Dynamically reconfigurable optical packet switch (DROPS)

NASA Astrophysics Data System (ADS)

Huang, Chi-Heng; Chou, Hsu-Feng; Bowers, John E.; Toudeh-Fallah, Farzam; Gyurek, Russ

2006-12-01

A novel Dynamically Reconfigurable Optical Packet Switch (DROPS) that combines both spectral and spatial switching capabilities is proposed and experimentally demonstrated for the first time. Compared with an Arrayed Waveguide Grating Router (AWGR), the added spatial switching capability provided by the microelectromechanical systems (MEMS) enables dynamically reconfigurable routing that is not possible with an AWGR alone. This methodology has several advantages over an AWGR including scalability, additional degrees of freedom in routing a packet from an ingress port to an egress port and more flexibility in path or line card recovery. The experimental demonstration implemented with 10-Gb/s packets shows that the added spatial switching does not degrade the bit-error-rate performance, indicating the promising potential of DROPS as a versatile and ultra-high capacity switch for optical packet-switched networks.

Flexible-rate optical packet generation/detection and label swapping for optical label switching networks

NASA Astrophysics Data System (ADS)

Wu, Zhongying; Li, Juhao; Tian, Yu; Ge, Dawei; Zhu, Paikun; Chen, Yuanxiang; Chen, Zhangyuan; He, Yongqi

2017-03-01

In recent years, optical label switching (OLS) gains lots of attentions due to its intrinsic advantages to implement protocol, bit-rate, granularity and data format transparency packet switching. In this paper, we propose a novel scheme to realize flexible-rate optical packet switching for OLS networks. At the transmitter node, flexible-rate packet is generated by parallel modulating different combinations of optical carriers generated from the optical multi-carrier generator (OMCG), among which the low-speed optical label occupies one carrier. At the switching node, label is extracted and re-generated in label processing unit (LPU). The payloads are switched based on routing information and new label is added after switching. At the receiver node, another OMCG serves as local oscillators (LOs) for optical payloads coherent detection. The proposed scheme offers good flexibility for dynamic optical packet switching by adjusting the payload bandwidth and could also effectively reduce the number of lasers, modulators and receivers for packet generation/detection. We present proof-of-concept demonstrations of flexible-rate packet generation/detection and label swapping in 12.5 GHz grid. The influence of crosstalk for cascaded label swapping is also investigated.

Optimal design of mixed-media packet-switching networks - Routing and capacity assignment

NASA Technical Reports Server (NTRS)

Huynh, D.; Kuo, F. F.; Kobayashi, H.

1977-01-01

This paper considers a mixed-media packet-switched computer communication network which consists of a low-delay terrestrial store-and-forward subnet combined with a low-cost high-bandwidth satellite subnet. We show how to route traffic via ground and/or satellite links by means of static, deterministic procedures and assign capacities to channels subject to a given linear cost such that the network average delay is minimized. Two operational schemes for this network model are investigated: one is a scheme in which the satellite channel is used as a slotted ALOHA channel; the other is a new multiaccess scheme we propose in which whenever a channel collision occurs, retransmission of the involved packets will route through ground links to their destinations. The performance of both schemes is evaluated and compared in terms of cost and average packet delay tradeoffs for some examples. The results offer guidelines for the design and optimal utilization of mixed-media networks.

Adaptive packet switch with an optical core (demonstrator)

NASA Astrophysics Data System (ADS)

Abdo, Ahmad; Bishtein, Vadim; Clark, Stewart A.; Dicorato, Pino; Lu, David T.; Paredes, Sofia A.; Taebi, Sareh; Hall, Trevor J.

2004-11-01

A three-stage opto-electronic packet switch architecture is described consisting of a reconfigurable optical centre stage surrounded by two electronic buffering stages partitioned into sectors to ease memory contention. A Flexible Bandwidth Provision (FBP) algorithm, implemented on a soft-core processor, is used to change the configuration of the input sectors and optical centre stage to set up internal paths that will provide variable bandwidth to serve the traffic. The switch is modeled by a bipartite graph built from a service matrix, which is a function of the arriving traffic. The bipartite graph is decomposed by solving an edge-colouring problem and the resulting permutations are used to configure the switch. Simulation results show that this architecture exhibits a dramatic reduction of complexity and increased potential for scalability, at the price of only a modest spatial speed-up k, 1

Advances in integrated photonic circuits for packet-switched interconnection

NASA Astrophysics Data System (ADS)

Williams, Kevin A.; Stabile, Ripalta

2014-03-01

Sustained increases in capacity and connectivity are needed to overcome congestion in a range of broadband communication network nodes. Packet routing and switching in the electronic domain are leading to unsustainable energy- and bandwidth-densities, motivating research into hybrid solutions: optical switching engines are introduced for massive-bandwidth data transport while the electronic domain is clocked at more modest GHz rates to manage routing. Commercially-deployed optical switching engines using MEMS technologies are unwieldy and too slow to reconfigure for future packet-based networking. Optoelectronic packet-compliant switch technologies have been demonstrated as laboratory prototypes, but they have so far mostly used discretely pigtailed components, which are impractical for control plane development and product assembly. Integrated photonics has long held the promise of reduced hardware complexity and may be the critical step towards packet-compliant optical switching engines. Recently a number of laboratories world-wide have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip. Our own work has focused on multi-input to multi-output switching matrices. Recently we have demonstrated 8×8×8λ space and wavelength selective switches using gated cyclic routers and 16×16 broadband switching chips using monolithic multi-stage networks. We now operate these advanced circuits with custom control planes implemented with FPGAs to explore real time packet routing in multi-wavelength, multi-port test-beds. We review our contributions in the context of state of the art photonic integrated circuit technology and packet optical switching hardware demonstrations.

Enhancing In-Flight Transoceanic Communications Using Swift-64 Packet Mode Service

NASA Technical Reports Server (NTRS)

Slywczak, Richard A.

2004-01-01

Current aeronautical communications can be divided into two segments. The first provides state of the art, packet switched technology to the cabin passengers so that they have access to e-mail and web services. The second provides basic circuit switch communication technology to the cockpit, which does not use bandwidth as efficiently as packet switching nor promotes resource sharing. This paper explores the research efforts currently being conducted by the NASA/Glenn Research Center (GRC) for transoceanic communications. The goal is to bring packet mode services to both the cabin and the cockpit of the aircraft and be able to attain benefits by sharing the data link with cabin services. First, this paper will outline the goals of the program and detail the benefits and issues related to this research. We will explain our current laboratory setup and show an architecture implemented in the testbed. Finally, we will present a work plan that will show the progression of research over the next year. This plan will describe a complete cycle from conceptual design and laboratory implementation to the final flight testing.

A multi-ring optical packet and circuit integrated network with optical buffering.

PubMed

Furukawa, Hideaki; Shinada, Satoshi; Miyazawa, Takaya; Harai, Hiroaki; Kawasaki, Wataru; Saito, Tatsuhiko; Matsunaga, Koji; Toyozumi, Tatuya; Wada, Naoya

2012-12-17

We newly developed a 3 × 3 integrated optical packet and circuit switch-node. Optical buffers and burst-mode erbium-doped fiber amplifiers with the gain flatness are installed in the 3 × 3 switch-node. The optical buffer can prevent packet collisions and decrease packet loss. We constructed a multi-ring optical packet and circuit integrated network testbed connecting two single-ring networks and a client network by the 3 × 3 switch-node. For the first time, we demonstrated 244 km fiber transmission and 5-node hopping of multiplexed 14-wavelength 10 Gbps optical paths and 100 Gbps optical packets encapsulating 10 Gigabit Ethernet frames on the testbed. Error-free (frame error rate < 1 × 10(-4)) operation was achieved with optical packets of various packet lengths. In addition, successful avoidance of packet collisions by optical buffers was confirmed.

Packet Switching Networks: An Introduction with Some Attention to Selected Vendors.

ERIC Educational Resources Information Center

Sanchez, James Joseph

The purpose of this paper is to provide an overview of the history, development, and services of the packet switching network services that currently exist in the United States. The character of packet switching, a computerized method of transmitting data, is used as the basis for tracing the development of the industry itself. Contending that the…

Packet-aware transport for video distribution [Invited

NASA Astrophysics Data System (ADS)

Aguirre-Torres, Luis; Rosenfeld, Gady; Bruckman, Leon; O'Connor, Mannix

2006-05-01

We describe a solution based on resilient packet rings (RPR) for the distribution of broadcast video and video-on-demand (VoD) content over a packet-aware transport network. The proposed solution is based on our experience in the design and deployment of nationwide Triple Play networks and relies on technologies such as RPR, multiprotocol label switching (MPLS), and virtual private LAN service (VPLS) to provide the most efficient solution in terms of utilization, scalability, and availability.

Next generation communications satellites: Multiple access and network studies

NASA Technical Reports Server (NTRS)

Stern, T. E.; Schwartz, M.; Meadows, H. E.; Ahmadi, H. K.; Gadre, J. G.; Gopal, I. S.; Matsmo, K.

1980-01-01

Following an overview of issues involved in the choice of promising system architectures for efficient communication with multiple small inexpensive Earth stations serving hetergeneous user populations, performance evaluation via analysis and simulation for six SS/TDMA (satellite-switched/time-division multiple access) system architectures is discussed. These configurations are chosen to exemplify the essential alternatives available in system design. Although the performance evaluation analyses are of fairly general applicability, whenever possible they are considered in the context of NASA's 30/20 GHz studies. Packet switched systems are considered, with the assumption that only a part of transponder capacit is devoted to packets, the integration of circuit and packet switched traffic being reserved for further study. Three types of station access are distinguished: fixed (FA), demand (DA), and random access (RA). Similarly, switching in the satellite can be assigned on a fixed (FS) or demand (DS) basis, or replaced by a buffered store-and-forward system (SF) onboard the satellite. Since not all access/switching combinations are practical, six systems are analyzed in detail: three FS SYSTEMS, FA/FS, DA/ES, RA/FS; one DS system, DA/DS; and two SF systems, FA/SF, DA/SF. Results are presented primarily in terms of delay-throughput characteristics.

Packet telemetry and packet telecommand - The new generation of spacecraft data handling techniques

NASA Technical Reports Server (NTRS)

Hooke, A. J.

1983-01-01

Because of rising costs and reduced reliability of spacecraft and ground network hardware and software customization, standardization Packet Telemetry and Packet Telecommand concepts are emerging as viable alternatives. Autonomous packets of data, within each concept, which are created within ground and space application processes through the use of formatting techniques, are switched end-to-end through the space data network to their destination application processes through the use of standard transfer protocols. This process may result in facilitating a high degree of automation and interoperability because of completely mission-independent-designed intermediate data networks. The adoption of an international guideline for future space telemetry formatting of the Packet Telemetry concept, and the advancement of the NASA-ESA Working Group's Packet Telecommand concept to a level of maturity parallel to the of Packet Telemetry are the goals of the Consultative Committee for Space Data Systems. Both the Packet Telemetry and Packet Telecommand concepts are reviewed.

Electronic-To-Optical-To-Electronic Packet-Data Conversion

NASA Technical Reports Server (NTRS)

Monacos, Steve

1996-01-01

Space-time multiplexer (STM) cell-based communication system designed to take advantage of both high throughput attainable in optical transmission links and flexibility and functionality of electronic processing, storage, and switching. Long packets segmented and transmitted optically by wavelength-division multiplexing. Performs optoelectronic and protocol conversion between electronic "store-and-forward" protocols and optical "hot-potato" protocols.

Lambda network having 2.sup.m-1 nodes in each of m stages with each node coupled to four other nodes for bidirectional routing of data packets between nodes

DOEpatents

Napolitano, Jr., Leonard M.

1995-01-01

The Lambda network is a single stage, packet-switched interprocessor communication network for a distributed memory, parallel processor computer. Its design arises from the desired network characteristics of minimizing mean and maximum packet transfer time, local routing, expandability, deadlock avoidance, and fault tolerance. The network is based on fixed degree nodes and has mean and maximum packet transfer distances where n is the number of processors. The routing method is detailed, as are methods for expandability, deadlock avoidance, and fault tolerance.

Traffic shaping and scheduling for OBS-based IP/WDM backbones

NASA Astrophysics Data System (ADS)

Elhaddad, Mahmoud S.; Melhem, Rami G.; Znati, Taieb; Basak, Debashis

2003-10-01

We introduce Proactive Reservation-based Switching (PRS) -- a switching architecture for IP/WDM networks based on Labeled Optical Burst Switching. PRS achieves packet delay and loss performance comparable to that of packet-switched networks, without requiring large buffering capacity, or burst scheduling across a large number of wavelengths at the core routers. PRS combines proactive channel reservation with periodic shaping of ingress-egress traffic aggregates to hide the offset latency and approximate the utilization/buffering characteristics of discrete-time queues with periodic arrival streams. A channel scheduling algorithm imposes constraints on burst departure times to ensure efficient utilization of wavelength channels and to maintain the distance between consecutive bursts through the network. Results obtained from simulation using TCP traffic over carefully designed topologies indicate that PRS consistently achieves channel utilization above 90% with modest buffering requirements.

A Fully Implemented 12 × 12 Data Vortex Optical Packet Switching Interconnection Network

NASA Astrophysics Data System (ADS)

Shacham, Assaf; Small, Benjamin A.; Liboiron-Ladouceur, Odile; Bergman, Keren

2005-10-01

A fully functional optical packet switching (OPS) interconnection network based on the data vortex architecture is presented. The photonic switching fabric uniquely capitalizes on the enormous bandwidth advantage of wavelength division multiplexing (WDM) wavelength parallelism while delivering minimal packet transit latency. Utilizing semiconductor optical amplifier (SOA)-based switching nodes and conventional fiber-optic technology, the 12-port system exhibits a capacity of nearly 1 Tb/s. Optical packets containing an eight-wavelength WDM payload with 10 Gb/s per wavelength are routed successfully to all 12 ports while maintaining a bit error rate (BER) of 10-12 or better. Median port-to-port latencies of 110 ns are achieved with a distributed deflection routing network that resolves packet contention on-the-fly without the use of optical buffers and maintains the entire payload path in the optical domain.

Integrated DoD Voice and Data Networks and Ground Packet Radio Technology

DTIC Science & Technology

1976-08-01

as the traffic requirement level increases. Moreover, the satellite switch selection problem is only meaningful over a limited traffic range. When...5: CPU TIMES VS. NUMBER OF SWITCHES SATELLITE SWITCH SELECTION ALGORITHM Computer Used: PDP-10 ♦O’S" means 0 minutes and 5 seconds. 5.30...Saturation Algorithm for Topo\\ogical Design of Parket-Switched Communications Networks," National Te3 ecommunications Conference Proceed- ings, San

ATM encryption testing

NASA Astrophysics Data System (ADS)

Capell, Joyce; Deeth, David

1996-01-01

This paper describes why encryption was selected by Lockheed Martin Missiles & Space as the means for securing ATM networks. The ATM encryption testing program is part of an ATM network trial provided by Pacific Bell under the California Research Education Network (CalREN). The problem being addressed is the threat to data security which results when changing from a packet switched network infrastructure to a circuit switched ATM network backbone. As organizations move to high speed cell-based networks, there is a break down in the traditional security model which is designed to protect packet switched data networks from external attacks. This is due to the fact that most data security firewalls filter IP packets, restricting inbound and outbound protocols, e.g. ftp. ATM networks, based on cell-switching over virtual circuits, does not support this method for restricting access since the protocol information is not carried by each cell. ATM switches set up multiple virtual connections, thus there is no longer a single point of entry into the internal network. The problem is further complicated by the fact that ATM networks support high speed multi-media applications, including real time video and video teleconferencing which are incompatible with packet switched networks. The ability to restrict access to Lockheed Martin networks in support of both unclassified and classified communications is required before ATM network technology can be fully deployed. The Lockheed Martin CalREN ATM testbed provides the opportunity to test ATM encryption prototypes with actual applications to assess the viability of ATM encryption methodologies prior to installing large scale ATM networks. Two prototype ATM encryptors are being tested: (1) `MILKBUSH' a prototype encryptor developed by NSA for transmission of government classified data over ATM networks, and (2) a prototype ATM encryptor developed by Sandia National Labs in New Mexico, for the encryption of proprietary data.

Lambda network having 2{sup m{minus}1} nodes in each of m stages with each node coupled to four other nodes for bidirectional routing of data packets between nodes

DOEpatents

Napolitano, L.M. Jr.

1995-11-28

The Lambda network is a single stage, packet-switched interprocessor communication network for a distributed memory, parallel processor computer. Its design arises from the desired network characteristics of minimizing mean and maximum packet transfer time, local routing, expandability, deadlock avoidance, and fault tolerance. The network is based on fixed degree nodes and has mean and maximum packet transfer distances where n is the number of processors. The routing method is detailed, as are methods for expandability, deadlock avoidance, and fault tolerance. 14 figs.

Photonic integrated circuit optical buffer for packet-switched networks.

PubMed

Burmeister, Emily F; Mack, John P; Poulsen, Henrik N; Masanović, Milan L; Stamenić, Biljana; Blumenthal, Daniel J; Bowers, John E

2009-04-13

A chip-scale optical buffer performs autonomous contention resolution for 40-byte packets with 99% packet recovery. The buffer consists of a fast, InP-based 2 x 2 optical switch and a silica-on-silicon low loss delay loop. The buffer is demonstrated in recirculating operation, but may be reconfigured in feed-forward operation for longer packet lengths. The recirculating buffer provides packet storage in integer multiples of the delay length of 12.86 ns up to 64.3 ns with 98% packet recovery. The buffer is used to resolve contention between two 40 Gb/s packet streams using multiple photonic chip optical buffers.

Future optical communication networks beyond 160 Gbit/s based on OTDM

NASA Astrophysics Data System (ADS)

Prati, Giancarlo; Bogoni, Antonella; Poti, Luca

2005-01-01

The virtually unlimited bandwidth of optical fibers has caused a great increase in data transmission speed over the past decade and, hence, stimulated high-demand multimedia services such as distance learning, video-conferencing and peer to peer applications. For this reason data traffic is exceeding telephony traffic, and this trend is driving the convergence of telecommunications and computer communications. In this scenario Internet Protocol (IP) is becoming the dominant protocol for any traffic, shifting the attention of the network designers from a circuit switching approach to a packet switching approach. A role of paramount importance in packet switching networks is played by the router that must implement the functionalities to set up and maintain the inter-nodal communications. The main functionalities a router must implement are routing, forwarding, switching, synchronization, contention resolution, and buffering. Nowadays, opto-electronic conversion is still required at each network node to process the incoming signal before routing that to the right output port. However, when the single channel bit rate increases beyond electronic speed limit, Optical Time Division Multiplexing (OTDM) becomes a forced choice, and all-optical processing must be performed to extract the information from the incoming packet. In this paper enabling techniques for ultra-fast all-optical network will be addressed. First a 160 Gbit/s complete transmission system will be considered. As enabling technique, an overview for all-optical logics will be discussed and experimental results will be presented using a particular reconfigurable NOLM based on Self-Phase-Modulation (SPM) or Cross-Phase-Modulation (XPM). Finally, a rough experiment on label extraction, all-optical switching and packet forwarding is shown.

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks.

PubMed

Shen, Yiwen; Hattink, Maarten H N; Samadi, Payman; Cheng, Qixiang; Hu, Ziyiz; Gazman, Alexander; Bergman, Keren

2018-04-16

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. We present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly network testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 µs control plane latency for data-center and high performance computing platforms.

Performance of highly connected photonic switching lossless metro-access optical networks

NASA Astrophysics Data System (ADS)

Martins, Indayara Bertoldi; Martins, Yara; Barbosa, Felipe Rudge

2018-03-01

The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The "lossless" photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

MPNACK: an optical switching scheme enabling the buffer-less reliable transmission

NASA Astrophysics Data System (ADS)

Yu, Xiaoshan; Gu, Huaxi; Wang, Kun; Xu, Meng; Guo, Yantao

2016-01-01

Optical data center networks are becoming an increasingly promising solution to solve the bottlenecks faced by electrical networks, such as low transmission bandwidth, high wiring complexity, and unaffordable power consumption. However, the optical circuit switching (OCS) network is not flexible enough to carry the traffic burst while the optical packet switching (OPS) network cannot solve the packet contention in an efficient way. To this end, an improved switching strategy named OPS with multi-hop Negative Acknowledgement (MPNACK) is proposed. This scheme uses a feedback mechanism, rather than the buffering structure, to handle the optical packet contention. The collided packet is treated as a NACK packet and sent back to the source server. When the sender receives this NACK packet, it knows a collision happens in the transmission path and a retransmission procedure is triggered. Overall, the OPS-NACK scheme enables a reliable transmission in the buffer-less optical network. Furthermore, with this scheme, the expensive and energy-hungry elements, optical or electrical buffers, can be removed from the optical interconnects, thus a more scalable and cost-efficient network can be constructed for cloud computing data centers.

Fault tolerant onboard packet switch architecture for communication satellites: Shared memory per beam approach

NASA Technical Reports Server (NTRS)

Shalkhauser, Mary JO; Quintana, Jorge A.; Soni, Nitin J.

1994-01-01

The NASA Lewis Research Center is developing a multichannel communication signal processing satellite (MCSPS) system which will provide low data rate, direct to user, commercial communications services. The focus of current space segment developments is a flexible, high-throughput, fault tolerant onboard information switching processor. This information switching processor (ISP) is a destination-directed packet switch which performs both space and time switching to route user information among numerous user ground terminals. Through both industry study contracts and in-house investigations, several packet switching architectures were examined. A contention-free approach, the shared memory per beam architecture, was selected for implementation. The shared memory per beam architecture, fault tolerance insertion, implementation, and demonstration plans are described.

Sampled-Data Consensus of Linear Multi-agent Systems With Packet Losses.

PubMed

Zhang, Wenbing; Tang, Yang; Huang, Tingwen; Kurths, Jurgen

In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.

Scalable, high-capacity optical switches for Internet routers and moving platforms

NASA Astrophysics Data System (ADS)

Joe, In-Sung

Internet traffic nearly doubles every year, and we need faster routers with higher ports count, yet lower electrical power consumption. Current internet routers use electrical switches that consume large amounts of electrical power to operate at high data rates. These internet routers dissipate ˜ 10kW per rack, and their capacity is limited by cooling constraints. The power consumption is also critical for moving platforms. As avionics advance, the demand for larger capacity networks increases. Optical fibers are already chosen for high speed data transmission in advanced aircraft. In optical communication systems, integrated passive optical components, such as Array Waveguide Gratings (AWGs), have provided larger capacity with lower power consumption, because minimal electrical power is required for their operation. In addition, compact, wavelength-tunable semiconductor lasers with wide tuning ranges that can switch their wavelengths in tens of nanoseconds have been demonstrated. Here we present a wavelength-selective optical packet switch based on Waveguide Grating Routers (WGRs), passive splitters, and combiners. Tunable lasers on the transmitter side are the only active switching elements. The WGR is operated on multiple Free Spectral Ranges (FSRs) to achieve increased port count and switching capacity while maintaining strict-sense, non-blocking operation. Switching times of less than 24ns between two wavelengths covering three FSRs is demonstrated experimentally. The electrical power consumption, size, weight, and cost of our optical switch is compared with those of conventional electrical switches, showing substantial improvements at large throughputs (˜2 Tb/s full duplex). A revised switch design that does not suffer optical loss from star couplers is proposed. This switch design uses only WGRs, and it is suitable for networks with stringent power budgets. The burst nature of the optical packet transmission requires clock recovery for every incoming packet, and conventional continuous-mode receivers are not suitable for this application. An Embedded Clock Transport (ECT) technique is adopted here. The ECT combines a clock tone with the data payload before the transmission. Simple band pass filtering can extract the transmitted clock tone, and low pass filtering can recover the data. Error-free transmissions at 2.488 Gb/s with ˜16 ns clock recovery time were demonstrated.

