carlo simulations and percolation theory

    NASA Astrophysics Data System (ADS)

    Kondrashova, Daria; Valiullin, Rustem; Kärger, Jörg; Bunde, Armin

    2017-07-01

    Nanoporous silicon consisting of tubular pores imbedded in a silicon matrix has found many technological applications and provides a useful model system for studying phase transitions under confinement. Recently, a model for mass transfer in these materials has been elaborated [Kondrashova et al., Sci. Rep. 7, 40207 (2017)], which assumes that adjacent channels can be connected by "bridges" (with probability pbridge) which allows diffusion perpendicular to the channels. Along the channels, diffusion can be slowed down by "necks" which occur with probability pneck. In this paper we use Monte-Carlo simulations to study diffusion along the channels and perpendicular to them, as a function of pbridge and pneck, and find remarkable correlations between the diffusivities in longitudinal and radial directions. For clarifying the diffusivity in radial direction, which is governed by the concentration of bridges, we applied percolation theory. We determine analytically how the critical concentration of bridges depends on the size of the system and show that it approaches zero in the thermodynamic limit. Our analysis suggests that the critical properties of the model, including the diffusivity in radial direction, are in the universality class of two-dimensional lattice percolation, which is confirmed by our numerical study.

  5. Polymer (PDMS-Fe3O4) magneto-dielectric substrate for a MIMO antenna array

    NASA Astrophysics Data System (ADS)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Kamarudin, Muhammad Ramlee

    2016-01-01

    This paper presents the design of a 2 × 4 multiple-input multiple-output (MIMO) antenna array fabricated on a nanocomposite magneto-dielectric polymer substrate. The 10-nm iron oxide (Fe3O4) nanoparticles and polydimethylsiloxane (PDMS) composite is used as substrate to enhance the performance of a MIMO antenna array. The measured results showed up to 40.8 % enhancement in terms of bandwidth, 9.95 dB gain, and 57 % of radiation efficiency. Furthermore, it is found that the proposed magneto-dielectric (PDMS-Fe3O4) composite substrate provides excellent MIMO parameters such as correlation coefficient, diversity gain, and mutual coupling. The prototype of the proposed antenna is transparent, flexible, lightweight, and resistant against dust and corrosion. Measured results indicate that the proposed antenna is suitable for WLAN and ultra-wideband biomedical applications within frequency range of 5.33-7.70 GHz.

  6. Potency of irritation by benzylidenemalononitriles in humans correlates with TRPA1 ion channel activation

    PubMed Central

    Lindsay, Christopher D.; Green, Christopher; Bird, Mike; Jones, James T. A.; Riches, James R.; McKee, Katherine K.; Sandford, Mark S.; Wakefield, Debra A.; Timperley, Christopher M.

    2015-01-01

    We show that the physiological activity of solid aerosolized benzylidenemalononitriles (BMNs) including ‘tear gas’ (CS) in historic human volunteer trials correlates with activation of the human transient receptor potential ankyrin 1 ion channel (hTRPA1). This suggests that the irritation caused by the most potent of these compounds results from activation of this channel. We prepared 50 BMNs and measured their hTRPA1 agonist potencies. A mechanism of action consistent with their physiological activity, involving their dissolution in water on contaminated body surfaces, cell membrane penetration and reversible thiolation by a cysteine residue of hTRPA1, supported by data from nuclear magnetic resonance experiments with a model thiol, explains the structure–activity relationships. The correlation provides evidence that hTRPA1 is a receptor for irritants on nociceptive neurons involved in pain perception; thus, its activation in the eye, nose, mouth and skin would explain the symptoms of lachrymation, sneezing, coughing and stinging, respectively. The structure–activity results and the use of the BMNs as pharmacological tools in future by other researchers may contribute to a better understanding of the TRPA1 channel in humans (and other animals) and help facilitate the discovery of treatments for human diseases involving this receptor. PMID:26064575

  7. Correlation character of ionic current fluctuations: analysis of ion current through a voltage-dependent potassium single channel.

    PubMed

    Tong-Han, Lan; Huang, Xi; Jia-Rui, Lin

    2005-10-03

    The gating of ion channels has widely been modeled by assuming the transition between open and closed states is a memoryless process. Nevertheless, the statistical analysis of an ionic current signal recorded from voltage dependence K(+) single channel is presented. Calculating the sample auto-correlation function of the ionic current based on the digitized signals, rather than the sequence of open and closed states duration time. The results provide evidence for the existence of memory. For different voltages, the ion channel current fluctuation has different correlation attributions. The correlations in data generated by simulation of two Markov models, on one hand, auto-correlation function of the ionic current shows a weaker memory, after a delayed period of time, the attribute of memory does not exist; on the other hand, the correlation depends on the number of states in the Markov model. For V(p)=-60 mV pipette potential, spectral analysis of ion channel current was conducted, the result indicates that the spectrum is not a flat spectrum, the data set from ionic current fluctuations shows considerable variability with a broad 1/f -like spectrum, alpha=1.261+/-0.24. Thus the ion current fluctuations give information about the kinetics of the channel protein, the results suggest the correlation character of ion channel protein nonlinear kinetics regardless of whether the channel is in open or closed state.

  8. A Low-Complexity Antenna Selection Scheme in MIMO Systems

    NASA Astrophysics Data System (ADS)

    Chen, Jung-Chieh

    This paper considers the use of an antenna selection mechanism to reduce the cost of multiple analog transmit/receive chains in multiple-input multiple-output (MIMO) systems. With the optimal antenna selection scheme, radio-frequency chains can optimally connect with the best subset of transmitter and/or receiver antennas. However, the optimal antenna selection algorithm requires an exhaustive search of all possible combinations to find the optimum subset at the transmitter and/or receiver, thus resulting in high complexity. In order to reduce the computational load while still maximizing channel capacity, we introduce the simulated annealing (SA) method, an effective algorithm that solves various combinatorial optimization problems, to search the optimal subset. The simulation results show that the performance of the proposed SA method provides almost the same channel capacity as that of the optimal exhaustive search algorithm while maintaining low complexity.

  9. Ultrahigh capacity 2 × 2 MIMO RoF system at 60  GHz employing single-sideband single-carrier modulation.

    PubMed

    Lin, Chun-Ting; Ho, Chun-Hung; Huang, Hou-Tzu; Cheng, Yu-Hsuan

    2014-03-15

    This article proposes and experimentally demonstrates a radio-over-fiber system employing single-sideband single-carrier (SSB-SC) modulation at 60 GHz. SSB-SC modulation has a lower peak-to-average-power ratio than orthogonal frequency division multiplex (OFDM) modulation; therefore, the SSB-SC signals provide superior nonlinear tolerance, compared to OFDM signals. Moreover, multiple-input multiple-output (MIMO) technology was used extensively to enhance spectral efficiency. A least-mean-square-based equalizer was implemented, including MIMO channel estimation, frequency response equalization, and I/Q imbalance compensation to recover the MIMO signals. Thus, using 2×2 MIMO technology and 64-QAM SSB-SC signals, we achieved the highest data rate of 84 Gbps with 12  bit/s/Hz spectral efficiency using the 7-GHz license-free band at 60 GHz.

  10. Parallel encryption for multi-channel images based on an optical joint transform correlator

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Bai, Tingzhu; Shen, Xueju; Dou, Shuaifeng; Lin, Chao; Cai, Jianjun

    2017-08-01

    We propose an optical encryption method allowing the parallel encryption for multi-channel images based on a joint transform correlator (JTC). Distinguished from the conventional multi-image encryption methods, our proposed cryptosystem can encrypt multi-channel images simultaneously into a single ciphertext, which also can be used to recover arbitrary original images with corresponding keys. This method can achieve the compressed storage of ciphertext. In order to avoid the cross talk between multi-channel images, we restrict the respective joint power spectrum (JPS) into a specific area with optimized phase masks and split the multiple JPS by controlling the position of single JPS using the linear phase shifts. All of these operations are realized by optimizing and designing the phase masks which can be flexibly reconfigured on the spatial light modulator (SLM), leading to a feasible optical implementation with no increase of optical hardware and complexity. Computer simulations provide the validation for it. Experimental implementation is performed in a JTC-based cryptosystem to further verify the feasibility of our proposed method.

  11. Discrimination of correlated and entangling quantum channels with selective process tomography

    DOE PAGES

    Dumitrescu, Eugene; Humble, Travis S.

    2016-10-10

    The accurate and reliable characterization of quantum dynamical processes underlies efforts to validate quantum technologies, where discrimination between competing models of observed behaviors inform efforts to fabricate and operate qubit devices. We present a protocol for quantum channel discrimination that leverages advances in direct characterization of quantum dynamics (DCQD) codes. We demonstrate that DCQD codes enable selective process tomography to improve discrimination between entangling and correlated quantum dynamics. Numerical simulations show selective process tomography requires only a few measurement configurations to achieve a low false alarm rate and that the DCQD encoding improves the resilience of the protocol to hiddenmore » sources of noise. Lastly, our results show that selective process tomography with DCQD codes is useful for efficiently distinguishing sources of correlated crosstalk from uncorrelated noise in current and future experimental platforms.« less

  12. Discrimination of correlated and entangling quantum channels with selective process tomography

    SciTech Connect

    Dumitrescu, Eugene; Humble, Travis S.

    2016-10-10

    The accurate and reliable characterization of quantum dynamical processes underlies efforts to validate quantum technologies, where discrimination between competing models of observed behaviors inform efforts to fabricate and operate qubit devices. We present a protocol for quantum channel discrimination that leverages advances in direct characterization of quantum dynamics (DCQD) codes. We demonstrate that DCQD codes enable selective process tomography to improve discrimination between entangling and correlated quantum dynamics. Numerical simulations show selective process tomography requires only a few measurement configurations to achieve a low false alarm rate and that the DCQD encoding improves the resilience of the protocol to hidden sources of noise. Lastly, our results show that selective process tomography with DCQD codes is useful for efficiently distinguishing sources of correlated crosstalk from uncorrelated noise in current and future experimental platforms.

  13. Discrimination of correlated and entangling quantum channels with selective process tomography

    NASA Astrophysics Data System (ADS)

    Dumitrescu, Eugene; Humble, Travis S.

    2016-10-01

    The accurate and reliable characterization of quantum dynamical processes underlies efforts to validate quantum technologies, where discrimination between competing models of observed behaviors inform efforts to fabricate and operate qubit devices. We present a protocol for quantum channel discrimination that leverages advances in direct characterization of quantum dynamics (DCQD) codes. We demonstrate that DCQD codes enable selective process tomography to improve discrimination between entangling and correlated quantum dynamics. Numerical simulations show selective process tomography requires only a few measurement configurations to achieve a low false alarm rate and that the DCQD encoding improves the resilience of the protocol to hidden sources of noise. Our results show that selective process tomography with DCQD codes is useful for efficiently distinguishing sources of correlated crosstalk from uncorrelated noise in current and future experimental platforms.

  14. Discrimination of correlated and entangling quantum channels with selective process tomography

    SciTech Connect

    Dumitrescu, Eugene; Humble, Travis S.

    2016-10-10

    The accurate and reliable characterization of quantum dynamical processes underlies efforts to validate quantum technologies, where discrimination between competing models of observed behaviors inform efforts to fabricate and operate qubit devices. We present a protocol for quantum channel discrimination that leverages advances in direct characterization of quantum dynamics (DCQD) codes. We demonstrate that DCQD codes enable selective process tomography to improve discrimination between entangling and correlated quantum dynamics. Numerical simulations show selective process tomography requires only a few measurement configurations to achieve a low false alarm rate and that the DCQD encoding improves the resilience of the protocol to hidden sources of noise. Lastly, our results show that selective process tomography with DCQD codes is useful for efficiently distinguishing sources of correlated crosstalk from uncorrelated noise in current and future experimental platforms.

  15. Performance Analysis of MIMO Relay Network via Propagation Measurement in L-Shaped Corridor Environment

    NASA Astrophysics Data System (ADS)

    Lertwiram, Namzilp; Tran, Gia Khanh; Mizutani, Keiichi; Sakaguchi, Kei; Araki, Kiyomichi

    Setting relays can address the shadowing problem between a transmitter (Tx) and a receiver (Rx). Moreover, the Multiple-Input Multiple-Output (MIMO) technique has been introduced to improve wireless link capacity. The MIMO technique can be applied in relay network to enhance system performance. However, the efficiency of relaying schemes and relay placement have not been well investigated with experiment-based study. This paper provides a propagation measurement campaign of a MIMO two-hop relay network in 5GHz band in an L-shaped corridor environment with various relay locations. Furthermore, this paper proposes a Relay Placement Estimation (RPE) scheme to identify the optimum relay location, i.e. the point at which the network performance is highest. Analysis results of channel capacity show that relaying technique is beneficial over direct transmission in strong shadowing environment while it is ineffective in non-shadowing environment. In addition, the optimum relay location estimated with the RPE scheme also agrees with the location where the network achieves the highest performance as identified by network capacity. Finally, the capacity analysis shows that two-way MIMO relay employing network coding has the best performance while cooperative relaying scheme is not effective due to shadowing effect weakening the signal strength of the direct link.

  16. Adaptive CQI Update and Feedback for Codebook Based MU-MIMO in E-UTRA

    NASA Astrophysics Data System (ADS)

    Zhu, Jianchi; She, Xiaoming; Liu, Jingxiu; Chen, Lan

    Codebook based multiple-input multiple-output (MIMO) precoding can significantly improve the system spectral efficiency with limited feedback and has been accepted as one of the most promising techniques for the Evolved UTRA (E-UTRA). Compared with single-user (SU) MIMO, multi-user (MU) MIMO can further improve the system spectral efficiency due to increased multi-user diversity gain. MU-MIMO is preferred for the case of a large number of users, when the total feedback overhead will become a problem. In order to reduce the feedback overhead, feedback of single channel quality indicator (CQI), e.g. rank 1 CQI, is required in E-UTRA currently. The main challenge is how to obtain CQIs of other ranks at Node B for rank adaptation with single CQI feedback. In this paper, an adaptive CQI update scheme at Node B based on statistical characteristics of CQI of various ranks is proposed. To further increase the accuracy of CQI at Node B for data transmission, an adaptive CQI feedback scheme is then proposed in which single CQI with the rank same as previously scheduled is fed back. Simulation results show that our proposed CQI update scheme can achieve 2.5-5% gain compared with the conventional method with fixed backoff. Moreover, with the proposed adaptive feedback scheme, 20-40% performance gain can be obtained and the performance can approach the upper bound.

  17. Effectiveness of Space-Division Multiple-Access in MIMO Communication Systems with Parallel Data Transmission

    NASA Astrophysics Data System (ADS)

    Ermolayev, V. T.; Flaksman, A. G.; Averin, I. M.; Gribov, D. V.

    2004-02-01

    We consider multiple-input multiple-output (MIMO) cellular communication systems with antenna arrays at both link ends and data transmission via parallel eigenchannels matched with a random spatial channel. We analyze the effectiveness of the space-division multiple-access (SDMA) method, which does not require estimation of signal-arrival directions and is based on orthogonalization of the parallel channels of all users. We obtained approximate analytical expressions for the mean ratio of the signal power to the noise power and the MIMO system capacity, which are derived for the case of Rayleigh fading of signals. Although the obtained formulas are much simpler than the exact ones, they ensure high accuracy for an arbitrary number of transmitting and receiving antennas and an arbitrary power of transmitter. Our results demonstrate the high effectiveness of the proposed SDMA method.

  18. Propagation velocity and space-time correlation of perturbations in turbulent channel flow

    NASA Technical Reports Server (NTRS)

    Kim, John; Hussain, Fazle

    1992-01-01

    A database obtained from direct numerical simulation of a turbulent channel flow is analyzed to extract the propagation velocity V of velocity, vorticity, and pressure fluctuations from their space-time correlations. A surprising result is that V is approximately the same as the local mean velocity for most of the channel, except for the near-wall region. For y(+) is less than or equal to 15, V is virtually constant, implying that perturbations of all flow variables propagate like waves near the wall. In this region V is 55 percent of the centerline velocity U(sub c) for velocity and vorticity perturbations and 75 percent of U(sub c) for pressure perturbations. Scale-dependence of V is also examined by analyzing the bandpass filtered flow fields. Comprehensive documentation of the propagation velocities and space-time correlation data, which should prove useful in the evaluation of Taylor's hypothesis is presented. An attempt was made to explain some of the data in terms of our current understanding of organized structures, although not all of the data can be explained this way.

  19. Correlations of Surface Deformation and 3D Flow Field in a Compliant Wall Turbulent Channel Flow.

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Zhang, Cao; Katz, Joseph

    2015-11-01

    This study focuses on the correlations between surface deformation and flow features, including velocity, vorticity and pressure, in a turbulent channel flow over a flat, compliant Polydimethylsiloxane (PDMS) wall. The channel centerline velocity is 2.5 m/s, and the friction Reynolds number is 2.3x103. Analysis is based on simultaneous measurements of the time resolved 3D velocity and surface deformation using tomographic PIV and Mach-Zehnder Interferometry. The volumetric pressure distribution is calculated plane by plane by spatially integrating the material acceleration using virtual boundary, omni-directional method. Conditional sampling based on local high/low pressure and deformation events reveals the primary flow structures causing the deformation. High pressure peaks appear at the interface between sweep and ejection, whereas the negative deformations peaks (dent) appear upstream, under the sweeps. The persistent phase lag between flow and deformations are presumably caused by internal damping within the PDMS. Some of the low pressure peaks and strong ejections are located under the head of hairpin vortices, and accordingly, are associated with positive deformation (bump). Others bumps and dents are correlated with some spanwise offset large inclined quasi-streamwise vortices that are not necessarily associated with hairpins. Sponsored by ONR.

  20. Multi-channel analysis of passive surface waves based on cross-correlations

    NASA Astrophysics Data System (ADS)

    Cheng, F.; Xia, J.; Xu, Z.; Hu, Y.

    2015-12-01

    Traditional active seismic survey can no longer be properly applied in highly populated urban areas due to restrictions in modern civilian life styles. Passive seismic methods, however, have gained much more attention from the engineering geophysics community because of their environmental friendly and deeper investigation depth. Due to extracting signal from noise has never been as comfortable as that in active seismic survey, how to make it more efficiently and accurately has been emphasized. We propose a multi-channel analysis of passive surface waves (MAPW) based on long noise sequences cross-correlations to meet the demand for increasing investigation depth by acquiring surface-wave data at a relative low-frequency range (1 Hz ≤ f ≤ 10 Hz) in urban areas. We utilize seismic interferometry to produce common virtual source gathers from one-hour-long noise records and do dispersion measurements by using the classic passive multi-channel analysis of surface waves (PMASW). We used synthetic tests to demonstrate the advantages of MAPW for various noise distributions. Results show that our method has the superiority of maximizing the analysis accuracy. Finally, we used two field data applications to demonstrate the advantages of our MAPW over the classic PMASW on isolating azimuth of the predominant noise sources and the effectivity of combined survey of active multi-channel analysis of surface waves (MASW) and MAPW. We suggest, for the field operation using MAPW, that a parallel receiver line which is close to a main road or river, if any, with one or two hours noise observation will be an effective means for an unbiased dispersion image. Keywords: passive seismic method, MAPW, MASW, cross-correlation, directional noise source, spatial-aliasing effects, inversion

  1. Iterative Block Decision Feedback Equalization for MIMO Underwater Acoustic Communications

    DTIC Science & Technology

    2010-06-01

    multiple - input , multiple - output ( MIMO ) underwa- ter acoustic (UWA...communications are limited to several kilo-bits per second within 40 km range. Multiple - input , multiple - output ( MIMO ) communications which improve the data...has been proposed in [16], both for single- input single- output (SISO) systems. In this paper, we develop an iterative BDFE for MIMO systems and

  2. Waveform Design for MIMO Radar Using an Alternating Projection Approach

    DTIC Science & Technology

    2010-01-23

    multiple - input multiple - output ( MIMO ) radar waveform design problem which optimizes both minimum mean-square error estimation (MMSE) and...Report Title ABSTRACT Revisiting an earlier examined multiple - input multiple - output ( MIMO ) radar waveform design problem which optimizes both minimum...mtu.edu Abstract— Revisiting an earlier examined multiple - input multiple - output ( MIMO ) radar waveform design problem which

  3. The correlated k-distribution technique as applied to the AVHRR channels

    NASA Technical Reports Server (NTRS)

    Kratz, David P.

    1995-01-01

    Correlated k-distributions have been created to account for the molecular absorption found in the spectral ranges of the five Advanced Very High Resolution Radiometer (AVHRR) satellite channels. The production of the k-distributions was based upon an exponential-sum fitting of transmissions (ESFT) technique which was applied to reference line-by-line absorptance calculations. To account for the overlap of spectral features from different molecular species, the present routines made use of the multiplication transmissivity property which allows for considerable flexibility, especially when altering relative mixing ratios of the various molecular species. To determine the accuracy of the correlated k-distribution technique as compared to the line-by-line procedure, atmospheric flux and heating rate calculations were run for a wide variety of atmospheric conditions. For the atmospheric conditions taken into consideration, the correlated k-distribution technique has yielded results within about 0.5% for both the cases where the satellite spectral response functions were applied and where they were not. The correlated k-distribution's principal advantages is that it can be incorporated directly into multiple scattering routines that consider scattering as well as absorption by clouds and aerosol particles.

  4. Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

    NASA Astrophysics Data System (ADS)

    Mohammed, H. A.; Sibley, M. J. N.; Mather, P. J.

    2012-05-01

    The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-input multiple-output (MIMO) is a promising mobile air interface solution for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. This paper details the design of a highly robust and efficient OFDM-MIMO system to support permanent accessibility and higher data rates to users moving at high speeds, such as users travelling on trains. It has high relevance for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The paper begins with a comprehensive literature review focused on both technologies. This is followed by the modelling of the OFDM-MIMO physical layer based on Simulink/Matlab that takes into consideration high vehicular mobility. Then the entire system is simulated and analysed under different encoding and channel estimation algorithms. The use of High Altitude Platform system (HAPs) technology is considered and analysed.

  5. Azimuth sidelobe suppression technique for near-field MIMO radar imaging

    NASA Astrophysics Data System (ADS)

    Liu, Yongze; Xu, Xiaojian

    2015-10-01

    Multiple-input multiple-output (MIMO) radar is getting more and more applications over the last decade. In near field imaging using a linear MIMO array, the azimuth sampling is non-uniform, resulting in spatially variant point spread function (PSF) over a large imaging zone. In this work, an azimuth sidelobe suppression technique is proposed where apodization or complex amplitude weighting is applied to the multiple channel data prior to image reconstruction. For best sidelobe suppression, the optimal channel weights wopt are obtained through mathematical optimization. The overall process mainly includes three steps. Firstly, the expression of PSF in azimuth is acquired by the azimuth focusing process; Secondly, based on the fact that, for an ideal PSF the maximum value of the mainlobe should be one and the values of sidelobes should be zeros, the problem of finding wopt is mathematically fomulated as an optimization problem; Lastly, by setting proper mainlobe width and sidelobe level, the optimal weights can be solved through convex optimization algorithm. Simulations of a MIMO radar system where channel amplitude-phase error and antenna elements position deviation exist are presented and the performance of the proposed technique is studied.

  6. Beyond the Classical Performance Limitations Controlling Uncertain MIMO Systems: UAV Applications

    DTIC Science & Technology

    2008-05-01

    multiple - input - multiple - output , MIMO ) with model...theory (QFT) [8]. 2.0 NON-DIAGONAL MIMO QFT CONTROL DESIGN METHODOLOGY [2-7] Control of multivariable systems ( multiple - input - multiple - output , MIMO ... MIMO QFT, Horowitz proposed to translate the original nxn MIMO problem into n separate quantitative multiple - input -single- output MISO problems,

  7. Channels

    NASA Image and Video Library

    2015-11-20

    Today's VIS image shows a number of unnamed channels located on the northeastern margin of Terra Sabaea. Orbit Number: 61049 Latitude: 33.5036 Longitude: 58.6967 Instrument: VIS Captured: 2015-09-18 12:54 http://photojournal.jpl.nasa.gov/catalog/PIA20097

  8. Quadratic Forms on Complex Random Matrices and Multi-Antenna Channel Capacity

    DTIC Science & Technology

    2004-03-16

    channel capacity and capacity versus outage of multiple - input multiple - output ( MIMO ) Rayleigh-distributed wireless communication channels. Both... output ( MIMO ) wireless communication systems.jointLet us denote the number of inputs (or transmitters) and formation theory. These densities are...be represented channel capacity and capacity versus outage of multiple - by an n, ×nt complex random matrix H - CN(0, Er®Et), input multiple - output

  9. Radio-over-optical waveguide system-on-wafer for massive delivery capacity 5G MIMO access networks

    NASA Astrophysics Data System (ADS)

    Binh, Le N.

    2017-01-01

    Delivering maximum information capacity over MIMO antennae systems beam steering is critical so as to achieve the flexibility via beam steering, maximizing the number of users or community of users in Gb/s rate per user over distributed cloud-based optical-wireless access networks. This paper gives an overview of (i) demands of optical - wireless delivery with high flexibility, especially the beam steering of multi-Tbps information channels to information hungry community of users via virtualized beam steering MIMO antenna systems at the free-license mmW region; (ii) Proposing a novel photonic planar integrated waveguide systems composing several passive and active, passive and amplification photonic devices so as to generate mmW carrier and embedded baseband information channels to feed to antenna elements; (iii) Integration techniques to generate a radio over optical waveguide (RoOW) system-on-wafer (SoW) comprising MIMO planar antenna elements and associate photonic integrated circuits for both up- and down- links; (iv) Challenges encountered in the implementation of the SoW in both wireless and photonic domains; (v) Photonic modulation techniques to achieve maximum transmission capacity per wavelength per MIMO antenna system. (vi) A view on control-feedback systems for fast and accurate generation of phase pattern for MIMO beam steering via a bank of optical phase modulators to mmW carrier phases and their preservation in the converted mmW domain . (vi) The overall operational principles of the novel techniques and technologies based on the coherent mixing of two lightwave channels The entire SoW can be implemented on SOI Si-photonic technology or via hybrid integration. These technological developments and their pros- and cons- will be discussed to achieve 50Tera-bps over the extended 110 channel Cband single mode fiber with mmW centered at 58.6GHz and 7GHz free-license band.

  10. Cooperative MIMO technology in multiple hops wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Yuan, Lina; Chen, Huajun; Gong, Jing

    2017-03-01

    The limited lifetime is one of the important factors restricted wireless sensor networks (WSNs), when possible, wireless nodes often operate with small batteries, while battery replacement is a very difficult and expensive. So the nodes must work long hours in the case of no battery replacement. Therefore, in WSNs, minimizing energy consumption is an important design consideration, at the same time, the transmission strategies of energy efficiency must be used for data forwarding. This paper, using cooperative multiple input multiple output(MIMO) technology combined with multiple hops technology, has put forward a new transmission model, i.e., the MIMO-MISO(multi-input multi-output)/MIMO-MIMO model. Simulation results demonstrate the proposed MIMO-MISO/MIMO-MIMO to minimize energy consumption of each node every node for multi-hop WSNs, to save a great deal of energy for a larger transmission distance, which makes the life of the entire network be extended.

  11. Effective channel estimation and efficient symbol detection for multi-input multi-output underwater acoustic communications

    NASA Astrophysics Data System (ADS)

    Ling, Jun

    Achieving reliable underwater acoustic communications (UAC) has long been recognized as a challenging problem owing to the scarce bandwidth available and the reverberant spread in both time and frequency domains. To pursue high data rates, we consider a multi-input multi-output (MIMO) UAC system, and our focus is placed on two main issues regarding a MIMO UAC system: (1) channel estimation, which involves the design of the training sequences and the development of a reliable channel estimation algorithm, and (2) symbol detection, which requires interference cancelation schemes due to simultaneous transmission from multiple transducers. To enhance channel estimation performance, we present a cyclic approach for designing training sequences with good auto- and cross-correlation properties, and a channel estimation algorithm called the iterative adaptive approach (IAA). Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, we present sparse learning via iterative minimization (SLIM) and demonstrate that SLIM gives similar performance to IAA but at a much lower computational cost. Furthermore, an extension of the SLIM algorithm is introduced to estimate the sparse and frequency modulated acoustic channels. The extended algorithm is referred to as generalization of SLIM (GoSLIM). Regarding symbol detection, a linear minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. We show that RELAX-BLAST can be implemented efficiently by making use of the conjugate gradient method and diagonalization properties of circulant matrices. This fast implementation approach requires only simple fast Fourier transform operations and facilitates parallel implementations. The effectiveness of the proposed MIMO schemes

  12. Temporal evolution of helix hydration in a light-gated ion channel correlates with ion conductance.

    PubMed

    Lórenz-Fonfría, Víctor A; Bamann, Christian; Resler, Tom; Schlesinger, Ramona; Bamberg, Ernst; Heberle, Joachim

    2015-10-27

    The discovery of channelrhodopsins introduced a new class of light-gated ion channels, which when genetically encoded in host cells resulted in the development of optogenetics. Channelrhodopsin-2 from Chlamydomonas reinhardtii, CrChR2, is the most widely used optogenetic tool in neuroscience. To explore the connection between the gating mechanism and the influx and efflux of water molecules in CrChR2, we have integrated light-induced time-resolved infrared spectroscopy and electrophysiology. Cross-correlation analysis revealed that ion conductance tallies with peptide backbone amide I vibrational changes at 1,665(-) and 1,648(+) cm(-1). These two bands report on the hydration of transmembrane α-helices as concluded from vibrational coupling experiments. Lifetime distribution analysis shows that water influx proceeded in two temporally separated steps with time constants of 10 μs (30%) and 200 μs (70%), the latter phase concurrent with the start of ion conductance. Water efflux and the cessation of the ion conductance are synchronized as well, with a time constant of 10 ms. The temporal correlation between ion conductance and hydration of helices holds for fast (E123T) and slow (D156E) variants of CrChR2, strengthening its functional significance.

  13. Doppler-Offset Waveforms for MIMO Radar

    DTIC Science & Technology

    2010-01-01

    Division Multiple Access, or FDMA . In the MIMO radar literature, the term FDMA is used, generically, to refer to sets of waveforms occupying different...frequencies at the same time. Mathematically, the lit" FDMA waveform can be written as: S" (I) = s (I) ej 2K I.’ 0 5, 1 5, T . for /I = I, ... ,N...noise) whenever i i’ j . Page 3 of 13 Pages On transmit, FDMA MIMO radars emit all N, frequency offset waveforms simultaneously. Then, each of the N

  14. Aircraft Free-Space MIMO Communications

    DTIC Science & Technology

    2011-08-01

    separation of 700 m. The capacity limit for large longitudinal separation is 6.92 bits/sec per Hz, the keyhole[3] single- input - multiple (12)- output (SIMO...DATES COVERED (From - To) JAN 2008 – JAN 2009 4. TITLE AND SUBTITLE AIRCRAFT FREE-SPACE MIMO COMMUNICATIONS 5a. CONTRACT NUMBER IN-HOUSE 5b. GRANT...ABSTRACT We investigate the use of MIMO to increase the data rate of air to air wireless links without scattered propagation. The conditions for

  15. Robust adaptive beamforming for MIMO monopulse radar

    NASA Astrophysics Data System (ADS)

    Rowe, William; Ström, Marie; Li, Jian; Stoica, Petre

    2013-05-01

    Researchers have recently proposed a widely separated multiple-input multiple-output (MIMO) radar using monopulse angle estimation techniques for target tracking. The widely separated antennas provide improved tracking performance by mitigating complex target radar cross-section fades and angle scintillation. An adaptive array is necessary in this paradigm because the direct path from any transmitter could act as a jammer at a receiver. When the target-free covariance matrix is not available, it is critical to include robustness into the adaptive beamformer weights. This work explores methods of robust adaptive monopulse beamforming techniques for MIMO tracking radar.

  16. Ion-water and ion-polypeptide correlations in a gramicidin-like channel. A molecular dynamics study.

    PubMed Central

    Jordan, P C

    1990-01-01

    This work describes a molecular dynamics study of ion-water and ion-polypeptide correlation in a model gramicidin-like channel (the polyglycine analogue) based upon interaction between polarizable, multipolar groups. The model suggests that the vicinity of the dimer junction and of the ethanolamine tail are regions of unusual flexibility. Cs+ binds weakly in the mouth of the channel: there it coordinates five water molecules and the #11CO group with which it interacts strongly and is ideally aligned. In the channel interior it is generally pentacoordinate; at the dimer junction, because of increased channel flexibility, it again becomes essentially hexacoordinate. The ion is also strongly coupled to the #13 CO but not to either #9 or #15, consistent with 13C NMR data. Water in the channel interior is strikingly different from bulk water; it has a much lower mean dipole moment. This correlates with our observation (which differs from that of previous studies) that water-water angular correlations do not persist within the channel, a result independent of ion occupancy or ionic polarity. In agreement with streaming potential measurements, there are seven single file water molecules associated with Cs+ permeation; one of these is always in direct contact with bulk water. At the mouth of an ion-free channel, there is a pattern of dipole moment alteration among the polar groups. Due to differential interaction with water, exo-carbonyls have unusually large dipole moments whereas those of the endo-carbonyls are low. The computed potential of mean force for CS+ translocation is qualitatively reasonable. However, it only exhibits a weakly articulated binding site and it does not quantitatively account for channel energetics. Correction for membrane polarization reduces, but does not eliminate, these problems. PMID:1705448

  17. Polarization-interleave-multiplexed discrete multi-tone modulation with direct detection utilizing MIMO equalization.

    PubMed

    Zhou, Xian; Zhong, Kangping; Gao, Yuliang; Sui, Qi; Dong, Zhenghua; Yuan, Jinhui; Wang, Liang; Long, Keping; Lau, Alan Pak Tao; Lu, Chao

    2015-04-06

    Discrete multi-tone (DMT) modulation is an attractive modulation format for short-reach applications to achieve the best use of available channel bandwidth and signal noise ratio (SNR). In order to realize polarization-multiplexed DMT modulation with direct detection, we derive an analytical transmission model for dual polarizations with intensity modulation and direct diction (IM-DD) in this paper. Based on the model, we propose a novel polarization-interleave-multiplexed DMT modulation with direct diction (PIM-DMT-DD) transmission system, where the polarization de-multiplexing can be achieved by using a simple multiple-input-multiple-output (MIMO) equalizer and the transmission performance is optimized over two distinct received polarization states to eliminate the singularity issue of MIMO demultiplexing algorithms. The feasibility and effectiveness of the proposed PIM-DMT-DD system are investigated via theoretical analyses and simulation studies.

  18. Optical and millimeter-wave radio seamless MIMO transmission based on a radio over fiber technology.

    PubMed

    Kanno, Atsushi; Kuri, Toshiaki; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Yasumura, Yoshihiro; Kitayama, Ken-ichi

    2012-12-31

    Multi-input multi-output (MIMO) transmission of two millimeter-wave radio signals seamlessly converted from polarization-division-multiplexed quadrature-phase-shift-keying optical signals is successfully demonstrated, where a radio access unit basically consisting of only optical-to-electrical converters and a radio receiver performs total signal equalization of both the optical and the radio paths and demodulation with digital signal processing (DSP). Orthogonally polarized optical components that are directly converted to two-channel radio components can be demultiplexed and demodulated with high-speed DSP as in optical digital coherent detection. 20-Gbaud optical and radio seamless MIMO transmission provides a total capacity of 74.4 Gb/s with a forward error correction overhead of 7%.