On-board B-ISDN fast packet switching architectures. Phase 1: Study

NASA Technical Reports Server (NTRS)

Faris, Faris; Inukai, Thomas; Lee, Fred; Paul, Dilip; Shyy, Dong-Jye

1993-01-01

The broadband integrate services digital network (B-ISDN) is an emerging telecommunications technology that will meet most of the telecommunications networking needs in the mid-1990's to early next century. The satellite-based system is well positioned for providing B-ISDN service with its inherent capabilities of point-to-multipoint and broadcast transmission, virtually unlimited connectivity between any two points within a beam coverage, short deployment time of communications facility, flexible and dynamic reallocation of space segment capacity, and distance insensitive cost. On-board processing satellites, particularly in a multiple spot beam environment, will provide enhanced connectivity, better performance, optimized access and transmission link design, and lower user service cost. The following are described: the user and network aspects of broadband services; the current development status in broadband services; various satellite network architectures including system design issues; and various fast packet switch architectures and their detail designs.

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks

DOE PAGES

Shen, Yiwen; Hattink, Maarten; Samadi, Payman; ...

2018-04-13

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. Here, we present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly networkmore » testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 microsecond control plane latency for data-center and high performance computing platforms.« less

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yiwen; Hattink, Maarten; Samadi, Payman

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. Here, we present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly networkmore » testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 microsecond control plane latency for data-center and high performance computing platforms.« less

Multistage switching hardware and software implementations for student experiment purpose

NASA Astrophysics Data System (ADS)

Sani, A.; Suherman

2018-02-01

Current communication and internet networks are underpinned by the switching technologies that interconnect one network to the others. Students’ understanding on networks rely on how they conver the theories. However, understanding theories without touching the reality may exert spots in the overall knowledge. This paper reports the progress of the multistage switching design and implementation for student laboratory activities. The hardware and software designs are based on three stages clos switching architecture with modular 2x2 switches, controlled by an arduino microcontroller. The designed modules can also be extended for batcher and bayan switch, and working on circuit and packet switching systems. The circuit analysis and simulation show that the blocking probability for each switch combinations can be obtained by generating random or patterned traffics. The mathematic model and simulation analysis shows 16.4% blocking probability differences as the traffic generation is uniform. The circuits design components and interfacing solution have been identified to allow next step implementation.

Moving the boundary between wavelength resources in optical packet and circuit integrated ring network.

PubMed

Furukawa, Hideaki; Miyazawa, Takaya; Wada, Naoya; Harai, Hiroaki

2014-01-13

Optical packet and circuit integrated (OPCI) networks provide both optical packet switching (OPS) and optical circuit switching (OCS) links on the same physical infrastructure using a wavelength multiplexing technique in order to deal with best-effort services and quality-guaranteed services. To immediately respond to changes in user demand for OPS and OCS links, OPCI networks should dynamically adjust the amount of wavelength resources for each link. We propose a resource-adjustable hybrid optical packet/circuit switch and transponder. We also verify that distributed control of resource adjustments can be applied to the OPCI ring network testbed we developed. In cooperation with the resource adjustment mechanism and the hybrid switch and transponder, we demonstrate that automatically allocating a shared resource and moving the wavelength resource boundary between OPS and OCS links can be successfully executed, depending on the number of optical paths in use.

On-board congestion control for satellite packet switching networks

NASA Technical Reports Server (NTRS)

Chu, Pong P.

1991-01-01

It is desirable to incorporate packet switching capability on-board for future communication satellites. Because of the statistical nature of packet communication, incoming traffic fluctuates and may cause congestion. Thus, it is necessary to incorporate a congestion control mechanism as part of the on-board processing to smooth and regulate the bursty traffic. Although there are extensive studies on congestion control for both baseband and broadband terrestrial networks, these schemes are not feasible for space based switching networks because of the unique characteristics of satellite link. Here, we propose a new congestion control method for on-board satellite packet switching. This scheme takes into consideration the long propagation delay in satellite link and takes advantage of the the satellite's broadcasting capability. It divides the control between the ground terminals and satellite, but distributes the primary responsibility to ground terminals and only requires minimal hardware resource on-board satellite.

Adaptive Topological Configuration of an Integrated Circuit/Packet-Switched Computer Network.

DTIC Science & Technology

1984-01-01

Gitman et al. [45] state that there are basically two approaches to the integrated network design problem: (1) solve the link/capacity problem for...1972), 1385-1397. 33. Frank, H., and Gitman , I. Economic analysis of integrated voice and data networks: a case study. Proc. of IEEE 66 , 11 (Nov. 1978...1974), 1074-1079. 45. Gitman , I., Hsieh, W., and Occhiogrosso, B. J. Analysis and design of hybrid switching networks. IEEE Trans. on Comm. Com-29

Experimental demonstration of tunable multiple optical orthogonal codes sequences-based optical label for optical packets switching

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Zhou, Heng; Ling, Yun; Wang, Yawei; Xu, Bo

2010-03-01

In this paper, the tunable multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) is experimentally demonstrated for the first time. The tunable MOOCS-based optical label is performed by using fiber Bragg grating (FBG)-based optical en/decoders group and optical switches configured by using Field Programmable Gate Array (FPGA), and the optical label is erased by using Semiconductor Optical Amplifier (SOA). Some waveforms of the MOOCS-based optical label, optical packet including the MOOCS-based optical label and the payloads are obtained, the switching control mechanism and the switching matrix are discussed, the bit error rate (BER) performance of this system is also studied. These experimental results show that the tunable MOOCS-OPS scheme is effective.

A Study of Quality of Service Communication for High-Speed Packet-Switching Computer Sub-Networks

NASA Technical Reports Server (NTRS)

Cui, Zhenqian

1999-01-01

In this thesis, we analyze various factors that affect quality of service (QoS) communication in high-speed, packet-switching sub-networks. We hypothesize that sub-network-wide bandwidth reservation and guaranteed CPU processing power at endpoint systems for handling data traffic are indispensable to achieving hard end-to-end quality of service. Different bandwidth reservation strategies, traffic characterization schemes, and scheduling algorithms affect the network resources and CPU usage as well as the extent that QoS can be achieved. In order to analyze those factors, we design and implement a communication layer. Our experimental analysis supports our research hypothesis. The Resource ReSerVation Protocol (RSVP) is designed to realize resource reservation. Our analysis of RSVP shows that using RSVP solely is insufficient to provide hard end-to-end quality of service in a high-speed sub-network. Analysis of the IEEE 802.lp protocol also supports the research hypothesis.

On-board processing architectures for satellite B-ISDN services

NASA Technical Reports Server (NTRS)

Inukai, Thomas; Shyy, Dong-Jye; Faris, Faris

1991-01-01

Onboard baseband processing architectures for future satellite broadband integrated services digital networks (B-ISDN's) are addressed. To assess the feasibility of implementing satellite B-ISDN services, critical design issues, such as B-ISDN traffic characteristics, transmission link design, and a trade-off between onboard circuit and fast packet switching, are analyzed. Examples of the two types of switching mechanisms and potential onboard network control functions are presented. A sample network architecture is also included to illustrate a potential onboard processing system.

On-board processing satellite network architectures for broadband ISDN

NASA Technical Reports Server (NTRS)

Inukai, Thomas; Faris, Faris; Shyy, Dong-Jye

1992-01-01

Onboard baseband processing architectures for future satellite broadband integrated services digital networks (B-ISDN's) are addressed. To assess the feasibility of implementing satellite B-ISDN services, critical design issues, such as B-ISDN traffic characteristics, transmission link design, and a trade-off between onboard circuit and fast packet switching, are analyzed. Examples of the two types of switching mechanisms and potential onboard network control functions are presented. A sample network architecture is also included to illustrate a potential onboard processing system.

Packet communications in satellites with multiple-beam antennas and signal processing

NASA Technical Reports Server (NTRS)

Davies, R.; Chethik, F.; Penick, M.

1980-01-01

A communication satellite with a multiple-beam antenna and onboard signal processing is considered for use in a 'message-switched' data relay system. The signal processor may incorporate demodulation, routing, storage, and remodulation of the data. A system user model is established and key functional elements for the signal processing are identified. With the throughput and delay requirements as the controlled variables, the hardware complexity, operational discipline, occupied bandwidth, and overall user end-to-end cost are estimated for (1) random-access packet switching; and (2) reservation-access packet switching. Other aspects of this network (eg, the adaptability to channel switched traffic requirements) are examined. For the given requirements and constraints, the reservation system appears to be the most attractive protocol.

Performance of circuit switching in the Internet

NASA Astrophysics Data System (ADS)

Molinero-Fernández, Pablo; McKeown, Nick

2003-04-01

We study the performance of an Internet that uses circuit switching (CS) instead of, or in addition to, packet switching (PS). On the face of it, this would seem a pointless exercise; the Internet is packet switched, and it was deliberately built that way to enable the efficiencies afforded by statistical multiplexing and the robustness of fast rerouting around failures. But link utilization is low particularly at the core of the Internet, which makes statistical multiplexing less important than it once was. Moreover, circuit switches today are capable of rapid reconfiguration around failures. There is also renewed interest in CS because of the ease of building very-high-capacity optical circuit switches. Although several proposals have suggested ways in which CS may be introduced into the Internet, the research presented here is based on Transmission Control Protocol (TCP) switching, in which a new circuit is created for each application flow. Here we explore the performance of a network that uses TCP switching, with particular emphasis on the response time experienced by users. We use simple M/GI/1 and M/GI/N queues to model application flows in both packet-switched and circuit-switched networks, as well as ns-2 simulations. We conclude that because of high-bandwidth long-lived flows, it does not make sense to use CS in shared-access or local area networks. But our results suggest that in the core of the network, where high capacity is needed most, and where peak flow rate is limited by the access link, there is little or no difference in performance between CS and PS. Given that circuit switches can be built to be much faster than packet switches, this suggests that a circuit-switched core warrants further investigation.

Method and allocation device for allocating pending requests for data packet transmission at a number of inputs to a number of outputs of a packet switching device in successive time slots

DOEpatents

Abel, Francois [Rueschlikon, CH; Iliadis, Ilias [Rueschlikon, CH; Minkenberg, Cyriel J. A. [Adliswil, CH

2009-02-03

A method for allocating pending requests for data packet transmission at a number of inputs to a number of outputs of a switching system in successive time slots, including a matching method including the steps of providing a first request information in a first time slot indicating data packets at the inputs requesting transmission to the outputs of the switching system, performing a first step in the first time slot depending on the first request information to obtain a first matching information, providing a last request information in a last time slot successive to the first time slot, performing a last step in the last time slot depending on the last request information and depending on the first matching information to obtain a final matching information, and assigning the pending data packets at the number of inputs to the number of outputs based on the final matching information.

Flow-aggregated traffic-driven label mapping in label-switching networks

NASA Astrophysics Data System (ADS)

Nagami, Kenichi; Katsube, Yasuhiro; Esaki, Hiroshi; Nakamura, Osamu

1998-12-01

Label switching technology enables high performance, flexible, layer-3 packet forwarding based on the fixed length label information mapped to the layer-3 packet stream. A Label Switching Router (LSR) forwards layer-3 packets based on their label information mapped to the layer-3 address information as well as their layer-3 address information. This paper evaluates the required number of labels under traffic-driven label mapping policy using the real backbone traffic traces. The evaluation shows that the label mapping policy requires a large number of labels. In order to reduce the required number of labels, we propose a label mapping policy which is a traffic-driven label mapping for the traffic toward the same destination network. The evaluation shows that the proposed label mapping policy requires only about one tenth as many labels compared with the traffic-driven label mapping for the host-pair packet stream,and the topology-driven label mapping for the destination network packet stream.

Recovery Act: Energy Efficiency of Data Networks through Rate Adaptation (EEDNRA) - Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthew Andrews; Spyridon Antonakopoulos; Steve Fortune

2011-07-12

This Concept Definition Study focused on developing a scientific understanding of methods to reduce energy consumption in data networks using rate adaptation. Rate adaptation is a collection of techniques that reduce energy consumption when traffic is light, and only require full energy when traffic is at full provisioned capacity. Rate adaptation is a very promising technique for saving energy: modern data networks are typically operated at average rates well below capacity, but network equipment has not yet been designed to incorporate rate adaptation. The Study concerns packet-switching equipment, routers and switches; such equipment forms the backbone of the modern Internet.more » The focus of the study is on algorithms and protocols that can be implemented in software or firmware to exploit hardware power-control mechanisms. Hardware power-control mechanisms are widely used in the computer industry, and are beginning to be available for networking equipment as well. Network equipment has different performance requirements than computer equipment because of the very fast rate of packet arrival; hence novel power-control algorithms are required for networking. This study resulted in five published papers, one internal report, and two patent applications, documented below. The specific technical accomplishments are the following: • A model for the power consumption of switching equipment used in service-provider telecommunication networks as a function of operating state, and measured power-consumption values for typical current equipment. • An algorithm for use in a router that adapts packet processing rate and hence power consumption to traffic load while maintaining performance guarantees on delay and throughput. • An algorithm that performs network-wide traffic routing with the objective of minimizing energy consumption, assuming that routers have less-than-ideal rate adaptivity. • An estimate of the potential energy savings in service-provider networks using feasibly-implementable rate adaptivity. • A buffer-management algorithm that is designed to reduce the size of router buffers, and hence energy consumed. • A packet-scheduling algorithm designed to minimize packet-processing energy requirements. Additional research is recommended in at least two areas: further exploration of rate-adaptation in network switching equipment, including incorporation of rate-adaptation in actual hardware, allowing experimentation in operational networks; and development of control protocols that allow parts of networks to be shut down while minimizing disruption to traffic flow in the network. The research is an integral part of a large effort within Bell Laboratories, Alcatel-Lucent, aimed at dramatic improvements in the energy efficiency of telecommunication networks. This Study did not explicitly consider any commercialization opportunities.« less

An iteration algorithm for optimal network flows

NASA Astrophysics Data System (ADS)

Woong, C. J.

1983-09-01

A packet switching network has the desirable feature of rapidly handling short (bursty) messages of the type often found in computer communication systems. In evaluating packet switching networks, the average time delay per packet is one of the most important measures of performance. The problem of message routing to minimize time delay is analyzed here using two approaches, called "successive saturation' and "max-slack', for various traffic requirement matrices and networks with fixed topology and link capacities.

Network speech systems technology program

NASA Astrophysics Data System (ADS)

Weinstein, C. J.

1981-09-01

This report documents work performed during FY 1981 on the DCA-sponsored Network Speech Systems Technology Program. The two areas of work reported are: (1) communication system studies in support of the evolving Defense Switched Network (DSN) and (2) design and implementation of satellite/terrestrial interfaces for the Experimental Integrated Switched Network (EISN). The system studies focus on the development and evaluation of economical and endurable network routing procedures. Satellite/terrestrial interface development includes circuit-switched and packet-switched connections to the experimental wideband satellite network. Efforts in planning and coordination of EISN experiments are reported in detail in a separate EISN Experiment Plan.

Performance Tradeoffs and Hierarchical Designs of Distributed Packet-Switching Communication Networks,

DTIC Science & Technology

1979-09-01

the traffic is ecenl\\ divided between groups. Gitman 1141 introduced Such a scheme and calculated the capaciy of two-level systems, lie assumed all...447-448. April 1976. 25 (141 Gitman , ., "On the Capacity of Slotted ALOH1A Networks and Sonic Design Problems," IEEE Transactions on Communicatons

A Cellular Neural Networks Based DiffServ Switch for Satellite Communication Systems

NASA Astrophysics Data System (ADS)

Tarchi, Daniele; Fantacci, Romano; Gubellini, Roberto; Pecorella, Tommaso

2003-07-01

Recent developments of Internet services and advanced compression methods has revived interest on IP based multimedia satellite communication systems. However a main problem arising here is to guarantee specific Quality of Service (QoS) constraints in order to have good performance for each traffic class.Among various QoS approach used in Internet, recently the DiffServ technique has became the most promising so- lution, mainly for its simplicity with respect to different alternatives. Moreover, in satellite communication systems, DiffServ policy computational capabilities are placed at the edge points (end-to-end philosophy); this is very important for a network constituted by one satellite link because it allows to reduce the implementation complexity of the satellite on-board equipments.The satellite switch under consideration makes use of the Multiple Input Queuing approach. Packets arrived at a switch input are stored in a shared buffer but they are logically ordered in individual queues, one for each possible output link. According to the DiffServ policy, within a same logical queue, packets are reordered in individual sub-queues according to the priority. A suitable implementation of the DiffServ policy based on a Cellular Neural Network (CNN) is proposed in the paper in order to achieve QoS requirements.The CNNs are a set of linear and nonlinear circuits connected among them that allow parallel and asynchronous computation. CNNs are a class of neural networks similar to Hopfield Neural Networks (HNN), but more flexible and suitable for solving the output contention problem, inherent of switching systems, for VLSI implementation.In this paper a CNN has been designed in order to maximize a cost functional, related to the on-board switch through- put and QoS constraints. The initial state for each neural cell is obtained looking at the presence of at least one packet from a certain input logical queue to a specific output line. The input value for each neural cell is a function of priority and length of each input logical queue. The versatility of neural network make feasible to take the best decision for the packet to be delivered to each output satellite beam, in order to meet specific QoS constraints. Numerical results for CNN approach highlights that Neural network convergence within a time slot is guaranteed, and an optimal, or at least near-optimal, solution in terms of cost function is achieved.The proposed system is based on the IETF (Internet Engineering Task Force) recommendations; this means that traffic entering the switching fabric could be marked as Expedited Forward (EF) or Assured Forward (AF), otherwise handled as Best Effort (BE). Two Assured Forward classes with different emission priority have been implemented, taking into account time spent inside the logical queue and its length. Expedited Forward traffic is typical of services to be delivered with the maximum priority, as streaming or interactive services. The packets, belonging to services that need a certain level of priority with low packet loss, are marked as Assured Forward. Best Effort traffic is related to e-mail or file transfer, or other that have not particular QoS requirements. The CNN used to solve conflict situations act as an arbiter for all the output links. Differently from other Multiple Input Queuing approach, where one arbiter for each output line is present, in proposed approach there exist only one arbiter that make the best decision. The selected rule has been defined in order to give priority to packets, according to opportunely defined functionals characteristic of each traffic class, under the constraint that no more than one packet can be delivered to the same output line. The functionals depend on queue length and time spent inside the queue by front packet.The performance of the proposed DiffServ switch has been derived in terms of delay and jitter; buffer occupancy has been analyzed for different configuration, such as a unique common buffer, one buffer for each input line, one buffer for each input line and each priority class.The obtained results highlight an high flexibility of satellite switch with CNN, taking into account that functional used to calculate priority of each queue could be easily changed, without any complexity gain nor change in CNN structure, in order to consider different traffic characteristic. Numerical results show that proposed algorithm outperform the switches based on Multiple Input Queuing, that use strictly priority methods, in terms of delay and jitter. Different buffer size have been also considered in order to analyze packet loss for CNN switch algorithm, comparing different configuration described above.The good behavior of the proposed DiffServ switch has been verified in the case of traffic with pareto distribution for packet length and a geometrical distribution for packet interarrival time, highlighting good performance in terms of delay and jitter. Numerical results also demonstrate the stability of this method for heavy load traffic; in particular maximum permitted load is higher for higher priority classes.

On-board processing satellite network architecture and control study

NASA Technical Reports Server (NTRS)

Campanella, S. Joseph; Pontano, B.; Chalmers, H.

1987-01-01

For satellites to remain a vital part of future national and international communications, system concepts that use their inherent advantages to the fullest must be created. Network architectures that take maximum advantage of satellites equipped with onboard processing are explored. Satellite generations must accommodate various services for which satellites constitute the preferred vehicle of delivery. Such services tend to be those that are widely dispersed and present thin to medium loads to the system. Typical systems considered are thin and medium route telephony, maritime, land and aeronautical radio, VSAT data, low bit rate video teleconferencing, and high bit rate broadcast of high definition video. Delivery of services by TDMA and FDMA multiplexing techniques and combinations of the two for individual and mixed service types are studied. The possibilities offered by onboard circuit switched and packet switched architectures are examined and the results strongly support a preference for the latter. A detailed design architecture encompassing the onboard packet switch and its control, the related demand assigned TDMA burst structures, and destination packet protocols for routing traffic are presented. Fundamental onboard hardware requirements comprising speed, memory size, chip count, and power are estimated. The study concludes with identification of key enabling technologies and identifies a plan to develop a POC model.

Analysis of adaptive algorithms for an integrated communication network

NASA Technical Reports Server (NTRS)

Reed, Daniel A.; Barr, Matthew; Chong-Kwon, Kim

1985-01-01

Techniques were examined that trade communication bandwidth for decreased transmission delays. When the network is lightly used, these schemes attempt to use additional network resources to decrease communication delays. As the network utilization rises, the schemes degrade gracefully, still providing service but with minimal use of the network. Because the schemes use a combination of circuit and packet switching, they should respond to variations in the types and amounts of network traffic. Also, a combination of circuit and packet switching to support the widely varying traffic demands imposed on an integrated network was investigated. The packet switched component is best suited to bursty traffic where some delays in delivery are acceptable. The circuit switched component is reserved for traffic that must meet real time constraints. Selected packet routing algorithms that might be used in an integrated network were simulated. An integrated traffic places widely varying workload demands on a network. Adaptive algorithms were identified, ones that respond to both the transient and evolutionary changes that arise in integrated networks. A new algorithm was developed, hybrid weighted routing, that adapts to workload changes.

Experimental demonstration of an OpenFlow based software-defined optical network employing packet, fixed and flexible DWDM grid technologies on an international multi-domain testbed.

PubMed

Channegowda, M; Nejabati, R; Rashidi Fard, M; Peng, S; Amaya, N; Zervas, G; Simeonidou, D; Vilalta, R; Casellas, R; Martínez, R; Muñoz, R; Liu, L; Tsuritani, T; Morita, I; Autenrieth, A; Elbers, J P; Kostecki, P; Kaczmarek, P

2013-03-11

Software defined networking (SDN) and flexible grid optical transport technology are two key technologies that allow network operators to customize their infrastructure based on application requirements and therefore minimizing the extra capital and operational costs required for hosting new applications. In this paper, for the first time we report on design, implementation & demonstration of a novel OpenFlow based SDN unified control plane allowing seamless operation across heterogeneous state-of-the-art optical and packet transport domains. We verify and experimentally evaluate OpenFlow protocol extensions for flexible DWDM grid transport technology along with its integration with fixed DWDM grid and layer-2 packet switching.

Speech transport for packet telephony and voice over IP

NASA Astrophysics Data System (ADS)

Baker, Maurice R.

1999-11-01

Recent advances in packet switching, internetworking, and digital signal processing technologies have converged to allow realizable practical implementations of packet telephony systems. This paper provides a tutorial on transmission engineering for packet telephony covering the topics of speech coding/decoding, speech packetization, packet data network transport, and impairments which may negatively impact end-to-end system quality. Particular emphasis is placed upon Voice over Internet Protocol given the current popularity and ubiquity of IP transport.

Advanced Teleprocessing Systems

DTIC Science & Technology

1980-03-31

75 Gitman , I., "On the Capacity of Slotted ALOHA Networks and Some Design Problems," IEEE Transactions on Communications, Vol. COM-23, March 1975, pp...305-317. GITM 76 Gitman , I., R. Van Slyke and H. Frank, "Routing in Packet-Switching Broadcast Radio Networks," IEEE Transactions on Communications

Performance Evaluation and Control of Distributed Computer Communication Networks.

DTIC Science & Technology

1984-09-01

including: L. Clare, L.A. De Moraes, J. Baker, M. Zuckerman, S. Katz, P. Rodrigues, R. Pazos , S. Resheff. Other participants are the following visiting...investigations have been reported in reference (1) and (2) below. References (1) M. Gerla, R. Pazos -Rangel "Bandwidth Allocation and Routing in ISDN’s," IEEE...and efficient methods for its solution are presented. (2) R.A. Pazos -Rangel "Evaluation and Design of Integrated Packet Switching and Circuit Switching

Design and implementation considerations of a MSAT packet data network

NASA Technical Reports Server (NTRS)

Karam, Fouad G.; Hearn, Terry; Rohr, Doug; Guibord, Arthur F.

1993-01-01

The Mobile Data System, which is intended to provide for packet switched data services is currently under development. The system is based on a star network topology consisting of a centralized Data Hub (DH) serving a large number of mobile terminals. Through the Data Hub, end-to-end connections can be established between terrestrial users on public or private data networks and mobile users. The MDS network will be capable of offering a variety of services some of which are based on the standard X.25 network interface protocol, and others optimized for short messages and broadcast messages. A description of these services and the trade-offs in the DH design are presented.