  19. MIMO-OFDM Precoding Technique for Minimizing BER Upper Bound of MLD

    NASA Astrophysics Data System (ADS)

    Pitakdumrongkija, Boonsarn; Fukawa, Kazuhiko; Suzuki, Hiroshi; Hagiwara, Takashi

    This paper proposes a new MIMO-OFDM precoding technique that aims to minimize a bit error rate (BER) upper bound of the maximum likelihood detection (MLD) in mobile radio communications. Using a steepest descent algorithm, the proposed method estimates linear precoding matrices that can minimize the upper bound of BER under power constraints. Since the upper bound is derived from all the pairwise error probabilities, this method can effectively optimize overall Euclidean distances between signals received by multiple antennas and their replicas. Computer simulations evaluate the BER performance and channel capacity of the proposed scheme for 2×2 and 4×4 MIMO-OFDM systems with BPSK, QPSK, and 16QAM. It is demonstrated that the proposed precoding technique is superior in terms of average BER to conventional precoding methods including a precoder which maximizes only the minimum Euclidean distance as the worst case.

  20. Resource Allocation Scheme in MIMO-OFDMA System for User's Different Data Throughput Requirements

    NASA Astrophysics Data System (ADS)

    Sann Maw, Maung; Sasase, Iwao

    In the subcarrier and power allocation schemes in Multi-Input Multi-Output and Orthogonal Frequency Division Multiple Access (MIMO-OFDMA) systems, only equal fairness among users has been considered and no scheme for proportional data rate fairness has been considered. In this paper, a subcarrier, bit and power allocation scheme is proposed to maximize the total throughput under the constraints of total power and proportional data rate fairness among users. In the proposed scheme, joint subchannel allocation and adaptive bit loading is firstly performed by using singular value decomposition (SVD) of channel matrix under the constraint of users' data throughput requirements, and then adaptive power loading is applied. Simulation results show that effective performance of the system has been improved as well as each throughput is proportionally distributed among users in MIMO-OFDMA systems.

  1. Recent amplification of miniature inverted-repeat transposable elements in the vector mosquito Culex pipiens: characterization of the Mimo family.

    PubMed

    Feschotte, C; Mouchès, C

    2000-05-30

    We describe a new family of repetitive elements, named Mimo, from the mosquito Culex pipiens. Structural characteristics of these elements fit well with those of miniature inverted-repeat transposable elements (MITEs), which are ubiquitous and highly abundant in plant genomes. The occurrence of Mimo in C. pipiens provides new evidence that MITEs are not restricted to plant genomes, but may be widespread in arthropods as well. The copy number of Mimo elements in C. pipiens ( approximately 1000 copies in a 540Mb genome) supports the hypothesis that there is a positive correlation between genome size and the magnitude of MITE proliferation. In contrast to most MITE families described so far, members of the Mimo family share a high sequence conservation, which may reflect a recent amplification history in this species. In addition, we found that Mimo elements are a frequent nest for other MITE-like elements, suggesting that multiple and successive MITE transposition events have occurred very recently in the C. pipiens genome. Despite evidence for recent mobility of these MITEs, no element has been found to encode a protein; therefore, we do not know how they have transposed and have spread in the genome. However, some sequence similarities in terminal inverted-repeats suggest a possible filiation of some of these mosquito MITEs with pogo-like DNA transposons.

  2. Dissolution testing of acetylsalicylic acid by a channel flow method-correlation to USP basket and intrinsic dissolution methods.

    PubMed

    Peltonen, Leena; Liljeroth, Peter; Heikkilä, Tiina; Kontturi, Kyösti; Hirvonen, Jouni

    2003-08-01

    A new modification of the channel flow dissolution method is introduced together with the theoretical basis to extract the solubility and mass transfer parameters from the dissolution experiments. Correlation of drug dissolution profiles in the channel flow apparatus was evaluated with respect to USP basket and intrinsic dissolution methods at pH 1.2 or 6.8. Acetylsalicylic acid (ASA) was studied as a pure drug substance and as three simple tablet compositions with microcrystalline cellulose (MCC) and/or lactose as excipients. The channel flow measurements of 100% ASA tablets correlated well with the results of intrinsic dissolution tests. In the channel flow method as well as in the USP basket method the release of ASA was fastest from the tablet compositions containing lactose, while the slowest dissolution rate was observed with the composition containing MCC as the only excipient. As presumed, the dissolution rate of the weak acid was decreased as the pH of the medium was lowered, which was clearly confirmed also by the three dissolution methods. MCC forms matrix tablets and in the USP basket method the dissolution profiles followed square root of time kinetics indicating that diffusion was the rate-controlling step of ASA dissolution. Also the channel flow results indicated that the dissolution of ASA was controlled by mass transfer. The swelling behaviour of the tablets is different in the channel flow method as compared to the basket method: only one tablet surface is exposed to the dissolution medium in the channel flow system. The contact between the tablet surface and the dissolution medium is more similar between the channel flow and intrinsic dissolution methods.

  3. 32-channel time-correlated-single-photon-counting system for high-throughput lifetime imaging

    NASA Astrophysics Data System (ADS)

    Peronio, P.; Labanca, I.; Acconcia, G.; Ruggeri, A.; Lavdas, A. A.; Hicks, A. A.; Pramstaller, P. P.; Ghioni, M.; Rech, I.

    2017-08-01

    Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively "long" measurement time. Multichannel systems have been developed in recent years aiming to overcome this limitation by managing several detectors or TCSPC devices in parallel. Nevertheless, if we look at state-of-the-art systems, there is still a strong trade-off between the parallelism level and performance: the higher the number of channels, the poorer the performance. In 2013, we presented a complete and compact 32 × 1 TCSPC system, composed of an array of 32 single-photon avalanche diodes connected to 32 time-to-amplitude converters, which showed that it was possible to overcome the existing trade-off. In this paper, we present an evolution of the previous work that is conceived for high-throughput fluorescence lifetime imaging microscopy. This application can be addressed by the new system thanks to a centralized logic, fast data management and an interface to a microscope. The new conceived hardware structure is presented, as well as the firmware developed to manage the operation of the module. Finally, preliminary results, obtained from the practical application of the technology, are shown to validate the developed system.

  4. Multi-channel poloidal correlation reflectometry on experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Qu, H.; Zhang, T.; Han, X.; Xiang, H. M.; Wen, F.; Geng, K. N.; Wang, Y. M.; Kong, D. F.; Cai, J. Q.; Huang, C. B.; Gao, Y.; Gao, X.; Zhang, S.

    2016-11-01

    A new multi-channel poloidal correlation reflectometry is developed at Experimental Advanced Superconducting Tokamak. Eight dielectric resonator oscillators with frequencies of 12.5 GHz, 13.5 GHz, 14.5 GHz, 15 GHz, 15.5 GHz, 16 GHz, 17 GHz, and 18 GHz are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together. The output waves are launched by one single antenna after passing through a 20 dB directional coupler which can provide the reference signal. Two poloidally separated antennae are installed to receive the reflected waves from plasma. The reference and reflected signals are down-converted by mixing with a quadrupled signal from a phase-locked source with a frequency of 14.2 GHz and the IF signals pass through the filter bank. The resulting signals from the mixers are detected by I/Q demodulators. The setup enables the measurement of density fluctuation at 8 (radial) × 2 (poloidal) spatial points. A coherent mode with an increasing velocity from 50 kHz to 100 kHz is observed by using the system. The mode is located in the steep gradient region of the pedestal.

  5. Multi-channel poloidal correlation reflectometry on experimental advanced superconducting tokamak.

    PubMed

    Qu, H; Zhang, T; Han, X; Xiang, H M; Wen, F; Geng, K N; Wang, Y M; Kong, D F; Cai, J Q; Huang, C B; Gao, Y; Gao, X; Zhang, S

    2016-11-01

    A new multi-channel poloidal correlation reflectometry is developed at Experimental Advanced Superconducting Tokamak. Eight dielectric resonator oscillators with frequencies of 12.5 GHz, 13.5 GHz, 14.5 GHz, 15 GHz, 15.5 GHz, 16 GHz, 17 GHz, and 18 GHz are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together. The output waves are launched by one single antenna after passing through a 20 dB directional coupler which can provide the reference signal. Two poloidally separated antennae are installed to receive the reflected waves from plasma. The reference and reflected signals are down-converted by mixing with a quadrupled signal from a phase-locked source with a frequency of 14.2 GHz and the IF signals pass through the filter bank. The resulting signals from the mixers are detected by I/Q demodulators. The setup enables the measurement of density fluctuation at 8 (radial) × 2 (poloidal) spatial points. A coherent mode with an increasing velocity from 50 kHz to 100 kHz is observed by using the system. The mode is located in the steep gradient region of the pedestal.

  6. Theoretical Results about MIMO Minimal Distance Precoder and Performances Comparison

    NASA Astrophysics Data System (ADS)

    Vrigneau, Baptiste; Letessier, Jonathan; Rostaing, Philippe; Collin, Ludovic; Burel, Gilles

    This study deals with two linear precoders: the maximization of the minimum Euclidean distance between received symbol-vectors, called here max-dmin, and the maximization of the post-processing signal-to-noise ratio termed max-SNR or beamforming. Both have been designed for reliable MIMO transmissions operating over uncorrelated Rayleigh fading channels. Here, we will explain why performances in terms of bit error rates show a significant enhancement of the max-dmin over the max-SNR whenever the number of antennas is increased. Then, from theoretical developments, we will demonstrate that, like the max-SNR precoder, the max-dmin precoder achieves the maximum diversity order, which is warrant of reliable transmissions. The current theoretical knowledge will be applied to the case-study of a system with two transmit- or two receive-antennas to calculate the probability density functions of two channel parameters directly linked to precoder performances for uncorrelated Rayleigh fading channels. At last, this calculation will allow us to quickly get the BER of the max-dmin precoder further to the derivation of a tight semi-theoretical approximation.

  7. MIMO-UAC for Rate Enhancement and Range Extension

    DTIC Science & Technology

    2008-12-01

    multiple transducers and hydrophones, we plan to develop multiple - input multiple - output ( MIMO -)UAC systems to provide range/rate enhancement...year, our research on multi- input multi- output underwater acoustic communications ( MIMO -UAC) can be categorized into two thrusts: Robust M1MO-UAC with...SUBJECT TERMS Underwater acoustic communications, multi- input multi- output ( MIMO ), transmit beamforming, differential modulation, diversity 16.

  8. Universal MIMO-OFDM SDR for Mobile Autonomous Networks (OPTIONS)

    DTIC Science & Technology

    2005-05-05

    Multiple such systems can be cascaded for larger MIMO configurations. The transmitter RF frontend is a two step up-conversion implementation with an... multiplications per second. This is shown graphically in Figure 3. A SISO-OFDM system (1x1) requires about 0.3 GOPS for all the algorithms. But as the MIMO ...to be MIMO decoded. Therefore multiple such processing units are required. However, depending on the bandwidth multiple subcarriers can be time

  9. A MIMO-Inspired Rapidly Switchable Photonic Interconnect Architecture (Postprint)

    DTIC Science & Technology

    2009-07-01

    Multiple Input Multiple Output ( MIMO ) architecture. 15. SUBJECT TERMS Free-space optical interconnects, Optical Phased Arrays, High-Speed...architecture takes advantage of spatial and wavelength diversity and in this regard may be regarded as a Multiple Input Multiple Output ( MIMO ) architecture...DATES COVERED (From - To) June 2008 – August 2008 4. TITLE AND SUBTITLE A MIMO -INSPIRED RAPIDLY SWITCHABLE PHOTONIC INTERCONNECT ARCHITECTURE

  10. MU-MIMO Pairing Algorithm Using Received Power

    NASA Astrophysics Data System (ADS)

    Kim, Young-Joon; Lee, Jung-Seung; Baik, Doo-Kwon

    In this letter, a new received power pairing scheduling (PPS) algorithm is proposed for Multi User Multiple Input and Multiple Output (MU-MIMO) systems. In contrast to existing algorithms that manage complex orthogonal factors, the PPS algorithm simply utilizes CINR to determine a MU-MIMO pair. Simulation results show that the PPS algorithm achieves up to 77% of MU-MIMO gain of determinant pairing scheduling (DPS) with low complexity.

  11. Distributed MIMO Radar for Imaging and High Resolution Target Localization

    DTIC Science & Technology

    2012-02-02

    28-2012 Final Report 04/15/2009 - 11/30/2011 Distributed MIMO Radar for Imaging and High Resolution Target Localization FA9550-09-1-0303 Alexander M...randomly placed sensors. MIMO radar, High-Resolution radar 19 Distributed MIMO Radar for Imaging and High Resolution Target Localization Air Force Office...configured with its antennas collocated [6] or distributed over an area [7, 8]. We refer to radio elements of a MIMO radar as nodes. Nodes may be equipped

  12. Wireless MIMO switching: distributed zero-forcing and MMSE relaying using network coding

    NASA Astrophysics Data System (ADS)

    Wang, Miao; Wang, Fanggang; Zhong, Zhangdui

    2013-12-01

    In a switching problem, a one-to-one mapping from the inputs to the outputs is conducted according to a switch pattern, i.e., a permutation matrix. In this paper, we investigate a wireless switching problem, in which a group of single-antenna relays acts together as a multiple-input-multiple-output (MIMO) switch to carry out distributed precode-and-forward. All users transmit simultaneously to the MIMO switch in the uplink and then the MIMO switch precodes the received signals and broadcasts in the downlink. Ideally, each user could receive its desired signal from one other user with no or little interference from other users. Self-interference is allowed in the received signals, as it can be canceled when each user has the channel gain of its self-interference. We propose two distributed relaying schemes based on two widely adopted criteria, i.e., zero-forcing relaying and minimum mean square error (MMSE) relaying. For the distributed zero-forcing relaying, we further propose a message passing approach, with which the proposed zero-forcing relaying achieves significant throughput gain with little attendant overhead. We also claim that the proposed MMSE relaying achieves even larger throughput at the expense of larger amount of message passing. Simulation results validate the throughput gains of the proposed relaying schemes.

  13. A study on the achievable data rate in massive MIMO system

    NASA Astrophysics Data System (ADS)

    Salh, Adeeb; Audah, Lukman; Shah, Nor Shahida M.; Hamzah, Shipun A.

    2017-09-01

    The achievable high data rates depend on the ability of massive multi-input-multi-output (MIMO) for the fifth-generation (5G) cellular networks, where the massive MIMO systems can support very high energy and spectral efficiencies. A major challenge in mobile broadband networks is how to support the throughput in the future 5G, where the highlight of 5G expected to provide high speed internet for every user. The performance massive MIMO system increase with linear minimum mean square error (MMSE), zero forcing (ZF) and maximum ratio transmission (MRT) when the number of antennas increases to infinity, by deriving the closed-form approximation for achievable data rate expressions. Meanwhile, the high signal-to-noise ratio (SNR) can be mitigated by using MMSE, ZF and MRT, which are used to suppress the inter-cell interference signals between neighboring cells. The achievable sum rate for MMSE is improved based on the distributed users inside cell, mitigated the inter-cell interference caused when send the same signal by other cells. By contrast, MMSE is better than ZF in perfect channel state information (CSI) for approximately 20% of the achievable sum rate.

  14. Hardware Impairments Aware Transceiver for Full-Duplex Massive MIMO Relaying

    NASA Astrophysics Data System (ADS)

    Xia, Xiaochen; Zhang, Dongmei; Xu, Kui; Ma, Wenfeng; Xu, Youyun

    2015-12-01

    This paper studies the massive MIMO full-duplex relaying (MM-FDR), where multiple source-destination pairs communicate simultaneously with the help of a common full-duplex relay equipped with very large antenna arrays. Different from the traditional MM-FDR protocol, a general model where sources/destinations are allowed to equip with multiple antennas is considered. In contrast to the conventional MIMO system, massive MIMO must be built with low-cost components which are prone to hardware impairments. In this paper, the effect of hardware impairments is taken into consideration, and is modeled using transmit/receive distortion noises. We propose a low complexity hardware impairments aware transceiver scheme (named as HIA scheme) to mitigate the distortion noises by exploiting the statistical knowledge of channels and antenna arrays at sources and destinations. A joint degree of freedom and power optimization algorithm is presented to further optimize the spectral efficiency of HIA based MM-FDR. The results show that the HIA scheme can mitigate the "ceiling effect" appears in traditional MM-FDR protocol, if the numbers of antennas at sources and destinations can scale with that at the relay.

  15. Performance analysis of MIMO FSO systems with radial array beams and finite sized detectors

    NASA Astrophysics Data System (ADS)

    Gökçe, Muhsin C.; Kamacıoǧlu, Canan; Uysal, Murat; Baykal, Yahya

    2014-10-01

    Multiple-input multiple-output (MIMO) systems are employed in free space optical (FSO) links to mitigate the degrading effects of atmospheric turbulence. In this paper, we consider a MIMO FSO system with practical transmitter and receiver configurations that consists of a radial laser array with Gaussian beams and finite sized detectors. We formulate the average received intensity and the power scinitillation as a function of the receiver coordinates in the presence of weak atmospheric turbulence by using the extended Huygens-Fresnel principle. Then, integrations over the finite sized multiple detectors are performed and the effect of the receiver aperture averaging is quantified. We further derive an outage probability expression of this MIMO system in the presence of turbulence-induced fading channels. Using the derived expressions, we demonstrate the effect of several practical system parameters such as the ring radius, the number of array beamlets, the source size, the link length, structure constant and the receiver aperture radius on the system performance.

  16. Information Theoretic Comparison of MIMO Wireless Communication Receivers in the Presence of Interference

    DTIC Science & Technology

    2004-12-20

    input multiple - output ( MIMO ) wireless communication provides a number of advantages over traditional single- input single- output (SISO) approaches...Performance Comparison 0 0 0 007)))o MIT Lincoln Laboratory mimoNTI-2 bliss MIMO Communication Multiple - Input Multiple - Output Complicated Multipath...difficult environments MIMO Communication - Ignore the possibility of jamming or Multiple - Input Multiple -

  17. Pilot Signal Design for Massive MIMO Systems: A Received Signal-To-Noise-Ratio-Based Approach

    NASA Astrophysics Data System (ADS)

    So, Jungho; Kim, Donggun; Lee, Yuni; Sung, Youngchul

    2015-05-01

    In this paper, the pilot signal design for massive MIMO systems to maximize the training-based received signal-to-noise ratio (SNR) is considered under two channel models: block Gauss-Markov and block independent and identically distributed (i.i.d.) channel models. First, it is shown that under the block Gauss-Markov channel model, the optimal pilot design problem reduces to a semi-definite programming (SDP) problem, which can be solved numerically by a standard convex optimization tool. Second, under the block i.i.d. channel model, an optimal solution is obtained in closed form. Numerical results show that the proposed method yields noticeably better performance than other existing pilot design methods in terms of received SNR.

  18. Two-point correlations for zero-pressure-gradient turbulent boundary layers and channels at Reτ ~ 1000 - 2000

    NASA Astrophysics Data System (ADS)

    Sillero, Juan A.; Jiménez, Javier; Moser, Robert D.

    2012-11-01

    Two-point 5-dimensional correlations Cξξ (x ;x' ; y ;y' Δz) are investigated to educe the structure of the velocity and pressure fluctuations in zero-pressure-gradient turbulent boundary layers in the range Reθ = 2780 - 6680 , and in matching channels at Reτ ~ 1000 - 2000 . Eddies in channels are coherent over longer distances than in boundary layers, especially for Cuu in the direction of the flow. At the 5% level, the maximum streamwise length of Cuu is O (6 δ) for boundary layers and O (15 h) for channels. The corresponding lengths for the transverse velocities and for the pressure are shorter, O (δ- 2 δ) , and of the same order for both flows. Integral correlation lengths in the streamwise and spanwise directions grow away from the wall, except for Luu , x, which peaks at y ~ 0 . 6 h in channels and at y ~ 0 . 2 δ in boundary layers, probably due to the outer intermittency in the latter. Above the buffer layer, Cuu is inclined by ~ 10 -12o from the wall, the wall-normal velocity and the pressure are roughly vertical, and Cww is inclined by ~30o . Those features seem unaffected by the Reynolds number and by the type of flow. Funded by CICYT, INCITE and ERC.

  19. Evoked potential correlates of selective attention with multi-channel auditory inputs

    NASA Technical Reports Server (NTRS)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  20. Evoked potential correlates of selective attention with multi-channel auditory inputs

    NASA Technical Reports Server (NTRS)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  1. Ion effects on gating of the Ca(2+)-activated K+ channel correlate with occupancy of the pore.

    PubMed Central

    Demo, S D; Yellen, G

    1992-01-01

    We studied the effects of permeant ions on the gating of the large conductance Ca(2+)-activated K+ channel from rat skeletal muscle. Rb+ blockade of inward K+ current caused an increase in the open probability as though Rb+ occupancy of the pore interferes with channel closing. In support of this hypothesis, we directly measured the occupancy of the pore by the impermeant ion Cs+ and found that it strongly correlates with its effect on gating. This is consistent with the "foot-in-the-door" model of gating, which states that channels cannot close with an ion in the pore. However, because Rb+ and Cs+ not only slow the closing rate (as predicted by the model), but also speed the opening rate, our results are more consistent with a modified version of the model in which the channel can indeed close while occupied, but the occupancy destabilizes the closed state. Increasing the occupancy of the pore by the addition of other permeant (K+ and Tl+) and impermeant (tetraethylammonium) ions did not affect the open probability. To account for this disparity, we used a two-site permeation model in which only one of the sites influenced gating. Occupancy of this "gating site" interferes with channel closing and hastens opening. Ions that directly or indirectly increase the occupancy of this site will increase the open probability. Images FIGURE 1 FIGURE 2 PMID:1504240

  2. Contractile abnormalities of mouse muscles expressing hyperkalemic periodic paralysis mutant NaV1.4 channels do not correlate with Na+ influx or channel content.

    PubMed

    Lucas, Brooke; Ammar, Tarek; Khogali, Shiemaa; DeJong, Danica; Barbalinardo, Michael; Nishi, Cameron; Hayward, Lawrence J; Renaud, Jean-Marc

    2014-06-01

    Hyperkalemic periodic paralysis (HyperKPP) is characterized by myotonic discharges that occur between episodic attacks of paralysis. Individuals with HyperKPP rarely suffer respiratory distress even though diaphragm muscle expresses the same defective Na(+) channel isoform (NaV1.4) that causes symptoms in limb muscles. We tested the hypothesis that the extent of the HyperKPP phenotype (low force generation and shift toward oxidative type I and IIA fibers) in muscle is a function of 1) the NaV1.4 channel content and 2) the Na(+) influx through the defective channels [i.e., the tetrodotoxin (TTX)-sensitive Na(+) influx]. We measured NaV1.4 channel protein content, TTX-sensitive Na(+) influx, force generation, and myosin isoform expression in four muscles from knock-in mice expressing a NaV1.4 isoform corresponding to the human M1592V mutant. The HyperKPP flexor digitorum brevis muscle showed no contractile abnormalities, which correlated well with its low NaV1.4 protein content and by far the lowest TTX-sensitive Na(+) influx. In contrast, diaphragm muscle expressing the HyperKPP mutant contained high levels of NaV1.4 protein and exhibited a TTX-sensitive Na(+) influx that was 22% higher compared with affected extensor digitorum longus (EDL) and soleus muscles. Surprisingly, despite this high burden of Na(+) influx, the contractility phenotype was very mild in mutant diaphragm compared with the robust abnormalities observed in EDL and soleus. This study provides evidence that HyperKPP phenotype does not depend solely on the NaV1.4 content or Na(+) influx and that the diaphragm does not depend solely on Na(+)-K(+) pumps to ameliorate the phenotype. Copyright © 2014 the American Physiological Society.

  3. Scalable System Design for Covert MIMO Communications

    DTIC Science & Technology

    2014-06-01

    Vehicles US United States VHDL VHSIC Hardware Description Language VLSI Very Large Scale Integration WARP Wireless open-Access Research Platform WLAN...considering the lessons learned in Chapter III a MIMO receiver is developed in VHSIC Hardware Description Language (VHDL). Resource utilization is...Military Communications Conference, vol. 2, pp. 1113–1117 vol.2, October 2002. [39] J. Milton and J. Arnold, Introduction to Probability and

  4. Channel modeling for fifth generation cellular networks and wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Torabi, Amir

    In view of exponential growth in data traffic demand, the wireless communications industry has aimed to increase the capacity of existing networks by 1000 times over the next 20 years. A combination of extreme cell densification, more bandwidth, and higher spectral efficiency is needed to support the data traffic requirements for fifth generation (5G) cellular communications. In this research, the potential improvements achieved by using three major 5G enabling technologies (i.e., small cells, millimeter-wave spectrum, and massive MIMO) in rural and urban environments are investigated. This work develops SPM and KA-based ray models to investigate the impact of geometrical parameters on terrain-based multiuser MIMO channel characteristic. Moreover, a new directional 3D channel model is developed for urban millimeter-wave (mmW) small cells. Path-loss, spatial correlation, coverage distance, and coherence length are studied in urban areas. Exploiting physical optics (PO) and geometric optics (GO) solutions, closed form expressions are derived for spatial correlation. Achievable spatial diversity is evaluated using horizontal and vertical linear arrays as well as planar 2D arrays. In another study, a versatile near-ground field prediction model is proposed to facilitate accurate wireless sensor network (WSN) simulations. Monte Carlo simulations are used to investigate the effects of antenna height, frequency of operation, polarization, and terrain dielectric and roughness properties on WSNs performance.

  5. A General Design Framework for MIMO Wireless Energy Transfer With Limited Feedback

    NASA Astrophysics Data System (ADS)

    Xu, Jie; Zhang, Rui

    2016-05-01

    Multi-antenna or multiple-input multiple-output (MIMO) technique can significantly improve the efficiency of radio frequency (RF) signal enabled wireless energy transfer (WET). To fully exploit the energy beamforming gain at the energy transmitter (ET), the knowledge of channel state information (CSI) is essential, which, however, is difficult to be obtained in practice due to the hardware limitation of the energy receiver (ER). To overcome this difficulty, under a point-to-point MIMO WET setup, this paper proposes a general design framework for a new type of channel learning method based on the ER's energy measurement and feedback. Specifically, the ER measures and encodes the harvested energy levels over different training intervals into bits, and sends them to the ET via a feedback link of limited rate. Based on the energy-level feedback, the ET adjusts transmit beamforming in subsequent training intervals and obtains refined estimates of the MIMO channel by leveraging the technique of analytic center cutting plane method (ACCPM) in convex optimization. Under this general design framework, we further propose two specific feedback schemes termed energy quantization and energy comparison, where the feedback bits at each interval are generated at the ER by quantizing the measured energy level at the current interval and comparing it with those in the previous intervals, respectively. Numerical results are provided to compare the performance of the two feedback schemes. It is shown that energy quantization performs better when the number of feedback bits per interval is large, while energy comparison is more effective with small number of feedback bits.

  6. The study and development of the empirical correlations equation of natural convection heat transfer on vertical rectangular sub-channels

    NASA Astrophysics Data System (ADS)

    Kamajaya, Ketut; Umar, Efrizon; Sudjatmi, K. S.

    2012-06-01

    This study focused on natural convection heat transfer using a vertical rectangular sub-channel and water as the coolant fluid. To conduct this study has been made pipe heaters are equipped with thermocouples. Each heater is equipped with five thermocouples along the heating pipes. The diameter of each heater is 2.54 cm and 45 cm in length. The distance between the central heating and the pitch is 29.5 cm. Test equipment is equipped with a primary cooling system, a secondary cooling system and a heat exchanger. The purpose of this study is to obtain new empirical correlations equations of the vertical rectangular sub-channel, especially for the natural convection heat transfer within a bundle of vertical cylinders rectangular arrangement sub-channels. The empirical correlation equation can support the thermo-hydraulic analysis of research nuclear reactors that utilize cylindrical fuel rods, and also can be used in designing of baffle-free vertical shell and tube heat exchangers. The results of this study that the empirical correlation equations of natural convection heat transfer coefficients with rectangular arrangement is Nu = 6.3357 (Ra.Dh/x)0.0740.

  7. Resource Allocation in MIMO-Based Ad Hoc Networks

    DTIC Science & Technology

    2011-03-01

    Multiple - Input Multiple - Output ( MIMO ...Hoc Networks Peng Wang∗, John Matyjas† and Michael Medley† †Air Force Research Lab, Rome, NY Abstract— Multiple - Input Multiple - Output ( MIMO ) commu... input multiple - output systems, capacity optimization, joint routing, scheduling and power control. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION

  8. Space-time processing for MIMO-OFDM using DFT-based complementary sequences

    NASA Astrophysics Data System (ADS)

    Lau, Chad C.; Calderbank, Robert; Zoltowski, Michael D.

    2010-04-01

    In this paper, a new space-time signaling scheme is proposed for Orthogonal Frequency Division Multiplexing (OFDM) using complementary sequences derived from the rows of the DFT matrix. The autocorrelative properties of the complementary sequences allows multiple complex data signals at the transmitter with an arbitrary number of antennas to be perfectly separated and reconstructed at the receiver without prior channel knowledge while achieving full-rate. This new method is proposed and derived for multiple MIMO-OFDM systems with multipath fading; at the receiver, symbol estimation is effected via maximum likelihood estimation (ML).

  9. Increased renal epithelial na channel expression and activity correlate with elevation of blood pressure in spontaneously hypertensive rats.

    PubMed

    Haloui, Mounsif; Tremblay, Johanne; Seda, Ondrej; Koltsova, Svetlana V; Maksimov, Georgy V; Orlov, Sergei N; Hamet, Pavel

    2013-10-01

    Elevation of blood pressure with age is one of the hallmarks of hypertension in both males and females. This study examined transcriptomic profiles in the kidney of 12-, 40-, and 80-week-old spontaneously hypertensive rats and 4 recombinant inbred strains in search for functional genetic elements supporting temporal dynamics of blood pressure elevation. We found that both in males and females of spontaneously hypertensive rats and hypertensive recombinant inbred strains age-dependent blood pressure increment was accompanied by 50% heightened expression of epithelial sodium channel β- and γ-subunits. Epithelial sodium channel subunit expression correlated positively with blood pressure but correlated negatively with renin expression. Increased epithelial sodium channel activity was observed in cultured epithelial cells isolated from the kidney medulla of 80-week-old spontaneously hypertensive rats but not in age-matched normotensive Wistar Kyoto. This difference remained evident after 24-hour treatment with aldosterone. 22Na uptake in the perfused kidney medulla was increased whereas the urinary Na/K ratio was decreased in old spontaneously hypertensive rats compared with normotensive controls. The difference was eliminated by the administration of epithelial sodium channel inhibitor benzamil. Observations in recombinant inbred strains representing various mixtures of parental hypertensive and normotensive genomes suggest that Scnn1g and Scnn1b genes themselves are not implicated in heightened expression and that the increased expression is neither secondary nor required for a partial elevation of blood pressure in contrast to spontaneously hypertensive rats. We suggest that spontaneously hypertensive rats display an intact negative feed-back between renin-angiotensin-system and epithelial Na channel activity whose upregulated expression is supported by a yet unknown mechanism.

  10. Electrostatics of aquaporin and aquaglyceroporin channels correlates with their transport selectivity

    PubMed Central

    Oliva, Romina; Calamita, Giuseppe; Thornton, Janet M.; Pellegrini-Calace, Marialuisa

    2010-01-01

    Aquaporins are homotetrameric channel proteins, which allow the diffusion of water and small solutes across biological membranes. According to their transport function, aquaporins can be divided into “orthodox aquaporins”, which allow the flux of water molecules only, and “aquaglyceroporins”, which facilitate the diffusion of glycerol and other small solutes in addition to water. The contribution of individual residues in the pore to the selectivity of orthodox aquaporins and aquaglyceroporins is not yet fully understood. To gain insights into aquaporin selectivity, we focused on the sequence variation and electrostatics of their channels. The continuum Poisson-Boltzmann electrostatic potential along the channel was calculated and compared for ten three-dimensional-structures which are representatives of different aquaporin subfamilies, and a panel of functionally characterized mutants, for which high-accuracy three-dimensional-models could be derived. Interestingly, specific electrostatic profiles associated with the main selectivity to water or glycerol could be identified. In particular: (i) orthodox aquaporins showed a distinctive electrostatic potential maximum at the periplasmic side of the channel around the aromatic/Arg (ar/R) constriction site; (ii) aquaporin-0 (AQP0), a mammalian aquaporin with considerably low water permeability, had an additional deep minimum at the cytoplasmic side; (iii) aquaglyceroporins showed a rather flat potential all along the channel; and (iv) the bifunctional protozoan PfAQP had an unusual all negative profile. Evaluation of electrostatics of the mutants, along with a thorough sequence analysis of the aquaporin pore-lining residues, illuminated the contribution of specific residues to the electrostatics of the channels and possibly to their selectivity. PMID:20147624

  11. Selenoprotein W redox-regulated Ca2+ channels correlate with selenium deficiency-induced muscles Ca2+ leak

    PubMed Central

    Zhao, Xia; Zhao, Wenchao; Liu, Wei; Yang, Jie; Sattar, Hamid; Zhao, Jinxin; Zhang, Ziwei; Xu, Shiwen

    2016-01-01

    Selenium (Se) deficiency induces Ca2+ leak and calcification in mammal skeletal muscles; however, the exact mechanism is still unclear. In the present study, both Se-deficient chicken muscle models and selenoprotein W (SelW) gene knockdown myoblast and embryo models were used to study the mechanism. The results showed that Se deficiency-induced typical muscular injuries accompanied with Ca2+ leak and oxidative stress (P < 0.05) injured the ultrastructure of the sarcoplasmic reticulum (SR) and mitochondria; decreased the levels of the Ca2+ channels, SERCA, SLC8A, CACNA1S, ORAI1, STIM1, TRPC1, and TRPC3 (P < 0.05); and increased the levels of Ca2+ channel PMCA (P < 0.05). Similarly, SelW knockdown also induced Ca2+ leak from the SR and cytoplasm; increased mitochondrial Ca2+ levels and oxidative stress; injured SR and mitochondrial ultrastructure; decreased levels of SLC8A, CACNA1S, ORA1, TRPC1, and TRPC3; and caused abnormal activities of Ca2+ channels in response to inhibitors in myoblasts and chicken embryos. Thus, both Se deficiency and SelW knockdown induced Ca2+ leak, oxidative stress, and Ca2+ channel reduction. In addition, Ca2+ levels and the expression of the Ca2+ channels, RyR1, SERCA, CACNA1S, TRPC1, and TRPC3 were recovered to normal levels by N-acetyl-L-cysteine (NAC) treatment compared with SelW knockdown cells. Thus, with regard to the decreased Ca2+ channels, SelW knockdown closely correlated Se deficiency with Ca2+ leak in muscles. The redox regulation role of SelW is crucial in Se deficiency-induced Ca2+ leak in muscles. PMID:27557522

  12. An online multi-channel SSVEP-based brain-computer interface using a canonical correlation analysis method.

    PubMed

    Bin, Guangyu; Gao, Xiaorong; Yan, Zheng; Hong, Bo; Gao, Shangkai

    2009-08-01

    In recent years, there has been increasing interest in using steady-state visual evoked potential (SSVEP) in brain-computer interface (BCI) systems. However, several aspects of current SSVEP-based BCI systems need improvement, specifically in relation to speed, user variation and ease of use. With these improvements in mind, this paper presents an online multi-channel SSVEP-based BCI system using a canonical correlation analysis (CCA) method for extraction of frequency information associated with the SSVEP. The key parameters, channel location, window length and the number of harmonics, are investigated using offline data, and the result used to guide the design of the online system. An SSVEP-based BCI system with six targets, which use nine channel locations in the occipital and parietal lobes, a window length of 2 s and the first harmonic, is used for online testing on 12 subjects. The results show that the proposed BCI system has a high performance, achieving an average accuracy of 95.3% and an information transfer rate of 58 +/- 9.6 bit min(-1). The positive characteristics of the proposed system are that channel selection and parameter optimization are not required, the possible use of harmonic frequencies, low user variation and easy setup.

  13. An online multi-channel SSVEP-based brain-computer interface using a canonical correlation analysis method

    NASA Astrophysics Data System (ADS)

    Bin, Guangyu; Gao, Xiaorong; Yan, Zheng; Hong, Bo; Gao, Shangkai

    2009-08-01

    In recent years, there has been increasing interest in using steady-state visual evoked potential (SSVEP) in brain-computer interface (BCI) systems. However, several aspects of current SSVEP-based BCI systems need improvement, specifically in relation to speed, user variation and ease of use. With these improvements in mind, this paper presents an online multi-channel SSVEP-based BCI system using a canonical correlation analysis (CCA) method for extraction of frequency information associated with the SSVEP. The key parameters, channel location, window length and the number of harmonics, are investigated using offline data, and the result used to guide the design of the online system. An SSVEP-based BCI system with six targets, which use nine channel locations in the occipital and parietal lobes, a window length of 2 s and the first harmonic, is used for online testing on 12 subjects. The results show that the proposed BCI system has a high performance, achieving an average accuracy of 95.3% and an information transfer rate of 58 ± 9.6 bit min-1. The positive characteristics of the proposed system are that channel selection and parameter optimization are not required, the possible use of harmonic frequencies, low user variation and easy setup.

  14. Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications.

    PubMed

    Nasir, Jamal; Jamaluddin, Mohd Haizal; Ahmad Khan, Aftab; Kamarudin, Muhammad Ramlee; Yen, Bruce Leow Chee; Owais, Owais

    2017-01-13

    An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE111 and higher order TE121 modes of the DRA. TE111 degenerate mode covers LTE band 2 (1.85-1.99 GHz), 3 (1.71-1.88 GHz), and 9 (1.7499-1.7849 GHz) at fr = 1.8 GHz whereas TE121 covers LTE band 7 (2.5-2.69 GHz) at fr = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work.

  15. Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications

    PubMed Central

    Nasir, Jamal; Jamaluddin, Mohd. Haizal; Ahmad Khan, Aftab; Kamarudin, Muhammad Ramlee; Leow, Chee Yen; Owais, Owais

    2017-01-01

    An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE111 and higher order TE121 modes of the DRA. TE111 degenerate mode covers LTE band 2 (1.85–1.99 GHz), 3 (1.71–1.88 GHz), and 9 (1.7499–1.7849 GHz) at fr = 1.8 GHz whereas TE121 covers LTE band 7 (2.5–2.69 GHz) at fr = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work. PMID:28098807

  16. On Modeling and Analysis of MIMO Wireless Mesh Networks with Triangular Overlay Topology

    DOE PAGES

    Cao, Zhanmao; Wu, Chase Q.; Zhang, Yuanping; ...

    2015-01-01

    Multiple input multiple output (MIMO) wireless mesh networks (WMNs) aim to provide the last-mile broadband wireless access to the Internet. Along with the algorithmic development for WMNs, some fundamental mathematical problems also emerge in various aspects such as routing, scheduling, and channel assignment, all of which require an effective mathematical model and rigorous analysis of network properties. In this paper, we propose to employ Cartesian product of graphs (CPG) as a multichannel modeling approach and explore a set of unique properties of triangular WMNs. In each layer of CPG with a single channel, we design a node coordinate scheme thatmore » retains the symmetric property of triangular meshes and develop a function for the assignment of node identity numbers based on their coordinates. We also derive a necessary-sufficient condition for interference-free links and combinatorial formulas to determine the number of the shortest paths for channel realization in triangular WMNs.« less

  17. Color enhancement of highly correlated images. II - Channel ratio and 'chromaticity' transformation techniques

    NASA Technical Reports Server (NTRS)

    Gillespie, Alan R.; Kahle, Anne B.; Walker, Richard E.

    1987-01-01

    Two techniques for enhancing the color of multispectral images are described; both involve ratioing of data from different image channels. In the first technique, the ratioed data are assigned the primary color for display as color ratio pictures, and in the second method, image data are transformed to RGB chromaticity coordinates by ratioing the data acquired in three channels to the sum of their intensities. The two techniques are applied to a NASA Thermal-IR Multispectral Scanner (TIMS) image of Death Valley and to a Landsat MSS image of the Mojave Desert. The basic principles of ratioing are discussed, and the effects of atmospheric path radiances on the interpretation of ratioed images are investigated. It is observed that the color pictures produced using these two enhancement techniques are similar to the pictures enhanced by decorrelation and hue-saturation-intensity methods.

  18. High-capacity mixed fiber-wireless backhaul networks using MMW radio-over-MCF and MIMO

    NASA Astrophysics Data System (ADS)

    Pham, Thu A.; Pham, Hien T. T.; Le, Hai-Chau; Dang, Ngoc T.

    2017-10-01

    In this paper, we have proposed a high-capacity backhaul network, which is based on mixed fiber-wireless systems using millimeter-wave radio-over-multi-core fiber (MMW RoMCF) and multiple-input multiple-output (MIMO) transmission, for next generation mobile access networks. In addition, we also investigate the use of avalanche photodiode (APD) to improve capacity of the proposed backhaul downlink. We then theoretically analyze the system capacity comprehensively while considering various physical impairments including noise, MCF crosstalk, and fading modeled by Rician MIMO channel. The feasibility of the proposed backhaul architecture is verified via the numerical simulation experiments. The research results demonstrate that our developed backhaul solution can significantly enhance the backhaul capacity; the system capacity of 24 bps/Hz can be achieved with 20-km 8-core MCF and 8 × 8 MIMO transmitted over 100-m Rician fading link. It is also shown that the system performance, in term of channel capacity, strongly depend on the MCF inter-core crosstalk, which is governed by the mode coupling coefficient, the core pitch, and the bending radius.

  19. Adaptive Channel Estimation for Multiple-Input Multiple-Output Frequency Domain Equalization

    DTIC Science & Technology

    2005-01-01

    FDE) in a single carrier (SC) multiple - input multiple - output ( MIMO ) system. Two types of channel estimation methods are proposed, assuming...Adaptive Channel Estimation for Multiple - Input Multiple - Output Frequency Domain Equalization Xu Zhu*, Fareq Malek*, Yi Gong+ and Yi Huang...perfect channel state information (CSI), and has a fast convergence speed and reasonably low complexity. Keywords- Multiple - Input Multiple - Output

  20. Crosstalk mitigation in a free-space orbital angular momentum multiplexed communication link using 4×4 MIMO equalization.

    PubMed

    Huang, Hao; Cao, Yinwen; Xie, Guodong; Ren, Yongxiong; Yan, Yan; Bao, Changjing; Ahmed, Nisar; Neifeld, Mark A; Dolinar, Samuel J; Willner, Alan E

    2014-08-01

    We demonstrate crosstalk mitigation using 4×4 multiple-input-multiple-output (MIMO) equalization on an orbital angular momentum (OAM) multiplexed free-space data link with heterodyne detection. Four multiplexed OAM beams, each carrying a 20  Gbit/s quadrature phase-shift keying signal, propagate through weak turbulence. The turbulence induces inter-channel crosstalk among each beam and degrades the signal performance. Experimental results demonstrate that with the assistance of MIMO processing, the signal quality and the bit-error-rate (BER) performance can be improved. The power penalty can be reduced by >4  dB at a BER of 3.8×10-3.

  1. MIMO-OFDM equaliser for spatial multiplexing transmission modes

    NASA Astrophysics Data System (ADS)

    Beinschob, P.; Zölzer, U.

    2010-10-01

    In search for faster and more reliable communication, multiple-input multiple-output (MIMO) in conjuction with Orthogonal Frequency Division Multiplexing (OFDM) are subject of extensive research. In spatial multiplexing transmission an instantaneous rise of data rates governed by the number of transmit antennas can be realised. The system performance depends highly on signal-to-interference-plus-noise ratios (SINR) at the receiver. The receiver's equaliser is supposed to maximize the SINR by mitigating the spatial interference and thus separating the transmitted signals. For this problem several solutions exist such as linear and nonlinear, per subcarrier or OFDM symbol-based. An overview of common algorithms is given and complexity is discussed. Bit error rate (BER) performance evaluations are presented. Another aspect is the impact of the equalisation strategy on the performance of bit-interleaved soft information-based channel coding schemes. As a representative, LDPC codes are chosen. Simulation results show a significant BER performance loss for symbol decision-based equalisers compared to the uncoded performance. To overcome this problem a modification of the Maximum Likelihood algorithm is proposed which yields good performance for low SNR applications.

  2. Noncoherent Maximum Likelihood Detection for Differential Spatial Multiplexing MIMO Systems

    NASA Astrophysics Data System (ADS)

    Jia, Ziyan; Yoshii, Katsunobu; Handa, Shiro; Sasamori, Fumihito; Oshita, Shinjiro

    In this paper, we propose a novel noncoherent maximum likelihood detection (NMLD) method for differential spatial multiplexing (SM) multiple-input multiple-output (MIMO) systems. Unlike the conventional maximum likelihood detection (MLD) method which needs the knowledge of channel state information (CSI) at the receiver, NMLD method has no need of CSI at either the transmitter orreceiver. After repartitioning the observation block of multiple-symbol differential detection (MSDD) and following a decision feedback process, the decision metric of NMLD is derived by reforming that of MSDD. Since the maximum Doppler frequency and noise power are included in the derived decision metric, estimations of both maximum Doppler frequency and noise power are needed at the receiver for NMLD. A fast calculation algorithm (FCA) is applied to reduce the computational complexity of NMLD. The feasibility of the proposed NMLD is demonstrated by computer simulations in both slow and fast fading environments. Simulation results show that the proposed NMLD has good bit error rate (BER) performance, approaching that of the conventional coherent MLD with the extension of reference symbols interval. It is also proved that the BER performance is not sensitive to the estimation errors in maximum Doppler frequency and noise power.

  3. Analog nonlinear MIMO receiver for optical mode division multiplexing transmission.

    PubMed

    Spalvieri, Arnaldo; Boffi, Pierpaolo; Pecorino, Simone; Barletta, Luca; Magarini, Maurizio; Gatto, Alberto; Martelli, Paolo; Martinelli, Mario

    2013-10-21

    The complexity and the power consumption of digital signal processing are crucial issues in optical transmission systems based on mode division multiplexing and coherent multiple-input multiple-output (MIMO) processing at the receiver. In this paper the inherent characteristic of spatial separation between fiber modes is exploited, getting a MIMO system where joint demultiplexing and detection is based on spatially separated photodetectors. After photodetection, one has a MIMO system with nonlinear crosstalk between modes. The paper shows that the nonlinear crosstalk can be dealt with by a low-complexity and non-adaptive detection scheme, at least in the cases presented in the paper.

  4. Correlation of changes in cardiac calcium channels with hemodynamics in Syrian hamster cardiomyopathy and heart failure

    SciTech Connect

    Finkel, M.S.; Marks, E.S.; Patterson, R.E.; Speir, E.H.; Steadman, K.A.; Keiser, H.R.

    1987-07-13

    The authors compared hemodynamics with (/sup 3/H)nitrendipine (calcium channel) binding to cardiac membranes from Bio 14.6 cardiomyopathic Syrian hamsters at 4 and 10 months with their F/sub 1/B controls. A 50% increase in the number (B/sub max/) of nitrendipine binding sites (calcium channels) was seen only in the 4 month old myopathic vs controls (B/sub max/ = 468 +/- 11 vs 309 +/- 10 fmol/mg prot with no change in affinity (K/sub D/) (K/sub D/ = .65 +/- .12 vs .75 +/- .14nM), while no differences in B/sub max/ or K/sub D/ were seen at 10 months (B/sub max/ = 375 +/- 9 vs 362 +/- 7 fmol/mg prot/K/sub D/ = .82 +/- .18 vs .89 +/- .17nM) myopathic vs control respectively. Hemodynamic studies revealed no significant differences in cardiac output, cardiac index, stroke volume, heart rate, mean arterial pressure, peripheral resistance, body weight, heart weight at 4 months, but a significant decrease in peripheral resistance (1120 +/- 360 vs 2080 +/- 240) increase in body weight (118 +/- 2 vs 94 +/- 2 grams) and heart weight (97 +/- 5 vs 78 +/- 2 gms/100gms body weight) in 10 month myopathic vs control animals. The authors conclude that the onset of cardiomyopathy at 4 months is associated with a selective increase in calcium channel binding sites and heart failure at 10 months is associated with a relative decrease in these sites. 14 references, 2 figures, 2 tables.

  5. Adaptive switching detection algorithm for iterative-MIMO systems to enable power savings

    NASA Astrophysics Data System (ADS)

    Tadza, N.; Laurenson, D.; Thompson, J. S.

    2014-11-01

    This paper attempts to tackle one of the challenges faced in soft input soft output Multiple Input Multiple Output (MIMO) detection systems, which is to achieve optimal error rate performance with minimal power consumption. This is realized by proposing a new algorithm design that comprises multiple thresholds within the detector that, in real time, specify the receiver behavior according to the current channel in both slow and fast fading conditions, giving it adaptivity. This adaptivity enables energy savings within the system since the receiver chooses whether to accept or to reject the transmission, according to the success rate of detecting thresholds. The thresholds are calculated using the mutual information of the instantaneous channel conditions between the transmitting and receiving antennas of iterative-MIMO systems. In addition, the power saving technique, Dynamic Voltage and Frequency Scaling, helps to reduce the circuit power demands of the adaptive algorithm. This adaptivity has the potential to save up to 30% of the total energy when it is implemented on Xilinx®Virtex-5 simulation hardware. Results indicate the benefits of having this "intelligence" in the adaptive algorithm due to the promising performance-complexity tradeoff parameters in both software and hardware codesign simulation.

  6. Outage-Optimal Transmission in Multiuser-MIMO Kronecker Channels

    DTIC Science & Technology

    2010-03-01

    San Diego 9500 Gilman Drive, La Jolla, CA 92093-0407 N/A N/A N/A In this work, we look at single user and multi user Multiple - Input Multiple - Output ...s1ghosh@ucsd.edu, brao@ece.ucsd.edu, zeidler@ece.ucsd.edu ABSTRACT In this work, we look at single user and multiuser Multiple - Input Multiple - Output

  7. Experimental Verification of Multiple-input Multiple Output (MIMO) Beamforming Capabilities Using a Time-division Coherent MIMO Radar

    DTIC Science & Technology

    2015-02-01

    output (MIMO) beamforming capabilities using a time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada...time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada Scientific Report DRDC-RDDC-2015-R051 April 2015... Moo , P. W.; Laneve, T. 5. DATE OF PUBLICATION (Month and year of publication of document.) April 2015 6a. NO. OF PAGES (Total containing information

  8. Experimental Verification of Multiple-input Multiple Output (MIMO) Beamforming Capabilities Using a Time-division Coherent MIMO Radar

    DTIC Science & Technology

    2015-04-01

    output (MIMO) beamforming capabilities using a time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada...time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada Scientific Report DRDC-RDDC-2015-R051 April 2015... Moo , P. W.; Laneve, T. 5. DATE OF PUBLICATION (Month and year of publication of document.) April 2015 6a. NO. OF PAGES (Total containing information

  9. Experimental Verification of Multiple-input Multiple Output (MIMO) Beamforming Capabilities Using a Time-division Coherent MIMO Radar

    DTIC Science & Technology

    2015-03-01

    output (MIMO) beamforming capabilities using a time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada...time-division coherent MIMO radar P. Sévigny P.W. Moo T. Laneve Defence Research and Development Canada Scientific Report DRDC-RDDC-2015-R051 April 2015... Moo , P. W.; Laneve, T. 5. DATE OF PUBLICATION (Month and year of publication of document.) April 2015 6a. NO. OF PAGES (Total containing information

  10. General correlation for prediction of critical heat flux ratio in water cooled channels

    SciTech Connect

    Pernica, R.; Cizek, J.

    1995-09-01

    The paper present the general empirical Critical Heat Flux Ration (CHFR) correlation which is valid for vertical water upflow through tubes, internally heated concentric annuli and rod bundles geometries with both wide and very tight square and triangular rods lattices. The proposed general PG correlation directly predicts the CHFR, it comprises axial and radial non-uniform heating, and is valid in a wider range of thermal hydraulic conditions than previously published critical heat flux correlations. The PG correlation has been developed using the critical heat flux Czech data bank which includes more than 9500 experimental data on tubes, 7600 data on rod bundles and 713 data on internally heated concentric annuli. Accuracy of the CHFR prediction, statistically assessed by the constant dryout conditions approach, is characterized by the mean value nearing 1.00 and the standard deviation less than 0.06. Moverover, a subchannel form of the PG correlations is statistically verified on Westinghouse and Combustion Engineering rod bundle data bases, i.e. more than 7000 experimental CHF points of Columbia University data bank were used.

  11. Heat transfer in plate heat exchanger channels: Experimental validation of selected correlation equations

    NASA Astrophysics Data System (ADS)

    Cieśliński, Janusz T.; Fiuk, Artur; Typiński, Krzysztof; Siemieńczuk, Bartłomiej

    2016-09-01

    This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx). The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.

  12. Negative and positive cross-correlations of current noises in quantum Hall edge channels at bulk filling factor [Formula: see text].

    PubMed

    Ota, T; Hashisaka, M; Muraki, K; Fujisawa, T

    2017-06-07

    Cross-correlation noise in electrical currents generated from a series connection of two quantum point contacts (QPCs), the injector and the detector, is described for investigating energy relaxation in quantum Hall edge channels at bulk filling factor [Formula: see text]. We address the importance of tuning the energy bias across the detector for this purpose. For a long channel with a macroscopic floating ohmic contact that thermalizes the electrons, the cross-correlation turns from negative values to the maximally positive value (identical noise in the two currents) by tuning the effective energy bias to zero. This can be understood by considering competition between the low-frequency charge fluctuation generated at the injector, which contributes positive correlation, and the partition noise at the detector, which gives negative correlation. Strikingly, even for a short channel without intentional thermalization, significantly large positive correlation is observed in contrast to negative values expected for coherent transport between the two QPCs.

  13. Controller certification: The generalized stability margin inference for a large number of MIMO controllers

    NASA Astrophysics Data System (ADS)

    Park, Jisang

    In this dissertation, we investigate MIMO stability margin inference of a large number of controllers using pre-established stability margins of a small number of nu-gap-wise adjacent controllers. The generalized stability margin and the nu-gap metric are inherently able to handle MIMO system analysis without the necessity of repeating multiple channel-by-channel SISO analyses. This research consists of three parts: (i) development of a decision support tool for inference of the stability margin, (ii) computational considerations for yielding the maximal stability margin with the minimal nu-gap metric in a less conservative manner, and (iii) experiment design for estimating the generalized stability margin with an assured error bound. A modern problem from aerospace control involves the certification of a large set of potential controllers with either a single plant or a fleet of potential plant systems, with both plants and controllers being MIMO and, for the moment, linear. Experiments on a limited number of controller/plant pairs should establish the stability and a certain level of margin of the complete set. We consider this certification problem for a set of controllers and provide algorithms for selecting an efficient subset for testing. This is done for a finite set of candidate controllers and, at least for SISO plants, for an infinite set. In doing this, the nu-gap metric will be the main tool. We provide a theorem restricting a radius of a ball in the parameter space so that the controller can guarantee a prescribed level of stability and performance if parameters of the controllers are contained in the ball. Computational examples are given, including one of certification of an aircraft engine controller. The overarching aim is to introduce truly MIMO margin calculations and to understand their efficacy in certifying stability over a set of controllers and in replacing legacy single-loop gain and phase margin calculations. We consider methods for the

  14. Time domain measures of inter-channel EEG correlations: a comparison of linear, nonparametric and nonlinear measures.

    PubMed

    Bonita, J D; Ambolode, L C C; Rosenberg, B M; Cellucci, C J; Watanabe, T A A; Rapp, P E; Albano, A M

    2014-02-01

    Correlations between ten-channel EEGs obtained from thirteen healthy adult participants were investigated. Signals were obtained in two behavioral states: eyes open no task and eyes closed no task. Four time domain measures were compared: Pearson product moment correlation, Spearman rank order correlation, Kendall rank order correlation and mutual information. The psychophysiological utility of each measure was assessed by determining its ability to discriminate between conditions. The sensitivity to epoch length was assessed by repeating calculations with 1, 2, 3, …, 8 s epochs. The robustness to noise was assessed by performing calculations with noise corrupted versions of the original signals (SNRs of 0, 5 and 10 dB). Three results were obtained in these calculations. First, mutual information effectively discriminated between states with less data. Pearson, Spearman and Kendall failed to discriminate between states with a 1 s epoch, while a statistically significant separation was obtained with mutual information. Second, at all epoch durations tested, the measure of between-state discrimination was greater for mutual information. Third, discrimination based on mutual information was more robust to noise. The limitations of this study are discussed. Further comparisons should be made with frequency domain measures, with measures constructed with embedded data and with the maximal information coefficient.

  15. Multipath Propagation for Helicopter-to-Ground MIMO Links

    DTIC Science & Technology

    2011-06-02

    AFFTC-PA-11118 Multipath Propagation for Helicopter-to-Ground MIMO Links Michael Rice, Michael Jensen AIR FORCE FLIGHT TEST CENTER...EDWARDS AFB, CA June 2, 2011 A F F T C m Approved for public release; distribution is unlimited. AIR FORCE FLIGHT TEST CENTER...TITLE AND SUBTITLE Multipath Propagation for Helicopter-to-Ground MIMO Links 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  16. High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR)

    PubMed Central

    Wang, Ruijia; Chen, Jie; Wang, Xing; Sun, Bing

    2017-01-01

    Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method. PMID:28075367

  17. High-Performance Anti-Retransmission Deception Jamming Utilizing Range Direction Multiple Input and Multiple Output (MIMO) Synthetic Aperture Radar (SAR).

    PubMed

    Wang, Ruijia; Chen, Jie; Wang, Xing; Sun, Bing

    2017-01-09

    Retransmission deception jamming seriously degrades the Synthetic Aperture Radar (SAR) detection efficiency and can mislead SAR image interpretation by forming false targets. In order to suppress retransmission deception jamming, this paper proposes a novel multiple input and multiple output (MIMO) SAR structure range direction MIMO SAR, whose multiple channel antennas are vertical to the azimuth. First, based on the multiple channels of range direction MIMO SAR, the orthogonal frequency division multiplexing (OFDM) linear frequency modulation (LFM) signal was adopted as the transmission signal of each channel, which is defined as a sub-band signal. This sub-band signal corresponds to the transmission channel. Then, all of the sub-band signals are modulated with random initial phases and concurrently transmitted. The signal form is more complex and difficult to intercept. Next, the echoes of the sub-band signal are utilized to synthesize a wide band signal after preprocessing. The proposed method will increase the signal to interference ratio and peak amplitude ratio of the signal to resist retransmission deception jamming. Finally, well-focused SAR imagery is obtained using a conventional imaging method where the retransmission deception jamming strength is degraded and defocused. Simulations demonstrated the effectiveness of the proposed method.

  18. BER performance enhancement for secure wireless communication systems based on chaotic-MIMO techniques

    NASA Astrophysics Data System (ADS)

    Abdulameer, Lwaa F.; Jignesh, Jokhakar D.; Sripati, U.; Kulkarni, Murlidhar

    2013-01-01

    The growing interest in the use of chaotic techniques for enabling secure communication in recent years has been motivated by the emergence of a number of wireless services which require the service provider to provide low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input-Multiple-Output (MIMO) channels. While the use of Chaotic maps can enhance security, it is seen that the overall BER performance gets degraded when compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. The performance of Chaos Shift Keying (CSK) with 2×1 and 2×2 Alamouti schemes for different chaotic maps over wireless channels has been studied. It has been shown that the use of these schemes can provide security enhancement without the penalty of degradation of BER performance.

  19. The architecture of blind equalizer for MIMO free space optical communication system

    NASA Astrophysics Data System (ADS)

    Li, Hongwei; Huang, Yongmei

    2016-10-01

    The free space optical (FSO) communication system has attracted many researchers from different countries, owning to its advantages such as high security, high speed and anti-interference. Among all kinds of the channels of the FSO communication system, the atmosphere channel is very difficult to deal with for two typical disadvantages at least. The one is the scintillation of the optical carrier intensity caused by the atmosphere turbulence and the other is the multipath effect by the optical scattering. A lot of studies have shown that the MIMO (Multiple Input Multiple Output) technology can overcome the scintillation of the optical carrier through the atmosphere effectively. So the background of this paper is a MIMO system which includes multiple optical transmitting antennas and multiple optical receiving antennas. A number of particles such as hazes, water droplets and aerosols exit in the atmosphere widely. When optical carrier meets these particles, the scattering phenomenon is inevitable, which leads to the multipath effect. As a result, a optical pulse transmitted by the optical transmitter becomes wider, to some extent, when it gets to the optical receiver due to the multipath effect. If the information transmission rate is quite low, there is less relationship between the multipath effect and the bit error rate (BER) of the communication system. Once the information transmission rate increases to a high level, the multipath effect will produce the problem called inter symbol inference (ISI) seriously and the bit error rate will increase severely. In order to take the advantage of the FSO communication system, the inter symbol inference problem must be solved. So it is necessary to use the channel equalization technology. This paper aims at deciding a equalizer and designing suitable equalization algorithm for a MIMO free space optical communication system to overcome the serious problem of bit error rate. The reliability and the efficiency of

  20. Expression of temperature-sensitive ion channel TRPM8 in sperm cells correlates with vertebrate evolution

    PubMed Central

    Majhi, Rakesh Kumar; Saha, Somdatta; Kumar, Ashutosh; Ghosh, Arijit; Swain, Nirlipta; Goswami, Luna; Mohapatra, Pratyush; Maity, Apratim; Kumar Sahoo, Vivek

    2015-01-01

    Transient Receptor Potential cation channel, subfamily Melastatin, member 8 (TRPM8) is involved in detection of cold temperature, different noxious compounds and in execution of thermo- as well as chemo-sensitive responses at cellular levels. Here we explored the molecular evolution of TRPM8 by analyzing sequences from various species. We elucidate that several regions of TRPM8 had different levels of selection pressure but the 4th–5th transmembrane regions remain highly conserved. Analysis of synteny suggests that since vertebrate origin, TRPM8 gene is linked with SPP2, a bone morphogen. TRPM8, especially the N-terminal region of it, seems to be highly variable in human population. We found 16,656 TRPM8 variants in 1092 human genomes with top variations being SNPs, insertions and deletions. A total of 692 missense mutations are also mapped to human TRPM8 protein of which 509 seem to be delateroiours in nature as supported by Polyphen V2, SIFT and Grantham deviation score. Using a highly specific antibody, we demonstrate that TRPM8 is expressed endogenously in the testis of rat and sperm cells of different vertebrates ranging from fish to higher mammals. We hypothesize that TRPM8 had emerged during vertebrate evolution (ca 450 MYA). We propose that expression of TRPM8 in sperm cell and its role in regulating sperm function are important factors that have guided its molecular evolution, and that these understandings may have medical importance. PMID:26500819

  1. Novel Wideband MIMO Antennas That Can Cover the Whole LTE Spectrum in Handsets and Portable Computers

    PubMed Central

    Sanad, Mohamed; Hassan, Noha

    2014-01-01

    A dual resonant antenna configuration is developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the LTE spectrums in portable communication equipment. The bandwidth that can be covered by each antenna exceeds 70% without using any matching or tuning circuits, with efficiencies that reach 80%. Thus, a dual configuration of them is capable of covering up to 39 LTE (4G) bands besides the existing 2G and 3G bands. 2 × 2 MIMO configurations have been also developed for the two wideband antennas with a maximum isolation and a minimum correlation coefficient between the primary and the diversity antennas. PMID:24558322

  2. Novel wideband MIMO antennas that can cover the whole LTE spectrum in handsets and portable computers.

    PubMed

    Sanad, Mohamed; Hassan, Noha

    2014-01-01

    A dual resonant antenna configuration is developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the LTE spectrums in portable communication equipment. The bandwidth that can be covered by each antenna exceeds 70% without using any matching or tuning circuits, with efficiencies that reach 80%. Thus, a dual configuration of them is capable of covering up to 39 LTE (4G) bands besides the existing 2G and 3G bands. 2×2 MIMO configurations have been also developed for the two wideband antennas with a maximum isolation and a minimum correlation coefficient between the primary and the diversity antennas.

  3. Capacity of MIMO free space optical communications using multiple partially coherent beams propagation through non-Kolmogorov strong turbulence.

    PubMed

    Deng, Peng; Kavehrad, Mohsen; Liu, Zhiwen; Zhou, Zhou; Yuan, Xiuhua

    2013-07-01

    We study the average capacity performance for multiple-input multiple-output (MIMO) free-space optical (FSO) communication systems using multiple partially coherent beams propagating through non-Kolmogorov strong turbulence, assuming equal gain combining diversity configuration and the sum of multiple gamma-gamma random variables for multiple independent partially coherent beams. The closed-form expressions of scintillation and average capacity are derived and then used to analyze the dependence on the number of independent diversity branches, power law α, refractive-index structure parameter, propagation distance and spatial coherence length of source beams. Obtained results show that, the average capacity increases more significantly with the increase in the rank of MIMO channel matrix compared with the diversity order. The effect of the diversity order on the average capacity is independent of the power law, turbulence strength parameter and spatial coherence length, whereas these effects on average capacity are gradually mitigated as the diversity order increases. The average capacity increases and saturates with the decreasing spatial coherence length, at rates depending on the diversity order, power law and turbulence strength. There exist optimal values of the spatial coherence length and diversity configuration for maximizing the average capacity of MIMO FSO links over a variety of atmospheric turbulence conditions.

  4. An Adaptive Cooperative Strategy for Underlay MIMO Cognitive Radio Networks: An Opportunistic and Low-Complexity Approach

    NASA Astrophysics Data System (ADS)

    Mazoochi, M.; Pourmina, M. A.; Bakhshi, H.

    2015-03-01

    The core aim of this work is the maximization of the achievable data rate of the secondary user pairs (SU pairs), while ensuring the QoS of primary users (PUs). All users are assumed to be equipped with multiple antennas. It is assumed that when PUs are present, the direct communications between SU pairs introduces intolerable interference to PUs and thereby SUs transmit signal using the cooperation of other SUs and avoid transmitting in the direct channel. In brief, an adaptive cooperative strategy for multiple-input/multiple-output (MIMO) cognitive radio networks is proposed. At the presence of PUs, the issue of joint relay selection and power allocation in Underlay MIMO Cooperative Cognitive Radio Networks (U-MIMO-CCRN) is addressed. The optimal approach for determining the power allocation and the cooperating SU is proposed. Besides, the outage probability of the proposed communication protocol is further derived. Due to high complexity of the optimal approach, a low-complexity approach is further proposed and its performance is evaluated using simulations. The simulation results reveal that the performance loss due to the low-complexity approach is only about 14%, while the complexity is greatly reduced.

  5. Design and Imaging of Ground-Based Multiple-Input Multiple-Output Synthetic Aperture Radar (MIMO SAR) with Non-Collinear Arrays.

    PubMed

    Hu, Cheng; Wang, Jingyang; Tian, Weiming; Zeng, Tao; Wang, Rui

    2017-03-15

    Multiple-Input Multiple-Output (MIMO) radar provides much more flexibility than the traditional radar thanks to its ability to realize far more observation channels than the actual number of transmit and receive (T/R) elements. In designing the MIMO imaging radar arrays, the commonly used virtual array theory generally assumes that all elements are on the same line. However, due to the physical size of the antennas and coupling effect between T/R elements, a certain height difference between T/R arrays is essential, which will result in the defocusing of edge points of the scene. On the other hand, the virtual array theory implies far-field approximation. Therefore, with a MIMO array designed by this theory, there will exist inevitable high grating lobes in the imaging results of near-field edge points of the scene. To tackle these problems, this paper derives the relationship between target's point spread function (PSF) and pattern of T/R arrays, by which the design criterion is presented for near-field imaging MIMO arrays. Firstly, the proper height between T/R arrays is designed to focus the near-field edge points well. Secondly, the far-field array is modified to suppress the grating lobes in the near-field area. Finally, the validity of the proposed methods is verified by two simulations and an experiment.

  6. Design and Imaging of Ground-Based Multiple-Input Multiple-Output Synthetic Aperture Radar (MIMO SAR) with Non-Collinear Arrays

    PubMed Central

    Hu, Cheng; Wang, Jingyang; Tian, Weiming; Zeng, Tao; Wang, Rui

    2017-01-01

    Multiple-Input Multiple-Output (MIMO) radar provides much more flexibility than the traditional radar thanks to its ability to realize far more observation channels than the actual number of transmit and receive (T/R) elements. In designing the MIMO imaging radar arrays, the commonly used virtual array theory generally assumes that all elements are on the same line. However, due to the physical size of the antennas and coupling effect between T/R elements, a certain height difference between T/R arrays is essential, which will result in the defocusing of edge points of the scene. On the other hand, the virtual array theory implies far-field approximation. Therefore, with a MIMO array designed by this theory, there will exist inevitable high grating lobes in the imaging results of near-field edge points of the scene. To tackle these problems, this paper derives the relationship between target’s point spread function (PSF) and pattern of T/R arrays, by which the design criterion is presented for near-field imaging MIMO arrays. Firstly, the proper height between T/R arrays is designed to focus the near-field edge points well. Secondly, the far-field array is modified to suppress the grating lobes in the near-field area. Finally, the validity of the proposed methods is verified by two simulations and an experiment. PMID:28294996

  7. Throughput Improvement with Discrete Pilot Signal Assignment and Iterative Channel Identification for MQRD-PCM/OFDM

    NASA Astrophysics Data System (ADS)

    Ahn, Chang-Jun

    In MIMO systems, the channel identification is important to distinguish transmitted signals from multiple transmit antennas. One of the most typical channel identification schemes is to employ a code division multiplexing (CDM) based scheme in which a unique spreading code is assigned to distinguish both BS and MS antenna elements. However, by increasing the number of base stations and transmit antenna elements, large spreading codes and pilot symbols are required to distinguish the received power from all the connectable BS, as well as to identify all the CSI for the combination of transmitter and receiver antenna elements. Furthermore, the complexity of maximum likelihood detection (MLD) for implementation of MIMO is a considerable work. To reduce these problems, in this paper, we propose the parallel detection algorithm using multiple QR decompositions with permuted channel matrix (MQRD-PCM) with discrete pilot signal assignment and iterative channel identification for MIMO/OFDM.