A low-latency optical switch architecture using integrated μm SOI-based contention resolution and switching

NASA Astrophysics Data System (ADS)

Mourgias-Alexandris, G.; Moralis-Pegios, M.; Terzenidis, N.; Cherchi, M.; Harjanne, M.; Aalto, T.; Vyrsokinos, K.; Pleros, N.

2018-02-01

The urgent need for high-bandwidth and high-port connectivity in Data Centers has boosted the deployment of optoelectronic packet switches towards bringing high data-rate optics closer to the ASIC, realizing optical transceiver functions directly at the ASIC package for high-rate, low-energy and low-latency interconnects. Even though optics can offer a broad range of low-energy integrated switch fabrics for replacing electronic switches and seamlessly interface with the optical I/Os, the use of energy- and latency-consuming electronic SerDes continues to be a necessity, mainly dictated by the absence of integrated and reliable optical buffering solutions. SerDes undertakes the role of optimally synergizing the lower-speed electronic buffers with the incoming and outgoing optical streams, suggesting that a SerDes-released chip-scale optical switch fabric can be only realized in case all necessary functions including contention resolution and switching can be implemented on a common photonic integration platform. In this paper, we demonstrate experimentally a hybrid Broadcast-and-Select (BS) / wavelength routed optical switch that performs both the optical buffering and switching functions with μm-scale Silicon-integrated building blocks. Optical buffering is carried out in a silicon-integrated variable delay line bank with a record-high on-chip delay/footprint efficiency of 2.6ns/mm2 and up to 17.2 nsec delay capability, while switching is executed via a BS design and a silicon-integrated echelle grating, assisted by SOA-MZI wavelength conversion stages and controlled by a FPGA header processing module. The switch has been experimentally validated in a 3x3 arrangement with 10Gb/s NRZ optical data packets, demonstrating error-free switching operation with a power penalty of <5dB.

Real-Time Communication Systems: Design, Analysis and Implementation

DTIC Science & Technology

1984-07-31

sively [141-[19). A two-hop configuration involving a ring of repeaters around a station has been analyzed by Gitman [20) ; STATION network capacity...control of the packet-switching broadcast channels," J. Ass. Comput Mach., vol. 24, pp. 375-386, July 1977. [201 I. Gitman , "On the capacity of

The sampled-data consensus of multi-agent systems with probabilistic time-varying delays and packet losses

NASA Astrophysics Data System (ADS)

Sui, Xin; Yang, Yongqing; Xu, Xianyun; Zhang, Shuai; Zhang, Lingzhong

2018-02-01

This paper investigates the consensus of multi-agent systems with probabilistic time-varying delays and packet losses via sampled-data control. On the one hand, a Bernoulli-distributed white sequence is employed to model random packet losses among agents. On the other hand, a switched system is used to describe packet dropouts in a deterministic way. Based on the special property of the Laplacian matrix, the consensus problem can be converted into a stabilization problem of a switched system with lower dimensions. Some mean square consensus criteria are derived in terms of constructing an appropriate Lyapunov function and using linear matrix inequalities (LMIs). Finally, two numerical examples are given to show the effectiveness of the proposed method.

A programmable Si-photonic node for SDN-enabled Bloom filter forwarding in disaggregated data centers

NASA Astrophysics Data System (ADS)

Moralis-Pegios, M.; Terzenidis, N.; Vagionas, C.; Pitris, S.; Chatzianagnostou, E.; Brimont, A.; Zanzi, A.; Sanchis, P.; Marti, J.; Kraft, J.; Rochracher, K.; Dorrestein, S.; Bogdan, M.; Tekin, T.; Syrivelis, D.; Tassiulas, L.; Miliou, A.; Pleros, N.; Vyrsokinos, K.

2017-02-01

Programmable switching nodes supporting Software-Defined Networking (SDN) over optical interconnecting technologies arise as a key enabling technology for future disaggregated Data Center (DC) environments. The SDNenabling roadmap of intra-DC optical solutions is already a reality for rack-to-rack interconnects, with recent research reporting on interesting applications of programmable silicon photonic switching fabrics addressing board-to-board and even on-board applications. In this perspective, simplified information addressing schemes like Bloom filter (BF)-based labels emerge as a highly promising solution for ensuring rapid switch reconfiguration, following quickly the changes enforced in network size, network topology or even in content location. The benefits of BF-based forwarding have been so far successfully demonstrated in the Information-Centric Network (ICN) paradigm, while theoretical studies have also revealed the energy consumption and speed advantages when applied in DCs. In this paper we present for the first time a programmable 4x4 Silicon Photonic switch that supports SDN through the use of BF-labeled router ports. Our scheme significantly simplifies packet forwarding as it negates the need for large forwarding tables, allowing for its remote control through modifications in the assigned BF labels. We demonstrate 1x4 switch operation controlling the Si-Pho switch by a Stratix V FPGA module, which is responsible for processing the packet ID and correlating its destination with the appropriate BF-labeled outgoing port. DAC- and amplifier-less control of the carrier-injection Si-Pho switches is demonstrated, revealing successful switching of 10Gb/s data packets with BF-based forwarding information changes taking place at a time-scale that equals the duration of four consecutive packets.

A packet switched communications system for GRO

NASA Astrophysics Data System (ADS)

Husain, Shabu; Yang, Wen-Hsing; Vadlamudi, Rani; Valenti, Joseph

1993-11-01

This paper describes the packet switched Instrumenters Communication System (ICS) that was developed for the Command Management Facility at GSFC to support the Gamma Ray Observatory (GRO) spacecraft. The GRO ICS serves as a vital science data acquisition link to the GRO scientists to initiate commands for their spacecraft instruments. The system is ready to send and receive messages at any time, 24 hours a day and seven days a week. The system is based on X.25 and the International Standard Organization's (ISO) 7-layer Open Systems Interconnection (OSI) protocol model and has client and server components. The components of the GRO ICS are discussed along with how the Communications Subsystem for Interconnection (CSFI) and Network Control Program Packet Switching Interface (NPSI) software are used in the system.

Distributed parallel messaging for multiprocessor systems

DOEpatents

Chen, Dong; Heidelberger, Philip; Salapura, Valentina; Senger, Robert M; Steinmacher-Burrow, Burhard; Sugawara, Yutaka

2013-06-04

A method and apparatus for distributed parallel messaging in a parallel computing system. The apparatus includes, at each node of a multiprocessor network, multiple injection messaging engine units and reception messaging engine units, each implementing a DMA engine and each supporting both multiple packet injection into and multiple reception from a network, in parallel. The reception side of the messaging unit (MU) includes a switch interface enabling writing of data of a packet received from the network to the memory system. The transmission side of the messaging unit, includes switch interface for reading from the memory system when injecting packets into the network.

Novel flat datacenter network architecture based on scalable and flow-controlled optical switch system.

PubMed

Miao, Wang; Luo, Jun; Di Lucente, Stefano; Dorren, Harm; Calabretta, Nicola

2014-02-10

We propose and demonstrate an optical flat datacenter network based on scalable optical switch system with optical flow control. Modular structure with distributed control results in port-count independent optical switch reconfiguration time. RF tone in-band labeling technique allowing parallel processing of the label bits ensures the low latency operation regardless of the switch port-count. Hardware flow control is conducted at optical level by re-using the label wavelength without occupying extra bandwidth, space, and network resources which further improves the performance of latency within a simple structure. Dynamic switching including multicasting operation is validated for a 4 x 4 system. Error free operation of 40 Gb/s data packets has been achieved with only 1 dB penalty. The system could handle an input load up to 0.5 providing a packet loss lower that 10(-5) and an average latency less that 500 ns when a buffer size of 16 packets is employed. Investigation on scalability also indicates that the proposed system could potentially scale up to large port count with limited power penalty.

Destination directed packet switch architecture for a 30/20 GHz FDMA/TDM geostationary communication satellite network

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Shalkhauser, Mary JO

1991-01-01

Emphasis is on a destination directed packet switching architecture for a 30/20 GHz frequency division multiplex access/time division multiplex (FDMA/TDM) geostationary satellite communication network. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment was considered concurrently to ensure cost efficiency and realistic operational constraints.

25-Gbit/s burst-mode optical receiver using high-speed avalanche photodiode for 100-Gbit/s optical packet switching.

PubMed

Nada, Masahiro; Nakamura, Makoto; Matsuzaki, Hideaki

2014-01-13

25-Gbit/s error-free operation of an optical receiver is successfully demonstrated against burst-mode optical input signals without preambles. The receiver, with a high-sensitivity avalanche photodiode and burst-mode transimpedance amplifier, exhibits sufficient receiver sensitivity and an extremely quick response suitable for burst-mode operation in 100-Gbit/s optical packet switching.

Destination-directed, packet-switching architecture for 30/20-GHz FDMA/TDM geostationary communications satellite network

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Shalkhauser, Mary JO

1992-01-01

A destination-directed packet switching architecture for a 30/20-GHz frequency division multiple access/time division multiplexed (FDMA/TDM) geostationary satellite communications network is discussed. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints.

On-board closed-loop congestion control for satellite based packet switching networks

NASA Technical Reports Server (NTRS)

Chu, Pong P.; Ivancic, William D.; Kim, Heechul

1993-01-01

NASA LeRC is currently investigating a satellite architecture that incorporates on-board packet switching capability. Because of the statistical nature of packet switching, arrival traffic may fluctuate and thus it is necessary to integrate congestion control mechanism as part of the on-board processing unit. This study focuses on the closed-loop reactive control. We investigate the impact of the long propagation delay on the performance and propose a scheme to overcome the problem. The scheme uses a global feedback signal to regulate the packet arrival rate of ground stations. In this scheme, the satellite continuously broadcasts the status of its output buffer and the ground stations respond by selectively discarding packets or by tagging the excessive packets as low-priority. The two schemes are evaluated by theoretical queuing analysis and simulation. The former is used to analyze the simplified model and to determine the basic trends and bounds, and the later is used to assess the performance of a more realistic system and to evaluate the effectiveness of more sophisticated control schemes. The results show that the long propagation delay makes the closed-loop congestion control less responsive. The broadcasted information can only be used to extract statistical information. The discarding scheme needs carefully-chosen status information and reduction function, and normally requires a significant amount of ground discarding to reduce the on-board packet loss probability. The tagging scheme is more effective since it tolerates more uncertainties and allows a larger margin of error in status information. It can protect the high-priority packets from excessive loss and fully utilize the downlink bandwidth at the same time.

A robust low-rate coding scheme for packet video

NASA Technical Reports Server (NTRS)

Chen, Y. C.; Sayood, Khalid; Nelson, D. J.; Arikan, E. (Editor)

1991-01-01

Due to the rapidly evolving field of image processing and networking, video information promises to be an important part of telecommunication systems. Although up to now video transmission has been transported mainly over circuit-switched networks, it is likely that packet-switched networks will dominate the communication world in the near future. Asynchronous transfer mode (ATM) techniques in broadband-ISDN can provide a flexible, independent and high performance environment for video communication. For this paper, the network simulator was used only as a channel in this simulation. Mixture blocking coding with progressive transmission (MBCPT) has been investigated for use over packet networks and has been found to provide high compression rate with good visual performance, robustness to packet loss, tractable integration with network mechanics and simplicity in parallel implementation.

Silicon-Germanium Fast Packet Switch Developed for Communications Satellites

NASA Technical Reports Server (NTRS)

Quintana, Jorge A.

1999-01-01

Emerging multimedia applications and future satellite systems will require high-speed switching networks to accommodate high data-rate traffic among thousands of potential users. This will require advanced switching devices to enable communication between satellites. The NASA Lewis Research Center has been working closely with industry to develop a state-of-the-art fast packet switch (FPS) to fulfill this requirement. Recently, the Satellite Industry Task Force identified the need for high-capacity onboard processing switching components as one of the "grand challenges" for the satellite industry in the 21st century. In response to this challenge, future generations of onboard processing satellites will require low power and low mass components to enable transmission of services in the 100 gigabit (1011 bits) per second (Gbps) range.

Distributed synchronization control of complex networks with communication constraints.

PubMed

Xu, Zhenhua; Zhang, Dan; Song, Hongbo

2016-11-01

This paper is concerned with the distributed synchronization control of complex networks with communication constraints. In this work, the controllers communicate with each other through the wireless network, acting as a controller network. Due to the constrained transmission power, techniques such as the packet size reduction and transmission rate reduction schemes are proposed which could help reduce communication load of the controller network. The packet dropout problem is also considered in the controller design since it is often encountered in networked control systems. We show that the closed-loop system can be modeled as a switched system with uncertainties and random variables. By resorting to the switched system approach and some stochastic system analysis method, a new sufficient condition is firstly proposed such that the exponential synchronization is guaranteed in the mean-square sense. The controller gains are determined by using the well-known cone complementarity linearization (CCL) algorithm. Finally, a simulation study is performed, which demonstrates the effectiveness of the proposed design algorithm. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

47 CFR 32.2212 - Digital electronic switching.

Code of Federal Regulations, 2012 CFR

2012-10-01

... shall include the original cost of digital electronic switching equipment used to provide circuit... electronic switching equipment used to provide both circuit and packet switching shall be recorded in the... 47 Telecommunication 2 2012-10-01 2012-10-01 false Digital electronic switching. 32.2212 Section...

47 CFR 32.2212 - Digital electronic switching.

Code of Federal Regulations, 2014 CFR

2014-10-01

... shall include the original cost of digital electronic switching equipment used to provide circuit... electronic switching equipment used to provide both circuit and packet switching shall be recorded in the... 47 Telecommunication 2 2014-10-01 2014-10-01 false Digital electronic switching. 32.2212 Section...

47 CFR 32.2212 - Digital electronic switching.

Code of Federal Regulations, 2011 CFR

2011-10-01

... shall include the original cost of digital electronic switching equipment used to provide circuit... electronic switching equipment used to provide both circuit and packet switching shall be recorded in the... 47 Telecommunication 2 2011-10-01 2011-10-01 false Digital electronic switching. 32.2212 Section...

47 CFR 32.2212 - Digital electronic switching.

Code of Federal Regulations, 2010 CFR

2010-10-01

... shall include the original cost of digital electronic switching equipment used to provide circuit... electronic switching equipment used to provide both circuit and packet switching shall be recorded in the... 47 Telecommunication 2 2010-10-01 2010-10-01 false Digital electronic switching. 32.2212 Section...

47 CFR 32.2212 - Digital electronic switching.

Code of Federal Regulations, 2013 CFR

2013-10-01

... shall include the original cost of digital electronic switching equipment used to provide circuit... electronic switching equipment used to provide both circuit and packet switching shall be recorded in the... 47 Telecommunication 2 2013-10-01 2013-10-01 false Digital electronic switching. 32.2212 Section...

Numerical and experimental study of a high port-density WDM optical packet switch architecture for data centers.

PubMed

Di Lucente, S; Luo, J; Centelles, R Pueyo; Rohit, A; Zou, S; Williams, K A; Dorren, H J S; Calabretta, N

2013-01-14

Data centers have to sustain the rapid growth of data traffic due to the increasing demand of bandwidth-hungry internet services. The current intra-data center fat tree topology causes communication bottlenecks in the server interaction process, power-hungry O-E-O conversions that limit the minimum latency and the power efficiency of these systems. In this paper we numerically and experimentally investigate an optical packet switch architecture with modular structure and highly distributed control that allow configuration times in the order of nanoseconds. Numerical results indicate that the candidate architecture scaled over 4000 ports, provides an overall throughput over 50 Tb/s and a packet loss rate below 10(-6) while assuring sub-microsecond latency. We present experimental results that demonstrate the feasibility of a 16x16 optical packet switch based on parallel 1x4 integrated optical cross-connect modules. Error-free operations can be achieved with 4 dB penalty while the overall energy consumption is of 66 pJ/b. Based on those results, we discuss feasibility to scale the architecture to a much larger port count.

IpexT: Integrated Planning and Execution for Military Satellite Tele-Communications

NASA Technical Reports Server (NTRS)

Plaunt, Christian; Rajan, Kanna

2004-01-01

The next generation of military communications satellites may be designed as a fast packet-switched constellation of spacecraft able to withstand substantial bandwidth capacity fluctuation in the face of dynamic resource utilization and rapid environmental changes including jamming of communication frequencies and unstable weather phenomena. We are in the process of designing an integrated scheduling and execution tool which will aid in the analysis of the design parameters needed for building such a distributed system for nominal and battlefield communications. This paper discusses the design of such a system based on a temporal constraint posting planner/scheduler and a smart executive which can cope with a dynamic environment to make a more optimal utilization of bandwidth than the current circuit switched based approach.

Unified study of Quality of Service (QoS) in OPS/OBS networks

NASA Astrophysics Data System (ADS)

Hailu, Dawit Hadush; Lema, Gebrehiwet Gebrekrstos; Yekun, Ephrem Admasu; Kebede, Samrawit Haylu

2017-07-01

With the growth of Internet traffic, an inevitable use of optical networks provide a large bandwidth, fast data transmission rates and Quality of Service (QoS) support. Currently, Optical Burst Switched (OBS)/Optical Packet Switched (OPS) networks are under study as future solutions for addressing the increase demand of Internet traffic. However, due to their high blocking probability in the intermediate nodes they have been delayed in the industries. Packet loss in OBS/OPS networks is mainly occur due to contention. Hence, the contribution of this study is to analyze the file loss ratio (FLR), packet overhead and number of disjoint paths, and processing delay over Coded Packet Transport (CPT) scheme for OBS/OPS network using simulation. The simulations show that CPT scheme reduces the FLR in OBS/OPS network for the evaluated scenarios since the data packets are chopped off into blocks of the data packet for transmission over a network. Simulation results for secrecy and survivability are verified with the help of the analytical model to define the operational range of CPT scheme.

Free-space optics technology employed in an UMTS release 4 bearer independent core network access part

NASA Astrophysics Data System (ADS)

Bibac, Ionut

2005-08-01

The UMTS Bearer Independent Core Network program introduced the 3rd Generation Partnership Program Release 4 BICN architecture into the legacy UMTS TDM-switched network. BICN is the application of calI server archltecture for voice and circuit switched data, enabling the provisioning of traditional circuit-switched services using a packet-switched transport network. Today"s business climate has made it essential for service providers to develop a comprehensive networking strategy that means introduction of RCBICN networks. The R4-BICN solution to the evolution of the Core Network in UMTS will enable operators to significantly reduce the capital and operational costs of delivering both traditional voice sewices and new multimedia services. To build the optical backbone, which can support the third generation (3G) packetized infrastructure, the operators could choose a fibre connection, or they could retain the benefits of a wireless connectivity by using a FSO - Free Space Optical lmk, the only wireless technology available that is capable of achieving data rates up to 2.4 Gbit/s. FSO offers viable alternatives for both core transmission networks and for replacing microwaves links in NodeB - RNC access networks. The paper and presentation aim to demonstrate the manner in which FSO products and networks are employed into R4-BICN design solutions.

Satellite networks in the ISDN era

NASA Astrophysics Data System (ADS)

Amadesi, P.; Haines, P.; Patacchini, A.

1986-12-01

The development of an integrated service digital network (ISDN) capable of supporting a wide range of services using a small set of standard multipurpose user-network interfaces is examined. The ISDN environment is expected to consist of functional elements such as, circuit switching, packet switching, and common channel signaling. The use of satellites or fiber optics in the ISDN is evaluated. The relation between satellites and the ISDN in the short-, medium-, and long-terms is analyzed. The recommendations of the consultative committee, CCIR, concerning the definition of the hypothetical reference digital path and the required quality and availability for ISDN applications, and the proposed plans of Eutelsat and Intelsat for satellite systems compatible with an ISDN are discussed. The application of business satellite networks and packet satellite networks to an ISDN is studied. The long-term objectives for an ISDN is a wideband system that accommodates digital transmission on circuit and packet switched bases.

High-performance flat data center network architecture based on scalable and flow-controlled optical switching system

NASA Astrophysics Data System (ADS)

Calabretta, Nicola; Miao, Wang; Dorren, Harm

2016-03-01

Traffic in data centers networks (DCNs) is steadily growing to support various applications and virtualization technologies. Multi-tenancy enabling efficient resource utilization is considered as a key requirement for the next generation DCs resulting from the growing demands for services and applications. Virtualization mechanisms and technologies can leverage statistical multiplexing and fast switch reconfiguration to further extend the DC efficiency and agility. We present a novel high performance flat DCN employing bufferless and distributed fast (sub-microsecond) optical switches with wavelength, space, and time switching operation. The fast optical switches can enhance the performance of the DCNs by providing large-capacity switching capability and efficiently sharing the data plane resources by exploiting statistical multiplexing. Benefiting from the Software-Defined Networking (SDN) control of the optical switches, virtual DCNs can be flexibly created and reconfigured by the DCN provider. Numerical and experimental investigations of the DCN based on the fast optical switches show the successful setup of virtual network slices for intra-data center interconnections. Experimental results to assess the DCN performance in terms of latency and packet loss show less than 10^-5 packet loss and 640ns end-to-end latency with 0.4 load and 16- packet size buffer. Numerical investigation on the performance of the systems when the port number of the optical switch is scaled to 32x32 system indicate that more than 1000 ToRs each with Terabit/s interface can be interconnected providing a Petabit/s capacity. The roadmap to photonic integration of large port optical switches will be also presented.

Routing and Addressing Problems in Large Metropolitan-Scale Internetworks. ISI Research Report.

ERIC Educational Resources Information Center

Finn, Gregory G.

This report discusses some of the problems and limitations in existing internetwork design for the connection of packet-switching networks of different technologies and presents an algorithm that has been shown to be suitable for internetworks of unbounded size. Using a new form of address and a flat routing mechanism called Cartesian routing,…

Principle and verification of novel optical virtual private networks over multiprotocol label switching/optical packet switching networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Wang, Zhengsuan; Jin, Wei; Qiu, Kun

2012-11-01

A novel realization method of the optical virtual private networks (OVPN) over multiprotocol label switching/optical packet switching (MPLS/OPS) networks is proposed. In this scheme, the introduction of MPLS control plane makes OVPN over OPS networks more reliable and easier; OVPN makes use of the concept of high reconfiguration of light-paths offered by MPLS, to set up secure tunnels of high bandwidth across intelligent OPS networks. Through resource management, the signal mechanism, connection control, and the architecture of the creation and maintenance of OVPN are efficiently realized. We also present an OVPN architecture with two traffic priorities, which is used to analyze the capacity, throughput, delay time of the proposed networks, and the packet loss rate performance of the OVPN over MPLS/OPS networks based on full mesh topology. The results validate the applicability of such reliable connectivity to high quality services in the OVPN over MPLS/OPS networks. Along with the results, the feasibility of the approach as the basis for the next generation networks is demonstrated and discussed.

Programmable on-chip and off-chip network architecture on demand for flexible optical intra-datacenters.

PubMed

Rofoee, Bijan Rahimzadeh; Zervas, Georgios; Yan, Yan; Amaya, Norberto; Qin, Yixuan; Simeonidou, Dimitra

2013-03-11

The paper presents a novel network architecture on demand approach using on-chip and-off chip implementations, enabling programmable, highly efficient and transparent networking, well suited for intra-datacenter communications. The implemented FPGA-based adaptable line-card with on-chip design along with an architecture on demand (AoD) based off-chip flexible switching node, deliver single chip dual L2-Packet/L1-time shared optical network (TSON) server Network Interface Cards (NIC) interconnected through transparent AoD based switch. It enables hitless adaptation between Ethernet over wavelength switched network (EoWSON), and TSON based sub-wavelength switching, providing flexible bitrates, while meeting strict bandwidth, QoS requirements. The on and off-chip performance results show high throughput (9.86Ethernet, 8.68Gbps TSON), high QoS, as well as hitless switch-over.

Asynchronous State Estimation for Discrete-Time Switched Complex Networks With Communication Constraints.

PubMed

Zhang, Dan; Wang, Qing-Guo; Srinivasan, Dipti; Li, Hongyi; Yu, Li

2018-05-01

This paper is concerned with the asynchronous state estimation for a class of discrete-time switched complex networks with communication constraints. An asynchronous estimator is designed to overcome the difficulty that each node cannot access to the topology/coupling information. Also, the event-based communication, signal quantization, and the random packet dropout problems are studied due to the limited communication resource. With the help of switched system theory and by resorting to some stochastic system analysis method, a sufficient condition is proposed to guarantee the exponential stability of estimation error system in the mean-square sense and a prescribed performance level is also ensured. The characterization of the desired estimator gains is derived in terms of the solution to a convex optimization problem. Finally, the effectiveness of the proposed design approach is demonstrated by a simulation example.

Optical implementation of a parallel out-of-band controller for large broadband ATM switch applications

NASA Astrophysics Data System (ADS)

Cloonan, Thomas J.; Richards, Gaylord W.; Lentine, Anthony L.

1996-03-01

Asynchronous transfer mode (ATM) is rapidly becoming the transport mechanism of choice for the information superhighway, because it promises the bandwidth and flexibility needed for many voice, video and data service offerings. Some industry experts project that the required sizes for ATM switching equipment in the public-switched environment will reach the Tbps range by the beginning of the next decade. This paper analyzes the problems associated with controlling the flow of packets within a broadband ATM switch of this size. The analysis is based on the requirements of the growable packet switch architecture. The paper proposes a novel solution to the problem of hunting paths within an ATM packet switch network. The resulting control scheme is unconventional in two ways. First, it uses an out-of-band control algorithm instead of the more common self-routing approach. In particular, we explore the benefits of using a parallel processor as an out-of-band controller for a growable packet switch distribution network. The processor permits additional levels of parallelism to be added to the out-of-band control function so that path hunts can be performed for all N of the input ports within a single cell interval. The proposed approach is also unconventional because it uses free-space digital optics to guide signals between successive stages of the controller. The paper describes the underlying motivations for implementing an optical out-of-band controller for an ATM switch, and it also describes the logic within a controller node that has been fabricated using a hybrid Si CMOS/GaAs SEED technology. The node uses optical detectors (in GaAs), amplifiers and digital control logic (in Si), and optical modulators (in GaAs). Free-space optical connections between successive device arrays can be provided using either bulk optical elements or micro-optics, but the optical interconnects must provide massive fanout capability. An architectural analysis studying the feasibility of applying free-space optics in this proposed ATM switch controller also is presented.

Predictive onboard flow control for packet switching satellites

NASA Technical Reports Server (NTRS)

Bobinsky, Eric A.

1992-01-01

We outline two alternate approaches to predicting the onset of congestion in a packet switching satellite, and argue that predictive, rather than reactive, flow control is necessary for the efficient operation of such a system. The first method discussed is based on standard, statistical techniques which are used to periodically calculate a probability of near-term congestion based on arrival rate statistics. If this probability exceeds a present threshold, the satellite would transmit a rate-reduction signal to all active ground stations. The second method discussed would utilize a neural network to periodically predict the occurrence of buffer overflow based on input data which would include, in addition to arrival rates, the distributions of packet lengths, source addresses, and destination addresses.

MoNET: media over net gateway processor for next-generation network

NASA Astrophysics Data System (ADS)

Elabd, Hammam; Sundar, Rangarajan; Dedes, John

2001-12-01

MoNETTM (Media over Net) SX000 product family is designed using a scalable voice, video and packet-processing platform to address applications with channel densities from few voice channels to four OC3 per card. This platform is developed for bridging public circuit-switched network to the next generation packet telephony and data network. The platform consists of a DSP farm, RISC processors and interface modules. DSP farm is required to execute voice compression, image compression and line echo cancellation algorithms for large number of voice, video, fax, and modem or data channels. RISC CPUs are used for performing various packetizations based on RTP, UDP/IP and ATM encapsulations. In addition, RISC CPUs also participate in the DSP farm load management and communication with the host and other MoP devices. The MoNETTM S1000 communications device is designed for voice processing and for bridging TDM to ATM and IP packet networks. The S1000 consists of the DSP farm based on Carmel DSP core and 32-bit RISC CPU, along with Ethernet, Utopia, PCI, and TDM interfaces. In this paper, we will describe the VoIP infrastructure, building blocks of the S500, S1000 and S3000 devices, algorithms executed on these device and associated channel densities, detailed DSP architecture, memory architecture, data flow and scheduling.

Next generation communications satellites: multiple access and network studies

NASA Technical Reports Server (NTRS)

Meadows, H. E.; Schwartz, M.; Stern, T. E.; Ganguly, S.; Kraimeche, B.; Matsuo, K.; Gopal, I.

1982-01-01

Efficient resource allocation and network design for satellite systems serving heterogeneous user populations with large numbers of small direct-to-user Earth stations are discussed. Focus is on TDMA systems involving a high degree of frequency reuse by means of satellite-switched multiple beams (SSMB) with varying degrees of onboard processing. Algorithms for the efficient utilization of the satellite resources were developed. The effect of skewed traffic, overlapping beams and batched arrivals in packet-switched SSMB systems, integration of stream and bursty traffic, and optimal circuit scheduling in SSMB systems: performance bounds and computational complexity are discussed.

Implementation of a system to provide mobile satellite services in North America

NASA Technical Reports Server (NTRS)

Johanson, Gary A.; Davies, N. George; Tisdale, William R. H.

1993-01-01

This paper describes the implementation of the ground network to support Mobile Satellite Services (MSS). The system is designed to take advantage of a powerful new satellite series and provides significant improvements in capacity and throughput over systems in service today. The system is described in terms of the services provided and the system architecture being implemented to deliver those services. The system operation is described including examples of a circuit switched and packet switched call placement. The physical architecture is presented showing the major hardware components and software functionality placement within the hardware.

Multirate parallel distributed compensation of a cluster in wireless sensor and actor networks

NASA Astrophysics Data System (ADS)

Yang, Chun-xi; Huang, Ling-yun; Zhang, Hao; Hua, Wang

2016-01-01

The stabilisation problem for one of the clusters with bounded multiple random time delays and packet dropouts in wireless sensor and actor networks is investigated in this paper. A new multirate switching model is constructed to describe the feature of this single input multiple output linear system. According to the difficulty of controller design under multi-constraints in multirate switching model, this model can be converted to a Takagi-Sugeno fuzzy model. By designing a multirate parallel distributed compensation, a sufficient condition is established to ensure this closed-loop fuzzy control system to be globally exponentially stable. The solution of the multirate parallel distributed compensation gains can be obtained by solving an auxiliary convex optimisation problem. Finally, two numerical examples are given to show, compared with solving switching controller, multirate parallel distributed compensation can be obtained easily. Furthermore, it has stronger robust stability than arbitrary switching controller and single-rate parallel distributed compensation under the same conditions.

SDN architecture for optical packet and circuit integrated networks

NASA Astrophysics Data System (ADS)

Furukawa, Hideaki; Miyazawa, Takaya

2016-02-01

We have been developing an optical packet and circuit integrated (OPCI) network, which realizes dynamic optical path, high-density packet multiplexing, and flexible wavelength resource allocation. In the OPCI networks, a best-effort service and a QoS-guaranteed service are provided by employing optical packet switching (OPS) and optical circuit switching (OCS) respectively, and users can select these services. Different wavelength resources are assigned for OPS and OCS links, and the amount of their wavelength resources are dynamically changed in accordance with the service usage conditions. To apply OPCI networks into wide-area (core/metro) networks, we have developed an OPCI node with a distributed control mechanism. Moreover, our OPCI node works with a centralized control mechanism as well as a distributed one. It is therefore possible to realize SDN-based OPCI networks, where resource requests and a centralized configuration are carried out. In this paper, we show our SDN architecture for an OPS system that configures mapping tables between IP addresses and optical packet addresses and switching tables according to the requests from multiple users via a web interface. While OpenFlow-based centralized control protocol is coming into widespread use especially for single-administrative, small-area (LAN/data-center) networks. Here, we also show an interworking mechanism between OpenFlow-based networks (OFNs) and the OPCI network for constructing a wide-area network, and a control method of wavelength resource selection to automatically transfer diversified flows from OFNs to the OPCI network.

Prioritized retransmission in slotted all-optical packet-switched networks

NASA Astrophysics Data System (ADS)

Ghaffar Pour Rahbar, Akbar; Yang, Oliver

2006-12-01

We consider an all-optical slotted packet-switched network interconnected by a number of bufferless all-optical switches with contention-based operation. One approach to reduce the cost of the expensive contention resolution hardware could be retransmission in which each ingress switch keeps a copy of the transmitted traffic in the electronic buffer and retransmits whenever required. The conventional retransmission technique may need a higher number of retransmissions until traffic passes through the network. This in turn may lead to a retransmission at a higher layer and reduce the network throughput. In this paper, we propose and analyze a simple but effective prioritized retransmission technique in which dropped traffic is prioritized when retransmitted from ingress switches so that the core switch can process them with a higher priority. We present the analysis of both techniques in multifiber network architecture and verify it via simulation to demonstrate that our proposed algorithm can limit the number of retransmissions significantly and can improve TCP throughput better than the conventional retransmission technique.

GLOBECOM '89 - IEEE Global Telecommunications Conference and Exhibition, Dallas, TX, Nov. 27-30, 1989, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

The present conference discusses topics in multiwavelength network technology and its applications, advanced digital radio systems in their propagation environment, mobile radio communications, switching programmability, advancements in computer communications, integrated-network management and security, HDTV and image processing in communications, basic exchange communications radio advancements in digital switching, intelligent network evolution, speech coding for telecommunications, and multiple access communications. Also discussed are network designs for quality assurance, recent progress in coherent optical systems, digital radio applications, advanced communications technologies for mobile users, communication software for switching systems, AI and expert systems in network management, intelligent multiplexing nodes, video and image coding, network protocols and performance, system methods in quality and reliability, the design and simulation of lightwave systems, local radio networks, mobile satellite communications systems, fiber networks restoration, packet video networks, human interfaces for future networks, and lightwave networking.

Research and development of a NYNEX switched multi-megabit data service prototype system

NASA Astrophysics Data System (ADS)

Maman, K. H.; Haines, Robert; Chatterjee, Samir

1991-02-01

Switched Multi-megabit Data Service (SMDS) is a proposed high-speed packet-switched service which will support broadband applications such as Local Area Network (LAN) interconnections across a metropolitan area and beyond. This service is designed to take advantage of evolving Metropolitan Area Network (MAN) standards and technology which will provide customers with 45-mbps and 1 . 5-mbps access to high-speed public data communications networks. This paper will briefly discuss SMDS and review its architecture including the Subscriber Network Interface (SNI) and the SMDS Interface Protocol (SIP). It will review the fundamental features of SMDS such as address screening addressing scheme and access classes. Then it will describe the SMDS prototype system developed in-house by NYNEX Science Technology.

A novel all-optical label processing based on multiple optical orthogonal codes sequences for optical packet switching networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Xu, Bo; Ling, Yun

2008-05-01

This paper proposes an all-optical label processing scheme that uses the multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) networks. In this scheme, each MOOCS is a permutation or combination of the multiple optical orthogonal codes (MOOC) selected from the multiple-groups optical orthogonal codes (MGOOC). Following a comparison of different optical label processing (OLP) schemes, the principles of MOOCS-OPS network are given and analyzed. Firstly, theoretical analyses are used to prove that MOOCS is able to greatly enlarge the number of available optical labels when compared to the previous single optical orthogonal code (SOOC) for OPS (SOOC-OPS) network. Then, the key units of the MOOCS-based optical label packets, including optical packet generation, optical label erasing, optical label extraction and optical label rewriting etc., are given and studied. These results are used to verify that the proposed MOOCS-OPS scheme is feasible.

PAD_AUDIT -- PAD Auditing Package

NASA Astrophysics Data System (ADS)

Clayton, C. A.

The PAD (Packet Assembler Disassembler) utility is the part of the VAX/VMS Coloured Book Software (CBS) which allows a user to log onto remote computers from a local VAX. Unfortunately, logging into a computer via either the Packet SwitchStream (PSS) or the International Packet SwitchStream (IPSS) costs real money. Some users either do not appreciate this or do not care and have been known to clock up rather large quarterly bills. This software package allows a system manager to determine who has used PAD to call where and (most importantly) how much it has cost. The system manager can then take appropriate action - either charging the individuals, warning them to use the facility with more care or even denying access to a greedy user to one or more sites.

A microprocessor based high speed packet switch for satellite communications

NASA Technical Reports Server (NTRS)

Arozullah, M.; Crist, S. C.

1980-01-01

The architectures of a single processor, a three processor, and a multiple processor system are described. The hardware circuits, and software routines required for implementing the three and multiple processor designs are presented. A bit-slice microprocessor was designed and microprogrammed. Maximum throughput was calculated for all three designs. Queue theoretic models for these three designs were developed and utilized to obtain analytical expressions for the average waiting times, overall average response times and average queue sizes. From these expressions, graphs were obtained showing the effect on the system performance of a number of design parameters.

A knowledge-based system with learning for computer communication network design

NASA Technical Reports Server (NTRS)

Pierre, Samuel; Hoang, Hai Hoc; Tropper-Hausen, Evelyne

1990-01-01

Computer communication network design is well-known as complex and hard. For that reason, the most effective methods used to solve it are heuristic. Weaknesses of these techniques are listed and a new approach based on artificial intelligence for solving this problem is presented. This approach is particularly recommended for large packet switched communication networks, in the sense that it permits a high degree of reliability and offers a very flexible environment dealing with many relevant design parameters such as link cost, link capacity, and message delay.

Stochastic sampled-data control for synchronization of complex dynamical networks with control packet loss and additive time-varying delays.

PubMed

Rakkiyappan, R; Sakthivel, N; Cao, Jinde

2015-06-01

This study examines the exponential synchronization of complex dynamical networks with control packet loss and additive time-varying delays. Additionally, sampled-data controller with time-varying sampling period is considered and is assumed to switch between m different values in a random way with given probability. Then, a novel Lyapunov-Krasovskii functional (LKF) with triple integral terms is constructed and by using Jensen's inequality and reciprocally convex approach, sufficient conditions under which the dynamical network is exponentially mean-square stable are derived. When applying Jensen's inequality to partition double integral terms in the derivation of linear matrix inequality (LMI) conditions, a new kind of linear combination of positive functions weighted by the inverses of squared convex parameters appears. In order to handle such a combination, an effective method is introduced by extending the lower bound lemma. To design the sampled-data controller, the synchronization error system is represented as a switched system. Based on the derived LMI conditions and average dwell-time method, sufficient conditions for the synchronization of switched error system are derived in terms of LMIs. Finally, numerical example is employed to show the effectiveness of the proposed methods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Capture and playback synchronization in video conferencing

NASA Astrophysics Data System (ADS)

Shae, Zon-Yin; Chang, Pao-Chi; Chen, Mon-Song

1995-03-01

Packet-switching based video conferencing has emerged as one of the most important multimedia applications. Lip synchronization can be disrupted in the packet network as the result of the network properties: packet delay jitters at the capture end, network delay jitters, packet loss, packet arrived out of sequence, local clock mismatch, and video playback overlay with the graphic system. The synchronization problem become more demanding as the real time and multiparty requirement of the video conferencing application. Some of the above mentioned problem can be solved in the more advanced network architecture as ATM having promised. This paper will present some of the solutions to the problems that can be useful at the end station terminals in the massively deployed packet switching network today. The playback scheme in the end station will consist of two units: compression domain buffer management unit and the pixel domain buffer management unit. The pixel domain buffer management unit is responsible for removing the annoying frame shearing effect in the display. The compression domain buffer management unit is responsible for parsing the incoming packets for identifying the complete data blocks in the compressed data stream which can be decoded independently. The compression domain buffer management unit is also responsible for concealing the effects of clock mismatch, lip synchronization, and packet loss, out of sequence, and network jitters. This scheme can also be applied to the multiparty teleconferencing environment. Some of the schemes presented in this paper have been implemented in the Multiparty Multimedia Teleconferencing (MMT) system prototype at the IBM watson research center.

Intelligent deflection routing in buffer-less networks.

PubMed

Haeri, Soroush; Trajković, Ljiljana

2015-02-01

Deflection routing is employed to ameliorate packet loss caused by contention in buffer-less architectures such as optical burst-switched networks. The main goal of deflection routing is to successfully deflect a packet based only on a limited knowledge that network nodes possess about their environment. In this paper, we present a framework that introduces intelligence to deflection routing (iDef). iDef decouples the design of the signaling infrastructure from the underlying learning algorithm. It consists of a signaling and a decision-making module. Signaling module implements a feedback management protocol while the decision-making module implements a reinforcement learning algorithm. We also propose several learning-based deflection routing protocols, implement them in iDef using the ns-3 network simulator, and compare their performance.

A novel coherent optical en/decoder for optical label processing of OCDM-based optical packets switching networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun

2007-11-01

A coherent optical en/decoder based on photonic crystal (PhC) for optical code-division-multiple (OCDM)-based optical label (OCDM-OL) optical packets switching (OPS) networks is proposed in this paper. In this scheme, the optical pulse phase and time delay can be flexibly controlled by the photonic crystal phase shifter and delayer using the appropriate design of fabrication. In this design, the combination calculation of the impurity and normal period layers is applied, according to the PhC transmission matrix theorem. The design and theoretical analysis of the PhC-based optical coherent en/decoder is mainly focused. In addition, the performances of the PhC-based optical en/decoders are analyzed in detail. The reflection, the transmission, delay characteristic and the optical spectrum of pulse en/decoded are studied for the waves tuned in the photonic band-gap by the numerical calculation, taking into account 1-Dimension (1D) PhC. Theoretical analysis and numerical results show that optical pulse is achieved to properly phase modulation and time delay by the proposed scheme, optical label based on OCDM is rewrote successfully by new code for OCDM-based OPS (OCDM-OPS), and an over 8.5 dB ration of auto- and cross-correlation is gained, which demonstrates the applicability of true pulse phase modulation in a number of applications.

Smart home design for electronic devices monitoring based wireless gateway network using cisco packet tracer

NASA Astrophysics Data System (ADS)

Sihombing, Oloan; Zendrato, Niskarto; Laia, Yonata; Nababan, Marlince; Sitanggang, Delima; Purba, Windania; Batubara, Diarmansyah; Aisyah, Siti; Indra, Evta; Siregar, Saut

2018-04-01

In the era of technological development today, the technology has become the need for the life of today's society. One is needed to create a smart home in turning on and off electronic devices via smartphone. So far in turning off and turning the home electronic device is done by pressing the switch or remote button, so in control of electronic device control less effective. The home smart design is done by simulation concept by testing system, network configuration, and wireless home gateway computer network equipment required by a smart home network on cisco packet tracer using Internet Thing (IoT) control. In testing the IoT home network wireless network gateway system, multiple electronic devices can be controlled and monitored via smartphone based on predefined configuration conditions. With the Smart Ho me can potentially increase energy efficiency, decrease energy usage costs, control electronics and change the role of residents.

7 CFR 1770.15 - Supplementary accounts required of all borrowers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Switching—Circuit. 2212.2 2212.2 Digital Electronic Switching—Packet. 2230.11 Central Office Transmission... Retirement Work in Progress. Current Liabilities 2232.1 2232.1 Circuit Equipment—Electronic. 2232.2 2232.2... Expense—Circuit. 6212.2 6212.2 Digital Electronic Switching Expense—Packet. 6230.11 Radio Systems Expense...

7 CFR 1770.15 - Supplementary accounts required of all borrowers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Switching—Circuit. 2212.2 2212.2 Digital Electronic Switching—Packet. 2230.11 Central Office Transmission... Retirement Work in Progress. Current Liabilities 2232.1 2232.1 Circuit Equipment—Electronic. 2232.2 2232.2... Expense—Circuit. 6212.2 6212.2 Digital Electronic Switching Expense—Packet. 6230.11 Radio Systems Expense...

7 CFR 1770.15 - Supplementary accounts required of all borrowers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Switching—Circuit. 2212.2 2212.2 Digital Electronic Switching—Packet. 2230.11 Central Office Transmission... Retirement Work in Progress. Current Liabilities 2232.1 2232.1 Circuit Equipment—Electronic. 2232.2 2232.2... Expense—Circuit. 6212.2 6212.2 Digital Electronic Switching Expense—Packet. 6230.11 Radio Systems Expense...

Digital optical processing of optical communications: towards an Optical Turing Machine

NASA Astrophysics Data System (ADS)

Touch, Joe; Cao, Yinwen; Ziyadi, Morteza; Almaiman, Ahmed; Mohajerin-Ariaei, Amirhossein; Willner, Alan E.

2017-01-01

Optical computing is needed to support Tb/s in-network processing in a way that unifies communication and computation using a single data representation that supports in-transit network packet processing, security, and big data filtering. Support for optical computation of this sort requires leveraging the native properties of optical wave mixing to enable computation and switching for programmability. As a consequence, data must be encoded digitally as phase (M-PSK), semantics-preserving regeneration is the key to high-order computation, and data processing at Tb/s rates requires mixing. Experiments have demonstrated viable approaches to phase squeezing and power restoration. This work led our team to develop the first serial, optical Internet hop-count decrement, and to design and simulate optical circuits for calculating the Internet checksum and multiplexing Internet packets. The current exploration focuses on limited-lookback computational models to reduce the need for permanent storage and hybrid nanophotonic circuits that combine phase-aligned comb sources, non-linear mixing, and switching on the same substrate to avoid the macroscopic effects that hamper benchtop prototypes.

A scheme for synchronizing clocks connected by a packet communication network

NASA Astrophysics Data System (ADS)

dos Santos, R. V.; Monteiro, L. H. A.

2012-07-01

Consider a communication system in which a transmitter equipment sends fixed-size packets of data at a uniform rate to a receiver equipment. Consider also that these equipments are connected by a packet-switched network, which introduces a random delay to each packet. Here we propose an adaptive clock recovery scheme able of synchronizing the frequencies and the phases of these devices, within specified limits of precision. This scheme for achieving frequency and phase synchronization is based on measurements of the packet arrival times at the receiver, which are used to control the dynamics of a digital phase-locked loop. The scheme performance is evaluated via numerical simulations performed by using realistic parameter values.

Destination-directed, packet-switched architecture for a geostationary communications satellite network

NASA Technical Reports Server (NTRS)

Ivancic, William D.; Shalkhauser, Mary JO; Bobinsky, Eric A.; Soni, Nitin J.; Quintana, Jorge A.; Kim, Heechul; Wager, Paul; Vanderaar, Mark

1993-01-01

A major goal of the Digital Systems Technology Branch at the NASA Lewis Research Center is to identify and develop critical digital components and technologies that either enable new commercial missions or significantly enhance the performance, cost efficiency, and/or reliability of existing and planned space communications systems. NASA envisions a need for low-data-rate, interactive, direct-to-the-user communications services for data, voice, facsimile, and video conferencing. The network would provide enhanced very-small-aperture terminal (VSAT) communications services and be capable of handling data rates of 64 kbps through 2.048 Mbps in 64-kbps increments. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints. The focus of current space segment developments is a flexible, high-throughput, fault-tolerant onboard information-switching processor (ISP) for a geostationary satellite communications network. The Digital Systems Technology Branch is investigating both circuit and packet architectures for the ISP. Destination-directed, packet-switched architectures for geostationary communications satellites are addressed.

Network traffic behaviour near phase transition point

NASA Astrophysics Data System (ADS)

Lawniczak, A. T.; Tang, X.