  8. MU-MIMO Precoding Methods for Reducing the Transmit Normalization Factor by Perturbing Data of the Codebook

    NASA Astrophysics Data System (ADS)

    Yang, Hyunwook; Choi, Seungwon

    In this paper, we present an algorithm for reducing the transmit normalization factor by perturbing the transmit signal in a Multi-User Multiple Input Multiple Output (MU-MIMO) system which uses the channel inverse matrix as its precoding matrix. A base station must normalize unnormalized transmit signals due to the limitation of the constant transmit power. This paper defines the norm of the unnormalized transmit signal as the transmit normalization factor used to normalize the transmit signal. Recalling that the transmit normalization factor consists of a combination of the singular values from the channel inverse matrix, we provide a codebook that successively reduces the coefficients of these singular values. Through computer simulations, the proposed algorithm is compared to sphere encoding in terms of the Bit Error Rate (BER) and the outage probability in a MU-MIMO signal environment. Sphere encoding is known to be an optimal solution amongst the perturbation methods that reduce the transmit normalization factor [1]. This work demonstrates that the proposed algorithm is has very good performance, comparable to that of sphere encoding, while its computational load is nearly 200 times less. Since the codebook in our algorithm depends only on the given channel, the difference in the computational complexity becomes even greater when the channel state is not changed, because the codebook can be reused. Furthermore, the codebook exhibits the characteristic of robustness to the maximum Doppler shift.

  9. A frequency tunable, eight-channel correlation ECE system for electron temperature turbulence measurements on the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Sung, C.; Peebles, W. A.; Wannberg, C.; Rhodes, T. L.; Nguyen, X.; Lantsov, R.; Bardóczi, L.

    2016-11-01

    A new eight-channel correlation electron cyclotron emission diagnostic has recently been installed on the DIII-D tokamak to study both turbulent and coherent electron temperature fluctuations under various plasma conditions and locations. This unique system is designed to cover a broad range of operation space on DIII-D (1.6-2.1 T, detection frequency: 72-108 GHz) via four remotely selected local oscillators (80, 88, 96, and 104 GHz). Eight radial locations are measured simultaneously in a single discharge covering as much as half the minor radius. In this paper, we present design details of the quasi-optical system, the receiver, as well as representative data illustrating operation of the system.

  10. The structure of the vorticity field in turbulent channel flow. Part 1: Analysis of instantaneous fields and statistical correlations

    NASA Technical Reports Server (NTRS)

    Moin, P.; Kim, J.

    1984-01-01

    An investigation into the existence of hairpin vortices in turbulent channel flow is conducted using a database generated by the large eddy simulation technique. It is shown that away from the wall the distribution of the inclination angle of vorticity vector attains its maximum at about 45 deg to the wall. Two point correlations of velocity and vorticity fluctuations strongly support a flow model consisting of vortical structures inclined at 45 deg to the wall. The instantaneous vorticity vectors plotted in planes inclined at 45 deg show that the flow contains an appreciable number of hairpins. Vortex lines are used to display the three dimensional structure of hairpins, which are shown to be generated from deformation of transverse vortex filaments.

  11. A frequency tunable, eight-channel correlation ECE system for electron temperature turbulence measurements on the DIII-D tokamak.

    PubMed

    Sung, C; Peebles, W A; Wannberg, C; Rhodes, T L; Nguyen, X; Lantsov, R; Bardóczi, L

    2016-11-01

    A new eight-channel correlation electron cyclotron emission diagnostic has recently been installed on the DIII-D tokamak to study both turbulent and coherent electron temperature fluctuations under various plasma conditions and locations. This unique system is designed to cover a broad range of operation space on DIII-D (1.6-2.1 T, detection frequency: 72-108 GHz) via four remotely selected local oscillators (80, 88, 96, and 104 GHz). Eight radial locations are measured simultaneously in a single discharge covering as much as half the minor radius. In this paper, we present design details of the quasi-optical system, the receiver, as well as representative data illustrating operation of the system.

  12. On the Implementation of Iterative Detection in Real-World MIMO Wireless Systems

    DTIC Science & Technology

    2003-12-01

    multiple - input multiple - output ( MIMO ) wireless systems can achieve...addresses the use of iterative detection in real-world multiple - input multiple - output ( MIMO ) wireless systems, which are theoretically capable of achieving...search LLR log-likelihood ratio MAP maximum a posteriori MIMO multiple - input multiple - output ML maximum likelihood MLM-ITS multilevel mapping ITS

  13. Signal Waveforms and Range/Angle Coupling in Coherent Colocated MIMO Radar

    DTIC Science & Technology

    2014-10-09

    Signal Waveforms and Range/Angle Coupling in Coherent Colocated MIMO Radar Olivier Rabaste, Laurent Savy, Mathieu Cattenoz ONERA , The French...tests with a real MIMO radar: HYCAM. A. The HYCAM platform A multifunction MIMO radar - named HYCAM - has been designed and build by ONERA . The

  14. Assessment of absolute added correlative coding in optical intensity modulation and direct detection channels

    NASA Astrophysics Data System (ADS)

    Dong-Nhat, Nguyen; Elsherif, Mohamed A.; Malekmohammadi, Amin

    2016-06-01

    The performance of absolute added correlative coding (AACC) modulation format with direct detection has been numerically and analytically reported, targeting metro data center interconnects. Hereby, the focus lies on the performance of the bit error rate, noise contributions, spectral efficiency, and chromatic dispersion tolerance. The signal space model of AACC, where the average electrical and optical power expressions are derived for the first time, is also delineated. The proposed modulation format was also compared to other well-known signaling, such as on-off-keying (OOK) and four-level pulse-amplitude modulation, at the same bit rate in a directly modulated vertical-cavity surface-emitting laser-based transmission system. The comparison results show a clear advantage of AACC in achieving longer fiber delivery distance due to the higher dispersion tolerance.

  15. Modeling, Simulation and Performance Analysis of Multiple-Input Multiple-Output (MIMO) Systems with Multicarrier Time Delay Diversity Modulation

    DTIC Science & Technology

    2005-09-01

    MULTIPLE - INPUT MULTIPLE - OUTPUT ( MIMO ) SYSTEMS WITH MULTICARRIER TIME DELAY DIVERSITY MODULATION by Muhammad...SUBTITLE: Modeling, Simulation and Performance Analysis of Multiple - Input Multiple - Output ( MIMO ) Systems with Multicarrier Time Delay Diversity Modulation...MISO) and multiple - input multiple - output ( MIMO ) radio communication systems with space-time codes. A MISO system and MIMO

  16. The membrane lateral pressure-perturbing capacity of parabens and their effects on the mechanosensitive channel directly correlate with hydrophobicity.

    PubMed

    Kamaraju, Kishore; Sukharev, Sergei

    2008-10-07

    Lipid bilayers provide a natural anisotropic environment for membrane proteins and can serve as apolar reservoirs for lipid-derived second messengers or lipophilic drugs. Partitioning of lipophilic agents changes the lateral pressure distribution in the bilayer, affecting integral proteins. p-Hydroxybenzoic acid esters (parabens) are amphipathic compounds widely used as food and cosmetics preservatives, but the mechanisms of their broad antibacterial action are unknown. Here we describe effects of ethyl, propyl, and butyl parabens on the gating of the bacterial mechanosensitive channel of small conductance (MscS) and compare them with the surface activity and lateral pressure changes measured in lipid monolayers in the presence of these substances. Near the bilayer-monolayer equivalence pressure of 35 mN/m, ethyl, propyl, or butyl paraben present in the subphase at 1 mM increased the surface pressure of the monolayer by 5, 12.5, or 20%, respectively. No spontaneous activation of MscS channels was observed in patch-clamp experiments with parabens added from either the cytoplasmic or periplasmic side. Increasing concentrations of parabens on the cytoplasmic side of excised patches shifted activation curves of MscS toward higher tensions. A good correlation between the pressure increases in monolayers and shifts in activation midpoints in patch-clamp experiments suggested that the more hydrophobic parabens partition more strongly into the lipid and exert larger effects on channel gating through changes in lateral pressure. We show that cytoplasmically presented ethyl or butyl parabens both hasten the process of desensitization of MscS and influence inactivation differently. The higher rate of desensitization is likely due to increased lateral pressure in the cytoplasmic leaflet surrounding the gate. Neither of the parabens strongly affects the rate of recovery and does not seem to penetrate the TM2-TM3 interhelical clefts in MscS. We conclude that the bacterial

  17. New Closed-Form of the Largest Eigenvalue PDF for Max-SNR MIMO System Performances

    NASA Astrophysics Data System (ADS)

    Letessier, Jonathan; Vrigneau, Baptiste; Rostaing, Philippe; Burel, Gilles

    Multiple-input multiple-output (MIMO) maximum-SNR (max-SNR) system employs the maximum ratio combiner (MRC) at the receiver side and the maximum ratio transmitter (MRT) at the transmitter side. Its performances highly depend on MIMO channel characteristics, which vary according to both the number of antennas and their distribution between the transmitter and receiver sides. By using the decomposition of the ordered Wishart distribution in the uncorrelated Rayleigh case, we derived a closed-form expression of the largest eigenvalue probability density function (PDF). The final result yields to an expression form of the PDF where polynomials are multiplied by exponentials; it is worth underlining that, though this form had been previously observed for given couples of antennas, to date no formally-written closed-form was available in the literature for an arbitrary couple. Then, this new expression permits one to quickly and easily get the well known largest eigenvalue PDF and use it to determine the binary error probability (BEP) of the max-SNR.

  18. Accurate distortion estimation and optimal bandwidth allocation for scalable H.264 video transmission over MIMO systems.

    PubMed

    Jubran, Mohammad K; Bansal, Manu; Kondi, Lisimachos P; Grover, Rohan

    2009-01-01

    In this paper, we propose an optimal strategy for the transmission of scalable video over packet-based multiple-input multiple-output (MIMO) systems. The scalable extension of H.264/AVC that provides a combined temporal, quality and spatial scalability is used. For given channel conditions, we develop a method for the estimation of the distortion of the received video and propose different error concealment schemes. We show the accuracy of our distortion estimation algorithm in comparison with simulated wireless video transmission with packet errors. In the proposed MIMO system, we employ orthogonal space-time block codes (O-STBC) that guarantee independent transmission of different symbols within the block code. In the proposed constrained bandwidth allocation framework, we use the estimated end-to-end decoder distortion to optimally select the application layer parameters, i.e., quantization parameter (QP) and group of pictures (GOP) size, and physical layer parameters, i.e., rate-compatible turbo (RCPT) code rate and symbol constellation. Results show the substantial performance gain by using different symbol constellations across the scalable layers as compared to a fixed constellation.

  19. Space-Frequency Block Code with Matched Rotation for MIMO-OFDM System with Limited Feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Abhayapala, Thushara D.; Jayalath, Dhammika; Smith, David; Athaudage, Chandra

    2009-12-01

    This paper presents a novel matched rotation precoding (MRP) scheme to design a rate one space-frequency block code (SFBC) and a multirate SFBC for MIMO-OFDM systems with limited feedback. The proposed rate one MRP and multirate MRP can always achieve full transmit diversity and optimal system performance for arbitrary number of antennas, subcarrier intervals, and subcarrier groupings, with limited channel knowledge required by the transmit antennas. The optimization process of the rate one MRP is simple and easily visualized so that the optimal rotation angle can be derived explicitly, or even intuitively for some cases. The multirate MRP has a complex optimization process, but it has a better spectral efficiency and provides a relatively smooth balance between system performance and transmission rate. Simulations show that the proposed SFBC with MRP can overcome the diversity loss for specific propagation scenarios, always improve the system performance, and demonstrate flexible performance with large performance gain. Therefore the proposed SFBCs with MRP demonstrate flexibility and feasibility so that it is more suitable for a practical MIMO-OFDM system with dynamic parameters.

  20. Time-reversal techniques for MISO and MIMO wireless communication systems

    NASA Astrophysics Data System (ADS)

    Fouda, Ahmed E.; Teixeira, Fernando L.; Yavuz, Mehmet E.

    2012-10-01

    We consider the application of different time-reversal (TR) signal processing and beamforming techniques to multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) wireless communication systems. Conventional TR beamforming provides spatial focusing at the intended receiver; however, it does not yield perfect channel equalization. Time-reversed pilot can be normalized to provide perfect equalization at the expense of power level. This equalization is particularly important for high data rates where the bit error rate performance is dominated by internal noise due to intersymbol interference. To increase physical layer covertness, TR beamforming is combined with the multiple-signal-classification (MUSIC) technique to produce null fields at eavesdroppers. This technique is also applied to MIMO setups to eliminate interuser interference and hence increase system capacity. Differential TR is used to obtain and update pilot signals for passive moving receivers, i.e., those that cannot (or do not) transmit pilot signals. Time-reversed differential backscattered signal is able to provide satisfactory spatial and temporal focusing at the moving receiver.

  1. Multi-functional MIMO communication in multi-hop cellular systems

    NASA Astrophysics Data System (ADS)

    Roger, Sandra; Calabuig, Daniel; Monserrat, Jose F.; Cardona, Narcis

    2014-12-01

    In the context of multi-hop cellular communications, user equipment devices (UEs) with relaying capabilities provide a virtual infrastructure that can enhance the cell spectral efficiency. UE relays, which are generally transparent to the destination user and lack channel state information, mainly operate in an open-loop mode. Most open-loop transmission techniques for relaying are based on orthogonal space-time block coding (OSTBC), which offers a good trade-off between performance and complexity. In this paper, we consider the concept of multi-functional multiple-input multiple-output (MIMO) transmission, which combines OSTBC with beamforming techniques. This concept is applied to networks with multiple relays, which can offer a high number of antennas to implement multi-functional MIMO techniques. The proposed schemes are shown to reduce the bit error rate of the destination user with respect to a direct transmission from the base station (BS). Furthermore, the multi-functional setup exhibits better performance than conventional OSTBC at high transmission rates.

  2. Time-reversal techniques for MISO and MIMO wireless communication systems

    NASA Astrophysics Data System (ADS)

    Fouda, Ahmed E.; Teixeira, Fernando L.; Yavuz, Mehmet E.

    2012-10-01

    We consider the application of different time-reversal (TR) signal processing and beamforming techniques to multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) wireless communication systems. Conventional TR beamforming provides spatial focusing at the intended receiver; however, it does not yield perfect channel equalization. Time-reversed pilot can be normalized to provide perfect equalization at the expense of power level. This equalization is particularly important for high data rates where the bit error rate performance is dominated by internal noise due to intersymbol interference. To increase physical layer covertness, TR beamforming is combined with the multiple-signal-classification (MUSIC) technique to produce null fields at eavesdroppers. This technique is also applied to MIMO setups to eliminate interuser interference and hence increase system capacity. Differential TR is used to obtain and update pilot signals for passive moving receivers, i.e., those that cannot (or do not) transmit pilot signals. Time-reversed differential backscattered signal is able to provide satisfactory spatial and temporal focusing at the moving receiver.

  3. A coherent through-wall MIMO phased array imaging radar based on time-duplexed switching

    NASA Astrophysics Data System (ADS)

    Chen, Qingchao; Chetty, Kevin; Brennan, Paul; Lok, Lai Bun; Ritchie, Matthiew; Woodbridge, Karl

    2017-05-01

    Through-the-Wall (TW) radar sensors are gaining increasing interest for security, surveillance and search and rescue applications. Additionally, the integration of Multiple-Input, Multiple-Output (MIMO) techniques with phased array radar is allowing higher performance at lower cost. In this paper we present a 4-by-4 TW MIMO phased array imaging radar operating at 2.4 GHz with 200 MHz bandwidth. To achieve high imaging resolution in a cost-effective manner, the 4 Tx and 4 Rx elements are used to synthesize a uniform linear array (ULA) of 16 virtual elements. Furthermore, the transmitter is based on a single-channel 4-element time-multiplexed switched array. In transmission, the radar utilizes frequency modulated continuous wave (FMCW) waveforms that undergo de-ramping on receive to allow digitization at relatively low sampling rates, which then simplifies the imaging process. This architecture has been designed for the short-range TW scenarios envisaged, and permits sufficient time to switch between antenna elements. The paper first outlines the system characteristics before describing the key signal processing and imaging algorithms which are based on traditional Fast Fourier Transform (FFT) processing. These techniques are implemented in LabVIEW software. Finally, we report results from an experimental campaign that investigated the imaging capabilities of the system and demonstrated the detection of personnel targets. Moreover, we show that multiple targets within a room with greater than approximately 1 meter separation can be distinguished from one another.

  4. Superimposed Pilots Are Superior for Mitigating Pilot Contamination in Massive MIMO

    NASA Astrophysics Data System (ADS)

    Upadhya, Karthik; Vorobyov, Sergiy A.; Vehkapera, Mikko

    2017-06-01

    In this paper, superimposed pilots are introduced as an alternative to time-multiplexed pilot and data symbols for mitigating pilot contamination in massive multiple-input multiple-output (MIMO) systems. We propose a non-iterative scheme for uplink channel estimation based on superimposed pilots and derive an expression for the uplink signal-to-interference-plus-noise ratio (SINR) at the output of a matched filter employing this channel estimate. Based on this expression, we observe that power control is essential when superimposed pilots are employed. Moreover, the quality of the channel estimate can be improved by reducing the interference that results from transmitting data alongside the pilots, and an intuitive iterative data-aided scheme that reduces this component of interference is also proposed. Approximate expressions for the uplink SINR are provided for the iterative data-aided method as well. In addition, we show that a hybrid system with users utilizing both time-multiplexed and superimposed pilots is superior to an optimally designed system that employs only time-multiplexed pilots, even when the non-iterative channel estimate is used to build the detector and precoder. We also describe a simple approach to implement this hybrid system by minimizing the overall inter and intra-cell interference. Numerical simulations demonstrating the performance of the proposed channel estimation schemes and the superiority of the hybrid system are also provided.

  5. Reconfigurable architecture for MIMO systems based on CORDIC operators

    NASA Astrophysics Data System (ADS)

    Wang, Hongzhi; Leray, Pierre; Palicot, Jacques

    2006-09-01

    The MIMO system is an attractive technology for wireless 3G/4G systems. In this article we propose the realization on FPGA of a MIMO 'V-BLAST Square Root' algorithm based on a variable number of CORDIC operators. The CORDIC operator is highly suitable for this implementation as it only relies on simple techniques of addition and vector offsets. This square root algorithm architecture is reconfigurable in order to adapt itself to different numbers of antennas and different data rates. The proposed architecture can achieve a data rate of 600 Mbit/s in a Virtex-II FPGA circuit from Xilinx for the MIMO system with QPSK modulation. To cite this article: H. Wang et al., C. R. Physique 7 (2006).

  6. Bidirectional MIMO and SISO 3GPP LTE-advanced fronthaul architectures based on multicore fiber

    NASA Astrophysics Data System (ADS)

    Llorente, Roberto; Morant, Maria

    2017-01-01

    Multicore fiber (MCF) systems have been proposed for high capacity optical transmission applications ranging from the access network to long haul. In this paper we critically review the application of MCF-based systems in optical fronthaul technology with the simultaneous radio-over-fiber (RoF) transmission of 3GPP LTE-Advanced signals in downlink and uplink directions. The experimental study evaluates the quality of the received signals in terms of error vector magnitude (EVM) of the LTE-Advanced signal and of each channel frame according to the 3GPP wireless standard. The suitability of the 3GPP MIMO processing algorithms is also investigated experimentally evaluating two-antenna and four-antenna system configuration and compared with single-antenna (SISO) transmission in a 4-core MCF.

  7. Joint Stream-Wise THP Transceiver Design for the Multiuser MIMO Downlink

    NASA Astrophysics Data System (ADS)

    Miao, Wei; Chen, Xiang; Zhao, Ming; Zhou, Shidong; Wang, Jing

    This paper addresses the problem of joint transceiver design for Tomlinson-Harashima Precoding (THP) in the multiuser multiple-input-multiple-output (MIMO) downlink under both perfect and imperfect channel state information at the transmitter (CSIT). For the case of perfect CSIT, we differ from the previous work by performing stream-wise (both inter-user and intra-user) interference pre-cancelation at the transmitter. A minimum total mean square error (MT-MSE) criterion is used to formulate our optimization problem. By some convex analysis of the problem, we obtain the necessary conditions for the optimal solution. An iterative algorithm is proposed to handle this problem and its convergence is proved. Then we extend our designed algorithm to the robust version by minimizing the conditional expectation of the T-MSE under imperfect CSIT. Simulation results are given to verify the efficacy of our proposed schemes and to show their superiorities over existing MMSE-based THP schemes.

  8. Linearly polarized vector modes: enabling MIMO-free mode-division multiplexing.

    PubMed

    Wang, Lixian; Nejad, Reza Mirzaei; Corsi, Alessandro; Lin, Jiachuan; Messaddeq, Younès; Rusch, Leslie; LaRochelle, Sophie

    2017-05-15

    We experimentally investigate mode-division multiplexing in an elliptical ring core fiber (ERCF) that supports linearly polarized vector modes (LPV). Characterization show that the ERCF exhibits good polarization maintaining properties over eight LPV modes with effective index difference larger than 1 × 10(-4). The ERCF further displays stable mode power and polarization extinction ratio when subjected to external perturbations. Crosstalk between the LPV modes, after propagating through 0.9 km ERCF, is below -14 dB. By using six LPV modes as independent data channels, we achieved the transmission of 32 Gbaud QPSK over 0.9 km ERCF without any multiple-input-multiple-output (MIMO) or polarization-division multiplexing (PDM) signal processing.

  9. A Novel Nonlinear Precoding Detection Algorithm for VBLAST in MIMO-MC-CDMA Downlink System

    NASA Astrophysics Data System (ADS)

    Fu, Hongliang; Tao, Yong

    Considering the error propagation effect and high complexity of the Vertical Bell Labs Layered Space Time (V-BLAST), a novel nonlinear ZF-THP algorithm for VBLAST in MIMO-MC-CDMA downlink system is proposed in this paper. QR decomposition is used for precoding matrix, the nonlinear Tomlinson-Harashima Precoding (THP) is used between the sub-carrier channels of MC-CDMA to eliminate interference from other signals at the transmitter, and can obtain frequency diversity gain and eliminate effectively the error propagation effect. At the receiver, zero forcing criterion is used, and the complexity of the receiver can be reduced. Simulation results show that the proposed algorithm is better than the traditional zero forcing algorithm and the linear precoding algorithm in the system BER.

  10. Optimal modified tracking performance for MIMO networked control systems with communication constraints.

    PubMed

    Wu, Jie; Zhou, Zhu-Jun; Zhan, Xi-Sheng; Yan, Huai-Cheng; Ge, Ming-Feng

    2017-02-16

    This paper investigates the optimal modified tracking performance of multi-input multi-output (MIMO) networked control systems (NCSs) with packet dropouts and bandwidth constraints. Some explicit expressions are obtained by using co-prime factorization and the spectral decomposition technique. The obtained results show that the optimal modified tracking performance is related to the intrinsic properties of a given plant such as non-minimum phase (NMP) zeros, unstable poles, and their directions. Furthermore, the modified factor, packet dropouts probability and bandwidth also impact the optimal modified tracking performance of the NCSs. The optimal modified tracking performance with channel input power constraint is obtained by searching through all stabilizing two-parameter compensator. Finally, some typical examples are given to illustrate the effectiveness of the theoretical results.

  11. PMD tolerant direct-detection polarization division multiplexed OFDM systems with MIMO processing.

    PubMed

    Wei, Chia-Chien; Lin, Chun-Ting; Wang, Chih-Yun

    2012-03-26

    This work proposes a novel direct-detection polarization division multiplexed OFDM scheme without the need of dynamic polarization control at a polarization-diverse receiver, and the proposed scheme is robust against polarization mode dispersion. Setting the frequency difference between two polarization-orthogonal reference carriers as one subcarrier spacing, possible signal fading can be avoided, and the corresponding interference from adjacent subcarriers is eliminated by a novel MIMO algorithm. The penalty caused by high channel matrix condition number can be decreased by inserting empty tones among subcarriers, and the polarization-dependent OSNR penalty at the BER of 10⁻³ is <3.6 dB with an empty tone inserted every 8 subcarriers. Moreover, the numerical results demonstrate the 16 × 10³-ps/nm chromatic dispersion and the 300-ps differential group delay will not induce additional penalty.

  12. Method and apparatus for a single channel digital communications system. [synchronization of received PCM signal by digital correlation with reference signal

    NASA Technical Reports Server (NTRS)

    Couvillon, L. A., Jr.; Carl, C.; Goldstein, R. M.; Posner, E. C.; Green, R. R. (Inventor)

    1973-01-01

    A method and apparatus are described for synchronizing a received PCM communications signal without requiring a separate synchronizing channel. The technique provides digital correlation of the received signal with a reference signal, first with its unmodulated subcarrier and then with a bit sync code modulated subcarrier, where the code sequence length is equal in duration to each data bit.

  13. Performance Evaluation Of Modified V-Blast In Mimo System

    NASA Astrophysics Data System (ADS)

    Suneetha, Ch.; Harathi, N.; Sudha, K.

    2012-03-01

    The MIMO system (multiple Antennas at the transmitter and receiver)is a capable of very high theoretical capacities, the most popular architecture is so called vertical VBLAST. VBLAST is an effective detection method for MIMO communication system, but has large computational complexity due its successive iteration . In this paper we used modified VBLAST to lessen its computational complexity reducing the number of successive iterations. As a result of this simplification, the computational complexity of the detection is lowered significantly. Simulation results show that the proposed V-BLAST reduces calculation complexity by about 30% while achieving a very close BER performance s the original one.

  14. Image reconstruction and compressive sensing in MIMO radar

    NASA Astrophysics Data System (ADS)

    Sun, Bing; Lopez, Juan; Qiao, Zhijun

    2014-05-01

    Multiple-input multiple-output (MIMO) radar utilizes the flexible configuration of transmitting and receiving antennas to construct images of target scenes. Because of the target scenes' sparsity, the compressive sensing (CS) technique can be used to realize a feasible reconstruction of the target scenes from undersampling data. This paper presents the signal model of MIMO radar and derive the corresponding CS measurement matrix, which shows success of the CS technique. Also the basis pursuit method and total-variation minimization method are adopted for different scenes' recovery. Numerical simulations are provided to illustrate the validity of reconstruction for one dimensional and two dimensional scenes.

  15. Linear precoding based on polynomial expansion: reducing complexity in massive MIMO.

    PubMed

    Mueller, Axel; Kammoun, Abla; Björnson, Emil; Debbah, Mérouane

    Massive multiple-input multiple-output (MIMO) techniques have the potential to bring tremendous improvements in spectral efficiency to future communication systems. Counterintuitively, the practical issues of having uncertain channel knowledge, high propagation losses, and implementing optimal non-linear precoding are solved more or less automatically by enlarging system dimensions. However, the computational precoding complexity grows with the system dimensions. For example, the close-to-optimal and relatively "antenna-efficient" regularized zero-forcing (RZF) precoding is very complicated to implement in practice, since it requires fast inversions of large matrices in every coherence period. Motivated by the high performance of RZF, we propose to replace the matrix inversion and multiplication by a truncated polynomial expansion (TPE), thereby obtaining the new TPE precoding scheme which is more suitable for real-time hardware implementation and significantly reduces the delay to the first transmitted symbol. The degree of the matrix polynomial can be adapted to the available hardware resources and enables smooth transition between simple maximum ratio transmission and more advanced RZF. By deriving new random matrix results, we obtain a deterministic expression for the asymptotic signal-to-interference-and-noise ratio (SINR) achieved by TPE precoding in massive MIMO systems. Furthermore, we provide a closed-form expression for the polynomial coefficients that maximizes this SINR. To maintain a fixed per-user rate loss as compared to RZF, the polynomial degree does not need to scale with the system, but it should be increased with the quality of the channel knowledge and the signal-to-noise ratio.

  16. Frequency-Domain Iterative Parallel Interference Cancellation for Multicode Spread-Spectrum MIMO Multiplexing

    NASA Astrophysics Data System (ADS)

    Nakajima, Akinori; Garg, Deepshikha; Adachi, Fumiyuki

    Very high-speed data services are demanded in the next generation wireless systems. However, the available bandwidth is limited. The use of multi-input multi-output (MIMO) multiplexing can increase the transmission rate without bandwidth expansion. For high-speed data transmission, however, the channel becomes severely frequency-selective and the achievable bit error rate (BER) performance degrades. In our previous work, we proposed the joint use of iterative frequency-domain parallel interference cancellation (PIC) and two-dimensional (2D) MMSE-FDE for the non-spread single-carrier (SC) transmission in a frequency-selective fading channel. The joint use of PIC and 2D MMSE-FDE can effectively suppress the inter-path interference (IPI) and the inter-code interference (ICI), resulting from the channel frequency-selectivity, and the interference from other antennas simultaneously. An iterative PIC with 2D MMSE-FDE has a high computational complexity. In this paper, to well suppress the interference from other antennas while reducing the computational complexity, we propose to replace 2D MMSE-FDE by 1D MMSE-FDE except for the initial iteration stage and to use multicode spread-spectrum (SS) transmission instead of the non-spread SC transmission. The BER performance of the proposed scheme in a frequency-selective Rayleigh fading channel is evaluated by computer simulation to show that the proposed scheme can basically match the BER performance of 2D MMSE-FDE with lower complexity.

  17. MIMO radar for through-wall target identification in single and two wall scenarios

    NASA Astrophysics Data System (ADS)

    Gebhardt, Evan T.; Narayanan, Ram M.; Broderick, Sean P.

    2016-05-01

    MIMO radar provides improvement over traditional phased array radars for through wall imaging. By transmitting independent waveforms from a transmit array to a receive array an effective virtual array is created. This array has improved degrees of freedom over phased arrays and mono-static MIMO systems. This virtual array allows us to achieve the same effective aperture length as a phased array with less elements because the virtual array can be described as the convolution of transmit and receive array positions. In addition, data from multiple walls of the same room can be used to collect target information. If two walls are perpendicular to each other and the geometry of transmit and receive arrays is known, then data can be processed independently of each other. Since the geometry of the arrays is known, a target scene can be created where the two data sets overlap. The overlapped scene can then be processed so that image artifacts that do not correlate between the data sets can be excised. The result gives improved target detection, reduction in false alarms, robustness to noise, and robustness against errors such as improperly aligned antennas.

  18. Correlation between cloud thickness and brightness using Nimbus 4 THIR data /11.5-micron channel/ and ATS 3 digital data

    NASA Technical Reports Server (NTRS)

    Park, S.-U.; Sikdar, D. N.; Suomi, V. E.

    1974-01-01

    Nimbus 4 data (11.5-micron) channel and ATS 3 digitized data were analyzed for three days during April and May 1970. Cloud-top temperature, as measured by the 11.5-micron channel of the satellite radiometer, shows a close negative correlation with cloud brightness measured by the ATS 3 satellite. This is especially true in well-developed cumulonimbus clouds. An estimate of cloud heights corresponding to cloud-top temperature was obtained by using radiosonde data and radar images, and the relationships between the cloud thickness and brightness counts were derived for the cumulonimbus clouds.

  19. Correlation between cloud thickness and brightness using Nimbus 4 THIR data /11.5-micron channel/ and ATS 3 digital data

    NASA Technical Reports Server (NTRS)

    Park, S.-U.; Sikdar, D. N.; Suomi, V. E.

    1974-01-01

    Nimbus 4 data (11.5-micron) channel and ATS 3 digitized data were analyzed for three days during April and May 1970. Cloud-top temperature, as measured by the 11.5-micron channel of the satellite radiometer, shows a close negative correlation with cloud brightness measured by the ATS 3 satellite. This is especially true in well-developed cumulonimbus clouds. An estimate of cloud heights corresponding to cloud-top temperature was obtained by using radiosonde data and radar images, and the relationships between the cloud thickness and brightness counts were derived for the cumulonimbus clouds.

  20. Performance Evaluation of Analog Beamforming with Hardware Impairments for mmW Massive MIMO Communication in an Urban Scenario

    PubMed Central

    Gimenez, Sonia; Roger, Sandra; Baracca, Paolo; Martín-Sacristán, David; Monserrat, Jose F.; Braun, Volker; Halbauer, Hardy

    2016-01-01

    The use of massive multiple-input multiple-output (MIMO) techniques for communication at millimeter-Wave (mmW) frequency bands has become a key enabler to meet the data rate demands of the upcoming fifth generation (5G) cellular systems. In particular, analog and hybrid beamforming solutions are receiving increasing attention as less expensive and more power efficient alternatives to fully digital precoding schemes. Despite their proven good performance in simple setups, their suitability for realistic cellular systems with many interfering base stations and users is still unclear. Furthermore, the performance of massive MIMO beamforming and precoding methods are in practice also affected by practical limitations and hardware constraints. In this sense, this paper assesses the performance of digital precoding and analog beamforming in an urban cellular system with an accurate mmW channel model under both ideal and realistic assumptions. The results show that analog beamforming can reach the performance of fully digital maximum ratio transmission under line of sight conditions and with a sufficient number of parallel radio-frequency (RF) chains, especially when the practical limitations of outdated channel information and per antenna power constraints are considered. This work also shows the impact of the phase shifter errors and combiner losses introduced by real phase shifter and combiner implementations over analog beamforming, where the former ones have minor impact on the performance, while the latter ones determine the optimum number of RF chains to be used in practice. PMID:27669241

  1. Performance Evaluation of Analog Beamforming with Hardware Impairments for mmW Massive MIMO Communication in an Urban Scenario.

    PubMed

    Gimenez, Sonia; Roger, Sandra; Baracca, Paolo; Martín-Sacristán, David; Monserrat, Jose F; Braun, Volker; Halbauer, Hardy

    2016-09-22

    The use of massive multiple-input multiple-output (MIMO) techniques for communication at millimeter-Wave (mmW) frequency bands has become a key enabler to meet the data rate demands of the upcoming fifth generation (5G) cellular systems. In particular, analog and hybrid beamforming solutions are receiving increasing attention as less expensive and more power efficient alternatives to fully digital precoding schemes. Despite their proven good performance in simple setups, their suitability for realistic cellular systems with many interfering base stations and users is still unclear. Furthermore, the performance of massive MIMO beamforming and precoding methods are in practice also affected by practical limitations and hardware constraints. In this sense, this paper assesses the performance of digital precoding and analog beamforming in an urban cellular system with an accurate mmW channel model under both ideal and realistic assumptions. The results show that analog beamforming can reach the performance of fully digital maximum ratio transmission under line of sight conditions and with a sufficient number of parallel radio-frequency (RF) chains, especially when the practical limitations of outdated channel information and per antenna power constraints are considered. This work also shows the impact of the phase shifter errors and combiner losses introduced by real phase shifter and combiner implementations over analog beamforming, where the former ones have minor impact on the performance, while the latter ones determine the optimum number of RF chains to be used in practice.

  2. Efficient hierarchical list decoder for massive optical MIMO transmission.

    PubMed

    Greenberg, Maxim; Nazarathy, Moshe; Orenstein, Meir

    2008-01-21

    We propose a novel MIMO scheme over multimode fiber, acting as a distributed random code generator fed by spatial codes, using silicon photonics in the transmitter and efficient list-based hierarchical submaximum-likelihood electronic detection in the receiver, providing an alternative to CWDM for implementation of ultra-high speed parallel transmission over short-range optical interconnects.