2006-03-01

We explore packet traffic dynamics in a data network model near phase transition point from free flow to congestion. The model of data network is an abstraction of the Network Layer of the OSI (Open Systems Interconnect) Reference Model of packet switching networks. The Network Layer is responsible for routing packets across the network from their sources to their destinations and for control of congestion in data networks. Using the model we investigate spatio-temporal packets traffic dynamics near the phase transition point for various network connection topologies, and static and adaptive routing algorithms. We present selected simulation results and analyze them.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dong; Heidelberger, Philip; Sugawara, Yutaka

An apparatus and method for extending the scalability and improving the partitionability of networks that contain all-to-all links for transporting packet traffic from a source endpoint to a destination endpoint with low per-endpoint (per-server) cost and a small number of hops. An all-to-all wiring in the baseline topology is decomposed into smaller all-to-all components in which each smaller all-to-all connection is replaced with star topology by using global switches. Stacking multiple copies of the star topology baseline network creates a multi-planed switching topology for transporting packet traffic. Point-to-point unified stacking method using global switch wiring methods connects multiple planes ofmore » a baseline topology by using the global switches to create a large network size with a low number of hops, i.e., low network latency. Grouped unified stacking method increases the scalability (network size) of a stacked topology.« less

Final report for the Multiprotocol Label Switching (MPLS) control plane security LDRD project.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Torgerson, Mark Dolan; Michalski, John T.; Tarman, Thomas David

2003-09-01

As rapid Internet growth continues, global communications becomes more dependent on Internet availability for information transfer. Recently, the Internet Engineering Task Force (IETF) introduced a new protocol, Multiple Protocol Label Switching (MPLS), to provide high-performance data flows within the Internet. MPLS emulates two major aspects of the Asynchronous Transfer Mode (ATM) technology. First, each initial IP packet is 'routed' to its destination based on previously known delay and congestion avoidance mechanisms. This allows for effective distribution of network resources and reduces the probability of congestion. Second, after route selection each subsequent packet is assigned a label at each hop, whichmore » determines the output port for the packet to reach its final destination. These labels guide the forwarding of each packet at routing nodes more efficiently and with more control than traditional IP forwarding (based on complete address information in each packet) for high-performance data flows. Label assignment is critical in the prompt and accurate delivery of user data. However, the protocols for label distribution were not adequately secured. Thus, if an adversary compromises a node by intercepting and modifying, or more simply injecting false labels into the packet-forwarding engine, the propagation of improperly labeled data flows could create instability in the entire network. In addition, some Virtual Private Network (VPN) solutions take advantage of this 'virtual channel' configuration to eliminate the need for user data encryption to provide privacy. VPN's relying on MPLS require accurate label assignment to maintain user data protection. This research developed a working distributive trust model that demonstrated how to deploy confidentiality, authentication, and non-repudiation in the global network label switching control plane. Simulation models and laboratory testbed implementations that demonstrated this concept were developed, and results from this research were transferred to industry via standards in the Optical Internetworking Forum (OIF).« less

Control of propagation of spatially localized polariton wave packets in a Bragg mirror with embedded quantum wells

NASA Astrophysics Data System (ADS)

Sedova, I. E.; Chestnov, I. Yu.; Arakelian, S. M.; Kavokin, A. V.; Sedov, E. S.

2018-01-01

We considered the nonlinear dynamics of Bragg polaritons in a specially designed stratified semiconductor structure with embedded quantum wells, which possesses a convex dispersion. The model for the ensemble of single periodically arranged quantum wells coupled with the Bragg photon fields has been developed. In particular, the generalized Gross-Pitaevskii equation with the non-parabolic dispersion has been obtained for the Bragg polariton wave function. We revealed a number of dynamical regimes for polariton wave packets resulting from competition of the convex dispersion and the repulsive nonlinearity effects. Among the regimes are spreading, breathing and soliton propagation. When the control parameters including the exciton-photon detuning, the matter-field coupling and the nonlinearity are manipulated, the dynamical regimes switch between themselves.

Designing Two-Layer Optical Networks with Statistical Multiplexing

NASA Astrophysics Data System (ADS)

Addis, B.; Capone, A.; Carello, G.; Malucelli, F.; Fumagalli, M.; Pedrin Elli, E.

The possibility of adding multi-protocol label switching (MPLS) support to transport networks is considered an important opportunity by telecom carriers that want to add packet services and applications to their networks. However, the question that arises is whether it is suitable to have MPLS nodes just at the edge of the network to collect packet traffic from users, or also to introduce MPLS facilities on a subset of the core nodes in order to exploit packet switching flexibility and multiplexing, thus providing induction of a better bandwidth allocation. In this article, we address this complex decisional problem with the support of a mathematical programming approach. We consider two-layer networks where MPLS is overlaid on top of transport networks-synchronous digital hierarchy (SDH) or wavelength division multiplexing (WDM)-depending on the required link speed. The discussions' decisions take into account the trade-off between the cost of adding MPLS support in the core nodes and the savings in the link bandwidth allocation due to the statistical multiplexing and the traffic grooming effects induced by MPLS nodes. The traffic matrix specifies for each point-to-point request a pair of values: a mean traffic value and an additional one. Using this traffic model, the effect of statistical multiplexing on a link allows the allocation of a capacity equal to the sum of all the mean values of the traffic demands routed on the link and only the highest additional one. The proposed approach is suitable to solve real instances in reasonable time.

Call for Papers: Photonics in Switching

NASA Astrophysics Data System (ADS)

Wosinska, Lena; Glick, Madeleine

2006-04-01

Call for Papers: Photonics in Switching

Guest Editors:

Lena Wosinska, Royal Institute of Technology (KTH) / ICT Sweden Madeleine Glick, Intel Research, Cambridge, UK

Scope of Submission

• WDM node architectures
• Novel device technologies enabling photonics in switching, such as optical switch fabrics, optical memory, and wavelength conversion
• Routing protocols
• WDM switching and routing
• Quality of service
• Performance measurement and evaluation
• Next-generation optical networks: architecture, signaling, and control
• Traffic measurement and field trials
• Optical burst and packet switching
• OBS/OPS node architectures
• Burst/Packet scheduling and routing algorithms
• Contention resolution/avoidance strategies
• Services and applications for OBS/OPS (e.g., grid networks, storage-area networks, etc.)
• Burst assembly and ingress traffic shaping
• Hybrid OBS/TDM or OBS/wavelength routing

Manuscript Submission

The DDN (Defense Data Network) Course,

DTIC Science & Technology

1986-04-01

devices will share the same node-to-node channels. * Simultaneous availability of source and destination is not required. * Speed and code conversion can...address multiple addresses simultaneously 3) Disadvantages of Message Switching Systems Not suited to real time or interactive use * Long and highly...transmission b) Unlike message switching, packet switching requires the -. simultaneous availability of source and destination. 64 -4 ) ..xa...e s

End-to-End QoS for Differentiated Services and ATM Internetworking

NASA Technical Reports Server (NTRS)

Su, Hongjun; Atiquzzaman, Mohammed

2001-01-01

The Internet was initially design for non real-time data communications and hence does not provide any Quality of Service (QoS). The next generation Internet will be characterized by high speed and QoS guarantee. The aim of this paper is to develop a prioritized early packet discard (PEPD) scheme for ATM switches to provide service differentiation and QoS guarantee to end applications running over next generation Internet. The proposed PEPD scheme differs from previous schemes by taking into account the priority of packets generated from different application. We develop a Markov chain model for the proposed scheme and verify the model with simulation. Numerical results show that the results from the model and computer simulation are in close agreement. Our PEPD scheme provides service differentiation to the end-to-end applications.

Description and Simulation of a Fast Packet Switch Architecture for Communication Satellites

NASA Technical Reports Server (NTRS)

Quintana, Jorge A.; Lizanich, Paul J.

1995-01-01

The NASA Lewis Research Center has been developing the architecture for a multichannel communications signal processing satellite (MCSPS) as part of a flexible, low-cost meshed-VSAT (very small aperture terminal) network. The MCSPS architecture is based on a multifrequency, time-division-multiple-access (MF-TDMA) uplink and a time-division multiplex (TDM) downlink. There are eight uplink MF-TDMA beams, and eight downlink TDM beams, with eight downlink dwells per beam. The information-switching processor, which decodes, stores, and transmits each packet of user data to the appropriate downlink dwell onboard the satellite, has been fully described by using VHSIC (Very High Speed Integrated-Circuit) Hardware Description Language (VHDL). This VHDL code, which was developed in-house to simulate the information switching processor, showed that the architecture is both feasible and viable. This paper describes a shared-memory-per-beam architecture, its VHDL implementation, and the simulation efforts.

Modeling and performance analysis of an improved movement-based location management scheme for packet-switched mobile communication systems.

PubMed

Chung, Yun Won; Kwon, Jae Kyun; Park, Suwon

2014-01-01

One of the key technologies to support mobility of mobile station (MS) in mobile communication systems is location management which consists of location update and paging. In this paper, an improved movement-based location management scheme with two movement thresholds is proposed, considering bursty data traffic characteristics of packet-switched (PS) services. The analytical modeling for location update and paging signaling loads of the proposed scheme is developed thoroughly and the performance of the proposed scheme is compared with that of the conventional scheme. We show that the proposed scheme outperforms the conventional scheme in terms of total signaling load with an appropriate selection of movement thresholds.

DHCP Origin Traceback

NASA Astrophysics Data System (ADS)

Majumdar, Saugat; Kulkarni, Dhananjay; Ravishankar, Chinya V.

Imagine that the DHCP server is under attack from malicious hosts in your network. How would you know where these DHCP packets are coming from, or which path they took in the network? This paper investigates the problem of determining the origin of a DHCP packet in a network. We propose a practical method for adding a new option field that does not violate any RFC's, which we believe should be a crucial requirement while proposing any related solution. The new DHCP option will contain the ingress port and the switch MAC address. We recommend that this new option be added at the edge so that we can use the recorded value for performing traceback. The computational overhead of our solution is low, and the related network management tasks are low as well. We also address issues related to securing the field in order to maintain privacy of switch MAC addresses, fragmentation of packets, and possible attack scenarios. Our study shows that the traceback scheme is effective and practical to use in most network environments.

Communications Satellite Systems Conference, 9th, San Diego, CA, March 7-11, 1982, Collection of Technical Papers

NASA Astrophysics Data System (ADS)

The Shuttle-to-Geostationary Orbital Transfer by mid-level thrust is considered along with multibeam antenna concepts for global communications, the antenna pointing systems for large communication satellites, the connection phase of multidestination protocols for broadcast satellites, and an experiment in high-speed international packet switching. Attention is given to a dynamic switch matrix for the TDMA satellite switching system, the characterization of 16 bit microprocessors for space use, in-orbit operation and test of Intelsat V satellites, the first operational communications system via satellite in Europe, the Arab satellite communications systems, second generation business satellite systems for Europe, and a high performance Ku-band satellite for the 1980's. Other topics investigated are related to Ku-band terminal design tradeoffs, progress in the definition of the Italian satellite for domestic telecommunications, future global satellite systems for Intelsat, and satellite refuelling in orbit.

Dimensioning of 10 Gbit/s all-optical packet switched networks based on optical label swapping routers with multistage 2R regeneration.

PubMed

Puerto, G; Ortega, B; Manzanedo, M D; Martínez, A; Pastor, D; Capmany, J; Kovacs, G

2006-10-30

This paper describes both the experimental and theoretical investigations on the cascadability of all-optical routers in optical label swapping networks incorporating a multistage wavelength conversion with 2R regeneration. A full description of a novel experimental setup allows the packet by packet measurement up to 16 hops with 10 Gb/s payload showing 1 dB penalty with 10(-12) bit error rate. Similarly, the simulations on the system allow a prediction on the cascadability of the router up to 64 hops.

A first packet processing subdomain cluster model based on SDN

NASA Astrophysics Data System (ADS)

Chen, Mingyong; Wu, Weimin

2017-08-01

For the current controller cluster packet processing performance bottlenecks and controller downtime problems. An SDN controller is proposed to allocate the priority of each device in the SDN (Software Defined Network) network, and the domain contains several network devices and Controller, the controller is responsible for managing the network equipment within the domain, the switch performs data delivery based on the load of the controller, processing network equipment data. The experimental results show that the model can effectively solve the risk of single point failure of the controller, and can solve the performance bottleneck of the first packet processing.

Advanced optical fiber communication systems

NASA Astrophysics Data System (ADS)

Kazovsky, Leonid G.

1994-03-01

Our research is focused on three major aspects of advanced optical fiber communication systems: dynamic wavelength division multiplexing (WDM) networks, fiber nonlinearities, and high dynamic range coherent analog optical links. In the area of WDM networks, we have designed and implemented two high-speed interface boards and measured their throughput and latency. Furthermore, we designed and constructed an experimental PSK/ASK transceiver that simultaneously transmits packet-switched ASK data and circuit-switched PSK data on the same optical carrier. In the area of fiber nonlinearities, we investigated the theoretical impact of modulation frequency on cross-phase modulation (XPM) in dispersive fibers. In the area of high dynamic range coherent analog optical links, we developed theoretical expressions for the RF power transfer ratio (or RF power gain) and the noise figure (NF) of angle-modulated links. We then compared the RF power gains and noise figures of these links to that of an intensity modulated direct detection (DD) link.

Recognition of the optical packet header for two channels utilizing the parallel reservoir computing based on a semiconductor ring laser

NASA Astrophysics Data System (ADS)

Bao, Xiurong; Zhao, Qingchun; Yin, Hongxi; Qin, Jie

2018-05-01

In this paper, an all-optical parallel reservoir computing (RC) system with two channels for the optical packet header recognition is proposed and simulated, which is based on a semiconductor ring laser (SRL) with the characteristic of bidirectional light paths. The parallel optical loops are built through the cross-feedback of the bidirectional light paths where every optical loop can independently recognize each injected optical packet header. Two input signals are mapped and recognized simultaneously by training all-optical parallel reservoir, which is attributed to the nonlinear states in the laser. The recognition of optical packet headers for two channels from 4 bits to 32 bits is implemented through the simulation optimizing system parameters and therefore, the optimal recognition error ratio is 0. Since this structure can combine with the wavelength division multiplexing (WDM) optical packet switching network, the wavelength of each channel of optical packet headers for recognition can be different, and a better recognition result can be obtained.

User-oriented end-to-end transport protocols for the real-time distribution of telemetry data from NASA spacecraft

NASA Technical Reports Server (NTRS)

Hooke, A. J.

1979-01-01

A set of standard telemetry protocols for downlink data flow facilitating the end-to-end transport of instrument data from the spacecraft to the user in real time is proposed. The direct switching of data by autonomous message 'packets' that are assembled by the source instrument on the spacecraft is discussed. The data system consists thus of a format on a message rather than word basis, and such packet telemetry would include standardized protocol headers. Standards are being developed within the NASA End-to-End Data System (NEEDS) program for the source packet and transport frame protocols. The source packet protocol contains identification of both the sequence number of the packet as it is generated by the source and the total length of the packet, while the transport frame protocol includes a sequence count defining the serial number of the frame as it is generated by the spacecraft data system, and a field specifying any 'options' selected in the format of the frame itself.

Path Diversity Media Streaming over Best Effort Packet Switched Networks

DTIC Science & Technology

2003-01-01

intolerable sounds of my violin practice, but my mom was always there to defend and encourage her young violinist. When I left my full-time job for graduate...information can be incomplete or inaccurate. For exam - ple, traceroute can only differentiate between routers and not switches. Two paths with completely

Doubly differential star-16-QAM for fast wavelength switching coherent optical packet transceiver.

PubMed

Liu, Fan; Lin, Yi; Walsh, Anthony J; Yu, Yonglin; Barry, Liam P

2018-04-02

A coherent optical packet transceiver based on doubly differential star 16-ary quadrature amplitude modulation (DD-star-16-QAM) is presented for spectrally and energy efficient reconfigurable networks. The coding and decoding processes for this new modulation format are presented, simulations and experiments are then performed to investigate the performance of the DD-star-16-QAM in static and dynamic scenarios. The static results show that the influence of frequency offset (FO) can be cancelled out by doubly differential (DD) coding and the correction range is only limited by the electronic bandwidth of the receivers. In the dynamic scenario with a time-varying FO and linewidth, the DD-star-16-QAM can overcome the time-varying FO, and the switching time of around 70 ns is determined by the time it takes the dynamic linewidth to reach the requisite level. This format can thus achieve a shorter waiting time after switching tunable lasers than the commonly used square-16-QAM, in which the transmission performance is limited by the frequency transients after the wavelength switch.

Transmission and reflection of charge-density wave packets in a quantum Hall edge controlled by a metal gate

NASA Astrophysics Data System (ADS)

Matsuura, Masahiro; Mano, Takaaki; Noda, Takeshi; Shibata, Naokazu; Hotta, Masahiro; Yusa, Go

2018-02-01

Quantum energy teleportation (QET) is a proposed protocol related to quantum vacuum. The edge channels in a quantum Hall system are well suited for the experimental verification of QET. For this purpose, we examine a charge-density wave packet excited and detected by capacitively coupled front gate electrodes. We observe the waveform of the charge packet, which is proportional to the time derivative of the applied square voltage wave. Further, we study the transmission and reflection behaviors of the charge-density wave packet by applying a voltage to another front gate electrode to control the path of the edge state. We show that the threshold voltages where the dominant direction is switched in either transmission or reflection for dense and sparse wave packets are different from the threshold voltage where the current stops flowing in an equilibrium state.

Study on multiple-hops performance of MOOC sequences-based optical labels for OPS networks

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun; Ma, Chunli

2009-11-01

In this paper, we utilize a new study method that is under independent case of multiple optical orthogonal codes to derive the probability function of MOOCS-OPS networks, discuss the performance characteristics for a variety of parameters, and compare some characteristics of the system employed by single optical orthogonal code or multiple optical orthogonal codes sequences-based optical labels. The performance of the system is also calculated, and our results verify that the method is effective. Additionally it is found that performance of MOOCS-OPS networks would, negatively, be worsened, compared with single optical orthogonal code-based optical label for optical packet switching (SOOC-OPS); however, MOOCS-OPS networks can greatly enlarge the scalability of optical packet switching networks.

Optimized scalable network switch

DOEpatents

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton On Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Steinmacher-Burow, Burkhard D [Mount Kisco, NY; Takken, Todd E [Mount Kisco, NY; Vranas, Pavlos M [Bedford Hills, NY

2007-12-04

In a massively parallel computing system having a plurality of nodes configured in m multi-dimensions, each node including a computing device, a method for routing packets towards their destination nodes is provided which includes generating at least one of a 2m plurality of compact bit vectors containing information derived from downstream nodes. A multilevel arbitration process in which downstream information stored in the compact vectors, such as link status information and fullness of downstream buffers, is used to determine a preferred direction and virtual channel for packet transmission. Preferred direction ranges are encoded and virtual channels are selected by examining the plurality of compact bit vectors. This dynamic routing method eliminates the necessity of routing tables, thus enhancing scalability of the switch.

Optimized scalable network switch

DOEpatents

Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.

2010-02-23

In a massively parallel computing system having a plurality of nodes configured in m multi-dimensions, each node including a computing device, a method for routing packets towards their destination nodes is provided which includes generating at least one of a 2m plurality of compact bit vectors containing information derived from downstream nodes. A multilevel arbitration process in which downstream information stored in the compact vectors, such as link status information and fullness of downstream buffers, is used to determine a preferred direction and virtual channel for packet transmission. Preferred direction ranges are encoded and virtual channels are selected by examining the plurality of compact bit vectors. This dynamic routing method eliminates the necessity of routing tables, thus enhancing scalability of the switch.

A fiber optic tactical voice/data network based on FDDI

NASA Technical Reports Server (NTRS)

Bergman, L. A.; Hartmayer, R.; Marelid, S.; Wu, W. H.; Edgar, G.; Cassell, P.; Mancini, R.; Kiernicki, J.; Paul, L. J.; Jeng, J.

1988-01-01

An asynchronous high-speed fiber optic local area network is described that supports ordinary data packet traffic simultaneously with synchronous Tl voice traffic over a common FDDI token ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multi-tier backbones. A conventional single token access protocol was employed at the lowest layer, with fixed packet sizes for voice and variable for data. In addition, the higher layer packet data protocols are allowed to operate independently of those for the voice thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions were performed external to the network with PABX equipment.

Second year technical report on-board processing for future satellite communications systems

NASA Technical Reports Server (NTRS)

Brandon, W. T.; Green, W. K.; Hoffman, M.; Jean, P. N.; Neal, W. R.; White, B. E.

1980-01-01

Advanced baseband and microwave switching techniques for large domestic communications satellites operating in the 30/20 GHz frequency bands are discussed. The nominal baseband processor throughput is one million packets per second (1.6 Gb/s) from one thousand T1 carrier rate customer premises terminals. A frequency reuse factor of sixteen is assumed by using 16 spot antenna beams with the same 100 MHz bandwidth per beam and a modulation with a one b/s per Hz bandwidth efficiency. Eight of the beams are fixed on major metropolitan areas and eight are scanning beams which periodically cover the remainder of the U.S. under dynamic control. User signals are regenerated (demodulated/remodulated) and message packages are reformatted on board. Frequency division multiple access and time division multiplex are employed on the uplinks and downlinks, respectively, for terminals within the coverage area and dwell interval of a scanning beam. Link establishment and packet routing protocols are defined. Also described is a detailed design of a separate 100 x 100 microwave switch capable of handling nonregenerated signals occupying the remaining 2.4 GHz bandwidth with 60 dB of isolation, at an estimated weight and power consumption of approximately 400 kg and 100 W, respectively.

Second year technical report on-board processing for future satellite communications systems

NASA Astrophysics Data System (ADS)

Brandon, W. T.; Green, W. K.; Hoffman, M.; Jean, P. N.; Neal, W. R.; White, B. E.

1980-10-01

Advanced baseband and microwave switching techniques for large domestic communications satellites operating in the 30/20 GHz frequency bands are discussed. The nominal baseband processor throughput is one million packets per second (1.6 Gb/s) from one thousand T1 carrier rate customer premises terminals. A frequency reuse factor of sixteen is assumed by using 16 spot antenna beams with the same 100 MHz bandwidth per beam and a modulation with a one b/s per Hz bandwidth efficiency. Eight of the beams are fixed on major metropolitan areas and eight are scanning beams which periodically cover the remainder of the U.S. under dynamic control. User signals are regenerated (demodulated/remodulated) and message packages are reformatted on board. Frequency division multiple access and time division multiplex are employed on the uplinks and downlinks, respectively, for terminals within the coverage area and dwell interval of a scanning beam. Link establishment and packet routing protocols are defined. Also described is a detailed design of a separate 100 x 100 microwave switch capable of handling nonregenerated signals occupying the remaining 2.4 GHz bandwidth with 60 dB of isolation, at an estimated weight and power consumption of approximately 400 kg and 100 W, respectively.

Dynamically-allocated multi-queue buffers for VLSI communication switches

NASA Technical Reports Server (NTRS)

Tamir, Yuval; Frazier, Gregory L.

1992-01-01

Several buffer structures are discussed and compared in terms of implementation complexity, interswitch handshaking requirements, and their ability to deal with variations in traffic patterns and message lengths. A new design of buffers is presented that provide non-FIFO message handling and efficient storage allocation for variable size packets using linked lists managed by a simple on-chip controller. The new buffer design is evaluated by comparing it to several alternative designs in the context of a multistage interconnection network. The present modeling and simulations show that the new buffer outperforms alternative buffers and can thus be used to improve the performance of a wide variety of systems currently using less efficient buffers.

A system architecture for an advanced Canadian wideband mobile satellite system

NASA Technical Reports Server (NTRS)

Takats, P.; Keelty, M.; Moody, H.

1993-01-01

In this paper, the system architecture for an advanced Canadian ka-band geostationary mobile satellite system is described, utilizing hopping spot beams to support a 256 kbps wideband service for both N-ISDN and packet-switched interconnectivity to small briefcase-size portable and mobile terminals. An assessment is given of the technical feasibility of the satellite payload and terminal design in the post year 2000 timeframe. The satellite payload includes regeneration and on-board switching to permit single hop interconnectivity between mobile terminals. The mobile terminal requires antenna tracking and platform stabilization to ensure acquisition of the satellite signal. The potential user applications targeted for this wideband service includes: home-office, multimedia, desk-top (PC) videoconferencing, digital audio broadcasting, single and multi-user personal communications.

All-optical clocked delay flip-flop using a single terahertz optical asymmetric demultiplexer-based switch: a theoretical study.

PubMed

Chattopadhyay, Tanay

2010-10-01

A flip-flop (FF) is a kind of latch and the simplest form of memory device, which stores various values either temporarily or permanently. Optical FF memories form a fundamental building block for all-optical packet switches in next-generation communication networks. An all-optical clocked delay FF using a single terahertz optical asymmetric demultiplexer-based interferometric switch is proposed and described. Numerical simulation results are also reported.

Interprocess Communication Protocols for Computer Networks

DTIC Science & Technology

1975-12-01

this value without maintaining any state information about itp partner CCP. The receiving CCP returns a SYN giving its own ISN, or can reject...34Packet Arrival and Buffer Statistics in a Packet Switching Node," IBM Research Report RZ 594 {.s;Zni02),. September 1973. [Cochi73] B. J. Cochi...rwid 0. P. Karp, "Protocol for a Computer Netuork," IBM Sustem Journa! 12. 1, 1973, pp. 94-105. [ricKen2ie741 A. fl. McKenzie

Research in the Aloha system

NASA Technical Reports Server (NTRS)

Abramson, N.