  3. User-scheduling algorithm for a MU-MIMO system

    NASA Astrophysics Data System (ADS)

    Yu, Haiyang; Choi, Jaeho

    2015-12-01

    A user-scheduling algorithm for MU-MIMO systems is presented in this paper. The algorithm is a codebook based precoding method which can be suitable for the IEEE 802.16m mobile broadband standard. The proposed algorithm can effectively improve the sum capacity and fairness among the users.

  4. MimoPro: a more efficient Web-based tool for epitope prediction using phage display libraries

    PubMed Central

    2011-01-01

    Background A B-cell epitope is a group of residues on the surface of an antigen which stimulates humoral responses. Locating these epitopes on antigens is important for the purpose of effective vaccine design. In recent years, mapping affinity-selected peptides screened from a random phage display library to the native epitope has become popular in epitope prediction. These peptides, also known as mimotopes, share the similar structure and function with the corresponding native epitopes. Great effort has been made in using this similarity between such mimotopes and native epitopes in prediction, which has resulted in better outcomes than statistics-based methods can. However, it cannot maintain a high degree of satisfaction in various circumstances. Results In this study, we propose a new method that maps a group of mimotopes back to a source antigen so as to locate the interacting epitope on the antigen. The core of this method is a searching algorithm that is incorporated with both dynamic programming (DP) and branch and bound (BB) optimization and operated on a series of overlapping patches on the surface of a protein. These patches are then transformed to a number of graphs using an adaptable distance threshold (ADT) regulated by an appropriate compactness factor (CF), a novel parameter proposed in this study. Compared with both Pep-3D-Search and PepSurf, two leading graph-based search tools, on average from the results of 18 test cases, MimoPro, the Web-based implementation of our proposed method, performed better in sensitivity, precision, and Matthews correlation coefficient (MCC) than both did in epitope prediction. In addition, MimoPro is significantly faster than both Pep-3D-Search and PepSurf in processing. Conclusions Our search algorithm designed for processing well constructed graphs using an ADT regulated by CF is more sensitive and significantly faster than other graph-based approaches in epitope prediction. MimoPro is a viable alternative to both

  5. Multi-scaled normal mode analysis method for dynamics simulation of protein-membrane complexes: A case study of potassium channel gating motion correlations

    SciTech Connect

    Wu, Xiaokun; Han, Min; Ming, Dengming

    2015-10-07

    Membrane proteins play critically important roles in many cellular activities such as ions and small molecule transportation, signal recognition, and transduction. In order to fulfill their functions, these proteins must be placed in different membrane environments and a variety of protein-lipid interactions may affect the behavior of these proteins. One of the key effects of protein-lipid interactions is their ability to change the dynamics status of membrane proteins, thus adjusting their functions. Here, we present a multi-scaled normal mode analysis (mNMA) method to study the dynamics perturbation to the membrane proteins imposed by lipid bi-layer membrane fluctuations. In mNMA, channel proteins are simulated at all-atom level while the membrane is described with a coarse-grained model. mNMA calculations clearly show that channel gating motion can tightly couple with a variety of membrane deformations, including bending and twisting. We then examined bi-channel systems where two channels were separated with different distances. From mNMA calculations, we observed both positive and negative gating correlations between two neighboring channels, and the correlation has a maximum as the channel center-to-center distance is close to 2.5 times of their diameter. This distance is larger than recently found maximum attraction distance between two proteins embedded in membrane which is 1.5 times of the protein size, indicating that membrane fluctuation might impose collective motions among proteins within a larger area. The hybrid resolution feature in mNMA provides atomic dynamics information for key components in the system without costing much computer resource. We expect it to be a conventional simulation tool for ordinary laboratories to study the dynamics of very complicated biological assemblies. The source code is available upon request to the authors.

  6. Multi-scaled normal mode analysis method for dynamics simulation of protein-membrane complexes: A case study of potassium channel gating motion correlations

    NASA Astrophysics Data System (ADS)

    Wu, Xiaokun; Han, Min; Ming, Dengming

    2015-10-01

    Membrane proteins play critically important roles in many cellular activities such as ions and small molecule transportation, signal recognition, and transduction. In order to fulfill their functions, these proteins must be placed in different membrane environments and a variety of protein-lipid interactions may affect the behavior of these proteins. One of the key effects of protein-lipid interactions is their ability to change the dynamics status of membrane proteins, thus adjusting their functions. Here, we present a multi-scaled normal mode analysis (mNMA) method to study the dynamics perturbation to the membrane proteins imposed by lipid bi-layer membrane fluctuations. In mNMA, channel proteins are simulated at all-atom level while the membrane is described with a coarse-grained model. mNMA calculations clearly show that channel gating motion can tightly couple with a variety of membrane deformations, including bending and twisting. We then examined bi-channel systems where two channels were separated with different distances. From mNMA calculations, we observed both positive and negative gating correlations between two neighboring channels, and the correlation has a maximum as the channel center-to-center distance is close to 2.5 times of their diameter. This distance is larger than recently found maximum attraction distance between two proteins embedded in membrane which is 1.5 times of the protein size, indicating that membrane fluctuation might impose collective motions among proteins within a larger area. The hybrid resolution feature in mNMA provides atomic dynamics information for key components in the system without costing much computer resource. We expect it to be a conventional simulation tool for ordinary laboratories to study the dynamics of very complicated biological assemblies. The source code is available upon request to the authors.

  7. A Study on Trained and Differential Designs for MIMO Tactical Communications

    DTIC Science & Technology

    2008-09-29

    REPORT A Study on Trained and Differential Designs for MIMO Tactical Communications 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: During the project...From - To) 6-Apr-2006 Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - 5-Apr-2008 A Study on Trained and Differential Designs for MIMO ...Military Communications Conference, Orlando, FL, Oct. 29-31, 2007. [4] W. Zhang and X. Ma, "A Suboptimal equalizer for MIMO systems to guarantee maximum

  8. Multi-Input Multi-Output (MIMO) Radar - Diversity Means Superiority

    DTIC Science & Technology

    2008-10-15

    SISO) radar range-Doppler imaging and multiple - input multiple - output ( MIMO ) synthetic aperture radar (SAR) imaging as well as in space time adaptive...January 2008. A multi- input multi- output ( MIMO ) radar system, unlike standard phased-array radar, can transmit via its antennas multiple probing signals...15-10-2008 Annual Report Nov. 2007 - Oct. 2008 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Multi- Input Multi- Output ( MIMO ) Radar - Diversity Means

  9. On the Throughput of MIMO-Empowered Multi-hop Cognitive Radio Networks

    DTIC Science & Technology

    2010-01-01

    Senior Member, IEEE, and Sastry Kompella, Member, IEEE Abstract—Cognitive radio (CR) and multiple - input multiple - output ( MIMO ) are two independent physical...2011, Issue to be determined. 14. ABSTRACT Cognitive radio (CR) and multiple - input multiple - output ( MIMO ) are two independent physical layer...1 On the Throughput of MIMO -Empowered Multi-hop Cognitive Radio Networks Cunhao Gao, Student Member, IEEE, Yi Shi, Member, IEEE, Y. Thomas Hou

  10. Multi-Input Multi-Output (MIMO) Radar - Diversity Means Superiority

    DTIC Science & Technology

    2009-10-01

    multiple - input multiple - output ( MIMO ) radar system, unlike a standard phased-array radar, can...Office of Naval Research Grant No. N00014-07-1-0293 November 2006 - October 2009 20091117236 1. Summary A multiple - input multiple - output ( MIMO ...Processing, Vol. 55, No. 6, pp. 2375-2385, June 2007. We consider a multiple - input multiple - output ( MIMO ) radar system where both the transmitter

  11. Advanced Multiple In-Multiple Out (MIMO) Antenna Communications for Airborne Networks

    DTIC Science & Technology

    2015-03-01

    ADVANCED MULTIPLE IN-MULTIPLE OUT (MIMO) ANTENNA COMMUNICATIONS FOR AIRBORNE NETWORKS SYRACUSE UNIVERSITY MARCH 2015 FINAL TECHNICAL REPORT...COMMUNICATIONS FOR AIRBORNE NETWORKS 5a. CONTRACT NUMBER FA8750-11-1-0040 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER 62788F 6. AUTHOR(S) Biao Chen...MIMO system with over the air transmission. 15. SUBJECT TERMS Multiple In-Multiple Out (MIMO Antenna Communications, Airborne Networks , D-BLAST

  12. Conformational Changes in Alamethicin Associated with Substitution of Its α-Methylalanines with Leucines: A FTIR Spectroscopic Analysis and Correlation with Channel Kinetics

    PubMed Central

    Haris, Parvez I.; Molle, Gérard; Duclohier, Hervé

    2004-01-01

    Alamethicin, a 20 residue-long peptaibol remains a favorite high voltage-dependent channel-forming peptide. However, the structural significance of its abundant noncoded residues (α-methylalanine or Aib) for its ion channel activity remains unknown, although a previous study showed that replacement of all Aib residues with leucines preserved the essential channel behavior except for much faster single-channel events. To correlate these functional properties with structural data, here we compare the secondary structures of an alamethicin derivative where all the eight Aibs were replaced by leucines and the native alamethicin. Fourier transform infrared (FTIR) spectra of these peptides were recorded in methanol and in aqueous phospholipid membranes. Results obtained show a significant conformational change in alamethicin upon substitution of its Aib residues with Leu. The amide I band occurs at a lower frequency for the Leu-derivative indicating that its α-helices are involved in stronger hydrogen-bonding. In addition, the structure of the Leu-derivative is quite sensitive to membrane fluidity changes. The amide I band shifts to higher frequencies when the lipids are in the fluid phase. This indicates either a decreased solvation due to a more complete peptide insertion or a peptide stretching to match the full thickness of the bilayer. These results contribute to explain the fast single-channel kinetics displayed by the Leu-derivative. PMID:14695266

  13. Channel capacity and receiver deployment optimization for multi-input multi-output visible light communications.

    PubMed

    Wang, Jin-Yuan; Dai, Jianxin; Guan, Rui; Jia, Linqiong; Wang, Yongjin; Chen, Ming

    2016-06-13

    Multi-input multi-output (MIMO) technique is attractive for visible light communication (VLC), which exploits the high signal-to-noise ratio (SNR) of a single channel to overcome the capacity limitation due to the small modulation bandwidth of the light emitting diode. This paper establishes a MIMO VLC system under the non-negativity, peak power and dimmable average power constraints. Assume that perfect channel state information at the transmitter is known, the MIMO channel is changed to parallel, non-interfering sub-channels by using the singular value decomposition (SVD). Based on the SVD, the lower bound on the channel capacity for MIMO VLC is derived by employing entropy power inequality and variational method. Moreover, by maximizing the derived lower bound on the capacity under the given constraints, the receiver deployment optimization problem is formulated. The problem is solved by employing the principle of particle swarm optimization. Numerical results verify the derived capacity bound and the proposed deployment optimization scheme.

  14. Correlation between long-term marine temperature time series from the eastern and western English Channel: Scaling analysis using empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Derot, Jonathan; Schmitt, François Guillaume; Gentilhomme, Valérie; Morin, Pascal

    2016-05-01

    High-frequency temperature fluctuations recorded in the English Channel are compared using two long-term autonomous underwater monitoring stations at less than 20-min time resolution. Measurements were taken from 2005 to 2011 from two systems 460 km apart in the western and eastern parts of the English Channel. Spectral analysis reveals similar statistical behaviors, with approximate 5/3 spectra and several forcing frequencies in relation to tidal and daily cycles. A co-spectra study reveals a transition scale of 11 days. The influence of this scale is also visible though Time-Dependent Intrinsic Correlation analysis (TDIC)-a recently introduced cross-correlation analysis based on Empirical mode decomposition. This helps to spatialize high-frequency temporal records at a fixed location.

  15. Zero-Forcing Beamforming Multiuser-MIMO Systems with Finite Rate Feedback for Multiple Stream Transmission per User

    NASA Astrophysics Data System (ADS)

    Fujii, Masaaki

    We describe a channel-vector quantization scheme that is suitable for multiple stream transmission per user in zero-forcing beamforming (ZFBF) multiuser multiple-input and multiple output (MU-MIMO) systems with finite rate feedback. Multiple subsets of a channel matrix are quantized to vectors from random vector codebooks for finite rate feedback. The quantization vectors with an angle difference that is closer to orthogonal are then selected and their indexes are fed back to the transmitter. Simulation results demonstrate that the proposed scheme achieves a better average throughput than that serving a single stream per user when the number of active users is smaller than the number of transmit antennas and that it provides an average throughput close to that serving a single stream per user when the number of users is equal to the number of transmit antennas.

  16. Second-order statistics-based blind equalization of FIR/IIR multiple-input multiple-output channels with common zeros

    NASA Astrophysics Data System (ADS)

    Tugnait, Jitendra K.; Huang, Bin

    1998-10-01

    The problem of blind equalization of MIMO communications channels is considered using the second order statistics of the data. Such models arise when a single receiver data from multiple sources is fractionally sampled, or when an antenna array is used with or without fractional sampling. We focus on direct design of finite-length MMSE blind equalizers. We allow infinite impulse response channels. Our approaches also work when the 'subchannel' transfer functions have common zeros so long as the common zeros are minimum-phase zeros. We only require that the there exist a causal, stable left inverse to the MIMO transfer function and that the leading coefficient matrix of the MIMO channel impulse response have its rank equal to the number of sources. The channel length or model orders need not be known. The sources are recovered up to a unitary mixing matrix and are further 'unmixed' using higher- order statistics of the data. An illustrative simulation example is provided.

  17. Lack of correlation between the amplitudes of TRP channel-mediated responses to weak and strong stimuli in intracellular Ca(2+) imaging experiments.

    PubMed

    Alpizar, Yeranddy A; Sanchez, Alicia; Radwan, Ahmed; Radwan, Islam; Voets, Thomas; Talavera, Karel

    2013-11-01

    It is often observed in intracellular Ca(2+) imaging experiments that the amplitudes of the Ca(2+) signals elicited by newly characterized TRP agonists do not correlate with the amplitudes of the responses evoked subsequently by a specific potent agonist. We investigated this rather controversial phenomenon by first testing whether it is inherent to the comparison of the effects of weak and strong stimuli. Using five well-characterized TRP channel agonists in commonly used heterologous expression systems we found that the correlation between the amplitudes of the Ca(2+) signals triggered by two sequentially applied stimuli is only high when both stimuli are strong. Using mathematical simulations of intracellular Ca(2+) dynamics we illustrate that the innate heterogeneity in expression and functional properties of Ca(2+) extrusion (e.g. plasma membrane Ca(2+) ATPase) and influx (TRP channels) pathways across a cellular population is a sufficient condition for low correlation between the amplitude of Ca(2+) signals elicited by weak and strong stimuli. Taken together, our data demonstrate that this phenomenon is an expected outcome of intracellular Ca(2+) imaging experiments that cannot be taken as evidence for lack of specificity of low-efficacy stimuli, or as an indicator of the need of other cellular components for channel stimulation.

  18. MIMO equalization optimized for baud rate clock recovery in coherent 112 Gbit/sec DP-QPSK metro systems

    NASA Astrophysics Data System (ADS)

    Gorshtein, Albert; Sadot, Dan; Dorman, Guy

    2015-03-01

    A novel MIMO equalization architecture optimized for baud rate clock recovery (BCR-MIMO) in coherent 112 Gbit/sec dual polarization quadrature phase shift keying (DP-QPSK) metro systems is proposed. This architecture is designed to decouple between multiple-input-multiple-output (MIMO) equalization and clock recovery (CR) loops, avoiding the interaction between them. The decoupling between the two loops is achieved, while maintaining similar MIMO equalizer performance, as compared to the butterfly-structured equalizer.

  19. Anatomo-Functional Correlation between Head Zones and Acupuncture Channels and Points: A Comparative Analysis from the Perspective of Neural Therapy

    PubMed Central

    Beltrán Molano, Martha Liliana; Pinilla Bonilla, Laura Bibiana; Beltrán Dussan, Eduardo Humberto; Vásquez Londoño, Carlos Alberto

    2014-01-01

    Background. Neural therapy and traditional Chinese medicine (TCM) are part of complementary and alternative medicine in western world. Both of them share characteristics in diagnosis and therapeutics in search of changes in tenderness, pain, and skin stiffness related to visceral disease, as well as therapeutic procedures with specific stimuli on the skin that generate local, segmental, or remote reactions. Head zones explain segmental viscerocutaneous relations in neural therapy; however, interference fields and remote reactions after infiltration of local anesthetic go beyond this segmental distribution. Methods. This descriptive research required review and analysis of texts of Henry Head and traditional Chinese medicine. Results. Anatomical and functional relationships were found between Head zones in body, and head and neck with 14 acupuncture channels and their points. Anatomical areas of strong correlations were found: Head zones of heart and lung with heart and pericardium channels; Head zones of genitals with bladder and kidney channels. Strong functional relations between all Head zones, channels, and acupoints were found when following the pattern of segmental dermatomes; 235 acupuncture points were found in concordance. PMID:25506384

  20. Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

    DTIC Science & Technology

    2011-09-30

    channel interference mitigation for underwater acoustic MIMO-OFDM. 3) Turbo equalization for OFDM modulated physical layer network coding. 4) Blind CFO...Localization and tracking of underwater physical systems. 7) NAMS: A networked acoustic modem system for underwater applications . 8) OFDM receiver design in...3) Turbo Equalization for OFDM Modulated Physical Layer Network Coding. We have investigated a practical orthogonal frequency division multiplexing

  1. Design and optimization of LTE 1800 MIMO antenna.

    PubMed

    Wong, Huey Shin; Islam, Mohammad Tariqul; Kibria, Salehin

    2014-01-01

    A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide's outer shell. Isolation characteristics better than -15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz-1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi.

  2. Compressed Sensing in On-Grid MIMO Radar

    PubMed Central

    Minner, Michael F.

    2015-01-01

    The accurate detection of targets is a significant problem in multiple-input multiple-output (MIMO) radar. Recent advances of Compressive Sensing offer a means of efficiently accomplishing this task. The sparsity constraints needed to apply the techniques of Compressive Sensing to problems in radar systems have led to discretizations of the target scene in various domains, such as azimuth, time delay, and Doppler. Building upon recent work, we investigate the feasibility of on-grid Compressive Sensing-based MIMO radar via a threefold azimuth-delay-Doppler discretization for target detection and parameter estimation. We utilize a colocated random sensor array and transmit distinct linear chirps to a small scene with few, slowly moving targets. Relying upon standard far-field and narrowband assumptions, we analyze the efficacy of various recovery algorithms in determining the parameters of the scene through numerical simulations, with particular focus on the ℓ 1-squared Nonnegative Regularization method. PMID:27280124

  3. MIMO radar arrays with minimum redundancy: a design method

    NASA Astrophysics Data System (ADS)

    Kirschner, A. J.; Siart, U.; Guetlein, J.; Detlefsen, J.

    2013-10-01

    Coherent multiple-input multiple-output (MIMO) radar systems with co-located antennas, form monostatic vir- tual arrays by discrete convolution of a bistatic setup of transmitters and receivers. Thereby, a trade-off between maximum array dimension, element spacing and hardware efforts exists. In terms of estimating the direction of arrival, the covariance matrix of the array element signals plays an important role. Here, minimum redundancy arrays aim at a hardware reduction with signal reconstruction by exploiting the Toeplitz characteristics of the covariance matrix. However, the discrete spatial convolution complicates the finding of an optimal antenna setup with minimum redundancy. Combinatorial effort is the consequence. This paper presents a possible simplified algorithm in order to find MIMO array setups of maximum dimension with minimum redundancy.

  4. Compressed Sensing in On-Grid MIMO Radar.

    PubMed

    Minner, Michael F

    2015-01-01

    The accurate detection of targets is a significant problem in multiple-input multiple-output (MIMO) radar. Recent advances of Compressive Sensing offer a means of efficiently accomplishing this task. The sparsity constraints needed to apply the techniques of Compressive Sensing to problems in radar systems have led to discretizations of the target scene in various domains, such as azimuth, time delay, and Doppler. Building upon recent work, we investigate the feasibility of on-grid Compressive Sensing-based MIMO radar via a threefold azimuth-delay-Doppler discretization for target detection and parameter estimation. We utilize a colocated random sensor array and transmit distinct linear chirps to a small scene with few, slowly moving targets. Relying upon standard far-field and narrowband assumptions, we analyze the efficacy of various recovery algorithms in determining the parameters of the scene through numerical simulations, with particular focus on the ℓ 1-squared Nonnegative Regularization method.

  5. MIMO communications within the HF band using compact antenna arrays

    NASA Astrophysics Data System (ADS)

    Gunashekar, S. D.; Warrington, E. M.; Feeney, S. M.; Salous, S.; Abbasi, N. M.

    2010-12-01

    Measurements have been made over a 255 km radio path between Durham and Leicester in the UK in order to investigate the potential applicability of multiple input multiple output (MIMO) techniques to communications within the HF band. This paper describes the results from experiments in which compact heterogeneous antenna arrays have been employed. The results of these experiments indicate that traditional spaced HF antenna arrays can be replaced by compact, active, heterogeneous arrays in order to achieve the required levels of decorrelation between the various antenna elements. An example case study is also presented which highlights the importance of the variable nature of the ionosphere in the context of HF-MIMO radio links.

  6. Relationship between the field local quadrature and the quantum discord of a photon-added correlated channel under the influence of scattering and phase fluctuation noise

    NASA Astrophysics Data System (ADS)

    Domínguez-Serna, Francisco A.; Mendieta-Jimenez, Francisco J.; Rojas, Fernando

    2017-10-01

    We study quantum correlations and discord in a bipartite continuous variable hybrid system formed by linear combinations of coherent states {|{α }\\rangle } and single photon-added coherent states of the form {|{ψ }\\rangle }_{ {dp(pa)}}= N/√{2} (\\hat{a}^\\dagger {|{α }\\rangle }_a{|{α }\\rangle }_b ± \\hat{b}^\\dagger {|{α }\\rangle }_a{|{α }\\rangle }_b). We stablish a relationship between the quantum discord with a local observable (the quadrature variance for one subsystem) under the influence of scattering and phase fluctuation noise. For the pure states the quantum correlations are characterized by means of measurement induced disturbance (MID) with simultaneous quadrature measurements. In a scenario where homodyne conditional measurements are available we show that the MID provides an easy way to select optimal phases to obtain information of the maximal correlations in the channels. The quantum correlations of these entangled states with channel losses are quantitatively characterized with the quantum discord (QD) with a displaced qubit projector. We observe that as scattering increases, QD decreases monotonically. At the same time for the state {|{ψ }\\rangle }_{ {dp}}, QD is more resistant to high phase fluctuations when the average photon number n_0 is bigger than zero, but if phase fluctuations are low, QD is more resistant if n_0=0. For the dp model with scattering, we obtain an analytical expression of the QD as a function of the observable quadrature variance in a local subsystem. This relation allows us to have a way to obtain the degree of QD in the channel by just measuring a local property observable such as the quadrature variance. For the other model this relation still exists but is explored numerically. This relation is an important result that allows to identify quantum processing capabilities in terms of just local observables.

  7. Worst-Case Energy Efficiency Maximization in a 5G Massive MIMO-NOMA System

    PubMed Central

    Jeong, Yongchae; Jiang, Xueqin; Lee, Moon Ho

    2017-01-01

    In this paper, we examine the robust beamforming design to tackle the energy efficiency (EE) maximization problem in a 5G massive multiple-input multiple-output (MIMO)-non-orthogonal multiple access (NOMA) downlink system with imperfect channel state information (CSI) at the base station. A novel joint user pairing and dynamic power allocation (JUPDPA) algorithm is proposed to minimize the inter user interference and also to enhance the fairness between the users. This work assumes imperfect CSI by adding uncertainties to channel matrices with worst-case model, i.e., ellipsoidal uncertainty model (EUM). A fractional non-convex optimization problem is formulated to maximize the EE subject to the transmit power constraints and the minimum rate requirement for the cell edge user. The designed problem is difficult to solve due to its nonlinear fractional objective function. We firstly employ the properties of fractional programming to transform the non-convex problem into its equivalent parametric form. Then, an efficient iterative algorithm is proposed established on the constrained concave-convex procedure (CCCP) that solves and achieves convergence to a stationary point of the above problem. Finally, Dinkelbach’s algorithm is employed to determine the maximum energy efficiency. Comprehensive numerical results illustrate that the proposed scheme attains higher worst-case energy efficiency as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme. PMID:28927019

  8. Worst-Case Energy Efficiency Maximization in a 5G Massive MIMO-NOMA System.

    PubMed

    Chinnadurai, Sunil; Selvaprabhu, Poongundran; Jeong, Yongchae; Jiang, Xueqin; Lee, Moon Ho

    2017-09-18

    In this paper, we examine the robust beamforming design to tackle the energy efficiency (EE) maximization problem in a 5G massive multiple-input multiple-output (MIMO)-non-orthogonal multiple access (NOMA) downlink system with imperfect channel state information (CSI) at the base station. A novel joint user pairing and dynamic power allocation (JUPDPA) algorithm is proposed to minimize the inter user interference and also to enhance the fairness between the users. This work assumes imperfect CSI by adding uncertainties to channel matrices with worst-case model, i.e., ellipsoidal uncertainty model (EUM). A fractional non-convex optimization problem is formulated to maximize the EE subject to the transmit power constraints and the minimum rate requirement for the cell edge user. The designed problem is difficult to solve due to its nonlinear fractional objective function. We firstly employ the properties of fractional programming to transform the non-convex problem into its equivalent parametric form. Then, an efficient iterative algorithm is proposed established on the constrained concave-convex procedure (CCCP) that solves and achieves convergence to a stationary point of the above problem. Finally, Dinkelbach's algorithm is employed to determine the maximum energy efficiency. Comprehensive numerical results illustrate that the proposed scheme attains higher worst-case energy efficiency as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme.

  9. (DURIP) MIMO Radar Testbed for Waveform Adaptive Sensing Research

    DTIC Science & Technology

    2015-06-17

    and includes an onboard Phase Locked Loop ( PLL ) and Voltage Controlled Oscillator (VCO) to generate Local Oscillator (LO) signal from a local GPS...board PLL requires a reference signal of 50 MHz signal for locking, however the GPS conditioned reference is designed to generate a 10 MHz signal. Hence a...Final Report (DURIP) MIMO Radar Testbed for Waveform Adaptive Sensing Research PLL . Output of PLL is divided equally by a 3 dB splitter and further

  10. Aircraft Free-Space MIMO Wireless Communications (Preprint)

    DTIC Science & Technology

    2008-09-01

    presence of free space propagation by means of typical examples. 15. SUBJECT TERMS Multiple - input - multiple - output systems, airborne networks...longitudinal separation is 6.92 bits/sec per Hz, the keyhole[3] single- input - multiple (12)- output (SIMO) capacity. Modern jets cruise at about 0.25 km/sec. Two...use of MIMO communications, multiplexing many messages over the link by using multiple antennas at each end of the link. However, communication

  11. A TDMA MIMO SAR radar for automated position-keeping

    NASA Astrophysics Data System (ADS)

    Wang, Zhonghai; Lin, Xingping; Cumber, Steven; Fish, Ensign John; Pham, Khanh; Blasch, Erik; Chen, Genshe; Shen, Dan; Jia, Bin; Wang, Gang

    2015-05-01

    This paper presents a time division multiple access (TDMA) multiple-input and multiple-output (MIMO) synthetic aperture radar (SAR) with a sliding range window for automated position-keeping, which can be applied in vessel tracking/escorting, offshore deepwater drillship equipment servicing, etc. A MIMO SAR sensor predefines a special part of the target (i.e., the drillship, ship, or submarine) as the measurement target and does not need special assistant devices/targets installed on the target vessel/platform, so its application is convenient. In the measurement process, the sensor scans the target with multiple ranging gates, forms images of multiple sections of the target, detects the predefined part/target in these images, and then obtains the range and angle of the predefined target for relative localization. Our MIMO SAR has 13 transmitting antennas and 8 receiving antennas. All transmitting antennas share a transmitter and all receiving antennas share a receiver using switches to reduce cost. The MIMO SAR radar has 44 effective SAR phase centers, and the azimuth angle resolution is θ0.5/44 (finest, θ 0.5 is the antenna element's 3dB beamwidth). The transmitter transmits a chirped linear frequency modulated continuous wave (LFMCW) signal, and the receiver only processes the signal limited in the beat frequency region defined by the distance from the measurement target to the sensor and the interested measurement target extension, which is determined by the receiver bandwidth. With the sliding range window, the sensor covers a large range, and in the covered range window, it provides high accuracy measurements.

  12. MIMO Feedback Error Learning without Recourse to Positive Realness

    NASA Astrophysics Data System (ADS)

    Noguchi, Makoto; Sugimoto, Kenji

    This paper proposes an improved learning scheme for MIMO-FEL (Muliti-input multi-output feedback error learning) of prefilter-integration-type. Compared with an existing scheme, which is based on the gradient method and easily implemented, the proposed scheme does not require positive realness of the closed loop system. The paper shows the parameters converge to true values under a PE condition, and verifies its effectiveness in terms of simulation.

  13. MIMO Common Feedback Method for Multicast H-ARQ Transmission

    NASA Astrophysics Data System (ADS)

    Jung, Young-Ho

    An orthogonal sequence based MIMO common feedback method for multicast hybrid automatic-repeat-request (H-ARQ) transmission is presented. The proposed method can obtain more diversity gain proportional to the number of transmit antennas than the conventional on-off keying (OOK) based common feedback method. The ACK/NACK detection performance gain of the proposed scheme over the OOK based method is verified by analysis and computer simulation results.

  14. Robust High Data Rate MIMO Underwater Acoustic Communications

    DTIC Science & Technology

    2010-12-31

    Figure 2, on the other hand, plots the evolution of the Doppler frequency for each hydrophone. The reverberating Doppler frequency estimates obtained...Figure 3, by feeding 250 source bits into a 1/2 rate convolutional encoder followed by a random interleaver and QPSK modulation. Segment b, as well as...by leveraging the MIMO scheme. The payload sequence was divided into blocks, each of length 250, and each block was encoded using a lA convolutional

  15. Underwater acoustic channel estimation using multiple sources and receivers in shallow waters at very-high frequencies

    NASA Astrophysics Data System (ADS)

    Kaddouri, Samar

    The underwater channel poses numerous challenges for acoustic communication. Acoustic waves suffer long propagation delay, multipath, fading, and potentially high spatial and temporal variability. In addition, there is no typical underwater acoustic channel; every body of water exhibits quantifiably different properties. Underwater acoustic modems are traditionally operated at low frequencies. However, the use of broadband, high frequency communication is a good alternative because of the lower background noise compared to low-frequencies, considerably larger bandwidth and better source transducer efficiency. One of the biggest problems in the underwater acoustic communications at high frequencies is time-selective fading, resulting in the Doppler spread. While many Doppler detection, estimation and compensation techniques can be found in literature, the applications are limited to systems operating at low frequencies contained within frequencies ranging from a few hundred Hertz to around 30 kHz. This dissertation proposes two robust channel estimation techniques for simultaneous transmissions using multiple sources and multiple receivers (MIMO) that closely follows the rapidly time-varying nature of the underwater channel. The first method is a trended least square (LS) estimation that combines the traditional LS method with an empirical modal decomposition (EMD) based trend extraction algorithm. This method allows separating the slow fading modes in the MIMO channels from the fast-fading ones and thus achieves a close tracking of the channel impulse response time fluctuations. This dissertation also outlines a time-varying underwater channel estimation method based on the channel sparsity characteristic. The sparsity of the underwater communication channel is exploited by using the MIMO P-iterative greedy orthogonal matching pursuit (MIMO-OMP) algorithm for the channel estimation. Both techniques are demonstrated in a fully controlled environment, using simulated

  16. MIMO based 3D imaging system at 360 GHz

    NASA Astrophysics Data System (ADS)

    Herschel, R.; Nowok, S.; Zimmermann, R.; Lang, S. A.; Pohl, N.

    2016-05-01

    A MIMO radar imaging system at 360 GHz is presented as a part of the comprehensive approach of the European FP7 project TeraSCREEN, using multiple frequency bands for active and passive imaging. The MIMO system consists of 16 transmitter and 16 receiver antennas within one single array. Using a bandwidth of 30 GHz, a range resolution up to 5 mm is obtained. With the 16×16 MIMO system 256 different azimuth bins can be distinguished. Mechanical beam steering is used to measure 130 different elevation angles where the angular resolution is obtained by a focusing elliptical mirror. With this system a high resolution 3D image can be generated with 4 frames per second, each containing 16 million points. The principle of the system is presented starting from the functional structure, covering the hardware design and including the digital image generation. This is supported by simulated data and discussed using experimental results from a preliminary 90 GHz system underlining the feasibility of the approach.

  17. MIMO nonlinear ultrasonic tomography by propagation and backpropagation method.

    PubMed

    Dong, Chengdong; Jin, Yuanwei

    2013-03-01

    This paper develops a fast ultrasonic tomographic imaging method in a multiple-input multiple-output (MIMO) configuration using the propagation and backpropagation (PBP) method. By this method, ultrasonic excitation signals from multiple sources are transmitted simultaneously to probe the objects immersed in the medium. The scattering signals are recorded by multiple receivers. Utilizing the nonlinear ultrasonic wave propagation equation and the received time domain scattered signals, the objects are to be reconstructed iteratively in three steps. First, the propagation step calculates the predicted acoustic potential data at the receivers using an initial guess. Second, the difference signal between the predicted value and the measured data is calculated. Third, the backpropagation step computes updated acoustical potential data by backpropagating the difference signal to the same medium computationally. Unlike the conventional PBP method for tomographic imaging where each source takes turns to excite the acoustical field until all the sources are used, the developed MIMO-PBP method achieves faster image reconstruction by utilizing multiple source simultaneous excitation. Furthermore, we develop an orthogonal waveform signaling method using a waveform delay scheme to reduce the impact of speckle patterns in the reconstructed images. By numerical experiments we demonstrate that the proposed MIMO-PBP tomographic imaging method results in faster convergence and achieves superior imaging quality.

  18. Precodings for Transmission Rate Increasing in MIMO Single Carrier Block Transmissions

    DTIC Science & Technology

    2005-01-01

    Engineering, Osaka Prefecture University, Sakai, Osaka, Japan. summary In wireless communication systems, multi- input multi- output ( MIMO ) wireless, which...by the computer simulations. References [1] J. Yang and S. Roy, “On joint transmitter and receiver optimization for multiple - input - multiple - output ...Precodings for Transmission Rate Increasing in MIMO Single Carrier Block Transmissions Shusuke Narieda and Katsumi Yamashita Graduate School of

  19. A Hybrid MIMO Phased-Array Concept for Arbitrary Spatial Beampattern Synthesis

    DTIC Science & Technology

    2009-01-01

    Multiple - input multiple - output ( MIMO ) radar is a multiple aperture technology characterized by the...system. Index Terms— multiple - input multiple - output , beamforming, radar 1. INTRODUCTION Within the emerging multiple - input multiple - output ... multiple - output ( MIMO ) radar is a multiple aperture technology characterized by the ability to transmit diverse signals at each

  20. Advanced Signaling Strategies for the Hybrid MIMO Phased-Array Radar

    DTIC Science & Technology

    2010-05-01

    Multiple - Input Multiple Output , or MIMO , radar systems are next-generation radar systems with... Multiple - Input Multiple Output ( MIMO ) radar. A HMPAR comprises a large number MP, of T/R elements, organized into M subarrays of P elements each. Within...multisensor radar architecture that combines elements of traditional phased-array radar with the emerging technology of Multiple - Input Multiple Out-

  1. CR-Calculus and adaptive array theory applied to MIMO random vibration control tests

    NASA Astrophysics Data System (ADS)

    Musella, U.; Manzato, S.; Peeters, B.; Guillaume, P.