1974-01-01

The Aloha system was studied and developed and extended to advanced forms of computer communications networks. Theoretical and simulation studies of Aloha type radio channels for use in packet switched communications networks were performed. Improved versions of the Aloha communications techniques and their extensions were tested experimentally. A packet radio repeater suitable for use with the Aloha system operational network was developed. General studies of the organization of multiprocessor systems centered on the development of the BCC 500 computer were concluded.

Applications of High Speed Networks

DTIC Science & Technology

1991-09-01

plished in order to achieve a dpgree of parallelism by constructing a distributed switch. The type of switch, self -routing, processes the packet...control more than a dozen missiles in flight, and the four Mark 99 target illuminators direct missiles in the terminal phase. The self -contained Phalanx...military installations, weapon system respose and expected missile performance against a threat. Projects are already underway transposing of

MOBILESAT: Australia's own

NASA Technical Reports Server (NTRS)

Wagg, Michael

1990-01-01

Australia will be introducing a dedicated Mobile Satellite Communications System following the launch of the AUSSAT-B satellites late in 1991. The Mobile Satellite System, MOBILESAT, will provide circuit switched voice/data services and packet-switched data services for land, aeronautical and maritime users. Here, an overview is given of the development program being undertaken within Australia to enable a fully commercial service to be introduced in 1992.

Enhancing the Quality of Service for Real Time Traffic over Optical Burst Switching (OBS) Networks with Ensuring the Fairness for Other Traffics.

PubMed

Al-Shargabi, Mohammed A; Shaikh, Asadullah; Ismail, Abdulsamad S

2016-01-01

Optical burst switching (OBS) networks have been attracting much consideration as a promising approach to build the next generation optical Internet. A solution for enhancing the Quality of Service (QoS) for high priority real time traffic over OBS with the fairness among the traffic types is absent in current OBS' QoS schemes. In this paper we present a novel Real Time Quality of Service with Fairness Ratio (RT-QoSFR) scheme that can adapt the burst assembly parameters according to the traffic QoS needs in order to enhance the real time traffic QoS requirements and to ensure the fairness for other traffic. The results show that RT-QoSFR scheme is able to fulfill the real time traffic requirements (end to end delay, and loss rate) ensuring the fairness for other traffics under various conditions such as the type of real time traffic and traffic load. RT-QoSFR can guarantee that the delay of the real time traffic packets does not exceed the maximum packets transfer delay value. Furthermore, it can reduce the real time traffic packets loss, at the same time guarantee the fairness for non real time traffic packets by determining the ratio of real time traffic inside the burst to be 50-60%, 30-40%, and 10-20% for high, normal, and low traffic loads respectively.

Implementation of a tactical voice/data network over FDDI. [Fiber Distributed Data Interface

NASA Technical Reports Server (NTRS)

Bergman, L. A.; Halloran, F.; Martinez, J.

1988-01-01

An asynchronous high-speed fiber-optic local-area network is described that simultaneously supports packet data traffic with synchronous TI voice traffic over a standard asynchronous FDDI (fiber distributed data interface) token-ring channel. A voice interface module was developed that parses, buffers, and resynchronizes the voice data to the packet network. The technique is general, however, and can be applied to any deterministic class of networks, including multitier backbones. In addition, the higher layer packet data protocols may operate independently of those for the voice, thereby permitting great flexibility in reconfiguring the network. Voice call setup and switching functions are performed external to the network with PABX equipment.

Low latency adaptive streaming of HD H.264 video over 802.11 wireless networks with cross-layer feedback

NASA Astrophysics Data System (ADS)

Patti, Andrew; Tan, Wai-tian; Shen, Bo

2007-09-01

Streaming video in consumer homes over wireless IEEE 802.11 networks is becoming commonplace. Wireless 802.11 networks pose unique difficulties for streaming high definition (HD), low latency video due to their error-prone physical layer and media access procedures which were not designed for real-time traffic. HD video streaming, even with sophisticated H.264 encoding, is particularly challenging due to the large number of packet fragments per slice. Cross-layer design strategies have been proposed to address the issues of video streaming over 802.11. These designs increase streaming robustness by imposing some degree of monitoring and control over 802.11 parameters from application level, or by making the 802.11 layer media-aware. Important contributions are made, but none of the existing approaches directly take the 802.11 queuing into account. In this paper we take a different approach and propose a cross-layer design allowing direct, expedient control over the wireless packet queue, while obtaining timely feedback on transmission status for each packet in a media flow. This method can be fully implemented on a media sender with no explicit support or changes required to the media client. We assume that due to congestion or deteriorating signal-to-noise levels, the available throughput may drop substantially for extended periods of time, and thus propose video source adaptation methods that allow matching the bit-rate to available throughput. A particular H.264 slice encoding is presented to enable seamless stream switching between streams at multiple bit-rates, and we explore using new computationally efficient transcoding methods when only a high bit-rate stream is available.

On the impact of fiber-delay-lines (FDL) in an all-optical network (AON) bottleneck without wavelength conversion

NASA Astrophysics Data System (ADS)

Argibay-Losada, Pablo Jesus; Sahin, Gokhan

2014-08-01

Random access memories (RAM) are fundamental in conventional electronic switches and routers to manage short-term congestion and to decrease data loss probabilities. Switches in all-optical networks (AONs), however, do not have access to optical RAM, and therefore are prone to much higher loss levels than their electronic counterparts. Fiber-delay-lines (FDLs), able to delay an optical data packet a fixed amount of time, have been proposed in the literature as a means to alleviate those high loss levels. However, they are extremely bulky to manage, so their usage introduces a trade-off between practicality and performance in the design and operation of the AON. In this paper we study the influence that FDLs have in the performance of flows crossing an all-optical switch that acts as their bottleneck. We show how extremely low numbers of FDLs (e.g., 1 or 2) can help in reducing losses by several orders of magnitude in several illustrative scenarios with high aggregation levels. Our results therefore suggest that FDLs can be a practical means of dealing with congestion in AONs in the absence of optical RAM buffers or of suitable data interchange protocols specifically designed for AONs.

RF MEMS devices for multifunctional integrated circuits and antennas

NASA Astrophysics Data System (ADS)

Peroulis, Dimitrios

Micromachining and RF Micro-Electro-Mechanical Systems (RF MEMS) have been identified as two of the most significant enabling technologies in developing miniaturized low-cost communications systems and sensor networks. The key components in these MEMS-based architectures are the RF MEMS switches and varactors. The first part of this thesis focuses on three novel RF MEMS components with state-of-the-art performance. In particular, a broadband 6 V capacitive MEMS switch is presented with insertion loss of only 0.04 and 0.17 dB at 10 and 40 GHz respectively. Special consideration is given to particularly challenging issues, such as residual stress, planarity, power handling capability and switching speed. The need for switches operating below 1 GHz is also identified and a spring-loaded metal-to-metal contact switch is developed. The measured on-state contact resistance and off-state series capacitance are 0.5 O and 10 fF respectively for this switch. An analog millimeter-wave variable capacitor is the third MEMS component presented in this thesis. This variable capacitor shows an ultra high measured tuning range of nearly 4:1, which is the highest reported value for the millimeter-wave region. The second part of this thesis primarily concentrates on MEMS-based reconfigurable systems and their potential to revolutionize the design of future RF/microwave multifunctional systems. High-isolation switches and switch packets with isolation of more than 60 dB are designed and implemented. Furthermore, lowpass and bandpass tunable filters with 3:1 and 2:1 tuning ratios respectively are demonstrated. Similar methods have been also applied to the field of slot antennas and a novel design technique for compact reconfigurable antennas has been developed. The main advantage of these antennas is that they essentially preserve their impedance, radiation pattern, polarization, gain and efficiency for all operating frequencies. The thesis concludes by discussing the future challenges of RF MEMS, such as packaging and reliability.

Network Speech Systems Technology Program.

DTIC Science & Technology

1980-09-30

ognized that the lumped-speaker approximation could be extended even more generally to include cases of combined circuit-switched speech and packet...based on these tables. The first function is an im- portant element of the more general task of system control for a switched network, which in...programs are in preparation, as described below, for both steady-state evaluation and dynamic performance simulation of the algorithm in general

Influence of lattice vibrations on the field driven electronic transport in chains with correlated disorder

NASA Astrophysics Data System (ADS)

da Silva, L. D.; Sales, M. O.; Ranciaro Neto, A.; Lyra, M. L.; de Moura, F. A. B. F.

2016-12-01

We investigate electronic transport in a one-dimensional model with four different types of atoms and long-ranged correlated disorder. The latter was attained by choosing an adequate distribution of on-site energies. The wave-packet dynamics is followed by taking into account effects due to a static electric field and electron-phonon coupling. In the absence of electron-phonon coupling, the competition between correlated disorder and the static electric field promotes the occurrence of wave-packet oscillations in the regime of strong correlations. When the electron-lattice coupling is switched on, phonon scattering degrades the Bloch oscillations. For weak electron-phonon couplings, a coherent oscillatory-like dynamics of the wave-packet centroid persists for short periods of time. For strong couplings the wave-packet acquires a diffusive-like displacement and spreading. A slower sub-diffusive spreading takes place in the regime of weak correlations.

(abstract) Experimental Results From Internetworking Data Applications Over Various Wireless Networks Using a Single Flexible Error Control Protocol

NASA Technical Reports Server (NTRS)

Kanai, T.; Kramer, M.; McAuley, A. J.; Nowack, S.; Pinck, D. S.; Ramirez, G.; Stewart, I.; Tohme, H.; Tong, L.

1995-01-01

This paper describes results from several wireless field trials in New Jersey, California, and Colorado, conducted jointly by researchers at Bellcore, JPL, and US West over the course of 1993 and 1994. During these trials, applications communicated over multiple wireless networks including satellite, low power PCS, high power cellular, packet data, and the wireline Public Switched Telecommunications Network (PSTN). Key goals included 1) designing data applications and an API suited to mobile users, 2) investigating internetworking issues, 3) characterizing wireless networks under various field conditions, and 4) comparing the performance of different protocol mechanisms over the diverse networks and applications. We describe experimental results for different protocol mechanisms and parameters, such as acknowledgment schemes and packet sizes. We show the need for powerful error control mechanisms such as selective acknowledgements and combining data from multiple transmissions. We highlight the possibility of a common protocol for all wireless networks, from micro-cellular PCS to satellite networks.

Enhancing the Quality of Service for Real Time Traffic over Optical Burst Switching (OBS) Networks with Ensuring the Fairness for Other Traffics

PubMed Central

Al-Shargabi, Mohammed A.; Ismail, Abdulsamad S.

2016-01-01

Optical burst switching (OBS) networks have been attracting much consideration as a promising approach to build the next generation optical Internet. A solution for enhancing the Quality of Service (QoS) for high priority real time traffic over OBS with the fairness among the traffic types is absent in current OBS’ QoS schemes. In this paper we present a novel Real Time Quality of Service with Fairness Ratio (RT-QoSFR) scheme that can adapt the burst assembly parameters according to the traffic QoS needs in order to enhance the real time traffic QoS requirements and to ensure the fairness for other traffic. The results show that RT-QoSFR scheme is able to fulfill the real time traffic requirements (end to end delay, and loss rate) ensuring the fairness for other traffics under various conditions such as the type of real time traffic and traffic load. RT-QoSFR can guarantee that the delay of the real time traffic packets does not exceed the maximum packets transfer delay value. Furthermore, it can reduce the real time traffic packets loss, at the same time guarantee the fairness for non real time traffic packets by determining the ratio of real time traffic inside the burst to be 50–60%, 30–40%, and 10–20% for high, normal, and low traffic loads respectively. PMID:27583557

MSFC institutional area network and ATM technology

NASA Technical Reports Server (NTRS)

Amin, Ashok T.

1994-01-01

The New Institutional Area Network (NEWIAN) at Marshall supports over 5000 end users with access to 26 file servers providing work presentation services. It is comprised of some 150 Ethernet LAN's interconnected by bridges/routers which are in turn connected to servers over two dual FDDI rings. The network supports various higher level protocols such as IP, IPX, AppleTalk (AT), and DECNet. At present IPX and AT protocols packets are routed, and IP protocol packets are bridged; however, work is in progress to route all IP packets. The impact of routing IP packets on network operation is examined. Broadband Integrated Services Data Network (BISDN), presently at various stages of development, is intended to provide voice, video, and data transfer services over a single network. BISDN will use asynchronous transfer mode (ATM) as a data transfer technique which provides for transmission, multiplexing, switching, and relaying of small size data units called cells. Limited ATM Wide Area Network (WAN) services are offered by Wiltel, AT&T, Sprint, and others. NASA is testing a pilot ATM WAN with a view to provide Program Support Communication Network services using ATM. ATM supports wide range of data rates and quality of service requirements. It is expected that ATM switches will penetrate campus networks as well. However, presently products in these areas are at various stages of development and standards are not yet complete. We examine development of ATM to help assess its role in the evolution of NEWIAN.

ISDN Application in the Army Environment

DTIC Science & Technology

1992-02-01

Signalling System Number 7 ( SS7 ). SS7 is a packet switched signalling network operating in parallel with the traffic bearing network. The current, in...for example, require SS7 . Further into the future, broadband ISDN (B-ISDN) is expected to provide high-quality, full-motion video, High Definition...smaller business offices, ISDN could be a viable alternative to private networks, especially when switches are connected through SS7 . ISDN, in combination

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.

All-IP-Ethernet architecture for real-time sensor-fusion processing

NASA Astrophysics Data System (ADS)

Hiraki, Kei; Inaba, Mary; Tezuka, Hiroshi; Tomari, Hisanobu; Koizumi, Kenichi; Kondo, Shuya

2016-03-01

Serendipter is a device that distinguishes and selects very rare particles and cells from huge amount of population. We are currently designing and constructing information processing system for a Serendipter. The information processing system for Serendipter is a kind of sensor-fusion system but with much more difficulties: To fulfill these requirements, we adopt All IP based architecture: All IP-Ethernet based data processing system consists of (1) sensor/detector directly output data as IP-Ethernet packet stream, (2) single Ethernet/TCP/IP streams by a L2 100Gbps Ethernet switch, (3) An FPGA board with 100Gbps Ethernet I/F connected to the switch and a Xeon based server. Circuits in the FPGA include 100Gbps Ethernet MAC, buffers and preprocessing, and real-time Deep learning circuits using multi-layer neural networks. Proposed All-IP architecture solves existing problem to construct large-scale sensor-fusion systems.

Investigations into the Performance of a Distributed Routing Protocol for Packet Switching Networks.

DTIC Science & Technology

1982-12-01

normal printer output or both. A sample of the )u-tout f-mat used for this study is D:-ovided in Appendix E. 45 The implementation of the packet...LUl 16> CLU C.Z 9- - Z Q ZO M Zink - M XC Z- M 1-4 V) . ujW LU UJi eay) a- I--UJZ X<Wd Z OX -V) 1:1 =) m (XZ o OX .4 D UU-X .. cN U.""’ Z WI-’- L.A a

An architecture for the MSAT mobile data system

NASA Technical Reports Server (NTRS)

Kerr, R. W.; Skerry, B.

1990-01-01

The Mobile Satellite (MSAT) Mobile Data System (MDS) will offer a wide range of packet switched data services. The characteristics and requirements of the services are briefly examined. A proposed architecture to implement these services is presented along with its connectivity requirements. A description of the inbound and outbound channels is provided which are based upon the signalling for the circuit switched services. Additionally, the duties of the Network Management System are examined.

Digital Telematics: Present and Future.

ERIC Educational Resources Information Center

Stalberg, Christian E.

1987-01-01

This overview of developments in international telecommunications networks focuses on their importance for developing countries and the necessary interdependence of all countries. Highlights include digital technology, telephone service, packet switching networks, communications satellites, fiber optic cables, and possible future developments.…

Performance analysis of signaling protocols on OBS switches

NASA Astrophysics Data System (ADS)

Kirci, Pinar; Zaim, A. Halim

2005-10-01

In this paper, Just-In-Time (JIT), Just-Enough-Time (JET) and Horizon signalling schemes for Optical Burst Switched Networks (OBS) are presented. These signaling schemes run over a core dWDM network and a network architecture based on Optical Burst Switches (OBS) is proposed to support IP, ATM and Burst traffic. In IP and ATM traffic several packets are assembled in a single packet called burst and the burst contention is handled by burst dropping. The burst length distribution in IP traffic is arbitrary between 0 and 1, and is fixed in ATM traffic at 0,5. Burst traffic on the other hand is arbitrary between 1 and 5. The Setup and Setup ack length distributions are arbitrary. We apply the Poisson model with rate λ and Self-Similar model with pareto distribution rate α to identify inter-arrival times in these protocols. We consider a communication between a source client node and a destination client node over an ingress and one or more multiple intermediate switches.We use buffering only in the ingress node. The communication is based on single burst connections in which, the connection is set up just before sending a burst and then closed as soon as the burst is sent. Our analysis accounts for several important parameters, including the burst setup, burst setup ack, keepalive messages and the optical switching protocol. We compare the performance of the three signalling schemes on the network under as burst dropping probability under a range of network scenarios.

The ARPANET after twenty years

NASA Technical Reports Server (NTRS)

Denning, Peter J.

1989-01-01

The ARPANET began operations in 1969 with four nodes as an experiment in resource sharing among computers. It has evolved into a worldwide research network of over 60,000 nodes, influencing the design of other networks in business, education, and government. It demonstrated the speed and reliability of packet-switching networks. Its protocols have served as the models for international standards. And yet the significance of the ARPANET lies not in its technology, but in the profound alterations networking has produced in human practices. Network designers must now turn their attention to the discourses of scientific technology, business, education, and government that are being mixed together in the milieux of networking, and in particular the conflicts and misunderstandings that arise from the different world views of these discourses.

Pump-dump iterative squeezing of vibrational wave packets.

PubMed

Chang, Bo Y; Sola, Ignacio R

2005-12-22

The free motion of a nonstationary vibrational wave packet in an electronic potential is a source of interesting quantum properties. In this work we propose an iterative scheme that allows continuous stretching and squeezing of a wave packet in the ground or in an excited electronic state, by switching the wave function between both potentials with pi pulses at certain times. Using a simple model of displaced harmonic oscillators and delta pulses, we derive the analytical solution and the conditions for its possible implementation and optimization in different molecules and electronic states. We show that the main constraining parameter is the pulse bandwidth. Although in principle the degree of squeezing (or stretching) is not bounded, the physical resources increase quadratically with the number of iterations, while the achieved squeezing only increases linearly.

Quasi-light storage for optical data packets.

PubMed

Schneider, Thomas; Preußler, Stefan

2014-02-06

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing of the signals is done in the electrical domain. Direct storage in the optical domain would avoid the transfer of the packets to the electrical and back to the optical domain in every network node and, therefore, increase the speed and possibly reduce the energy consumption of telecommunications. However, light consists of photons which propagate with the speed of light in vacuum. Thus, the storage of light is a big challenge. There exist some methods to slow down the speed of the light, or to store it in excitations of a medium. However, these methods cannot be used for the storage of optical data packets used in telecommunications networks. Here we show how the time-frequency-coherence, which holds for every signal and therefore for optical packets as well, can be exploited to build an optical memory. We will review the background and show in detail and through examples, how a frequency comb can be used for the copying of an optical packet which enters the memory. One of these time domain copies is then extracted from the memory by a time domain switch. We will show this method for intensity as well as for phase modulated signals.

Packet Traffic Dynamics Near Onset of Congestion in Data Communication Network Model

NASA Astrophysics Data System (ADS)

Lawniczak, A. T.; Tang, X.

2006-05-01

The dominant technology of data communication networks is the Packet Switching Network (PSN). It is a complex technology organized as various hierarchical layers according to the International Standard Organization (ISO) Open Systems Interconnect (OSI) Reference Model. The Network Layer of the ISO OSI Reference Model is responsible for delivering packets from their sources to their destinations and for dealing with congestion if it arises in a network. Thus, we focus on this layer and present an abstraction of the Network Layer of the ISO OSI Reference Model. Using this abstraction we investigate how onset of traffic congestion is affected for various routing algorithms by changes in network connection topology. We study how aggregate measures of network performance depend on network connection topology and routing. We explore packets traffic spatio-temporal dynamics near the phase transition point from free flow to congestion for various network connection topologies and routing algorithms. We consider static and adaptive routings. We present selected simulation results.

3-DIMENSIONAL Optoelectronic

NASA Astrophysics Data System (ADS)

Krishnamoorthy, Ashok Venketaraman

This thesis covers the design, analysis, optimization, and implementation of optoelectronic (N,M,F) networks. (N,M,F) networks are generic space-division networks that are well suited to implementation using optoelectronic integrated circuits and free-space optical interconnects. An (N,M,F) networks consists of N input channels each having a fanout F_{rm o}, M output channels each having a fanin F_{rm i}, and Log_{rm K}(N/F) stages of K x K switches. The functionality of the fanout, switching, and fanin stages depends on the specific application. Three applications of optoelectronic (N,M,F) networks are considered. The first is an optoelectronic (N,1,1) content -addressable memory system that achieves associative recall on two-dimensional images retrieved from a parallel-access optical memory. The design and simulation of the associative memory are discussed, and an experimental emulation of a prototype system using images from a parallel-readout optical disk is presented. The system design provides superior performance to existing electronic content-addressable memory chips in terms of capacity and search rate, and uses readily available optical disk and VLSI technologies. Next, a scalable optoelectronic (N,M,F) neural network that uses free-space holographic optical interconnects is presented. The neural architecture minimizes the number of optical transmitters needed, and provides accurate electronic fanin with low signal skew, and dendritic-type fan-in processing capability in a compact layout. Optimal data-encoding methods and circuit techniques are discussed. The implementation of an prototype optoelectronic neural system, and its application to a simple recognition task is demonstrated. Finally, the design, analysis, and optimization of a (N,N,F) self-routing, packet-switched multistage interconnection network is described. The network is suitable for parallel computing and broadband switching applications. The tradeoff between optical and electronic interconnects is examined quantitatively by varying the electronic switch size K. The performance of the (N,N,F) network versus the fanning parameter F, is also analyzed. It is shown that the optoelectronic (N,N,F) networks provide a range of performance-cost alternatives, and offer superior performance-per-cost to fully electronic switching networks and to previous networks designs.

IP voice over ATM satellite: experimental results over satellite channels

NASA Astrophysics Data System (ADS)

Saraf, Koroush A.; Butts, Norman P.

1999-01-01

IP telephony, a new technology to provide voice communication over traditional data networks, has the potential to revolutionize telephone communication within the modern enterprise. This innovation uses packetization techniques to carry voice conversations over IP networks. This packet switched technology promises new integrated services, and lower cost long-distance communication compared to traditional circuit switched telephone networks. Future satellites will need to carry IP traffic efficiently in order to stay competitive in servicing the global data- networking and global telephony infrastructure. However, the effects of Voice over IP over switched satellite channels have not been investigated in detail. To fully understand the effects of satellite channels on Voice over IP quality; several experiments were conducted at Lockheed Martin Telecommunications' Satellite Integration Lab. The result of those experiments along with suggested improvements for voice communication over satellite are presented in this document. First, a detailed introduction of IP telephony as a suitable technology for voice communication over future satellites is presented. This is followed by procedures for the experiments, along with results and strategies. In conclusion we hope that these capability demonstrations will alleviate any uncertainty regarding the applicability of this technology to satellite networks.

Demonstration of optically controlled data routing with the use of multiple-quantum-well bistable and electro-optical devices.

PubMed

Koppa, P; Chavel, P; Oudar, J L; Kuszelewicz, R; Schnell, J P; Pocholle, J P

1997-08-10

We present experimental results on a 1-to-64-channel free-space photonic switching demonstration system based on GaAs/GaAlAs multiple-quantum-well active device arrays. Two control schemes are demonstrated: data transparent optical self-routing usable in a packet-switching environment and direct optical control with potential signal amplification for circuit switching. The self-routing operation relies on the optical recognition of the binary destination address coded in each packet header. Address decoding is implemented with elementary optical bistable devices and modulator pixels as all-optical latches and electro-optical and gates, respectively. All 60 defect-free channels of the system could be operated one by one, but the simultaneous operation of only three channels could be achieved mainly because of the spatial nonhomogeneities of the devices. Direct-control operation is based on directly setting the bistable device reflectivity with a variable-control beam power. This working mode turned out to be much more tolerant of spatial noises: 37 channels of the system could be operated simultaneously. Further development of the system to a crossbar of N inputs and M outputs and system miniaturization are also considered.