    2016-09-01

    Performing Multiple-Input Multiple-Output (MIMO) tests to reproduce the vibration environment in a user-defined number of control points of a unit under test is necessary in applications where a realistic environment replication has to be achieved. MIMO tests require vibration control strategies to calculate the required drive signal vector that gives an acceptable replication of the target. This target is a (complex) vector with magnitude and phase information at the control points for MIMO Sine Control tests while in MIMO Random Control tests, in the most general case, the target is a complete spectral density matrix. The idea behind this work is to tailor a MIMO random vibration control approach that can be generalized to other MIMO tests, e.g. MIMO Sine and MIMO Time Waveform Replication. In this work the approach is to use gradient-based procedures over the complex space, applying the so called CR-Calculus and the adaptive array theory. With this approach it is possible to better control the process performances allowing the step-by-step Jacobian Matrix update. The theoretical bases behind the work are followed by an application of the developed method to a two-exciter two-axis system and by performance comparisons with standard methods.

  2. Mechanisms of atrial fibrillation termination by rapidly unbinding Na+ channel blockers: insights from mathematical models and experimental correlates.

    PubMed

    Comtois, Philippe; Sakabe, Masao; Vigmond, Edward J; Munoz, Mauricio; Texier, Anne; Shiroshita-Takeshita, Akiko; Nattel, Stanley

    2008-10-01

    Atrial fibrillation (AF) is the most common sustained clinical arrhythmia and is a problem of growing proportions. Recent studies have increased interest in fast-unbinding Na(+) channel blockers like vernakalant (RSD1235) and ranolazine for AF therapy, but the mechanism of efficacy is poorly understood. To study how fast-unbinding I(Na) blockers affect AF, we developed realistic mathematical models of state-dependent Na(+) channel block, using a lidocaine model as a prototype, and studied the effects on simulated cholinergic AF in two- and three-dimensional atrial substrates. We then compared the results with in vivo effects of lidocaine on vagotonic AF in dogs. Lidocaine action was modeled with the Hondeghem-Katzung modulated-receptor theory and maximum affinity for activated Na(+) channels. Lidocaine produced frequency-dependent Na(+) channel blocking and conduction slowing effects and terminated AF in both two- and three-dimensional models with concentration-dependent efficacy (maximum approximately 89% at 60 microM). AF termination was not related to increases in wavelength, which tended to decrease with the drug, but rather to decreased source Na(+) current in the face of large ACh-sensitive K(+) current-related sinks, leading to the destabilization of primary generator rotors and a great reduction in wavebreak, which caused primary rotor annihilations in the absence of secondary rotors to resume generator activity. Lidocaine also reduced the variability and maximum values of the dominant frequency distribution during AF. Qualitatively similar results were obtained in vivo for lidocaine effects on vagal AF in dogs, with an efficacy of 86% at 2 mg/kg iv, as well as with simulations using the guarded-receptor model of lidocaine action. These results provide new insights into the mechanisms by which rapidly unbinding class I antiarrhythmic agents, a class including several novel compounds of considerable promise, terminate AF.

  3. KV10.1 K(+)-channel plasma membrane discrete domain partitioning and its functional correlation in neurons.

    PubMed

    Jiménez-Garduño, Aura M; Mitkovski, Miso; Alexopoulos, Ioannis K; Sánchez, Araceli; Stühmer, Walter; Pardo, Luis A; Ortega, Alicia

    2014-03-01

    KV10.1 potassium channels are implicated in a variety of cellular processes including cell proliferation and tumour progression. Their expression in over 70% of human tumours makes them an attractive diagnostic and therapeutic target. Although their physiological role in the central nervous system is not yet fully understood, advances in their precise cell localization will contribute to the understanding of their interactions and function. We have determined the plasma membrane (PM) distribution of the KV10.1 protein in an enriched mouse brain PM fraction and its association with cholesterol- and sphingolipid-rich domains. We show that the KV10.1 channel has two different populations in a 3:2 ratio, one associated to and another excluded from Detergent Resistant Membranes (DRMs). This distribution of KV10.1 in isolated PM is cholesterol- and cytoskeleton-dependent since alteration of those factors changes the relationship to 1:4. In transfected HEK-293 cells with a mutant unable to bind Ca(2+)/CaM to KV10.1 protein, Kv10.1 distribution in DRM/non-DRM is 1:4. Mean current density was doubled in the cholesterol-depleted cells, without any noticeable effects on other parameters. These results demonstrate that recruitment of the KV10.1 channel to the DRM fractions involves its functional regulation.

  4. Three-dimensional near-field MIMO array imaging using range migration techniques.

    PubMed

    Zhuge, Xiaodong; Yarovoy, Alexander G

    2012-06-01

    This paper presents a 3-D near-field imaging algorithm that is formulated for 2-D wideband multiple-input-multiple-output (MIMO) imaging array topology. The proposed MIMO range migration technique performs the image reconstruction procedure in the frequency-wavenumber domain. The algorithm is able to completely compensate the curvature of the wavefront in the near-field through a specifically defined interpolation process and provides extremely high computational efficiency by the application of the fast Fourier transform. The implementation aspects of the algorithm and the sampling criteria of a MIMO aperture are discussed. The image reconstruction performance and computational efficiency of the algorithm are demonstrated both with numerical simulations and measurements using 2-D MIMO arrays. Real-time 3-D near-field imaging can be achieved with a real-aperture array by applying the proposed MIMO range migration techniques.

  5. Radio frequency electromagnetic field compliance assessment of multi-band and MIMO equipped radio base stations.

    PubMed

    Thors, Björn; Thielens, Arno; Fridén, Jonas; Colombi, Davide; Törnevik, Christer; Vermeeren, Günter; Martens, Luc; Joseph, Wout

    2014-05-01

    In this paper, different methods for practical numerical radio frequency exposure compliance assessments of radio base station products were investigated. Both multi-band base station antennas and antennas designed for multiple input multiple output (MIMO) transmission schemes were considered. For the multi-band case, various standardized assessment methods were evaluated in terms of resulting compliance distance with respect to the reference levels and basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Both single frequency and multiple frequency (cumulative) compliance distances were determined using numerical simulations for a mobile communication base station antenna transmitting in four frequency bands between 800 and 2600 MHz. The assessments were conducted in terms of root-mean-squared electromagnetic fields, whole-body averaged specific absorption rate (SAR) and peak 10 g averaged SAR. In general, assessments based on peak field strengths were found to be less computationally intensive, but lead to larger compliance distances than spatial averaging of electromagnetic fields used in combination with localized SAR assessments. For adult exposure, the results indicated that even shorter compliance distances were obtained by using assessments based on localized and whole-body SAR. Numerical simulations, using base station products employing MIMO transmission schemes, were performed as well and were in agreement with reference measurements. The applicability of various field combination methods for correlated exposure was investigated, and best estimate methods were proposed. Our results showed that field combining methods generally considered as conservative could be used to efficiently assess compliance boundary dimensions of single- and dual-polarized multicolumn base station antennas with only minor increases in compliance distances.

  6. RELAP5/MOD3 code quality assurance plan for ORNL ANS narrow channel flow and heat transfer correlations

    SciTech Connect

    MIller, C.S.; Shumway, R.W.

    1992-11-01

    Modifications have been made to REIAP5 to account for flow and heat transfer in narrow channels between fuel plates such as found in the cores of the Advanced Neutron Source (ANS) and High Flux Isotope Reactor (HFIR) reactors. These early models were supplied by Art Ruggles of Oak Ridge National Laboratory (ORNL) and Don Fletcher of the Idaho National Engineering Laboratory (INEL) and were adapted to and implemented into RELAP5 by Rich Riemke, Rex Shumway and Ken Katsma. The purpose of this report is to document the current status of these special models in the standard version of RELAP5/MOD3 and describe the quality assurance procedures.

  7. Adaptive Precoded MIMO for LTE Wireless Communication

    NASA Astrophysics Data System (ADS)

    Nabilla, A. F.; Tiong, T. C.

    2015-04-01

    Long-Term Evolution (LTE) and Long Term Evolution-Advanced (ATE-A) have provided a major step forward in mobile communication capability. The objectives to be achieved are high peak data rates in high spectrum bandwidth and high spectral efficiencies. Technically, pre-coding means that multiple data streams are emitted from the transmit antenna with independent and appropriate weightings such that the link throughput is maximized at the receiver output thus increasing or equalizing the received signal to interference and noise (SINR) across the multiple receiver terminals. However, it is not reliable enough to fully utilize the information transfer rate to fit the condition of channel according to the bandwidth size. Thus, adaptive pre-coding is proposed. It applies pre-coding matrix indicator (PMI) channel state making it possible to change the pre-coding codebook accordingly thus improving the data rate higher than fixed pre-coding.

  8. Athena MIMOS II Mössbauer spectrometer investigation

    NASA Astrophysics Data System (ADS)

    Klingelhöfer, G.; Morris, R. V.; Bernhardt, B.; Rodionov, D.; de Souza, P. A.; Squyres, S. W.; Foh, J.; Kankeleit, E.; Bonnes, U.; Gellert, R.; Schröder, C.; Linkin, S.; Evlanov, E.; Zubkov, B.; Prilutski, O.

    2003-12-01

    Mössbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of Fe-bearing materials. The miniature Mössbauer spectrometer MIMOS II is a component of the Athena science payload launched to Mars in 2003 on both Mars Exploration Rover missions. The instrument has two major components: (1) a rover-based electronics board that contains power supplies, a dedicated central processing unit, memory, and associated support electronics and (2) a sensor head that is mounted at the end of the instrument deployment device (IDD) for placement of the instrument in physical contact with soil and rock. The velocity transducer operates at a nominal frequency of ~25 Hz and is equipped with two 57Co/Rh Mössbauer sources. The reference source (~5 mCi landed intensity), reference target (α-Fe2O3 plus α-Fe0), and PIN-diode detector are configured in transmission geometry and are internal to the instrument and used for its calibration. The analysis Mössbauer source (~150 mCi landed intensity) irradiates Martian surface materials with a beam diameter of ~1.4 cm. The backscatter radiation is measured by four PIN-diode detectors. Physical contact with surface materials is sensed with a switch-activated contact plate. The contact plate and reference target are instrumented with temperature sensors. Assuming ~18% Fe for Martian surface materials, experiment time is 6-12 hours during the night for quality spectra (i.e., good counting statistics); 1-2 hours is sufficient to identify and quantify the most abundant Fe-bearing phases. Data stored internal to the instrument for selectable return to Earth include Mössbauer and pulse-height analysis spectra (512 and 256 channels, respectively) for each of the five detectors in up to 13 temperature intervals (65 Mössbauer spectra), engineering data for the velocity transducer, and temperature measurements. The total data volume is ~150 kB. The mass and power consumption are ~500 g (~400 g for the sensor head) and ~2 W

  9. The empirical correlations for natural convection heat transfer Al2O3 and ZrO2 nanofluid in vertical sub-channel

    NASA Astrophysics Data System (ADS)

    Kamajaya, K.; Umar, E.; Sudjatmi

    2015-09-01

    Study on convection heat transfer using water-Al2O3 nanofluid as the working fluid in the vertical sub-channel has been conducted. The results of the study have been compared with the water-ZrO2 nanofluid and pure-water as the working fluid. The equipment used in this experiment is a vertical triangular sub-channel, equipped by primary cooling system, heat exchanger and a secondary cooling system. As a heating source used three vertical cylinders that have a uniform heat flux with a pitch to diameter ratio (P/D) 01:16. Cooling is used is water-Al2O3 colloid at 0.05 wt. %. Heat transfer from heating to cooling would occur in natural or forced convection. However, in this study will be discussed only natural convection heat transfer. The results showed that the natural convection heat transfer of water-Al2O3 nanofluid in a triangular sub-channels depending on the position. The results of the correlation as follows,

  10. Building antenna characteristics into multiple-input and multiple-output channel simulation

    NASA Astrophysics Data System (ADS)

    Tat Hui, Hon; Wang, Xuan

    2010-06-01

    A one-stop computer simulation method for multiple-input and multiple-output (MIMO) channels including a full-wave characterisation of the antenna characteristics is introduced. Unlike previous channel simulation methods which use antenna radiation patterns, the effect of the antenna response on the MIMO performance in this method is directly built into channel simulation through numerical calculation. This enables the effects of the antenna gain, antenna radiation characteristics, antenna mutual coupling, antenna terminal load, antenna dimensions, etc, to be directly included into the channel response without any additional analytical supplementary procedure. This method starts simulation from the input ports of the transmitting antennas and traces the multipath signals all the way from the transmitting antennas to the signal voltages developed at the terminal ports of the receiving antennas in a one-step complete simulation. The validity and accuracy of this method are demonstrated by numerical examples.

  11. 2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON.

    PubMed

    Deng, Lei; Pang, Xiaodan; Zhao, Ying; Othman, M B; Jensen, Jesper Bevensee; Zibar, Darko; Yu, Xianbin; Liu, Deming; Monroy, Idelfonso Tafur

    2012-02-13

    We propose a spectral efficient radio over wavelength division multiplexed passive optical network (WDM-PON) system by combining optical polarization division multiplexing (PDM) and wireless multiple input multiple output (MIMO) spatial multiplexing techniques. In our experiment, a training-based zero forcing (ZF) channel estimation algorithm is designed to compensate the polarization rotation and wireless multipath fading. A 797 Mb/s net data rate QPSK-OFDM signal with error free (<1 × 10(5)) performance and a 1.59 Gb/s net data rate 16QAM-OFDM signal with BER performance of 1.2 × 10(2) are achieved after transmission of 22.8 km single mode fiber followed by 3 m and 1 m air distances, respectively.

  12. Dual-channel telemetry system for recording vocalization-correlated neuronal activity in freely moving squirrel monkeys.

    PubMed

    Grohrock, P; Häusler, U; Jürgens, U

    1997-09-05

    A miniature telemetric system is described which allows simultaneous measurements of neural activity and vocalization in freely moving monkeys within their social group. Single and multi-unit activities were detected with medium impedance electrodes that were fixed to self-made microdrives allowing accurate vertical positioning over a range of 8 mm. Vocalizations were registered by means of a piezo-ceramic device sensing the vocalization-induced skull vibrations. This allowed identification of the vocalizing animal in a larger group and eliminated environmental noise. Neuronal activity and vocalization were transmitted via separate channels of a FM transmitter using different carrier frequencies. The signals were decoded in two conventional FM receivers equipped with an automatic frequency control. The signals were stored for off-line analysis on a HiFi videotape recorder.

  13. NMR and ion selective electrode studies of hydraphile channels correlate with biological activity in E. coli and B. subtilis

    PubMed Central

    Leevy, W. Matthew; Weber, Michelle E.; Schlesinger, Paul H.; Gokel, George W.

    2008-01-01

    Previous sodium ion transport results obtained by NMR methods are compared with those obtained by a new ISE technique and are found to correlate well with each other and with the biological activity against E. coli and B. subtilis. PMID:15614382

  14. Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar.

    PubMed

    Yang, Shouguo; Li, Yong; Zhang, Kunhui; Tang, Weiping

    2015-12-14

    A novel spatio-temporal 2-dimensional (2-D) processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters' outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD) and direction of arrival (DOA), and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD) of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results.

  15. Multiple-Parameter Estimation Method Based on Spatio-Temporal 2-D Processing for Bistatic MIMO Radar

    PubMed Central

    Yang, Shouguo; Li, Yong; Zhang, Kunhui; Tang, Weiping

    2015-01-01

    A novel spatio-temporal 2-dimensional (2-D) processing method that can jointly estimate the transmitting-receiving azimuth and Doppler frequency for bistatic multiple-input multiple-output (MIMO) radar in the presence of spatial colored noise and an unknown number of targets is proposed. In the temporal domain, the cross-correlation of the matched filters’ outputs for different time-delay sampling is used to eliminate the spatial colored noise. In the spatial domain, the proposed method uses a diagonal loading method and subspace theory to estimate the direction of departure (DOD) and direction of arrival (DOA), and the Doppler frequency can then be accurately estimated through the estimation of the DOD and DOA. By skipping target number estimation and the eigenvalue decomposition (EVD) of the data covariance matrix estimation and only requiring a one-dimensional search, the proposed method achieves low computational complexity. Furthermore, the proposed method is suitable for bistatic MIMO radar with an arbitrary transmitted and received geometrical configuration. The correction and efficiency of the proposed method are verified by computer simulation results. PMID:26694385

  16. Temporal correlation between two channels EEG of bipolar lead in the head midline is associated with sleep-wake stages.

    PubMed

    Li, Yanjun; Tang, Xiaoying; Xu, Zhi; Liu, Weifeng; Li, Jing

    2016-03-01

    Whether the temporal correlation between inter-leads Electroencephalogram (EEG) that located on the boundary between left and right brain hemispheres is associated with sleep stages or not is still unknown. The purpose of this paper is to evaluate the role of correlation coefficients between EEG leads Fpz-Cz and Pz-Oz for automatic classification of sleep stages. A total number of 39 EEG recordings (about 20 h each) were selected from the expanded sleep database in European data format for temporal correlation analysis. Original waveform of EEG was decomposed into sub-bands δ (1-4 Hz), θ (4-8 Hz), α (8-13 Hz) and β (13-30 Hz). The correlation coefficient between original EEG leads Fpz-Cz and Pz-Oz within frequency band 0.5-30 Hz was defined as r(EEG) and was calculated every 30 s, while that between the two leads EEG in sub-bands δ, θ, α and β were defined as r(δ), r(θ), r(α) and r(β), respectively. Classification of wakefulness and sleep was processed by fixed threshold that derived from the probability density function of correlation coefficients. There was no correlation between EEG leads Fpz-Cz and Pz-Oz during wakefulness (|r| < 0.1 for r(θ), r(α) and r(β), while 0.3 > r > 0.1 for r(EEG) and r(δ)), while low correlation existed during sleep (r ≈ -0.4 for r(EEG), r(δ), r(θ), r(α) and r(β)). There were significant differences (analysis of variance, P < 0.001) for r(EEG), r(δ), r(θ), r(α) and r(β) during sleep when in comparison with that during wakefulness, respectively. The accuracy for distinguishing states between wakefulness and sleep was 94.2, 93.4, 89.4, 85.2 and 91.4% in terms of r(EEG), r(δ), r(θ), r(α) and r(β), respectively. However, no correlation index between EEG leads Fpz-Cz and Pz-Oz could distinguish all five types of wakefulness, rapid eye movement (REM) sleep, N1 sleep, N2 sleep and N3 sleep. In conclusion, the temporal correlation between EEG bipolar leads Fpz-Cz and Pz-Oz are highly associated with sleep

  17. The miniaturised Moessbauer spectrometer MIMOS II: future developments.

    NASA Astrophysics Data System (ADS)

    Rodionov, D.; Blumers, M.; Klingelhöfer, G.; Bernhardt, B.; Fleischer, I.; Schröder, C.; Morris, R.; Girones Lopez, J.

    2007-08-01

    In January 2004, the first in situ extraterrestrial Mössbauer spectrum was received from the Martian surface. At the present time (May 2007) two Miniaturized Mössbauer Spectrometers (MIMOS II) on board of the two Mars Exploration Rovers "Spirit" and "Opportunity" continue to collect valuable scientific data. Both spectrometers are operational after more than 3 years of work. Originally, the mission was expected to last for 90 days. To date more than 600 spectra were obtained with a total integration time for both rovers exceeding 260 days. The MER mission has proven that Mössbauer spectroscopy is a valuable technique for the in situ exploration of extraterrestrial bodies and the study of Fe-bearing samples. The Mössbauer team at the University of Mainz has accumulated a lot of experience and learned many lessons during last three years. All that makes MIMOS II a feasible choice for the future missions to Mars and other targets. Currently MIMOS II is on the scientific payload of two missions: Phobos Grunt (Russian Space Agency) and ExoMars (European Space Agency). Phobos Grunt is scheduled to launch in 2009. The main goals of the mission are: a) Phobos regolith sample return, b) Phobos in situ study, c) Mars and Phobos remote sensing. MIMOS II will be installed on the arm of a landing module. Currently, we are manufacturing an engineering model for testing purposes. The ESA "ExoMars" mission involves the development of a MER-like rover with more complex scientific payload (Pasteur exobiology instruments, including a drilling system). Its aim is to further characterise the biological environment in preparation for robotic missions and eventually human exploration. Data from the mission will provide invaluable input to the field of exobiology - the study of the origin, the evolution and distribution of life in the universe. The launch date is scheduled for 2013. Like on MER, the MIMOS II instrument will be mounted on a robotic arm. Advanced and improved version of

  18. The Effects of Spatial Diversity and Imperfect Channel Estimation on Wideband MC-DS-CDMA and MC-CDMA

    DTIC Science & Technology

    2009-10-01

    input multiple-output (MIMO) system which employs Alamouti spacetime block coding at each sub-carrier frequency to achieve spatial diversity. We...number of pilot symbols per channel estimate. 13 N/A MC-DS-CDMA, MC-CDMA, Alamouti spacetime block coding, frequency-selective Rayleigh fading

  19. Enhanced channel estimation and symbol detection for high speed multi-input multi-output underwater acoustic communications.

    PubMed

    Ling, Jun; Yardibi, Tarik; Su, Xiang; He, Hao; Li, Jian

    2009-05-01

    The need for achieving higher data rates in underwater acoustic communications leverages the use of multi-input multi-output (MIMO) schemes. In this paper two key issues regarding the design of a MIMO communications system, namely, channel estimation and symbol detection, are addressed. To enhance channel estimation performance, a cyclic approach for designing training sequences and a channel estimation algorithm called the iterative adaptive approach (IAA) are presented. Sparse channel estimates can be obtained by combining IAA with the Bayesian information criterion (BIC). Moreover, the RELAX algorithm can be used to improve the IAA with BIC estimates further. Regarding symbol detection, a minimum mean-squared error based detection scheme, called RELAX-BLAST, which is a combination of vertical Bell Labs layered space-time (V-BLAST) algorithm and the cyclic principle of the RELAX algorithm, is presented and it is shown that RELAX-BLAST outperforms V-BLAST. Both simulated and experimental results are provided to validate the proposed MIMO scheme. RACE'08 experimental results employing a 4 x 24 MIMO system show that the proposed scheme enjoys an average uncoded bit error rate of 0.38% at a payload data rate of 31.25 kbps and an average coded bit error rate of 0% at a payload data rate of 15.63 kbps.

  20. Low-Cost Nested-MIMO Array for Large-Scale Wireless Sensor Applications

    PubMed Central

    Zhang, Duo; Wu, Wen; Fang, Dagang; Wang, Wenqin; Cui, Can

    2017-01-01

    In modern communication and radar applications, large-scale sensor arrays have increasingly been used to improve the performance of a system. However, the hardware cost and circuit power consumption scale linearly with the number of sensors, which makes the whole system expensive and power-hungry. This paper presents a low-cost nested multiple-input multiple-output (MIMO) array, which is capable of providing O(2N2) degrees of freedom (DOF) with O(N) physical sensors. The sensor locations of the proposed array have closed-form expressions. Thus, the aperture size and number of DOF can be predicted as a function of the total number of sensors. Additionally, with the help of time-sequence-phase-weighting (TSPW) technology, only one receiver channel is required for sampling the signals received by all of the sensors, which is conducive to reducing the hardware cost and power consumption. Numerical simulation results demonstrate the effectiveness and superiority of the proposed array. PMID:28498329

  1. Low-Cost Nested-MIMO Array for Large-Scale Wireless Sensor Applications.

    PubMed

    Zhang, Duo; Wu, Wen; Fang, Dagang; Wang, Wenqin; Cui, Can

    2017-05-12

    In modern communication and radar applications, large-scale sensor arrays have increasingly been used to improve the performance of a system. However, the hardware cost and circuit power consumption scale linearly with the number of sensors, which makes the whole system expensive and power-hungry. This paper presents a low-cost nested multiple-input multiple-output (MIMO) array, which is capable of providing O ( 2 N 2 ) degrees of freedom (DOF) with O ( N ) physical sensors. The sensor locations of the proposed array have closed-form expressions. Thus, the aperture size and number of DOF can be predicted as a function of the total number of sensors. Additionally, with the help of time-sequence-phase-weighting (TSPW) technology, only one receiver channel is required for sampling the signals received by all of the sensors, which is conducive to reducing the hardware cost and power consumption. Numerical simulation results demonstrate the effectiveness and superiority of the proposed array.

  2. Cross-layer Design for MIMO Systems with Transmit Antenna Selection and Imperfect CSI

    NASA Astrophysics Data System (ADS)

    Yu, Xiangbin; Liu, Yan; Rui, Yun; Zhou, Tingting; Yin, Xin

    2013-04-01

    In this paper, by combining adaptive modulation and automatic repeat request (ARQ), a cross-layer design (CLD) scheme for multiple-input and multiple-output (MIMO) system with transmit antenna selection (TAS) and imperfect channel state information (CSI) is presented. Based on the imperfect CSI, the probability density function of the effective signal to noise ratio (SNR) is derived, and the fading gain switching thresholds are also derived subject to a target packet loss rate and fixed power constraint. According to these results, we further derive the average spectrum efficiency (SE) and packet error rate (PER) of the system. As a result, closed-form expressions of the average SE and PER are obtained, respectively. The derived expressions include the expressions under perfect CSI as special cases, and can provide good performance evaluation for the CLD system with imperfect CSI. Simulation results verify the validity of the theoretical analysis. The results show that the CLD system with TAS provides better SE than that with space-time block coding, but the SE and PER performance of the system with imperfect CSI are worse than those with perfect CSI due to the estimation error.

  3. Strongly-coupled multi-core fiber and its optical characteristics for MIMO transmission systems

    NASA Astrophysics Data System (ADS)

    Sakamoto, Taiji; Mori, Takayoshi; Wada, Masaki; Yamamoto, Takashi; Yamamoto, Fumihiko; Nakajima, Kazuhide

    2017-02-01

    We review recent progress on coupled multi-core fiber (MCF) technologies for optical multiple-input multiple-output (MIMO) transmission. First, we define types of MCF, namely non-coupled/coupled single-/few-mode MCF, and briefly report recent work on non-coupled/coupled MCF. We next describe the advantage of using coupled MCF in MIMO transmission systems, and present a coupled MCF design based on an analysis of coupling between super-modes in twisted bent MCF. We finally describe our experimental results for our strongly coupled MCF and its applicability for optical MIMO transmission systems.

  4. The miniaturised Mössbauer spectrometer MIMOS IIA: Increased sensitivity and new capability for elemental analysis

    NASA Astrophysics Data System (ADS)

    Blumers, M.; Bernhardt, B.; Lechner, P.; Klingelhöfer, G.; d'Uston, C.; Soltau, H.; Strüder, L.; Eckhardt, R.; Brückner, J.; Henkel, H.; Lopez, J. G.; Maul, J.

    2010-12-01

    The Miniaturised Mössbauer Spectrometers MIMOS II on board the two Mars Exploration Rovers (MER) have now been collecting valuable scientific data for more than five years. Mössbauer Spectrometers are part of two future missions: Phobos Grunt (Russian Space Agency) and a joint ESA—NASA Rover in 2018. The new advanced MIMOS IIA instrument described in this paper uses Silicon Drift Detectors (SDD) allowing also X-ray fluorescence chemical analysis (XRF) simultaneously to Mössbauer acquisitions. This paper highlights the features and technological improvements of the new spectrometer MIMOS IIA.

  5. Modeling the Multiple-Antenna Wireless Channel Using Maximum Entropy Methods

    NASA Astrophysics Data System (ADS)

    Guillaud, M.; Debbah, M.; Moustakas, A. L.

    2007-11-01

    Analytical descriptions of the statistics of wireless channel models are desirable tools for communication systems engineering. When multiple antennas are available at the transmit and/or the receive side (the Multiple-Input Multiple-Output, or MIMO, case), the statistics of the matrix H representing the gains between the antennas of a transmit and a receive antenna array, and in particular the correlation between its coefficients, are known to be of paramount importance for the design of such systems. However these characteristics depend on the operating environment, since the electromagnetic propagation paths are dictated by the surroundings of the antenna arrays, and little knowledge about these is available at the time of system design. An approach using the Maximum Entropy principle to derive probability density functions for the channel matrix, based on various degrees of knowledge about the environment, is presented. The general idea is to apply the maximum entropy principle to obtain the distribution of each parameter of interest (e.g. correlation), and then to marginalize them out to obtain the full channel distribution. It was shown in previous works, using sophisticated integrals from statistical physics, that by using the full spatial correlation matrix E{vec(H)vec(H)H} as the intermediate modeling parameter, this method can yield surprisingly concise channel descriptions. In this case, the joint probability density function is shown to be merely a function of the Frobenius norm of the channel matrix |H|F. In the present paper, we investigate the case where information about the average covariance matrix is available (e.g. through measurements). The maximum entropy distribution of the covariance is derived under this constraint. Furthermore, we consider also the doubly correlated case, where the intermediate modeling parameters are chosen as the transmit- and receive-side channel covariance matrices (respectively E{HHH} and E{HHH}). We compare the

  6. Identification for the control of MIMO industrial processes

    NASA Astrophysics Data System (ADS)

    Backx, A. C. P. M.; Damen, A. A. H.

    1991-12-01

    A procedure for the identification of industrial processes with the intention of control system design is proposed. It is illustrated by an application to a full scale production process. The procedure was developed by directly meeting engineering constraints. The identification steps are motivated, keeping industrial applicability of the procedure in mind. The Multi Input Multi Output (MIMO) model set used is the common denominator form or minimum polynomial form. Parameter estimation is performed in several steps, thus adapting to estimation and control requirements. The proposed general scheme was successfully applied on various industrial applications. As an example of practical results obtained, the identification and control of a quartz tube glass process is described.

  7. Breast Cancer Nodes Detection Using Ultrasonic Microscale Subarrayed MIMO RADAR

    PubMed Central

    Siwamogsatham, Siwaruk; Pomalaza-Ráez, Carlos

    2014-01-01

    This paper proposes the use of ultrasonic microscale subarrayed MIMO RADARs to estimate the position of breast cancer nodes. The transmit and receive antenna arrays are divided into subarrays. In order to increase the signal diversity each subarray is assigned a different waveform from an orthogonal set. High-frequency ultrasonic transducers are used since a breast is considered to be a superficial structure. Closed form expressions for the optimal Neyman-Pearson detector are derived. The combination of the waveform diversity present in the subarrayed deployment and traditional phased-array RADAR techniques provides promising results. PMID:25309591

  8. Lens design for indoor MIMO visible light communications

    NASA Astrophysics Data System (ADS)

    Li, Shang-Bin; Gong, Chen; Wang, Peilin; Xu, Zhengyuan

    2017-04-01

    We proposed a lens design procedure to generate parallel light beams that facilitate optical MIMO communication with negligible interference between the un-intended transceiver pairs, in a 2×2 LED array. We designed an imaging receiver using two aspheric lenses instead of one single hemispherical lens to improve the light-beam separation performance. The proposed scheme can be extended to the scenario with ultra-dense LED array. Numerical results show that proper parameter setting in lens design can lead to negligible interference between un-intended transceiver pairs. The bit error rate performance is also evaluated.

  9. Dynamic Robust Games in MIMO Systems.

    PubMed

    Tembine, H

    2011-08-01

    In this paper, we study dynamic robust power-allocation games in multiple-input-multiple-output systems under the imperfectness of the channel-state information at the transmitters. Using a robust pseudopotential-game approach, we show the existence of robust solutions in both discrete and continuous action spaces under suitable conditions. Considering the imperfectness in terms of the payoff measurement at the transmitters, we propose a COmbined fully DIstributed Payoff and Strategy Reinforcement Learning (CODIPAS-RL) in which each transmitter learns its payoff function, as well as the associated optimal covariance matrix strategies. Under the heterogeneous CODIPAS-RL, the transmitters can use different learning patterns (heterogeneous learning) and different learning rates. We provide sufficient conditions for the almost-sure convergence of the heterogeneous learning to ordinary differential equations. Extensions of the CODIPAS-RL to Itô's stochastic differential equations are discussed.

  10. Correlation of T-channel coding gene expression, IT, and the low threshold Ca2+ spike in the thalamus of a rat model of absence epilepsy.

    PubMed

    Broicher, Tilman; Kanyshkova, Tatyana; Meuth, Patrick; Pape, Hans-Christian; Budde, Thomas

    2008-11-01

    T-type Ca(2+) current-dependent burst firing of thalamic neurons is thought to be involved in the hyper-synchronous activity observed during absence seizures. Here we investigate the correlation between the expression of T-channel coding genes (alpha1G, -H, -I), T-type Ca(2+) current, and the T-current-dependent low threshold Ca(2+) spike in three functionally distinct thalamic nuclei (lateral geniculate nucleus; centrolateral nucleus; reticular nucleus) in a rat model of absence epilepsy, the WAG/Rij rats, and a non-epileptic control strain, the ACI rats. The lateral geniculate nucleus and centrolateral nucleus were found to primarily express alpha1G and alpha1I, while the reticular thalamic nucleus expressed alpha1H and alpha1I. Expression was higher in WAG/Rij when compared to ACI. The T-type Ca(2+) current properties matched the predictions derived from the expression pattern analysis. Current density was larger in all nuclei of WAG/Rij rats when compared to ACI and correlated with LTS size and the minimum LTS generating slope, while T-type Ca(2+) current voltage dependency correlated with the LTS onset potential.

  11. Ion correlations in nanofluidic channels: Effects of ion size, valence, and concentration on voltage- and pressure-driven currents

    PubMed Central

    Hoffmann, Jordan

    2013-01-01

    The effects of ion-ion and ion-wall correlations in nanochannels are explored, specifically how they influence voltage- and pressure-driven currents and pressure-to-voltage energy conversion. Cations of different diameters (0.15, 0.3, and 0.9 nm) and different valences (+1, +2, and +3) at concentrations ranging from 10–6 M to 1 M are considered in 50 nm- and 100 nm-wide nanoslits with wall surface charges ranging from 0 C/m2 to –0.3 C/m2. These parameters are typical of nanofluidic devices. Ion correlations have significant effects on device properties over large parts of this parameter space. These effects are the result of ion layering (oscillatory concentration profiles) for large monovalent cations and charge inversion (more cations in the first layer near the wall than necessary to neutralize the surface charge) for the multivalent cations. The ions were modeled as charged, hard spheres using density functional theory of fluids and current was computed with the Navier-Stokes equations with two different no-slip conditions. PMID:23286510

  12. Validation of a MIMO Random Control Tool Using the CUBE™

    NASA Astrophysics Data System (ADS)

    Carrella, Alex; Janssens, Joris; Debille, Jan; Faignet, Eddy; Peetrs, Bart

    2012-07-01

    Environmental testing is an important engineering discipline which aims at simulating the effect of the environmnet on a given structure, item or system. A particular environment is the vibratory one. From development to qualification, engineering systems subject to harsh dynamic environments have to be tested in order to ensure their capability to withstand vibrations. To this end, there exist a wealth of test stadards which impose strict pass/fail criteria. However, these methods are rather dated and the testing community is constantly striving to update the standards to account for new technologies and ever more stringent requirements. Currently, the standard specify to carry out vibration tests along one axis at the time, that is using a Single-Input-Single-Ouput (SISO) or a Single-Input- Multiple-Ouput (SIMO) approach. However, there are a number of significant advanteges in using a Multiple- Input-Multiple-Ouput (MIMO) apporach. In this paper are presented the results of an experimental campaign aimed at assessing the capabilty of the new MIMO Random control developed at LMS.