Radiology/Imaging. Clinical Rotation. Instructor's Packet and Student Study Packet.

ERIC Educational Resources Information Center

Texas Univ., Austin. Extension Instruction and Materials Center.

The instructor's packet, the first of two packets, is one of a series of materials designed to help students who are investigating the activities within a radiology department or considering any of the imaging technologies as a career. The material is designed to relate training experience to information studied in the classroom. This packet…

Report of the Defense Science Board Task Force on Defensive Information Operations. 2000 Summer Study. Volume II

DTIC Science & Technology

2001-03-01

distinguishing between attacks and other events such as accidents, system failures, or hacking by thrill-seekers. This challenge is exacerbated by the...and is referred to as Signaling System # 7 ( SS7 ). Commercial Intelligent Network Architecture Switching Signal Point (SSP) Service - Originates...Wireless access point to fixed infrastructure Ut c Signaling Transfer Point (STP) - Packet switch in CCITT#7 Network SP SW SS7 System Data Bases Network

Glossary of Internet Terms.

ERIC Educational Resources Information Center

Microcomputers for Information Management, 1995

1995-01-01

Provides definitions for 71 terms related to the Internet, including Archie, bulletin board system, cyberspace, e-mail (electronic mail), file transfer protocol, gopher, hypertext, integrated services digital network, local area network, listserv, modem, packet switching, server, telnet, UNIX, WAIS (wide area information servers), and World Wide…

Performance and policy dimensions in internet routing

NASA Technical Reports Server (NTRS)

Mills, David L.; Boncelet, Charles G.; Elias, John G.; Schragger, Paul A.; Jackson, Alden W.; Thyagarajan, Ajit

1995-01-01

The Internet Routing Project, referred to in this report as the 'Highball Project', has been investigating architectures suitable for networks spanning large geographic areas and capable of very high data rates. The Highball network architecture is based on a high speed crossbar switch and an adaptive, distributed, TDMA scheduling algorithm. The scheduling algorithm controls the instantaneous configuration and swell time of the switch, one of which is attached to each node. In order to send a single burst or a multi-burst packet, a reservation request is sent to all nodes. The scheduling algorithm then configures the switches immediately prior to the arrival of each burst, so it can be relayed immediately without requiring local storage. Reservations and housekeeping information are sent using a special broadcast-spanning-tree schedule. Progress to date in the Highball Project includes the design and testing of a suite of scheduling algorithms, construction of software reservation/scheduling simulators, and construction of a strawman hardware and software implementation. A prototype switch controller and timestamp generator have been completed and are in test. Detailed documentation on the algorithms, protocols and experiments conducted are given in various reports and papers published. Abstracts of this literature are included in the bibliography at the end of this report, which serves as an extended executive summary.

Final Report for the project titled "Enabling Supernova Computations by Integrated Transport and Provisioning Methods Optimized for Dedicated Channels"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malathi Veeraraghavan

2007-10-31

A high-speed optical circuit network is one that offers users rate-guaranteed connectivity between two endpoints, unlike today’s IP-routed Internet in which the rate available to a pair of users fluctuates based on the volume of competing traffic. This particular research project advanced our understanding of circuit networks in two ways. First, transport protocols were developed for circuit networks. In a circuit network, since bandwidth resources are reserved for each circuit on an end-to-end basis (much like how a person reserves a seat on every leg of a multi-segment flight), and the sender is limited to send at the rate ofmore » the circuit, there is no possibility of congestion during data transfer. Therefore, no congestion control functions are necessary in a transport protocol designed for circuits. However, error control and flow control are still required because bits can become errored due to noise and interference even on highly reliable optical links, and receivers can, due to multitasking or other reasons, not deplete the receive buffer fast enough to keep up with the sending rate (e.g., if the receiving host is multitasking between receiving a file transfer and some other computation). In this work, we developed two transport protocols for circuits, both of which are described below. Second, this project developed techniques for internetworking different types of connection-oriented networks, which are of two types: circuit-switched or packet-switched. In circuit-switched networks, multiplexing on links is “position based,” where “position” refers to the frequency, time slot, and port (fiber), while connection-oriented packet-switched networks use packet header information to demultiplex packets and switch them from node to node. The latter are commonly referred to as virtual circuit networks. Examples of circuit networks are time-division multiplexed Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Wavelength Division Multiplexing (WDM) networks, while examples of virtual-circuit networks are MultiProtocol Label Switched (MPLS) networks and Ethernet Virtual Local Area Network (VLAN) networks. A series of new technologies have been developed to carry Ethernet VLAN tagged frames on SONET/SDH and WDM networks, such as Generic Framing Procedure (GFP) and ITU G.709, respectively. These technologies form the basis of our solution for connection-oriented internetworking. The benefit of developing such an architecture is that it allows different providers to choose different connection-oriented networking technologies for their networks, and yet be able to allow their customers to connect to those of other providers. As Metcalfe, the inventor of Ethernet, noted, the value of a network service grows exponentially with the number of endpoints to which any single endpoint can connect. Therefore internetworking solutions are key to commercial success. The technical effectiveness of our solutions was measured with proof-of-concept prototypes and experiments. These solutions were shown to be highly effective. Economic feasibility requires business case analyses that were beyond the scope of this project. The project results are beneficial to the public as they demonstrate the viability of simultaneously supporting different types of networks and data communication services much like the variety of services available for the transportation of people and goods. For example, Fedex service offers a deadline based delivery while the USPS offers basic package delivery service. Similarly, a circuit network can offer a deadline based delivery of a data file while the IP-routed network offers only basic delivery service with no guarantees. Two project Web sites, 13 publications, 7 software programs, 21 presentations resulted from this work. This report provides the complete list of publications, software programs and presentations. As for student education and training (human resources), this DOE project, along with an NSF project, jointly supported two postdoctoral fellowships, three PhDs, three Masters, and two undergraduate students. Specifically, two of the Masters students were directly funded on this DOE project.« less

An energy saving mechanism of EPON networks for real time video transmission

NASA Astrophysics Data System (ADS)

Liu, Chien-Ping; Wu, Ho-Ting; Chiang, Yun-Ting; Chien, Shieh-Chieh; Ke, Kai-Wei

2015-07-01

Modern access networks are constructed widely by passive optical networks (PONs) to meet the growing bandwidth demand. However, higher bandwidth means more energy consumption. To save energy, a few research works propose the dual-mode energy saving mechanism that allows the ONU to operate between active and sleep modes periodically. However, such dual-mode energy saving design may induce unnecessary power consumption or packet delay increase in the case where only downstream data exist for most of the time. In this paper, we propose a new tri-mode energy saving scheme for Ethernet PON (EPON). The new tri-mode energy saving design, combining the dual-mode saving mechanism with the doze mode, allows the ONU to switch among these three modes alternatively. In the doze mode, the ONU may receive downstream data while keeping its transmitter close. Such scenario is often observed for real time video downstream transmission. Furthermore, the low packet delay of high priority upstream data can be attained through the use of early wake-up mechanism employed in both energy saving modes. The energy saving and system efficiency can thus be achieved jointly while maintaining the differentiated QoS for data with various priorities. Performance results via simulation have demonstrated the effectiveness of such mechanism.

On-Line Databases in Mexico.

ERIC Educational Resources Information Center

Molina, Enzo

1986-01-01

Use of online bibliographic databases in Mexico is provided through Servicio de Consulta a Bancos de Informacion, a public service that provides information retrieval, document delivery, translation, technical support, and training services. Technical infrastructure is based on a public packet-switching network and institutional users may receive…

Access to Corporate Information Systems: Datafiles, Classified Documents, and Information Resources.

ERIC Educational Resources Information Center

Baumgartner, Kurt O.; And Others

1988-01-01

Three articles discuss aspects of corporate information systems: (1) "Packet Switching Networks: Worldwide Access to Corporate Datafiles" (Kurt O. Baumgartner); "Classified Documents in the Corporate Library" (Patricia M. Shores); and "From Library to Information Center: Case Studies in the Evolution of Corporate…

Experience with the EURECA Packet Telemetry and Packet Telecommand system

NASA Technical Reports Server (NTRS)

Sorensen, Erik Mose; Ferri, Paolo

1994-01-01

The European Retrieval Carrier (EURECA) was launched on its first flight on the 31st of July 1992 and retrieved on the 29th of June 1993. EURECA is characterized by several new on-board features, most notably Packet telemetry, and a partial implementation of packet telecommanding, the first ESA packetised spacecraft. Today more than one year after the retrieval the data from the EURECA mission has to a large extent been analysed and we can present some of the interesting results. This paper concentrates on the implementation and operational experience with the EURECA Packet Telemetry and Packet Telecommanding. We already discovered during the design of the ground system that the use of packet telemetry has major impact on the overall design and that processing of packet telemetry may have significant effect on the computer loading and sizing. During the mission a number of problems were identified with the on-board implementation resulting in very strange anomalous behaviors. Many of these problems directly violated basic assumptions for the design of the ground segment adding to the strange behavior. The paper shows that the design of a telemetry packet system should be flexible enough to allow a rapid configuration of the telemetry processing in order to adapt it to the new situation in case of an on-board failure. The experience gained with the EURECA mission control should be used to improve ground systems for future missions.

Optical Circuit Switched Protocol

NASA Technical Reports Server (NTRS)

Monacos, Steve P. (Inventor)

2000-01-01

The present invention is a system and method embodied in an optical circuit switched protocol for the transmission of data through a network. The optical circuit switched protocol is an all-optical circuit switched network and includes novel optical switching nodes for transmitting optical data packets within a network. Each optical switching node comprises a detector for receiving the header, header detection logic for translating the header into routing information and eliminating the header, and a controller for receiving the routing information and configuring an all optical path within the node. The all optical path located within the node is solely an optical path without having electronic storage of the data and without having optical delay of the data. Since electronic storage of the header is not necessary and the initial header is eliminated by the first detector of the first switching node. multiple identical headers are sent throughout the network so that subsequent switching nodes can receive and read the header for setting up an optical data path.

Next generation satellite communications networks

NASA Astrophysics Data System (ADS)

Garland, P. J.; Osborne, F. J.; Streibl, I.

The paper introduces two potential uses for new space hardware to permit enhanced levels of signal handling and switching in satellite communication service for Canada. One application involves increased private-sector services in the Ku band; the second supports new personal/mobile services by employing higher levels of handling and switching in the Ka band. First-generation satellite regeneration and switching experiments involving the NASA/ACTS spacecraft are described, where the Ka band and switching satellite network problems are emphasized. Second-generation satellite development is outlined based on demand trends for more packet-based switching, low-cost earth stations, and closed user groups. A demonstration mission for new Ka- and Ku-band technologies is proposed, including the payload configuration. The half ANIK E payload is shown to meet the demonstration objectives, and projected to maintain a fully operational payload for at least 10 years.

A Telecommunications Primer for College Presidents. Part I. The Technologies Defined. Educational Technology Profile 25.

ERIC Educational Resources Information Center

Smith, Ralph Lee

1978-01-01

Intended for use by presidents, planners, and administrators to acquaint them with developments in electronic communications, this primer describes cable television, common carrier, videotape recorders and videodiscs, satellites, microwave, circuit integration, digital transmission, data packet switching, and fiber optics. (LBH)

Pacific Educational Computer Network Study. Final Report.

ERIC Educational Resources Information Center

Hawaii Univ., Honolulu. ALOHA System.

The Pacific Educational Computer Network Feasibility Study examined technical and non-technical aspects of the formation of an international Pacific Area computer network for higher education. The technical study covered the assessment of the feasibility of a packet-switched satellite and radio ground distribution network for data transmission…

Threatened and Endangered Species: Tour Packet.

ERIC Educational Resources Information Center

Coats, Victoria; Samia, Cory

This resource unit contains a teacher information packet and a middle school student activity packet to be used in creating a threatened and endangered species unit. The packet of student activities is designed to help maximize a field trip to the zoo and build on students' zoo experience in the classroom. The teacher information packet covers the…

Dynamical jumping real-time fault-tolerant routing protocol for wireless sensor networks.

PubMed

Wu, Guowei; Lin, Chi; Xia, Feng; Yao, Lin; Zhang, He; Liu, Bing

2010-01-01

In time-critical wireless sensor network (WSN) applications, a high degree of reliability is commonly required. A dynamical jumping real-time fault-tolerant routing protocol (DMRF) is proposed in this paper. Each node utilizes the remaining transmission time of the data packets and the state of the forwarding candidate node set to dynamically choose the next hop. Once node failure, network congestion or void region occurs, the transmission mode will switch to jumping transmission mode, which can reduce the transmission time delay, guaranteeing the data packets to be sent to the destination node within the specified time limit. By using feedback mechanism, each node dynamically adjusts the jumping probabilities to increase the ratio of successful transmission. Simulation results show that DMRF can not only efficiently reduce the effects of failure nodes, congestion and void region, but also yield higher ratio of successful transmission, smaller transmission delay and reduced number of control packets.

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch.

PubMed

Huang, Tao; Yan, Siyu; Yang, Fan; Pan, Tian; Liu, Jiang

2016-01-19

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture.

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch

PubMed Central

Huang, Tao; Yan, Siyu; Yang, Fan; Pan, Tian; Liu, Jiang

2016-01-01

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture. PMID:26797616

The American mobile satellite system

NASA Technical Reports Server (NTRS)

Garner, William B.

1990-01-01

During 1989, the American Mobile Satellite Corporation (AMSC) was authorized to construct, launch, and operate satellites to provide mobile satellite services (MSS) to the U.S. and Puerto Rico. The AMSC has undertaken three major development programs to bring a full range of MSS services to the U.S. The first program is the space segment program that will result in the construction and launch of the satellites as well as the construction and installation of the supporting ground telemetry and command system. The second segment will result in the specification, design, development, construction, and installation of the Network Control System necessary for managing communications access to the satellites, and the specification and development of ground equipment for standard circuit switched and packet switched communications services. The third program is the Phase 1 program to provide low speed data services within the U.S. prior to availability of the AMSC satellites and ground segment. Described here are the present status and plans for these three programs as well as an update on related business arrangements and regulatory matters.

Energy Efficient, Cross-Layer Enabled, Dynamic Aggregation Networks for Next Generation Internet

NASA Astrophysics Data System (ADS)

Wang, Michael S.

Today, the Internet traffic is growing at a near exponential rate, driven predominately by data center-based applications and Internet-of-Things services. This fast-paced growth in Internet traffic calls into question the ability of the existing optical network infrastructure to support this continued growth. The overall optical networking equipment efficiency has not been able to keep up with the traffic growth, creating a energy gap that makes energy and cost expenditures scale linearly with the traffic growth. The implication of this energy gap is that it is infeasible to continue using existing networking equipment to meet the growing bandwidth demand. A redesign of the optical networking platform is needed. The focus of this dissertation is on the design and implementation of energy efficient, cross-layer enabled, dynamic optical networking platforms, which is a promising approach to address the exponentially growing Internet bandwidth demand. Chapter 1 explains the motivation for this work by detailing the huge Internet traffic growth and the unsustainable energy growth of today's networking equipment. Chapter 2 describes the challenges and objectives of enabling agile, dynamic optical networking platforms and the vision of the Center for Integrated Access Networks (CIAN) to realize these objectives; the research objectives of this dissertation and the large body of related work in this field is also summarized. Chapter 3 details the design and implementation of dynamic networking platforms that support wavelength switching granularity. The main contribution of this work involves the experimental validation of deep cross-layer communication across the optical performance monitoring (OPM), data, and control planes. The first experiment shows QoS-aware video streaming over a metro-scale test-bed through optical power monitoring of the transmission wavelength and cross-layer feedback control of the power level. The second experiment extends the performance monitoring capabilities to include real-time monitoring of OSNR and polarization mode dispersion (PMD) to enable dynamic wavelength switching and selective restoration. Chapter 4 explains the author?s contributions in designing dynamic networking at the sub-wavelength switching granularity, which can provide greater network efficiency due to its finer granularity. To support dynamic switching, regeneration, adding/dropping, and control decisions on each individual packet, the cross-layer enabled node architecture is enhanced with a FPGA controller that brings much more precise timing and control to the switching, OPM, and control planes. Furthermore, QoS-aware packet protection and dynamic switching, dropping, and regeneration functionalities were experimentally demonstrated in a multi-node network. Chapter 5 describes a technique to perform optical grooming, a process of optically combining multiple incoming data streams into a single data stream, which can simultaneously achieve greater bandwidth utilization and increased spectral efficiency. In addition, an experimental demonstration highlighting a fully functioning multi-node, agile optical networking platform is detailed. Finally, a summary and discussion of future work is provided in Chapter 6. The future of the Internet is very exciting, filled with not-yet-invented applications and services driven by cloud computing and Internet-of-Things. The author is cautiously optimistic that agile, dynamically reconfigurable optical networking is the solution to realizing this future.

Naval Research Logistics Quarterly. Volume 29, Number 3,

DTIC Science & Technology

1982-09-01

proposed for combining voice and data demands over the available channel bandwidth (Coviello and Vena [21, Fischer and Harris (41, Frank and Gitman 151...and Packet Switched Multiplex Structure," IEEE Transactions nn Communications, Com-24, 195-202 (1976). (51 Frank, H. and I. Gitman , "Integrated DOB

Online Searching at 9600 Baud.

ERIC Educational Resources Information Center

Scott, Ralph Lee; Scott, Nancy Sue Schell

1991-01-01

Discusses online searching with the new 9600 baud rate and describes test searches on the BRS, Data-Star, LEXIS, and Dow Jones databases through three packet-switching networks: US Sprint, MEADNET, and TYMNET. Hardware and software are described, data communications equipment standards are discussed, and the impact of higher baud rates on pricing…

Simulation of the Impact of Packet Errors on the Kademlia Peer-to-Peer Routing

DTIC Science & Technology

2010-09-01

during the routing process. Pastry [15] switches to a proximity based metric when approaching a node closely. This complicates the implementation...and Peter Druschel. Pastry : Scalable, distributed object location and routing for large-scale peer-to-peer systems. IFIP/ACM International Conference

The ARPANET and DARPA Internet.

ERIC Educational Resources Information Center

Perry, Dennis G.; And Others

1988-01-01

Reviews the development and growth of the ARPANET, a wide-area packet switching network initiated by the U.S. Department of Defense in 1969. Evolution of the ARPANET into the DARPA (Advanced Research Projects Agency) Internet in the 1970s and current uses of the internet are discussed. (16 references) (MES)

Using cyber vulnerability testing techniques to expose undocumented security vulnerabilities in DCS and SCADA equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollet, J.

2006-07-01

This session starts by providing an overview of typical DCS (Distributed Control Systems) and SCADA (Supervisory Control and Data Acquisition) architectures, and exposes cyber security vulnerabilities that vendors never admit, but are found through a comprehensive cyber testing process. A complete assessment process involves testing all of the layers and components of a SCADA or DCS environment, from the perimeter firewall all the way down to the end devices controlling the process, including what to look for when conducting a vulnerability assessment of real-time control systems. The following systems are discussed: 1. Perimeter (isolation from corporate IT or other non-criticalmore » networks) 2. Remote Access (third Party access into SCADA or DCS networks) 3. Network Architecture (switch, router, firewalls, access controls, network design) 4. Network Traffic Analysis (what is running on the network) 5. Host Operating Systems Hardening 6. Applications (how they communicate with other applications and end devices) 7. End Device Testing (PLCs, RTUs, DCS Controllers, Smart Transmitters) a. System Discovery b. Functional Discovery c. Attack Methodology i. DoS Tests (at what point does the device fail) ii. Malformed Packet Tests (packets that can cause equipment failure) iii. Session Hijacking (do anything that the operator can do) iv. Packet Injection (code and inject your own SCADA commands) v. Protocol Exploitation (Protocol Reverse Engineering / Fuzzing) This paper will provide information compiled from over five years of conducting cyber security testing on control systems hardware, software, and systems. (authors)« less

Multi-Domain SDN Survivability for Agricultural Wireless Sensor Networks.

PubMed

Huang, Tao; Yan, Siyu; Yang, Fan; Liu, Jiang

2016-11-06

Wireless sensor networks (WSNs) have been widely applied in agriculture field; meanwhile, the advent of multi-domain software-defined networks (SDNs) have improved the wireless resource utilization rate and strengthened network management. In recent times, multi-domain SDNs have been applied to agricultural sensor networks, namely multi-domain software-defined wireless sensor networks (SDWSNs). However, when the SDNs controlling agriculture networks suddenly become unavailable, whether intra-domain or inter-domain, sensor network communication is abnormal because of the loss of control. Moreover, there are controller and switch info-updating problems even if the controller becomes available again. To resolve these problems, this paper proposes a new approach based on an Open vSwitch extension for multi-domain SDWSNs, which can enhance agriculture network survivability and stability. We achieved this by designing a connection-state mechanism, a communication mechanism on both L2 and L3, and an info-updating mechanism based on Open vSwitch. The experimental results show that, whether it is agricultural inter-domain or intra-domain during the controller failure period, the sensor switches can enter failure recovery mode as soon as possible so that the sensor network keeps a stable throughput, a short failure recovery time below 300 ms, and low packet loss. Further, the domain can smoothly control the domain network again once the controller becomes available. This approach based on an Open vSwitch extension can enhance the survivability and stability of multi-domain SDWSNs in precision agriculture.

Multi-Domain SDN Survivability for Agricultural Wireless Sensor Networks

PubMed Central

Huang, Tao; Yan, Siyu; Yang, Fan; Liu, Jiang

2016-01-01

Wireless sensor networks (WSNs) have been widely applied in agriculture field; meanwhile, the advent of multi-domain software-defined networks (SDNs) have improved the wireless resource utilization rate and strengthened network management. In recent times, multi-domain SDNs have been applied to agricultural sensor networks, namely multi-domain software-defined wireless sensor networks (SDWSNs). However, when the SDNs controlling agriculture networks suddenly become unavailable, whether intra-domain or inter-domain, sensor network communication is abnormal because of the loss of control. Moreover, there are controller and switch info-updating problems even if the controller becomes available again. To resolve these problems, this paper proposes a new approach based on an Open vSwitch extension for multi-domain SDWSNs, which can enhance agriculture network survivability and stability. We achieved this by designing a connection-state mechanism, a communication mechanism on both L2 and L3, and an info-updating mechanism based on Open vSwitch. The experimental results show that, whether it is agricultural inter-domain or intra-domain during the controller failure period, the sensor switches can enter failure recovery mode as soon as possible so that the sensor network keeps a stable throughput, a short failure recovery time below 300 ms, and low packet loss. Further, the domain can smoothly control the domain network again once the controller becomes available. This approach based on an Open vSwitch extension can enhance the survivability and stability of multi-domain SDWSNs in precision agriculture. PMID:27827971

An overview of the technical design of MSAT mobile satellite communications services

NASA Astrophysics Data System (ADS)

Davies, N. George

The Canadian MSAT mobile satellite communications system is being implemented in cooperation with the American Mobile Satellite Consortium (AMSC). Two satellites are to be jointly acquired and each satellite is expected to backup the other. This paper describes the technical concepts of the services to be offered and the baseline planning of the infrastructure for the ground segment. MSAT service requirements are analyzed for mobile radio, telephone, data, and aeronautical services. The MSAT system will use nine beams in a narrow range of L-band frequencies with frequency reuse. Beams may be added to cover flight information areas in the Atlantic and Pacific oceans. The elements of the network architecture are: a network control centre, data hub stations, gateway stations, base stations, mobile terminals, and a signalling system to interconnect the elements of the system. The network control center will manage the network and allocate space segment capacity; data hub stations will support a switched packet mobile data service; the gateway stations will provide interconnection to the public telephone system and data networks; and the base stations will support private circuit switched voice and data services. Several alternative designs for the signalling system are described.