  13. MIMO-OFDM signal optimization for SAR imaging radar

    NASA Astrophysics Data System (ADS)

    Baudais, J.-Y.; Méric, S.; Riché, V.; Pottier, É.

    2016-12-01

    This paper investigates the optimization of the coded orthogonal frequency division multiplexing (OFDM) transmitted signal in a synthetic aperture radar (SAR) context. We propose to design OFDM signals to achieve range ambiguity mitigation. Indeed, range ambiguities are well known to be a limitation for SAR systems which operates with pulsed transmitted signal. The ambiguous reflected signal corresponding to one pulse is then detected when the radar has already transmitted the next pulse. In this paper, we demonstrate that the range ambiguity mitigation is possible by using orthogonal transmitted wave as OFDM pulses. The coded OFDM signal is optimized through genetic optimization procedures based on radar image quality parameters. Moreover, we propose to design a multiple-input multiple-output (MIMO) configuration to enhance the noise robustness of a radar system and this configuration is mainly efficient in the case of using orthogonal waves as OFDM pulses. The results we obtain show that OFDM signals outperform conventional radar chirps for range ambiguity suppression and for robustness enhancement in 2 ×2 MIMO configuration.

  14. High-resolution observations of plankton spatial distributions correlated with hydrography in the Great South Channel, Georges Bank

    NASA Astrophysics Data System (ADS)

    Gallager, Scott M.; Davis, Cabell S.; Epstein, Ari W.; Solow, Andy; Beardsley, Robert C.

    During a cruise to Georges Bank in May 1992, the Video Plankton Recorder (VPR) was towyoed while non-invasively obtaining images of the plankton and environmental (CTD) data. Data from an 8 h transect across the Great South Channel (GSC) were analyzed on a continuum of spatial scales from coarse-scale (100 km) to micro-scale (mm). Abundance was determined for 12 taxonomic groups including: invertebrate larvae (ophiopluteus larvae, anthozoa larvae: Cerianthus sp.), hydroids, copepods ( Calanus sp., Pseudocalanus sp.), pteropods ( Limacina retroversa, Clione sp.), ctenophores ( Mnemiopsis sp., Pleurobrachia sp.), larvacea ( Oikopleura sp.), chaetognatha ( Sagitta sp.), and diatom colonies ( Chaetoceros socialis). Species-specific plots of the positions of individual plankton in the water column and plots of the temperature and salinity at which the plankton were observed (temperature-salinity-plankton plots) showed that major taxonomic groups were patchy at coarse scales because of their association with specific water masses of different origin and associated temperature/density discontinuities (pycnocline and fronts). Analysis of the T- S characteristics of water types indicated that diatom colonies and ophiopluteus larvae of echinoderms were transported to GSC in a band of cold water originating on the south flank of Georges Bank. Within this band, diatom colonies formed an intense patch at a front reaching a density of 5 ml -1. Within each water mass, fine-scale (10s of meters) plankton patchiness was associated with regions of vertical stability as indicated by the association of plankton with regions of high gradient Richardson number. Aggregation of plankton at the microscale (<1 m) occurred significantly only for plankton capable of active swimming, suggesting a dynamic interaction between biological and physical variables at this spatial scale. On occasion, veliger larvae of Limacina retroversa were found in spawning patches at concentrations exceeding 600

  15. Locally optimum detector for MIMO radar in non-Gaussian clutter

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaobo; Wang, Shouyong

    2011-10-01

    The optimum Gaussian detector of MIMO radar no longer works well in non-Gaussian clutter environment. Therefore, a locally optimum (LO) detector based on alpha stable distribution is proposed for the signal detection of MIMO radar. The proposed method assumes that the MIMO radar clutter satisfies alpha stable distribution, according to the multiple-input multiple-output characteristics of the signal model, a locally optimum detection statistics for MIMO radar is presented based on the generalized Neyman-Pearson lemma. Both theoretical analysis and simulation results show that the optimum Gaussian detector suffers serious performance degradation in non-Gaussian clutter, whereas the proposed detector can achieve good performance and outperforms the Gaussian detector significantly.

  16. Evaluation of the Performance of the Distributed Phased-MIMO Sonar.

    PubMed

    Pan, Xiang; Jiang, Jingning; Wang, Nan

    2017-01-11

    A broadband signal model is proposed for a distributed multiple-input multiple-output (MIMO) sonar system consisting of two transmitters and a receiving linear array. Transmitters are widely separated to illuminate the different aspects of an extended target of interest. The beamforming technique is utilized at the reception ends for enhancement of weak target echoes. A MIMO detector is designed with the estimated target position parameters within the general likelihood rate test (GLRT) framework. For the high signal-to-noise ratio case, the detection performance of the MIMO system is better than that of the phased-array system in the numerical simulations and the tank experiments. The robustness of the distributed phased-MIMO sonar system is further demonstrated in localization of a target in at-lake experiments.

  17. The analysis of MAI in large scale MIMO-CDMA system

    NASA Astrophysics Data System (ADS)

    Berceanu, Madalina-Georgiana; Voicu, Carmen; Halunga, Simona

    2016-12-01

    Recently, technological development imposed a rapid growth in the use of data carried by cellular services, which also implies the necessity of higher data rates and lower latency. To meet the users' demands, it was brought into discussion a series of new data processing techniques. In this paper, we approached the MIMO technology that uses multiple antennas at the receiver and transmitter ends. To study the performances obtained by this technology, we proposed a MIMO-CDMA system, where image transmission has been used instead of random data transmission to take benefit of a larger range of quality indicators. In the simulations we increased the number of antennas, we observed how the performances of the system are modified and, based on that, we were able to make a comparison between a conventional MIMO and a Large Scale MIMO system, in terms of BER and MSSIM index, which is a metric that compares the quality of the image before transmission with the received one.

  18. Polyphase orthogonal waveform optimization for MIMO-SAR using Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Mehany, Wael; Jiao, Licheng; Hussien, Khaled

    2014-04-01

    A Multi-Input Multi-Output (MIMO) radar can be used to form a synthetic aperture for high resolution imaging. To successfully utilize the MIMO Synthetic Aperture Radar (SAR) system for practical imaging application, the orthogonal waveform design plays a critical role in image formation. Focusing on the SAR application, a definition for synthetic Integrated Side-Lobe level Ratio (ISLR) is proposed. In this paper a cost function containing ISLR and Peak Side-Lobe level Ratio (PSLR) is presented. A Genetic Algorithm (GA) is presented to numerically optimize orthogonal polyphase code sets design. The obtained waveform can be implemented for MIMO-SAR systems to improve the resolution. The simulation results show that the superiority of the proposed algorithm over other algorithms for the design of polyphase code sets used in MIMO-SAR.

  19. CS-MIMO radars for through-the-wall imaging in an indoor multipath environment

    NASA Astrophysics Data System (ADS)

    Yu, Yao; Ahmad, Fauzia; Petropulu, Athina P.; Amin, Moeness G.

    2014-05-01

    Through-the-wall radar (TWR) systems are indispensable for situational awareness in a wide range of civilian and military applications. Multi-input multi-output (MIMO) TWR provides high spatial resolution for improved target detection in indoor environments. When combined with compressive sensing (CS), MIMO TWR enables good performance with a reduced number of samples, which, in turn, reduces the data acquisition time. Most of the existing MIMO TWR systems, either conventional or CS based, employ time-multiplexed transmitters. In this paper, we present a CS-MIMO TWR approach for the indoor environment under multipath propagation, in which the transmit antennas simultaneously emit different waveforms, thus allowing for further reduction of acquisition time as compared to time-multiplexed transmissions. Supporting simulation results are provided.

  20. Layered Video Transmission with Network Coding in a Cooperative Virtual MIMO Cellular Relay Networks

    NASA Astrophysics Data System (ADS)

    Kim, Yo-Han; Yoon, Jisun; Shin, Jitae; Yang, Janghoon

    In this letter, we propose a layered video streaming technique that combines network coding (NC), multiple-input multiple-output (MIMO), and hierarchical modulation (HM) over cellular relay networks. We provide a performance analysis of different transmission modes of NC and MIMO in terms of the error rate in video layers, which is reflected in the total layered-video quality. The HM is used to differentiate the error rates among video layers. The simulation results show that the NC, the MIMO spatial multiplexing (SM), and the combination of both the NC and MIMO-SM gives video-quality gains of about 1.9dB, 6dB, and 12dB maximally, respectively, compared to the conventional single-input and single-output (SISO) single relay network (SRN) system.

  1. Evaluation of the Performance of the Distributed Phased-MIMO Sonar

    PubMed Central

    Pan, Xiang; Jiang, Jingning; Wang, Nan

    2017-01-01

    A broadband signal model is proposed for a distributed multiple-input multiple-output (MIMO) sonar system consisting of two transmitters and a receiving linear array. Transmitters are widely separated to illuminate the different aspects of an extended target of interest. The beamforming technique is utilized at the reception ends for enhancement of weak target echoes. A MIMO detector is designed with the estimated target position parameters within the general likelihood rate test (GLRT) framework. For the high signal-to-noise ratio case, the detection performance of the MIMO system is better than that of the phased-array system in the numerical simulations and the tank experiments. The robustness of the distributed phased-MIMO sonar system is further demonstrated in localization of a target in at-lake experiments. PMID:28085071

  2. Application of sparse array and MIMO in near-range microwave imaging

    NASA Astrophysics Data System (ADS)

    Qi, Yaolong; Wang, Yanping; Tan, Weixian; Hong, Wen

    2011-11-01

    Near range microwave imaging systems have broad application prospects in the field of concealed weapon detection, biomedical imaging, nondestructive testing, etc. In this paper, the techniques of MIMO and sparse line array are applied to near range microwave imaging, which can greatly reduce the complexity of imaging systems. In detail, the paper establishes two-dimensional near range MIMO imaging geometry and corresponding echo model, where the imaging geometry is formed by arranging sparse antenna array in azimuth direction and transmitting broadband signals in range direction; then, by analyzing the relationship between MIMO and convolution principle, the paper develops a method of arranging sparse line array which can be equivalent to a full array; and the paper deduces the backprojection algorithm applied to near ranging MIMO imaging geometry; finally, the imaging geometry and corresponding imaging algorithm proposed in this paper are investigated and verified by means of theoretical analysis and numerical simulations.

  3. A single-cell correlative nanoelectromechanosensing approach to detect cancerous transformation: monitoring the function of F-actin microfilaments in the modulation of the ion channel activity

    NASA Astrophysics Data System (ADS)

    AbdolahadThe Authors With Same Contributions., Mohammad; Saeidi, Ali; Janmaleki, Mohsen; Mashinchian, Omid; Taghinejad, Mohammad; Taghinejad, Hossein; Azimi, Soheil; Mahmoudi, Morteza; Mohajerzadeh, Shams

    2015-01-01

    Cancerous transformation may be dependent on correlation between electrical disruptions in the cell membrane and mechanical disruptions of cytoskeleton structures. Silicon nanotube (SiNT)-based electrical probes, as ultra-accurate signal recorders with subcellular resolution, may create many opportunities for fundamental biological research and biomedical applications. Here, we used this technology to electrically monitor cellular mechanosensing. The SiNT probe was combined with an electrically activated glass micropipette aspiration system to achieve a new cancer diagnostic technique that is based on real-time correlation between mechanical and electrical behaviour of single cells. Our studies demonstrated marked changes in the electrical response following increases in the mechanical aspiration force in healthy cells. In contrast, such responses were extremely weak for malignant cells. Confocal microscopy results showed the impact of actin microfilament remodelling on the reduction of the electrical response for aspirated cancer cells due to the significant role of actin in modulating the ion channel activity in the cell membrane.Cancerous transformation may be dependent on correlation between electrical disruptions in the cell membrane and mechanical disruptions of cytoskeleton structures. Silicon nanotube (SiNT)-based electrical probes, as ultra-accurate signal recorders with subcellular resolution, may create many opportunities for fundamental biological research and biomedical applications. Here, we used this technology to electrically monitor cellular mechanosensing. The SiNT probe was combined with an electrically activated glass micropipette aspiration system to achieve a new cancer diagnostic technique that is based on real-time correlation between mechanical and electrical behaviour of single cells. Our studies demonstrated marked changes in the electrical response following increases in the mechanical aspiration force in healthy cells. In contrast, such

  4. Robust THP Transceiver Designs for Multiuser MIMO Downlink with Imperfect CSIT

    NASA Astrophysics Data System (ADS)

    Ubaidulla, P.; Chockalingam, A.

    2009-12-01

    We present robust joint nonlinear transceiver designs for multiuser multiple-input multiple-output (MIMO) downlink in the presence of imperfections in the channel state information at the transmitter (CSIT). The base station (BS) is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas. The BS employs Tomlinson-Harashima precoding (THP) for interuser interference precancellation at the transmitter. We consider robust transceiver designs that jointly optimize the transmit THP filters and receive filter for two models of CSIT errors. The first model is a stochastic error (SE) model, where the CSIT error is Gaussian-distributed. This model is applicable when the CSIT error is dominated by channel estimation error. In this case, the proposed robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE) under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. The other model we consider is a norm-bounded error (NBE) model, where the CSIT error can be specified by an uncertainty set. This model is applicable when the CSIT error is dominated by quantization errors. In this case, we consider a worst-case design. For this model, we consider robust (i) minimum SMSE, (ii) MSE-constrained, and (iii) MSE-balancing transceiver designs. We propose iterative algorithms to solve these problems, wherein each iteration involves a pair of semidefinite programs (SDPs). Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We evaluate the robustness of the proposed algorithms to imperfections in CSIT through simulation, and show that the proposed robust designs outperform nonrobust designs as well as robust linear transceiver designs reported in the recent literature.

  5. Spatio-Temporal Waveform Design for Multiuser Massive MIMO Downlink With 1-bit Receivers

    NASA Astrophysics Data System (ADS)

    Gokceoglu, Ahmet; Bjornson, Emil; Larsson, Erik G.; Valkama, Mikko

    2017-03-01

    Internet-of-Things (IoT) refers to a high-density network of low-cost low-bitrate terminals and sensors where also low energy consumption is one central feature. As the power-budget of classical receiver chains is dominated by the high-resolution analog-to-digital converters (ADCs), there is a growing interest towards deploying receiver architectures with reduced-bit or even 1-bit ADCs. In this paper, we study waveform design, optimization and detection aspects of multi-user massive MIMO downlink where user terminals adopt very simple 1-bit ADCs with oversampling. In order to achieve spectral efficiency higher than 1 bit/s/Hz per real-dimension, we propose a two-stage precoding, namely a novel quantization precoder followed by maximum-ratio transmission (MRT) or zero-forcing (ZF) type spatial channel precoder which jointly form the multi-user-multiantenna transmit waveform. The quantization precoder outputs are optimized, under appropriate transmitter and receiver filter bandwidth constraints, to provide controlled inter-symbol-interference (ISI) enabling the input symbols to be uniquely detected from 1-bit quantized observations with a low-complexity symbol detector in the absence of noise. An additional optimization constraint is also imposed in the quantization precoder design to increase the robustness against noise and residual inter-user-interference (IUI). The purpose of the spatial channel precoder, in turn, is to suppress the IUI and provide high beamforming gains such that good symbol-error rates (SERs) can be achieved in the presence of noise and interference. Extensive numerical evaluations illustrate that the proposed spatio-temporal precoder based multiantenna waveform design can facilitate good multi-user link performance, despite the extremely simple 1-bit ADCs in the receivers, hence being one possible enabling technology for the future low-complexity IoT networks.

  6. Ambiguity Function Analysis for the Hybrid Mimo Phased-Array Radar (Postprint)

    DTIC Science & Technology

    2009-09-01

    Multiple - Input Multiple Output , or MIMO , radar systems are next-generation radar systems with multiple transmit and receive...architecture that combines elements of traditional phased-array radar with the emerging technology of Multiple - Input Multiple Out- put ( MIMO ) radar. A HMPAR...a multisensor radar architecture that combines elements of traditional phased-array radar with the emerging technology of Multiple - Input Multiple

  7. Surface Analysis in Archaeology Using the Miniaturized Mössbauer Spectrometer MIMOS II

    NASA Astrophysics Data System (ADS)

    de Souza, Paulo A., Jr.; Bernhardt, B.; Klingelhöfer, G.; Gütlich, P.

    2003-12-01

    A miniaturized Mössbauer spectrometer (MIMOS II) which was designed and constructed for extraterrestrial applications, such as iron-containing rock and soil analysis on the planet Mars, has been employed to investigate the iron-containing constituents in the paintings of a Lekythos Greek vase. Greek pottery is commonly painted with black figures. The Mössbauer backscattering spectra recorded with MIMOS II at room temperature show that the hand-painted black figures contain hematite.

  8. Joint DOD/DOA Estimation in MIMO Radar Exploiting Time-Frequency Signal Representations

    DTIC Science & Technology

    2012-05-08

    direction-of-departure (DOD) and direction-of- arrival (DOA) information of maneuvering targets in a bistatic multiple-input multiple-output (MIMO) radar...CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as Report ( SAR ) 18. NUMBER OF PAGES 21 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b...departure (DOD) and direction-of- arrival (DOA) information of maneuvering targets in a bistatic multiple-input multiple-output (MIMO) radar system

  9. Transient Receptor Potential Ankyrin 1 Channel Expression on Peripheral Blood Leukocytes from Rheumatoid Arthritic Patients and Correlation with Pain and Disability

    PubMed Central

    Pereira, Ione; Mendes, Saulo J. F.; Pereira, Domingos M. S.; Muniz, Thayanne F.; Colares, Valderlane L. P.; Monteiro, Cinara R. A. V.; Martins, Mahiba M. R. de S.; Grisotto, Marcos A. G.; Monteiro-Neto, Valério; Monteiro, Sílvio G.; Calixto, João B.; Brain, Susan D.; Fernandes, Elizabeth S.

    2017-01-01

    Patients with rheumatoid arthritis (RA) suffer from pain and joint disability. The transient receptor potential ankyrin 1 (TRPA1) channel expressed on sensory neurones and non-neuronal cells mediates pain transduction and inflammation and it has been implicated in RA. However, there is little information on the contribution of TRPA1 for human disease. Here, we investigated the expression of TRPA1 on peripheral blood leukocytes and the circulating levels of its endogenous activators 4-hydroxynonenal (4-HNE) and hydrogen peroxide (H2O2) in RA patients treated or not with the anti-rheumatic leflunomide (LFN) or the anti-TNFα adalimumab (ADA). We also assessed whether TRPA1 expression correlates with joint pain and disability, in addition to the immune changes in RA. TRPA1 expression on peripheral blood leukocytes correlated with pain severity and disability. TRPA1 levels on these cells were associated with the numbers of polymorphonuclear and the activation of CD14+ cells. No correlations were found between the lymphocyte population and TRPA1 expression, pain or disability. Patients recently diagnosed with RA expressed increased levels of TRPA1 on their leukocytes whilst treatment with either LFN or ADA down-regulated this receptor probably by reducing the numbers of polymorphonuclears and the activation of CD14+ cells. We suggest that the activation levels of CD14+ cells, the numbers of PMNs in the peripheral blood and the expression of TRPA1 on peripheral blood leukocytes correlate with RA progression, affecting joint pain sensitivity and loss of function. PMID:28239353

  10. Correlation analysis between the delayed rectifier potassium channel KCNE1 (G38S) polymorphism and atrial fibrillation among the senior Uygur population in Xinjiang.

    PubMed

    Wugeti, N; Yu-Jun, G; Juan, S; Mahemuti, A

    2015-12-07

    Current resources to support genetic screening among the Uygur population in Xinjiang territory for atrial fibrillation (AF) have not been well established and large-scale epidemiological analyses are needed. Using patients from the Xinjiang Uygur population as subjects, and the delayed rectifier potassium channel KCNE1 and its associated polymorphism G38S (rs1805127) as the candidate gene, we analyzed the correlation between the G38S polymorphism and AF among the senior Uygur population in Xinjiang Province. Peripheral blood from AF Uygur patients (patient group) or non-AF Uygur patients (control group) from Xinjiang territory was collected (70 patients each). DNA was purified and tested by polymerase chain reaction-restriction fragment length polymorphism for the genotype and allelic distribution of KCNE1 (G38S). Correlation analysis between AF and multiple health-related factors was performed by logistic regression. Among patients with the KCNE1 G38S polymorphism, the genotypes AA, AG, and GG were present at frequencies of 17.14, 27.14, and 55.71%, respectively, in the patient group, compared with 24.29, 50, and 25.71%, respectively, in the control group. The difference between these two groups was shown to be statistically significant (P < 0.05), and the frequency of the G allele was significantly higher in the patient group (P < 0.05). Logistic regression showed that the GG genotype is correlated with the incidence of AF in Uygur seniors (P < 0.05). The incidence of AF among the senior Uygur population in Xinjiang territory was correlated with the KCNE1 (G38S) polymorphism, which may be an independent risk factor for Uygur AF patients.

  11. Space-division multiplexed transmission over few-mode- and coupled-core fiber based on coherent MIMO digital signal processing

    NASA Astrophysics Data System (ADS)

    Ryf, Roland; Randel, Sebastian; Essiambre, René-Jean; Winzer, Peter J.

    2012-01-01

    The capacity of optical transmission systems has increased dramatically since their first deployments in the mid 1970s . However, studies show that the theoretical capacity limit of single-mode fiber is about to be reached, and space-division multiplexing has been proposed to overcome this limit. With the high levels of integration needed for economic deployment, space-division multiplexing may exhibit large crosstalk between the supported fiber modes. We propose to use coherent multiple-input multiple-output (MIMO) digital signal processing (DSP), a technique widely used in wireless communication, to compensate crosstalk present in spatial multiplexing over fibers. According to MIMO theory, crosstalk in multi-mode transmission systems can be completely reversed if the crosstalk is described by a unitary transformation. For optical fibers this is fulfilled if all available fiber modes can be selectively excited and if all the modes are coherently detected at the end of the fiber, provided that mode-dependent loss is negligible. We successfully applied the technique to demonstrate the transmission of six independent mode-multiplexed 20-Gbaud QPSK signals over a single, optically amplified span of 137-km few-mode fiber (FMF). Further, in a multi-span experiment, we reach 1200 km by transmitting over a 3-core coupled-core fiber (CCF). Details for both experiments will be presented, including the description of the supported polarization- and spatial modes of the fiber, the mode multiplexers used to launch and detect the modes, and the MIMO DSP algorithm used to recover the channels.

  12. Model-Free Primitive-Based Iterative Learning Control Approach to Trajectory Tracking of MIMO Systems With Experimental Validation.

    PubMed

    Radac, Mircea-Bogdan; Precup, Radu-Emil; Petriu, Emil M

    2015-11-01

    This paper proposes a novel model-free trajectory tracking of multiple-input multiple-output (MIMO) systems by the combination of iterative learning control (ILC) and primitives. The optimal trajectory tracking solution is obtained in terms of previously learned solutions to simple tasks called primitives. The library of primitives that are stored in memory consists of pairs of reference input/controlled output signals. The reference input primitives are optimized in a model-free ILC framework without using knowledge of the controlled process. The guaranteed convergence of the learning scheme is built upon a model-free virtual reference feedback tuning design of the feedback decoupling controller. Each new complex trajectory to be tracked is decomposed into the output primitives regarded as basis functions. The optimal reference input for the control system to track the desired trajectory is next recomposed from the reference input primitives. This is advantageous because the optimal reference input is computed straightforward without the need to learn from repeated executions of the tracking task. In addition, the optimization problem specific to trajectory tracking of square MIMO systems is decomposed in a set of optimization problems assigned to each separate single-input single-output control channel that ensures a convenient model-free decoupling. The new model-free primitive-based ILC approach is capable of planning, reasoning, and learning. A case study dealing with the model-free control tuning for a nonlinear aerodynamic system is included to validate the new approach. The experimental results are given.

  13. Performance analysis of cooperative virtual MIMO systems for wireless sensor networks.

    PubMed

    Rafique, Zimran; Seet, Boon-Chong; Al-Anbuky, Adnan

    2013-05-28

    Multi-Input Multi-Output (MIMO) techniques can be used to increase the data rate for a given bit error rate (BER) and transmission power. Due to the small form factor, energy and processing constraints of wireless sensor nodes, a cooperative Virtual MIMO as opposed to True MIMO system architecture is considered more feasible for wireless sensor network (WSN) applications. Virtual MIMO with Vertical-Bell Labs Layered Space-Time (V-BLAST) multiplexing architecture has been recently established to enhance WSN performance. In this paper, we further investigate the impact of different modulation techniques, and analyze for the first time, the performance of a cooperative Virtual MIMO system based on V-BLAST architecture with multi-carrier modulation techniques. Through analytical models and simulations using real hardware and environment settings, both communication and processing energy consumptions, BER, spectral efficiency, and total time delay of multiple cooperative nodes each with single antenna are evaluated. The results show that cooperative Virtual-MIMO with Binary Phase Shift Keying-Wavelet based Orthogonal Frequency Division Multiplexing (BPSK-WOFDM) modulation is a promising solution for future high data-rate and energy-efficient WSNs.

  14. Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

    PubMed

    Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

  15. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber

    PubMed Central

    Shaddad, R. Q.; Mohammad, A. B.; Al-Gailani, S. A.; Al-Hetar, A. M.

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength. PMID:24772009

  16. Performance Analysis of Cooperative Virtual MIMO Systems for Wireless Sensor Networks

    PubMed Central

    Rafique, Zimran; Seet, Boon-Chong; Al-Anbuky, Adnan

    2013-01-01

    Multi-Input Multi-Output (MIMO) techniques can be used to increase the data rate for a given bit error rate (BER) and transmission power. Due to the small form factor, energy and processing constraints of wireless sensor nodes, a cooperative Virtual MIMO as opposed to True MIMO system architecture is considered more feasible for wireless sensor network (WSN) applications. Virtual MIMO with Vertical-Bell Labs Layered Space-Time (V-BLAST) multiplexing architecture has been recently established to enhance WSN performance. In this paper, we further investigate the impact of different modulation techniques, and analyze for the first time, the performance of a cooperative Virtual MIMO system based on V-BLAST architecture with multi-carrier modulation techniques. Through analytical models and simulations using real hardware and environment settings, both communication and processing energy consumptions, BER, spectral efficiency, and total time delay of multiple cooperative nodes each with single antenna are evaluated. The results show that cooperative Virtual-MIMO with Binary Phase Shift Keying-Wavelet based Orthogonal Frequency Division Multiplexing (BPSK-WOFDM) modulation is a promising solution for future high data-rate and energy-efficient WSNs. PMID:23760087

  17. The 2010 ILSO-ISRU Field Test at Mauna Kea, Hawaii: Results from the Miniaturised Mossbauer Spectrometers Mimos II and Mimos IIA

    NASA Technical Reports Server (NTRS)

    Klingelhoefer, G.; Morris, R. V.; Blumers, M.; Bernhardt, B.; Graff, T.

    2011-01-01

    For the advanced Moessbauer instrument MIMOS IIA, the new detector technologies and electronic components increase sensitivity and performance significantly. In combination with the high energy resolution of the SDD it is possible to perform X-ray fluorescence analysis simultaneously to Moessbauer spectroscopy. In addition to the Fe-mineralogy, information on the sample's elemental composition will be gathered. The ISRU 2010 field campaign demonstrated that in-situ Moessbauer spectroscopy is an effective tool for both science and feedstock exploration and process monitoring. Engineering tests showed that a compact nickel metal hydride battery provided sufficient power for over 12 hr of continuous operation for the MIMOS instruments.

  18. Channel Modelling and Characterization of Mobile Satellite Communication Systems

    NASA Astrophysics Data System (ADS)

    Mohammed, Abbas; Seun, Ajayi; Yang, Zhe; Erman, Maria; Hult, Tommy

    2009-03-01

    Reliable characterization of the propagation environment and channel modelling of mobile satellite communication systems is necessary in order to provide better quality of service and efficient design of these systems. In this paper, the channel impairments affecting the performance and an overview of the satellite channel models are presented. The statistical distributions of the received signal that can be used to characterize the dynamic nature of these propagation channels are also presented. The main modelling parameters are investigated and simulation results show that the bit error rate (BER) performance is predominantly affected by the shadowing factor. Finally, in order to further test the channel models and the effect of the propagation environment, we investigate a novel application of using satellite diversity in conjunction with compact MIMO (multiple-input multiple-output) antenna array configurations in order to enhance the capacity of satellite communication links.

  19. Antiwindup analysis and design approaches for MIMO systems

    NASA Technical Reports Server (NTRS)

    Marcopoli, Vincent R.; Phillips, Stephen M.

    1994-01-01

    Performance degradation of multiple-input multiple-output (MIMO) control systems having limited actuators is often handled by augmenting the controller with an antiwindup mechanism, which attempts to maintain system performance when limits are encountered. The goals of this paper are: (1) To develop a method to analyze antiwindup systems to determine precisely what stability and performance degradation is incurred under limited conditions. It is shown that by reformulating limited actuator commands as resulting from multiplicative perturbations to the corresponding controller requests, mu-analysis tools can be utilized to obtain quantitative measures of stability and performance degradation. (2) To propose a linear, time invariant (LTI) criterion on which to base the antiwindup design. These analysis and design methods are illustrated through the evaluation of two competing antiwindup schemes augmenting the controller of a Short Take-Off and Vertical Landing (STOVL) aircraft in transition flight.

  20. Antiwindup analysis and design approaches for MIMO systems

    NASA Technical Reports Server (NTRS)

    Marcopoli, Vincent R.; Phillips, Stephen M.

    1993-01-01

    Performance degradation of multiple-input multiple-output (MIMO) control systems having limited actuators is often handled by augmenting the controller with an antiwindup mechanism, which attempts to maintain system performance when limits are encountered. The goals of this paper are: 1) to develop a method to analyze antiwindup systems to determine precisely what stability and performance degradation is incurred under limited conditions. It is shown that by reformulating limited actuator commands as resulting from multiplicative perturbations to the corresponding controller requests, mu-analysis tools can be utilized to obtain quantitative measures of stability and performance degradation. 2) To propose a linear, time invariant (LTI) criterion on which to base the antiwindup design. These analysis and design methods are illustrated through the evaluation of two competing antiwindup schemes augmenting the controller of a Short Take-Off and Vertical Landing (STOVL) aircraft in transition flight.

  1. Feedback linearizing control of a MIMO power system

    NASA Astrophysics Data System (ADS)

    Ilyes, Laszlo

    Prior research has demonstrated that either the mechanical or electrical subsystem of a synchronous electric generator may be controlled using single-input single-output (SISO) nonlinear feedback linearization. This research suggests a new approach which applies nonlinear feedback linearization to a multi-input multi-output (MIMO) model of the synchronous electric generator connected to an infinite bus load model. In this way, the electrical and mechanical subsystems may be linearized and simultaneously decoupled through the introduction of a pair of auxiliary inputs. This allows well known, linear, SISO control methods to be effectively applied to the resulting systems. The derivation of the feedback linearizing control law is presented in detail, including a discussion on the use of symbolic math processing as a development tool. The linearizing and decoupling properties of the control law are validated through simulation. And finally, the robustness of the control law is demonstrated.

  2. Antiwindup analysis and design approaches for MIMO systems

    NASA Technical Reports Server (NTRS)

    Marcopoli, Vincent R.; Phillips, Stephen M.

    1993-01-01

    Performance degradation of multiple-input multiple-output (MIMO) control systems having limited actuators is often handled by augmenting the controller with an antiwindup mechanism, which attempts to maintain system performance when limits are encountered. The goals of this paper are: 1) to develop a method to analyze antiwindup systems to determine precisely what stability and performance degradation is incurred under limited conditions. It is shown that by reformulating limited actuator commands as resulting from multiplicative perturbations to the corresponding controller requests, mu-analysis tools can be utilized to obtain quantitative measures of stability and performance degradation. 2) To propose a linear, time invariant (LTI) criterion on which to base the antiwindup design. These analysis and design methods are illustrated through the evaluation of two competing antiwindup schemes augmenting the controller of a Short Take-Off and Vertical Landing (STOVL) aircraft in transition flight.

  3. Inflammatory cytokine signaling in insulin producing beta-cells enhances the colocalization correlation coefficient between L-type voltage-dependent calcium channel and calcium-sensing receptor.

    PubMed

    Parkash, Jai

    2008-08-01

    The immunological processes in type 1 diabetes and metabolic/inflammatory disorder in type 2 diabetes converge on common signaling pathway(s) leading to beta-cell death in these two diseases. The cytokine-mediated beta-cell death seems to be dependent on voltage-dependent calcium channel (VDCC)-mediated Ca2+ entry. The Ca2+ handling molecular networks control the homeostasis of [Ca2+]i in the beta-cell. The activity and membrane density of VDCC are regulated by several mechanisms including G protein-coupled receptors (GPCRs). CaR is a 123-kDa seven transmembrane extracellular Ca2+ sensing protein that belongs to GPCR family C. Tumor necrosis factor-alpha (TNF-alpha), is a cytokine widely known to activate nuclear factor-kappaB (NF-kappaB) transcription in beta-cells. To obtain a better understanding of TNF-alpha-induced molecular interactions between CaR and VDCC, confocal fluorescence measurements were performed on insulin-producing beta-cells exposed to varying concentrations of TNF-alpha and the results are discussed in the light of increased colocalization correlation coefficient. The insulin producing beta-cells were exposed to 5, 10, 20, 30, and 50 ng/ml TNF-alpha for 24 h at 37 degrees . The cells were then immunolabelled with antibodies directed against CaR, VDCC, and NF-kappaB. The confocal fluorescence imaging data showed enhancement in the colocalization correlation coefficient between CaR and VDCC in beta-cells exposed to TNF-alpha thereby indicating increased membrane delimited spatial interactions between these two membrane proteins. TNF-alpha-induced colocalization of VDCC with CaR was inhibited by nimodipine, an inhibitor of L-type VDCC thereby suggesting that VDCC activity is required for spatial interactions with CaR. The 3-D confocal fluorescence imaging data also demonstrated that addition of TNF-alpha to RIN cells led to the translocation of NF-kappaB from the cytoplasm to the nucleus. Such molecular interactions between CaR and VDCC in tissues

  4. SIRE: a MIMO radar for landmine/IED detection

    NASA Astrophysics Data System (ADS)

    Ojowu, Ode; Wu, Yue; Li, Jian; Nguyen, Lam

    2013-05-01

    Multiple-input multiple-output (MIMO) radar systems have been shown to have significant performance improvements over their single-input multiple-output (SIMO) counterparts. For transmit and receive elements that are collocated, the waveform diversity afforded by this radar is exploited for performance improvements. These improvements include but are not limited to improved target detection, improved parameter identifiability and better resolvability. In this paper, we present the Synchronous Impulse Reconstruction Radar (SIRE) Ultra-wideband (UWB) radar designed by the Army Research Lab (ARL) for landmine and improvised explosive device (IED) detection as a 2 by 16 MIMO radar (with collocated antennas). Its improvement over its SIMO counterpart in terms of beampattern/cross range resolution are discussed and demonstrated using simulated data herein. The limitations of this radar for Radio Frequency Interference (RFI) suppression are also discussed in this paper. A relaxation method (RELAX) combined with averaging of multiple realizations of the measured data is presented for RFI suppression; results show no noticeable target signature distortion after suppression. In this paper, the back-projection (delay and sum) data independent method is used for generating SAR images. A side-lobe minimization technique called recursive side-lobe minimization (RSM) is also discussed for reducing side-lobes in this data independent approach. We introduce a data-dependent sparsity based spectral estimation technique called Sparse Learning via Iterative Minimization (SLIM) as well as a data-dependent CLEAN approach for generating SAR images for the SIRE radar. These data-adaptive techniques show improvement in side-lobe reduction and resolution for simulated data for the SIRE radar.

  5. MIMO B-MAC Interference Network Optimization Under Rate Constraints by Polite Water-Filling and Duality

    NASA Astrophysics Data System (ADS)

    Liu, An; Liu, Youjian; Xiang, Haige; Luo, Wu

    2011-01-01

    We take two new approaches to design efficient algorithms for transmitter optimization under rate constraints, to guarantee the Quality of Service in general MIMO interference networks, which is a combination of multiple interfering broadcast channels (BC) and multiaccess channels (MAC) and is named B-MAC Networks. Two related optimization problems, maximizing the minimum of weighted rates under a sum-power constraint and minimizing the sum-power under rate constraints, are considered. The first approach takes advantage of existing efficient algorithms for SINR problems by building a bridge between rate and SINR through the design of optimal mappings between them. The approach can be applied to other optimization problems as well. The second approach employs polite water-filling, which is the optimal network version of water-filling that we recently found. It replaces most generic optimization algorithms currently used for networks and reduces the complexity while demonstrating superior performance even in non-convex cases. Both centralized and distributed algorithms are designed and the performance is analyzed in addition to numeric examples.

  6. Correlation between a 2D Channelized Hotelling Observer and Human Observers in a Low-contrast Detection Task with Multi-slice Reading in CT

    PubMed Central

    Yu, Lifeng; Chen, Baiyu; Kofler, James M.; Favazza, Christopher P.; Leng, Shuai; Kupinski, Matthew A.; McCollough, Cynthia H.

    2017-01-01

    Purpose Model observers have been successfully developed and used to assess the quality of static 2D CT images. However, radiologists typically read images by paging through multiple 2D slices (i.e. multi-slice reading). The purpose of this study was to correlate human and model observer performance in a low-contrast detection task performed using both 2D and multi-slice reading, and to determine if the 2D model observer still correlate well with human observer performance in multi-slice reading. Methods A phantom containing 18 low-contrast spheres (6 sizes × 3 contrast levels) was scanned on a 192-slice CT scanner at 5 dose levels (CTDIvol = 27, 13.5, 6.8, 3.4, and 1.7 mGy), each repeated 100 times. Images were reconstructed using both filtered-backprojection (FBP) and an iterative reconstruction (IR) method (ADMIRE, Siemens). A 3D volume of interest (VOI) around each sphere was extracted and placed side-by-side with a signal-absent VOI to create a 2-alternative forced choice (2AFC) trial. Sixteen 2AFC studies were generated, each with 100 trials, to evaluate the impact of radiation dose, lesion size and contrast, and reconstruction methods on object detection. In total, 1600 trials were presented to both model and human observers. Three medical physicists acted as human observers and were allowed to page through the 3D volumes to make a decision for each 2AFC trial. The human observer performance was compared with the performance of a multi-slice channelized Hotelling observer (CHO_MS), which integrates multi-slice image data, and with the performance of previously validated CHO, which operates on static 2D images (CHO_2D). For comparison, the same 16 2AFC studies were also performed in a 2D viewing mode by the human observers and compared with the multi-slice viewing performance and the two CHO models. Results Human observer performance was well correlated with the CHO_2D performance in the 2D viewing mode (Pearson product-moment correlation coefficient R=0

  7. MIMO capacities and outage probabilities in spatially multiplexed optical transport systems.

    PubMed

    Winzer, Peter J; Foschini, Gerard J

    2011-08-15

    With wavelength-division multiplexing (WDM) rapidly nearing its scalability limits, space-division multiplexing (SDM) seems the only option to further scale the capacity of optical transport networks. In order for SDM systems to continue the WDM trend of reducing energy and cost per bit with system capacity, integration will be key to SDM. Since integration is likely to introduce non-negligible crosstalk between multiple parallel transmission paths, multiple-input multiple output (MIMO) signal processing techniques will have to be used. In this paper, we discuss MIMO capacities in optical SDM systems, including related outage considerations which are an important part in the design of such systems. In order to achieve the low-outage standards required for optical transport networks, SDM transponders should be capable of individually addressing, and preferably MIMO processing all modes supported by the optical SDM waveguide. We then discuss the effect of distributed optical noise in MIMO SDM systems and focus on the impact of mode-dependent loss (MDL) on system capacity and system outage. Through extensive numerical simulations, we extract scaling rules for mode-average and mode-dependent loss and show that MIMO SDM systems composed of up to 128 segments and supporting up to 128 modes can tolerate up to 1 dB of per-segment MDL at 90% of the system's full capacity at an outage probability of 10(-4). © 2011 Optical Society of America

  8. MimoDB: a new repository for mimotope data derived from phage display technology.

    PubMed

    Ru, Beibei; Huang, Jian; Dai, Ping; Li, Shiyong; Xia, Zhongkui; Ding, Hui; Lin, Hao; Guo, Fengbiao; Wang, Xianlong

    2010-11-15

    Peptides selected from phage-displayed random peptide libraries are valuable in two aspects. On one hand, these peptides are candidates for new diagnostics, therapeutics and vaccines. On the other hand, they can be used to predict the networks or sites of protein-protein interactions. MimoDB, a new repository for these peptides, was developed, in which 10,716 peptides collected from 571 publications were grouped into 1,229 sets. Besides peptide sequences, other important information, such as the target, template, library and complex structure, was also included. MimoDB can be browsed and searched through a user-friendly web interface. For computational biologists, MimoDB can be used to derive customized data sets and benchmarks, which are useful for new algorithm development and tool evaluation. For experimental biologists, their results can be searched against the MimoDB database to exclude possible target-unrelated peptides. The MimoDB database is freely accessible at http://immunet.cn/mimodb/.

  9. Channel characterization and empirical model for ergodic capacity of free-space optical communication link

    NASA Astrophysics Data System (ADS)

    Alimi, Isiaka; Shahpari, Ali; Ribeiro, Vítor; Sousa, Artur; Monteiro, Paulo; Teixeira, António

    2017-05-01

    In this paper, we present experimental results on channel characterization of single input single output (SISO) free-space optical (FSO) communication link that is based on channel measurements. The histograms of the FSO channel samples and the log-normal distribution fittings are presented along with the measured scintillation index. Furthermore, we extend our studies to diversity schemes and propose a closed-form expression for determining ergodic channel capacity of multiple input multiple output (MIMO) FSO communication systems over atmospheric turbulence fading channels. The proposed empirical model is based on SISO FSO channel characterization. Also, the scintillation effects on the system performance are analyzed and results for different turbulence conditions are presented. Moreover, we observed that the histograms of the FSO channel samples that we collected from a 1548.51 nm link have good fits with log-normal distributions and the proposed model for MIMO FSO channel capacity is in conformity with the simulation results in terms of normalized mean-square error (NMSE).

  10. Neural network L1 adaptive control of MIMO systems with nonlinear uncertainty.

    PubMed

    Zhen, Hong-tao; Qi, Xiao-hui; Li, Jie; Tian, Qing-min

    2014-01-01

    An indirect adaptive controller is developed for a class of multiple-input multiple-output (MIMO) nonlinear systems with unknown uncertainties. This control system is comprised of an L 1 adaptive controller and an auxiliary neural network (NN) compensation controller. The L 1 adaptive controller has guaranteed transient response in addition to stable tracking. In this architecture, a low-pass filter is adopted to guarantee fast adaptive rate without generating high-frequency oscillations in control signals. The auxiliary compensation controller is designed to approximate the unknown nonlinear functions by MIMO RBF neural networks to suppress the influence of uncertainties. NN weights are tuned on-line with no prior training and the project operator ensures the weights bounded. The global stability of the closed-system is derived based on the Lyapunov function. Numerical simulations of an MIMO system coupled with nonlinear uncertainties are used to illustrate the practical potential of our theoretical results.

  11. Development of characteristic equations and robust stability analysis for MIMO move suppressed and shifted DMC.

    PubMed

    Dubay, R; Kember, G; Lakshminarayan, C V; Pramujati, B

    2005-10-01

    Discrete-time controller and closed-loop transfer functions were developed for move suppressed lambda and the recently formulated m-shifted multiple-input-multiple-output (MIMO) dynamic matrix control (DMC). Using these transfer functions, robust analyses were conducted for MIMO plants by varying corresponding delay and gain ratios of the system. In all instances, robust plots indicate that the shifted DMC is less sensitive and hence more robust to variations in the plant parameters than move suppressed DMC. It was shown that the design of these MIMO DMC controllers depends on the plant closed-loop performance and overall stability, since the selection of lambda and m directly influences the plant robustness and closed-loop dynamics.

  12. Performance evaluation of space-time-frequency spreading for MIMO OFDM-CDMA systems

    NASA Astrophysics Data System (ADS)

    Dahman, Haysam; Shayan, Yousef

    2011-12-01

    In this article, we propose a multiple-input-multiple-output, orthogonal frequency division multiplexing, code-division multiple-access (MIMO OFDM-CDMA) scheme. The main objective is to provide extra flexibility in user multiplexing and data rate adaptation, that offer higher system throughput and better diversity gains. This is done by spreading on all the signal domains; i.e, space-time frequency spreading is employed to transmit users' signals. The flexibility to spread on all three domains allows us to independently spread users' data, to maintain increased system throughput and to have higher diversity gains. We derive new accurate approximations for the probability of symbol error and signal-to-interference noise ratio (SINR) for zero forcing (ZF) receiver. This study and simulation results show that MIMO OFDM-CDMA is capable of achieving diversity gains significantly larger than that of the conventional 2-D CDMA OFDM and MIMO MC CDMA schemes.

  13. Output feedback control of a class of discrete MIMO nonlinear systems with triangular form inputs.

    PubMed

    Zhang, Jin; Ge, Shuzhi Sam; Lee, Tong Heng

    2005-11-01

    In this paper, adaptive neural network (NN) control is investigated for a class of discrete-time multi-input-multi-output (MIMO) nonlinear systems with triangular form inputs. Each subsystem of the MIMO system is in strict feedback form. First, through two phases of coordinate transformation, the MIMO system is transformed into input-output representation with the triangular form input structure unchanged. By using high-order neural networks (HONNs) as the emulators of the desired controls, effective output feedback adaptive control is developed using backstepping. The closed-loop system is proved to be semiglobally uniformly ultimate bounded (SGUUB) by using Lyapunov method. The output tracking errors are guaranteed to converge into a compact set whose size is adjustable, and all the other signals in the closed-loop system are proved to be bounded. Simulation results show the effectiveness of the proposed control scheme.

  14. Dynamic Quantizer Design for MIMO Systems Based on Communication Rate Constraint

    NASA Astrophysics Data System (ADS)

    Okajima, Hiroshi; Sawada, Kenji; Matsunaga, Nobutomo; Minami, Yuki

    This paper proposes a design method of dynamic quantizers for MIMO networked control systems. It is well known that feedback type dynamic quantizers are effective for quantization of the data series in the meaning of noise shaping. The dynamic quantizers include a set of a dynamic filter and a static quantizer. When it is required to use the quantizer under the network communication, the data size of signal should be minimized appropriately by the quantizers. The authors have proposed a design method of the dynamic quantizers for SISO systems based on the communication rate constraint. In this paper, the design method is extended to MIMO systems. By this extension, we can handle the communication rate constraint for a kind of concentrated systems. In the setting of the quantizer for MIMO system, bit assignment is important matter for appropriate design of information flow. The effectiveness of proposed design method is shown by numerical examples.

  15. Neural Network L 1 Adaptive Control of MIMO Systems with Nonlinear Uncertainty

    PubMed Central

    Zhen, Hong-tao; Qi, Xiao-hui; Li, Jie; Tian, Qing-min

    2014-01-01

    An indirect adaptive controller is developed for a class of multiple-input multiple-output (MIMO) nonlinear systems with unknown uncertainties. This control system is comprised of an L 1 adaptive controller and an auxiliary neural network (NN) compensation controller. The L 1 adaptive controller has guaranteed transient response in addition to stable tracking. In this architecture, a low-pass filter is adopted to guarantee fast adaptive rate without generating high-frequency oscillations in control signals. The auxiliary compensation controller is designed to approximate the unknown nonlinear functions by MIMO RBF neural networks to suppress the influence of uncertainties. NN weights are tuned on-line with no prior training and the project operator ensures the weights bounded. The global stability of the closed-system is derived based on the Lyapunov function. Numerical simulations of an MIMO system coupled with nonlinear uncertainties are used to illustrate the practical potential of our theoretical results. PMID:25147871

  16. RF Lens-Embedded Massive MIMO Systems: Fabrication Issues and Codebook Design

    NASA Astrophysics Data System (ADS)

    Kwon, Taehoon; Lim, Yeon-Geun; Min, Byung-Wook; Chae, Chan-Byoung

    2016-07-01

    In this paper, we investigate a radio frequency (RF) lens-embedded massive multiple-input multiple-output (MIMO) system and evaluate the system performance of limited feedback by utilizing a technique for generating a suitable codebook for the system. We fabricate an RF lens that operates on a 77 GHz (mmWave) band. Experimental results show a proper value of amplitude gain and an appropriate focusing property. In addition, using a simple numerical technique--beam propagation method (BPM)--we estimate the power profile of the RF lens and verify its accordance with experimental results. We also design a codebook--multi-variance codebook quantization (MVCQ)--for limited feedback by considering the characteristics of the RF lens antenna for massive MIMO systems. Numerical results confirm that the proposed system shows significant performance enhancement over a conventional massive MIMO system without an RF lens.

  17. Trade-Offs in a 1 Tbps Multiple-Input and Multiple-Output (MIMO) Communication System Between an Airship and Ground Receive Antennas

    DTIC Science & Technology

    2012-03-01

    covariance PT T Ir, where R is the number of receive antennas. The capacity is given by B × log2 ∣ ∣Ir + PT T HHH ∣ ∣. From his theorem, Telatar stated that...Applying Telatar’s theorem to 2.9, the capacity for a MIMO system can be rewritten as C = B log2 ∣ ∣ ∣ ∣ I+ PT T HHH ∣ ∣ ∣ ∣ , (2.13) where I is the identity...as a MMSE equalizer and is modeled as H† = ( HHH + σ2 n I)−1HH, (2.39) where H is the channel gain matrix, σ2n is the SNR per transmit antenna, x H

  18. An approach to design controllers for MIMO fractional-order plants based on parameter optimization algorithm.

    PubMed

    Xue, Dingyü; Li, Tingxue

    2017-04-27

    The parameter optimization method for multivariable systems is extended to the controller design problems for multiple input multiple output (MIMO) square fractional-order plants. The algorithm can be applied to search for the optimal parameters of integer-order controllers for fractional-order plants with or without time delays. Two examples are given to present the controller design procedures for MIMO fractional-order systems. Simulation studies show that the integer-order controllers designed are robust to plant gain variations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  19. A Desired PAR-Achieving Precoder Design for Multiuser MIMO OFDM Based on Concentration of Measure

    NASA Astrophysics Data System (ADS)

    Cha, Hyun-Su; Kim, Dong Ku

    2017-03-01

    For multi-user multiple-input and multiple-output (MIMO) wireless communications in orthogonal frequency di- vision multiplexing systems, we propose a MIMO precoding scheme providing a desired peak-to-average power ratio (PAR) at the minimum cost that is defined as received SNR degradation. By taking advantage of the concentration of measure, we formulate a convex problem with constraint on the desired PAR. Consequently, the proposed scheme almost exactly achieves the desired PAR on average, and asymptotically attains the desired PAR at the 0.001 point of its complementary cumulative distribution function, as the number of subcarriers increases.

  20. Ion channel mechanisms related to sudden cardiac death in phenotype-negative long-QT syndrome genotype-phenotype correlations of the KCNQ1(S349W) mutation.

    PubMed

    Horr, Samuel; Goldenberg, Ilan; Moss, Arthur J; O-Uchi, Jin; Barsheshet, Alon; Connelly, Heather; Gray, Daniel A; Zareba, Wojciech; Lopes, Coeli M B

    2011-02-01

      Data regarding possible ion channel mechanisms that predispose to ventricular tachyarrhythmias in patients with phenotype-negative long-QT syndrome (LQTS) are limited. We carried out cellular expression studies for the S349W mutation in the KCNQ1 channel, which was identified in 15 patients from the International LQTS Registry who experienced a high rate of cardiac events despite lack of significant QTc prolongation. The clinical outcome of S349W mutation carriers was compared with that of QTc-matched carriers of haploinsufficient missense (n = 30) and nonsense (n = 45) KCNQ1 mutations. The channels containing the mutant S349W subunit showed a mild reduction in current (<50%), in the haploinsuficient range, with an increase in maximal conductance compared with wild-type channels. In contrast, expression of the S349W mutant subunit produced a pronounced effect on both the voltage dependence of activation and the time constant of activation, while haploinsuficient channels showed no effect on either parameter. The cumulative probability of cardiac events from birth through age 20 years was significantly higher among S349W mutation carriers (58%) as compared with carriers of QTc-matched haploinsufficent missense (21%, P = 0.004) and nonsense (25%, P = 0.01) mutations. The S349W mutation in the KCNQ1 potassium channel exerts a relatively mild effect on the ion channel current, whereas an increase in conductance compensates for impaired voltage activation of the channel. The changes observed in voltage activation of the channel may underlie the mechanisms predisposing to arrhythmic risk among LQTS patients with a normal-range QTc. © 2010 Wiley Periodicals, Inc.

  1. Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System

    PubMed Central

    Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

    2016-01-01

    This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks. PMID:27472338

  2. Detection of Multiple Stationary Humans Using UWB MIMO Radar

    PubMed Central

    Liang, Fulai; Qi, Fugui; An, Qiang; Lv, Hao; Chen, Fuming; Li, Zhao; Wang, Jianqi

    2016-01-01

    Remarkable progress has been achieved in the detection of single stationary human. However, restricted by the mutual interference of multiple humans (e.g., strong sidelobes of the torsos and the shadow effect), detection and localization of the multiple stationary humans remains a huge challenge. In this paper, ultra-wideband (UWB) multiple-input and multiple-output (MIMO) radar is exploited to improve the detection performance of multiple stationary humans for its multiple sight angles and high-resolution two-dimensional imaging capacity. A signal model of the vital sign considering both bi-static angles and attitude angle of the human body is firstly developed, and then a novel detection method is proposed to detect and localize multiple stationary humans. In this method, preprocessing is firstly implemented to improve the signal-to-noise ratio (SNR) of the vital signs, and then a vital-sign-enhanced imaging algorithm is presented to suppress the environmental clutters and mutual affection of multiple humans. Finally, an automatic detection algorithm including constant false alarm rate (CFAR), morphological filtering and clustering is implemented to improve the detection performance of weak human targets affected by heavy clutters and shadow effect. The simulation and experimental results show that the proposed method can get a high-quality image of multiple humans and we can use it to discriminate and localize multiple adjacent human targets behind brick walls. PMID:27854356

  3. Smart panels with SISO or MIMO velocity feedback control systems

    NASA Astrophysics Data System (ADS)

    Gardonio, Paolo; Elliott, Stephen

    2003-10-01

    This paper summarizes and contrasts the research work that has been carried out on two types of smart panels with ASAC control systems: first, a SISO velocity feedback control system with a sensor that detects the volumetric component of the vibration of the panel and an actuator that exerts a uniform force over the surface of the panel and, second, a MIMO decentralized feedback control system using a grid of sensors that measure the point velocities of the panel and a grid of actuators that generates point excitations in the locations of the sensors. Both theoretical predictions and experimental results are presented for a reference problem of control of sound radiation by a rectangular panel clamped along the perimeter. The simulations carried out for the two systems have shown that the smart panel with the volume velocity sensor and uniform force actuator can in principle give better control performance than the smart panel with the sixteen decentralized control units. However, the practical implementation of the smart panel with the volume velocity sensor and uniform force actuator is limited by stability problems which are instead a minor issue for the panel with 16 decentralized velocity feedback control units.

  4. Robust Decentralized Nonlinear Control for a Twin Rotor MIMO System.

    PubMed

    Belmonte, Lidia María; Morales, Rafael; Fernández-Caballero, Antonio; Somolinos, José Andrés

    2016-07-27

    This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks.

  5. Multi-static MIMO along track interferometry (ATI)

    NASA Astrophysics Data System (ADS)

    Knight, Chad; Deming, Ross; Gunther, Jake

    2016-05-01

    Along-track interferometry (ATI) has the ability to generate high-quality synthetic aperture radar (SAR) images and concurrently detect and estimate the positions of ground moving target indicators (GMTI) with moderate processing requirements. This paper focuses on several different ATI system configurations, with an emphasis on low-cost configurations employing no active electronic scanned array (AESA). The objective system has two transmit phase centers and four receive phase centers and supports agile adaptive radar behavior. The advantages of multistatic, multiple input multiple output (MIMO) ATI system configurations are explored. The two transmit phase centers can employ a ping-pong configuration to provide the multistatic behavior. For example, they can toggle between an up and down linear frequency modulated (LFM) waveform every other pulse. The four receive apertures are considered in simple linear spatial configurations. Simulated examples are examined to understand the trade space and verify the expected results. Finally, actual results are collected with the Space Dynamics Laboratorys (SDL) FlexSAR system in diverse configurations. The theory, as well as the simulated and actual SAR results, are presented and discussed.

  6. Design and implementation of SMO for a nonlinear MIMO AHRS

    NASA Astrophysics Data System (ADS)

    Doostdar, Parisa; Keighobadi, Jafar

    2012-10-01

    In a low-cost attitude heading reference system (AHRS), the measurements made by MEMS inertial and magnetic sensors are affected by large parameter uncertainties, stochastic noises and unknown disturbances. In this paper, considering the robustness of the sliding mode observers (SMO) against both structured and unstructured uncertainties as well as exogenous inputs, the process of design and implementation of a nonlinear SMO is proposed for a low-cost AHRS. For simultaneous estimation of orientation variables and calibration biases of gyroscopes, a nonlinear and non-affine model of the AHRS is considered. Therefore, based on the Lie-algebraic method, the estimation algorithm is designed for a general class of non-affine nonlinear MIMO systems. In the proposed observer, owing to decreasing the required assumptions for coordinate transformation in recent literatures, the design process of the SMO is simplified. The gain matrices of the proposed SMO are obtained through ensuring the stability and the convergence of estimation errors based on Lyapunov's direct method. The expected tracking performance of the robust state and parameter estimation algorithm compared to that of the extended Kalman filter (EKF) is evaluated through simulations and real experiments of a strapped AHRS on a ground vehicle.

  7. MIMO-OFDM for a Cellular Deployment - Concepts, Real-Time Implementation and Measurements Towards 3GPP-LTE

    DTIC Science & Technology

    2007-09-01

    Figure 1: Functional blocks of the down-link base band chain. Left: Transmitter at BS; Right: Receiver at one UE MIMO -OFDM FOR A CELLULAR DEPLOYMENT...ABSTRACT In this paper we report on the system design and a real- time implementation of a MIMO -OFDM radio transmission system close to physical layer...transmission with a single user set-up occupying 20 MHz bandwidth and achieving more than 150 Mbit/s gross data rate in the 2x2 MIMO down-link and more

  8. Low complexity MIMO method based on matrix transformation for few-mode multi-core optical transmission system

    NASA Astrophysics Data System (ADS)

    Pan, Xiaolong; Liu, Bo; Li, Li; Tian, Qinghua

    2016-07-01

    This paper proposes and demonstrates a low complexity multiple-input multiple-output (MIMO) equalization digital signal processing (DSP) method for the few mode multi-core (FMMC) fiber optical transmission system. The MIMO equalization algorithm offers adaptive equalization taps according to the degree of crosstalk in cores or modes, which eliminates the interference among different modes and cores in space division multiplexing (SDM) transmission system. Compared with traditional MIMO method, the proposed scheme has increased the convergence rate by 4 times and reduced the number of finite impulse response (FIR) filters by 55% when the numbers of mode and core are three.

  9. Target parameter estimation for spatial and temporal formulations in MIMO radars using compressive sensing

    NASA Astrophysics Data System (ADS)

    Ali, Hussain; Ahmed, Sajid; Al-Naffouri, Tareq Y.; Sharawi, Mohammad S.; Alouini, Mohamed-S.

    2017-01-01

    Conventional algorithms used for parameter estimation in colocated multiple-input-multiple-output (MIMO) radars require the inversion of the covariance matrix of the received spatial samples. In these algorithms, the number of received snapshots should be at least equal to the size of the covariance matrix. For large size MIMO antenna arrays, the inversion of the covariance matrix becomes computationally very expensive. Compressive sensing (CS) algorithms which do not require the inversion of the complete covariance matrix can be used for parameter estimation with fewer number of received snapshots. In this work, it is shown that the spatial formulation is best suitable for large MIMO arrays when CS algorithms are used. A temporal formulation is proposed which fits the CS algorithms framework, especially for small size MIMO arrays. A recently proposed low-complexity CS algorithm named support agnostic Bayesian matching pursuit (SABMP) is used to estimate target parameters for both spatial and temporal formulations for the unknown number of targets. The simulation results show the advantage of SABMP algorithm utilizing low number of snapshots and better parameter estimation for both small and large number of antenna elements. Moreover, it is shown by simulations that SABMP is more effective than other existing algorithms at high signal-to-noise ratio.

  10. Quantum inspired PSO for the optimization of simultaneous recurrent neural networks as MIMO learning systems.

    PubMed

    Luitel, Bipul; Venayagamoorthy, Ganesh Kumar

    2010-06-01

    Training a single simultaneous recurrent neural network (SRN) to learn all outputs of a multiple-input-multiple-output (MIMO) system is a difficult problem. A new training algorithm developed from combined concepts of swarm intelligence and quantum principles is presented. The training algorithm is called particle swarm optimization with quantum infusion (PSO-QI). To improve the effectiveness of learning, a two-step learning approach is introduced in the training. The objective of the learning in the first step is to find the optimal set of weights in the SRN considering all output errors. In the second step, the objective is to maximize the learning of each output dynamics by fine tuning the respective SRN output weights. To demonstrate the effectiveness of the PSO-QI training algorithm and the two-step learning approach, two examples of an SRN learning MIMO systems are presented. The first example is learning a benchmark MIMO system and the second one is the design of a wide area monitoring system for a multimachine power system. From the results, it is observed that SRNs can effectively learn MIMO systems when trained using the PSO-QI algorithm and the two-step learning approach. Copyright 2009 Elsevier Ltd. All rights reserved.

  11. A Unitary ESPRIT Scheme of Joint Angle Estimation for MOTS MIMO Radar

    PubMed Central

    Wen, Chao; Shi, Guangming

    2014-01-01

    The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme. PMID:25106023

  12. Quantification of MDL-induced signal degradation in MIMO-OFDM mode-division multiplexing systems.

    PubMed

    Tian, Yu; Li, Juhao; Zhu, Paikun; Wu, Zhongying; Chen, Yuanxiang; He, Yongqi; Chen, Zhangyuan

    2016-08-22

    Mode-division multiplexing (MDM) transmission over few-mode optical fiber has emerged as a promising technology to enhance transmission capacity, in which multiple-input-multiple-output (MIMO) digital signal processing (DSP) after coherent detection is used to demultiplex the signals. Compared with conventional single-mode systems, MIMO-MDM systems suffer non-recoverable signal degradation induced by mode-dependent loss (MDL). In this paper, the MDL-induced signal degradation in orthogonal-frequency-division-multiplexing (OFDM) MDM systems is theoretically quantified in terms of mode-average error vector magnitude (EVM) through frequency domain norm analysis. A novel scalar MDL metric is proposed considering the probability distribution of the practical MDM input signals, and a closed-form expression for EVM measured after zero-force (ZF) MIMO equalization is derived. Simulation results show that the EVM estimations utilizing the novel MDL metric remain unbiased for unrepeated links. For a 6 × 100 km 20-mode MDM transmission system, the estimation accuracy is improved by more than 90% compared with that utilizing traditional condition number (CN) based MDL metric. The proposed MDL metric can be used to predict the MDL-induced SNR penalty in a theoretical manner, which will be beneficial for the design of practical MIMO-MDM systems.

  13. A robust and scalable neuromorphic communication system by combining synaptic time multiplexing and MIMO-OFDM.

    PubMed

    Srinivasa, Narayan; Zhang, Deying; Grigorian, Beayna

    2014-03-01

    This paper describes a novel architecture for enabling robust and efficient neuromorphic communication. The architecture combines two concepts: 1) synaptic time multiplexing (STM) that trades space for speed of processing to create an intragroup communication approach that is firing rate independent and offers more flexibility in connectivity than cross-bar architectures and 2) a wired multiple input multiple output (MIMO) communication with orthogonal frequency division multiplexing (OFDM) techniques to enable a robust and efficient intergroup communication for neuromorphic systems. The MIMO-OFDM concept for the proposed architecture was analyzed by simulating large-scale spiking neural network architecture. Analysis shows that the neuromorphic system with MIMO-OFDM exhibits robust and efficient communication while operating in real time with a high bit rate. Through combining STM with MIMO-OFDM techniques, the resulting system offers a flexible and scalable connectivity as well as a power and area efficient solution for the implementation of very large-scale spiking neural architectures in hardware.

  14. Cooperative MIMO communication at wireless sensor network: an error correcting code approach.

    PubMed

    Islam, Mohammad Rakibul; Han, Young Shin

    2011-01-01

    Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error p(b). It is observed that C-MIMO performs more efficiently when the targeted p(b) is smaller. Also the lower encoding rate for LDPC code offers better error characteristics.

  15. A unitary ESPRIT scheme of joint angle estimation for MOTS MIMO radar.

    PubMed

    Wen, Chao; Shi, Guangming

    2014-08-07

    The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme.

  16. Deep-subwavelength Decoupling for MIMO Antennas in Mobile Handsets with Singular Medium.

    PubMed

    Xu, Su; Zhang, Ming; Wen, Huailin; Wang, Jun

    2017-09-22

    Decreasing the mutual coupling between Multi-input Multi-output (MIMO) antenna elements in a mobile handset and achieving a high data rate is a challenging topic as the 5(th)-generation (5G) communication age is coming. Conventional decoupling components for MIMO antennas have to be re-designed when the geometries or frequencies of antennas have any adjustment. In this paper, we report a novel metamaterial-based decoupling strategy for MIMO antennas in mobile handsets with wide applicability. The decoupling component is made of subwavelength metal/air layers, which can be treated as singular medium over a broad frequency band. The flexible applicable property of the decoupling strategy is verified with different antennas over different frequency bands with the same metamaterial decoupling element. Finally, 1/100-wavelength 10-dB isolation is demonstrated for a 24-element MIMO antenna in mobile handsets over the frequency band from 4.55 to 4.75 GHz.

  17. Stretch-activated calcium channel protein TRPC1 is correlated with the different degrees of the dystrophic phenotype in mdx mice.

    PubMed

    Matsumura, Cíntia Yuri; Taniguti, Ana Paula Tiemi; Pertille, Adriana; Santo Neto, Humberto; Marques, Maria Julia

    2011-12-01

    In Duchenne muscular dystrophy (DMD) and in the mdx mouse model of DMD, the lack of dystrophin is related to enhanced calcium influx and muscle degeneration. Stretch-activated channels (SACs) might be directly involved in the pathology of DMD, and transient receptor potential cation channels have been proposed as likely candidates of SACs. We investigated the levels of transient receptor potential canonical channel 1 (TRPC1) and the effects of streptomycin, a SAC blocker, in muscles showing different degrees of the dystrophic phenotype. Mdx mice (18 days old, n = 16) received daily intraperitoneal injections of streptomycin (182 mg/kg body wt) for 18 days, followed by removal of the diaphragm, sternomastoid (STN), biceps brachii, and tibialis anterior muscles. Control mdx mice (n = 37) were injected with saline. Western blot analysis showed higher levels of TRPC1 in diaphragm muscle compared with STN and limb muscles. Streptomycin reduced creatine kinase and prevented exercise-induced increases of total calcium and Evans blue dye uptake in diaphragm and in STN muscles. It is suggested that different levels of the stretch-activated calcium channel protein TRPC1 may contribute to the different degrees of the dystrophic phenotype seen in mdx mice. Early treatment designed to regulate the activity of these channels may ameliorate the progression of dystrophy in the most affected muscle, the diaphragm.

  18. Adaptive neural network control for a class of MIMO nonlinear systems with disturbances in discrete-time.

    PubMed

    Ge, Shuzhi Sam; Zhang, Jin; Lee, Tong Heng

    2004-08-01

    In this paper, adaptive neural network (NN) control is investigated for a class of multiinput and multioutput (MIMO) nonlinear systems with unknown bounded disturbances in discrete-time domain. The MIMO system under study consists of several subsystems with each subsystem in strict feedback form. The inputs of the MIMO system are in triangular form. First, through a coordinate transformation, the MIMO system is transformed into a sequential decrease cascade form (SDCF). Then, by using high-order neural networks (HONN) as emulators of the desired controls, an effective neural network control scheme with adaptation laws is developed. Through embedded backstepping, stability of the closed-loop system is proved based on Lyapunov synthesis. The output tracking errors are guaranteed to converge to a residue whose size is adjustable. Simulation results show the effectiveness of the proposed control scheme.

  19. Experimental investigation of inter-core crosstalk tolerance of MIMO-OFDM/OQAM radio over multicore fiber system.

    PubMed

    He, Jiale; Li, Borui; Deng, Lei; Tang, Ming; Gan, Lin; Fu, Songnian; Shum, Perry Ping; Liu, Deming

    2016-06-13

    In this paper, the feasibility of space division multiplexing for optical wireless fronthaul systems is experimentally demonstrated by implementing high speed MIMO-OFDM/OQAM radio signals over 20km 7-core fiber and 0.4m wireless link. Moreover, the impact of optical inter-core crosstalk in multicore fibers on the proposed MIMO-OFDM/OQAM radio over fiber system is experimentally evaluated in both SISO and MIMO configurations for comparison. The experimental results show that the inter-core crosstalk tolerance of the proposed radio over fiber system can be relaxed to -10 dB by using the proposed MIMO-OFDM/OQAM processing. These results could guide high density multicore fiber design to support a large number of antenna modules and a higher density of radio-access points for potential applications in 5G cellular system.

  20. Is there a genetic correlation between the resistance of channel catfish to Edwardsiella ictaluri and Flavobacterium columnare, and how do we get there?

    USDA-ARS?s Scientific Manuscript database

    Two major problems in the channel catfish (Ictalurus punctatus) aquaculture industry have been high disease losses to enteric septicemia of catfish (ESC), caused by Edwardsiella ictaluri and columnaris disease, caused by Flavobacterium columnare. Methods to control and prevent these diseases includ...