Environmental Fluctuations and Acoustic Data Communications

DTIC Science & Technology

2015-09-30

July 2011 along with subsequent analysis of the experiment data. KAM11 Experiment (2011) A shallow water acoustic communications experiment...packet and packet-to-packet variability. Algorithm Design and Experiment Data Analysis Communication receiver algorithm design for shallow water is...exhibited substantial daily oceanographic variability. Analysis of the KAM11 experiment data this past year has focused on fixed source transmissions

Process and methodology of developing Cassini G and C Telemetry Dictionary

NASA Technical Reports Server (NTRS)

Kan, Edwin P.

1994-01-01

While the Cassini spacecraft telemetry design had taken on the new approach of 'packetized telemetry', the AACS (Attitude and Articulation Subsystem) had further extended into the design of 'mini-packets' in its telemetry system. Such telemetry packet and mini-packet design produced the AACS Telemetry Dictionary; iterations of the latter in turn provided changes to the former. The ultimate goals were to achieve maximum telemetry packing density, optimize the 'freshness' of more time-critical data, and to effect flexibility, i.e., multiple AACS data collection schemes, without needing to change the overall spacecraft telemetry mode. This paper describes such a systematic process and methodology, evidenced by various design products related to, or as part of, the AACS Telemetry Dictionary.

Evaluation of multicast schemes in optical burst-switched networks: the case with dynamic sessions

NASA Astrophysics Data System (ADS)

Jeong, Myoungki; Qiao, Chunming; Xiong, Yijun; Vandenhoute, Marc

2000-10-01

In this paper, we evaluate the performance of several multicast schemes in optical burst-switched WDM networks taking into accounts the overheads due to control packets and guard bands (Gbs) of bursts on separate channels (wavelengths). A straightforward scheme is called Separate Multicasting (S-MCAST) where each source node constructs separate bursts for its multicast (per each multicast session) and unicast traffic. To reduce the overhead due to Gbs (and control packets), one may piggyback the multicast traffic in bursts containing unicast traffic using a scheme called Multiple Unicasting (M-UCAST). The third scheme is called Tree-Shared Multicasting (TS-MCAST) wehreby multicast traffic belonging to multiple multicast sesions can be mixed together in a burst, which is delivered via a shared multicast tree. In [1], we have evaluated several multicast schemes with static sessions at the flow level. In this paper, we perform a simple analysis for the multicast schemes and evaluate the performance of three multicast schemes, focusing on the case with dynamic sessions in terms of the link utilization, bandwidth consumption, blocking (loss) probability, goodput and the processing loads.

Anderson localization and Mott insulator phase in the time domain

PubMed Central

Sacha, Krzysztof

2015-01-01

Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There is an intriguing question if solid state phenomena can be observed in the time domain. Here we show that wave-packets localized on resonant classical trajectories of periodically driven systems are ideal elements to realize Anderson localization or Mott insulator phase in the time domain. Uniform superpositions of the wave-packets form stationary states of a periodically driven particle. However, an additional perturbation that fluctuates in time results in disorder in time and Anderson localization effects emerge. Switching to many-particle systems we observe that depending on how strong particle interactions are, stationary states can be Bose-Einstein condensates or single Fock states where definite numbers of particles occupy the periodically evolving wave-packets. Our study shows that non-trivial crystal-like phenomena can be observed in the time domain. PMID:26074169

Mixture block coding with progressive transmission in packet video. Appendix 1: Item 2. M.S. Thesis

NASA Technical Reports Server (NTRS)

Chen, Yun-Chung

1989-01-01

Video transmission will become an important part of future multimedia communication because of dramatically increasing user demand for video, and rapid evolution of coding algorithm and VLSI technology. Video transmission will be part of the broadband-integrated services digital network (B-ISDN). Asynchronous transfer mode (ATM) is a viable candidate for implementation of B-ISDN due to its inherent flexibility, service independency, and high performance. According to the characteristics of ATM, the information has to be coded into discrete cells which travel independently in the packet switching network. A practical realization of an ATM video codec called Mixture Block Coding with Progressive Transmission (MBCPT) is presented. This variable bit rate coding algorithm shows how a constant quality performance can be obtained according to user demand. Interactions between codec and network are emphasized including packetization, service synchronization, flow control, and error recovery. Finally, some simulation results based on MBCPT coding with error recovery are presented.

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born–Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersionmore » of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.« less

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

DOE PAGES

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; ...

2017-05-24

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born–Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersionmore » of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.« less

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

NASA Astrophysics Data System (ADS)

Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; van Driel, Tim B.; Chollet, Matthieu; Glownia, James M.; Song, Sanghoon; Zhu, Diling; Pace, Elisabetta; Matar, Samir F.; Nielsen, Martin M.; Benfatto, Maurizio; Gaffney, Kelly J.; Collet, Eric; Cammarata, Marco

2017-05-01

The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.

Children's Literature with a Science Emphasis: Twenty Teacher-Developed K-8 Activity Packets.

ERIC Educational Resources Information Center

Butler, Malcolm B.

This document features 10 science activity packets developed for elementary students by science teachers in a graduate seminar. The activity packets were designed to cover existing commercial children's books on specific content areas. The 10 activity packets are: (1) "Bringing the Rain to Kapiti Plain," which explains the water cycle;…

Accounting Clerk Guide, Exercise and Worksheet Packet--Part I.

ERIC Educational Resources Information Center

Foster, Brian; And Others

The exercise and worksheet packet is part of an eight volume unit for grades 10, 11, and 12, designed for individualized progression in preparing students for entry into the occupation of accounting clerk. The exercise and worksheet packet contains a copy of every worksheet in the learner packet for lessons 1 through 11 so that the instructor can…

Analysis of Cisco Open Network Environment (ONE) OpenFlow Controller Implementation

DTIC Science & Technology

2014-08-01

Software - Defined Networking ( SDN ), when fully realized, offer many improvements over the current rigid and...functionalities like handshake, connection setup, switch management, and security. 15. SUBJECT TERMS OpenFlow, software - defined networking , Cisco ONE, SDN ...innovating packet-forwarding technologies. Network device roles are strictly defined with little or no flexibility. In Software - Defined Networks ( SDNs ),

The Use of Austpac at Deakin University for Distance Education. Computer Communications Working Group Report No. 1.

ERIC Educational Resources Information Center

Castro, Angela; Stirzaker, Lee

This paper discusses Australia's two packet-switching networks, AUSTPAC and MIDAS, which are used for data transmissions with other computers located within Australia or between overseas destinations. Although the facilities of both are similar, a comparison of their services based on traffic volume, connection, registration, and rental charges is…

Ship-Shore Packet Switched Communications System.

DTIC Science & Technology

1986-06-01

PERFORMING ORGANIZATION 6b OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION (If applicable ) Naval Postgraduate School 54 Naval Postgraduate School 6c...OFFICE SYMBOL 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATION (If applicable ) 8c ADDRESS (City, State, and ZIPCode) 10 SOURCE OF FUNDING...level acknowledgement system. 37 Network Protocol Application P re sen tation Session ____ ____ ____ ___Internet TranportProtocol Network

Design and Evaluation of a Proxy-Based Monitoring System for OpenFlow Networks.

PubMed

Taniguchi, Yoshiaki; Tsutsumi, Hiroaki; Iguchi, Nobukazu; Watanabe, Kenzi

2016-01-01

Software-Defined Networking (SDN) has attracted attention along with the popularization of cloud environment and server virtualization. In SDN, the control plane and the data plane are decoupled so that the logical topology and routing control can be configured dynamically depending on network conditions. To obtain network conditions precisely, a network monitoring mechanism is necessary. In this paper, we focus on OpenFlow which is a core technology to realize SDN. We propose, design, implement, and evaluate a network monitoring system for OpenFlow networks. Our proposed system acts as a proxy between an OpenFlow controller and OpenFlow switches. Through experimental evaluations, we confirm that our proposed system can capture packets and monitor traffic information depending on administrator's configuration. In addition, we show that our proposed system does not influence significant performance degradation to overall network performance.

Cross-Layer Design for Space-Time coded MIMO Systems over Rice Fading Channel

NASA Astrophysics Data System (ADS)

Yu, Xiangbin; Zhou, Tingting; Liu, Xiaoshuai; Yin, Xin

A cross-layer design (CLD) scheme for space-time coded MIMO systems over Rice fading channel is presented by combining adaptive modulation and automatic repeat request, and the corresponding system performance is investigated well. The fading gain switching thresholds subject to a target packet error rate (PER) and fixed power constraint are derived. According to these results, and using the generalized Marcum Q-function, the calculation formulae of the average spectrum efficiency (SE) and PER of the system with CLD are derived. As a result, closed-form expressions for average SE and PER are obtained. These expressions include some existing expressions in Rayleigh channel as special cases. With these expressions, the system performance in Rice fading channel is evaluated effectively. Numerical results verify the validity of the theoretical analysis. The results show that the system performance in Rice channel is effectively improved as Rice factor increases, and outperforms that in Rayleigh channel.

Design and Evaluation of a Proxy-Based Monitoring System for OpenFlow Networks

PubMed Central

Taniguchi, Yoshiaki; Tsutsumi, Hiroaki; Iguchi, Nobukazu; Watanabe, Kenzi

2016-01-01

Software-Defined Networking (SDN) has attracted attention along with the popularization of cloud environment and server virtualization. In SDN, the control plane and the data plane are decoupled so that the logical topology and routing control can be configured dynamically depending on network conditions. To obtain network conditions precisely, a network monitoring mechanism is necessary. In this paper, we focus on OpenFlow which is a core technology to realize SDN. We propose, design, implement, and evaluate a network monitoring system for OpenFlow networks. Our proposed system acts as a proxy between an OpenFlow controller and OpenFlow switches. Through experimental evaluations, we confirm that our proposed system can capture packets and monitor traffic information depending on administrator's configuration. In addition, we show that our proposed system does not influence significant performance degradation to overall network performance. PMID:27006977

Congestion control and routing over satellite networks

NASA Astrophysics Data System (ADS)

Cao, Jinhua

Satellite networks and transmissions find their application in fields of computer communications, telephone communications, television broadcasting, transportation, space situational awareness systems and so on. This thesis mainly focuses on two networking issues affecting satellite networking: network congestion control and network routing optimization. Congestion, which leads to long queueing delays, packet losses or both, is a networking problem that has drawn the attention of many researchers. The goal of congestion control mechanisms is to ensure high bandwidth utilization while avoiding network congestion by regulating the rate at which traffic sources inject packets into a network. In this thesis, we propose a stable congestion controller using data-driven, safe switching control theory to improve the dynamic performance of satellite Transmission Control Protocol/Active Queue Management (TCP/AQM) networks. First, the stable region of the Proportional-Integral (PI) parameters for a nominal model is explored. Then, a PI controller, whose parameters are adaptively tuned by switching among members of a given candidate set, using observed plant data, is presented and compared with some classical AQM policy examples, such as Random Early Detection (RED) and fixed PI control. A new cost detectable switching law with an interval cost function switching algorithm, which improves the performance and also saves the computational cost, is developed and compared with a law commonly used in the switching control literature. Finite-gain stability of the system is proved. A fuzzy logic PI controller is incorporated as a special candidate to achieve good performance at all nominal points with the available set of candidate controllers. Simulations are presented to validate the theory. An effocient routing algorithm plays a key role in optimizing network resources. In this thesis, we briefly analyze Low Earth Orbit (LEO) satellite networks, review the Cross Entropy (CE) method and then develop a novel on-demand routing system named Cross Entropy Accelerated Ant Routing System (CEAARS) for regular constellation LEO satellite networks. By implementing simulations on an Iridium-like satellite network, we compare the proposed CEAARS algorithm with the two approaches to adaptive routing protocols on the Internet: distance-vector (DV) and link-state (LS), as well as with the original Cross Entropy Ant Routing System (CEARS). DV algorithms are based on distributed Bellman Ford algorithm, and LS algorithms are implementation of Dijkstras single source shortest path. The results show that CEAARS not only remarkably improves the convergence speed of achieving optimal or suboptimal paths, but also reduces the number of overhead ants (management packets).

A hybrid optical switch architecture to integrate IP into optical networks to provide flexible and intelligent bandwidth on demand for cloud computing

NASA Astrophysics Data System (ADS)

Yang, Wei; Hall, Trevor J.

2013-12-01

The Internet is entering an era of cloud computing to provide more cost effective, eco-friendly and reliable services to consumer and business users. As a consequence, the nature of the Internet traffic has been fundamentally transformed from a pure packet-based pattern to today's predominantly flow-based pattern. Cloud computing has also brought about an unprecedented growth in the Internet traffic. In this paper, a hybrid optical switch architecture is presented to deal with the flow-based Internet traffic, aiming to offer flexible and intelligent bandwidth on demand to improve fiber capacity utilization. The hybrid optical switch is capable of integrating IP into optical networks for cloud-based traffic with predictable performance, for which the delay performance of the electronic module in the hybrid optical switch architecture is evaluated through simulation.

ISDN at NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Bakes, Catherine Murphy; Goldberg, Fredric; Eubanks, Steven W.

1992-01-01

An expository investigation of the potential impact of the Integrated Services Digital Network (ISDN) at NASA Lewis Research Center is described. To properly frame the subject, the paper contains a detailed survey of the components of Narrowband ISDN. The principles and objectives are presented as decreed by the Consultative Committee for International Telephone and Telegraph (CCITT). The various channel types are delineated and their associated service combinations are described. The subscriber-access network functions are explained pictorially via the ISDN reference configuration. A section on switching techniques is presented to enable the reader to understand the emergence of the concept of fast packet switching. This new technology is designed to operate over the high bandwidth, low error rate transmission media that characterizes the LeRC environment. A brief introduction to the next generation of networks is covered with sections on Broadband ISDM (B-ISDN), Asynchronous Transfer Mode (ATM), and Synchronous Optical Networks (SONET). Applications at LeRC are presented, first in terms of targets of opportunity, then in light of compatibility constraints. In-place pilot projects and testing are described that demonstrate actual usage at LeRC.

SDN-enabled hybrid emergency message transmission architecture in internet-of-vehicles

NASA Astrophysics Data System (ADS)

Zhu, Wanting; Gao, Deyun; Zhao, Weicheng; Zhang, Hongke; Chiang, Hua-Pei

2018-04-01

With the increasing number of vehicles connected to the Internet-of-Things (IoT), Internet-of-Vehicles (IoV) is becoming a hot research topic. It can improve traffic safety and efficiency and promote the development of the intelligent transportation that is a very important element in Smart Cities. As an important part of the safety application in IoV, the emergency message transmission is designed to inform all the vehicles in the relevant area timely of the accident information through the multi-hop broadcast communication. In this paper, we propose a hybrid emergency message transmission (HEMT), which introduces the SDN technology into the vehicular network environment and utilizes the flexibility of inter-vehicle communication. By deploying SDN-enabled central controller and RSU switches, we can obtain reliable and fast emergency message dissemination. Moreover, considering the space between the coverages of RSUs caused by the sparse deployment, we also use inter-vehicle multi-hop broadcast communication to improve the message coverage ratio by adding the packet modification module on the RSU switch. Simulation results show the feasibility and effectiveness of our proposed scheme.

Research on moving target defense based on SDN

NASA Astrophysics Data System (ADS)

Chen, Mingyong; Wu, Weimin

2017-08-01

An address mutation strategy was proposed. This strategy provided an unpredictable change in address, replacing the real address of the packet forwarding process and path mutation, thus hiding the real address of the host and path. a mobile object defense technology based on Spatio-temporal Mutation on this basis is proposed, Using the software Defined Network centralized control architecture advantage combines sFlow traffic monitoring technology and Moving Target Defense. A mutated time period which can be changed in real time according to the network traffic is changed, and the destination address is changed while the controller abruptly changes the address while the data packet is transferred between the switches to construct a moving target, confusing the host within the network, thereby protecting the host and network.

Optical multicast system for data center networks.

PubMed

Samadi, Payman; Gupta, Varun; Xu, Junjie; Wang, Howard; Zussman, Gil; Bergman, Keren

2015-08-24

We present the design and experimental evaluation of an Optical Multicast System for Data Center Networks, a hardware-software system architecture that uniquely integrates passive optical splitters in a hybrid network architecture for faster and simpler delivery of multicast traffic flows. An application-driven control plane manages the integrated optical and electronic switched traffic routing in the data plane layer. The control plane includes a resource allocation algorithm to optimally assign optical splitters to the flows. The hardware architecture is built on a hybrid network with both Electronic Packet Switching (EPS) and Optical Circuit Switching (OCS) networks to aggregate Top-of-Rack switches. The OCS is also the connectivity substrate of splitters to the optical network. The optical multicast system implementation requires only commodity optical components. We built a prototype and developed a simulation environment to evaluate the performance of the system for bulk multicasting. Experimental and numerical results show simultaneous delivery of multicast flows to all receivers with steady throughput. Compared to IP multicast that is the electronic counterpart, optical multicast performs with less protocol complexity and reduced energy consumption. Compared to peer-to-peer multicast methods, it achieves at minimum an order of magnitude higher throughput for flows under 250 MB with significantly less connection overheads. Furthermore, for delivering 20 TB of data containing only 15% multicast flows, it reduces the total delivery energy consumption by 50% and improves latency by 55% compared to a data center with a sole non-blocking EPS network.

High-port low-latency optical switch architecture with optical feed-forward buffering for 256-node disaggregated data centers.

PubMed

Terzenidis, Nikos; Moralis-Pegios, Miltiadis; Mourgias-Alexandris, George; Vyrsokinos, Konstantinos; Pleros, Nikos

2018-04-02

Departing from traditional server-centric data center architectures towards disaggregated systems that can offer increased resource utilization at reduced cost and energy envelopes, the use of high-port switching with highly stringent latency and bandwidth requirements becomes a necessity. We present an optical switch architecture exploiting a hybrid broadcast-and-select/wavelength routing scheme with small-scale optical feedforward buffering. The architecture is experimentally demonstrated at 10Gb/s, reporting error-free performance with a power penalty of <2.5dB. Moreover, network simulations for a 256-node system, revealed low-latency values of only 605nsec, at throughput values reaching 80% when employing 2-packet-size optical buffers, while multi-rack network performance was also investigated.

Market capture by 30/20 GHz satellite systems. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Gamble, R. B.; Saporta, L.

1981-01-01

Demand for 30/20 GHz satellite systems over the next two decades is projected. Topics include a profile of the communications market, switched, dedicated, and packet transmission modes, deferred and real-time traffic, quality and reliability considerations, the capacity of competing transmission media, and scenarios for the growth and development of 30/20 GHz satellite communications.

Market capture by 30/20 GHz satellite systems. Volume 1: Executive summary

NASA Astrophysics Data System (ADS)

Gamble, R. B.; Saporta, L.

1981-04-01

Demand for 30/20 GHz satellite systems over the next two decades is projected. Topics include a profile of the communications market, switched, dedicated, and packet transmission modes, deferred and real-time traffic, quality and reliability considerations, the capacity of competing transmission media, and scenarios for the growth and development of 30/20 GHz satellite communications.

Canoeing.

ERIC Educational Resources Information Center

Little, Mildred J.; Smith, Carole F.

Designed to be used in conjunction with the book "Canoeing", published by the American Red Cross in 1977, the teaching packet provides assistance in organizing and teaching a basic canoeing class. The packet lists 20 class objectives and details essential and recommended equipment and safety precautions. The packet contains a 15-day unit…

Evolving PSTN to NGN

NASA Astrophysics Data System (ADS)

Wu, Liang T.

2004-04-01

The concept of Next Generation Network (NGN) was conceived around 1998 as an integrated solution to combine the quality and features of the PSTN with the low cost and routing flexibility of the Internet to provide a single infrastructure for the future public network. This carrier grade Internet solution calls for the creation of a consolidated, packet transport and switching infrastructure and the development of a flexible, open, software switch (softswitch) to handle voice telephony as well as multimedia services. Almost all the telecom equipment manufacturers as well as some Internet equipment vendors immediately subscribed to this vision and joined the race to create convergent products for the NGN market.

Advertising and the Economy: A Teaching Package.

ERIC Educational Resources Information Center

Proctor and Gamble Co., Cincinnati, OH.

This teaching packet is designed to enrich lessons and motivate students, and is based on real-life marketing problems. The packet includes a booklet containing background for instructors on advertising's crucial economic role and its history in the United States, eight reproducible lessons, and teaching tips for each lesson. The packet also…

Cebuano Language Packet.

ERIC Educational Resources Information Center

Peace Corps, Manila (Philippines).

The materials in this packet were designed for the rapid Cebuano language training of Peace Corps volunteers, focusing on daily communication needs in this context. The packet contains: lists of common phrases, expressions, and vocabulary on a variety of topics related to Peace Corps work; a list of core competencies for specific topics…

Learn about Seabirds. Teaching Packet, Grades 4-6.

ERIC Educational Resources Information Center

Fish and Wildlife Service (Dept. of Interior), Anchorage, AK.

This teaching packet is designed to teach Alaskan students in grades 4-6 about Alaska's seabird populations, the worldwide significance of seabirds, and the environmental conditions to which seabirds are sensitive. The packet includes a curriculum guide (containing a teacher's background story and 12 teaching activities), a separately published…

Fiber optic voice/data network

NASA Technical Reports Server (NTRS)

Bergman, Larry A. (Inventor)

1989-01-01

An asynchronous, high-speed, fiber optic local area network originally developed for tactical environments with additional benefits for other environments such as spacecraft, and the like. The network supports ordinary data packet traffic simultaneously with synchronous T1 voice traffic over a common token ring channel; however, the techniques and apparatus of this invention can be applied to any deterministic class of packet data networks, including multitier backbones, that must transport stream data (e.g., video, SAR, sensors) as well as data. A voice interface module parses, buffers, and resynchronizes the voice data to the packet network employing elastic buffers on both the sending and receiving ends. Voice call setup and switching functions are performed external to the network with ordinary PABX equipment. Clock information is passed across network boundaries in a token passing ring by preceeding the token with an idle period of non-transmission which allows the token to be used to re-establish a clock synchronized to the data. Provision is made to monitor and compensate the elastic receiving buffers so as to prevent them from overflowing or going empty.

Energy in Our Society.

ERIC Educational Resources Information Center

Philadelphia Electric Co., PA. Energy Education Advisory Council.

This publication is a series of 13 original classroom instructional packets and an additional 4 units adapted from National Science Teachers Association units. Each packet is designed to supplement specific existing subject curricula. Units have been designed for physics, chemistry, English, mathematics, general science and studies. Packets…

Rethinking Mobile Telephony with the IMP

DTIC Science & Technology

2011-01-01

in the telephony industry, and portions of it such as SS7 or SCTP signaling are packet-switched, deployed mobile telephony access infrastructure is...deployment of wireless LAN technology raises the question of how a mobile telephony system might instead be architected to use wireless LAN access ...and wireless access points has made universal Internet access increasingly convenient. There are clearly barriers to this vision of accessing a

Integrating mitosis, toxicity, and transgene expression in a telecommunications packet-switched network model of lipoplex-mediated gene delivery.

PubMed

Martin, Timothy M; Wysocki, Beata J; Beyersdorf, Jared P; Wysocki, Tadeusz A; Pannier, Angela K

2014-08-01

Gene delivery systems transport exogenous genetic information to cells or biological systems with the potential to directly alter endogenous gene expression and behavior with applications in functional genomics, tissue engineering, medical devices, and gene therapy. Nonviral systems offer advantages over viral systems because of their low immunogenicity, inexpensive synthesis, and easy modification but suffer from lower transfection levels. The representation of gene transfer using models offers perspective and interpretation of complex cellular mechanisms,including nonviral gene delivery where exact mechanisms are unknown. Here, we introduce a novel telecommunications model of the nonviral gene delivery process in which the delivery of the gene to a cell is synonymous with delivery of a packet of information to a destination computer within a packet-switched computer network. Such a model uses nodes and layers to simplify the complexity of modeling the transfection process and to overcome several challenges of existing models. These challenges include a limited scope and limited time frame, which often does not incorporate biological effects known to affect transfection. The telecommunication model was constructed in MATLAB to model lipoplex delivery of the gene encoding the green fluorescent protein to HeLa cells. Mitosis and toxicity events were included in the model resulting in simulation outputs of nuclear internalization and transfection efficiency that correlated with experimental data. A priori predictions based on model sensitivity analysis suggest that increasing endosomal escape and decreasing lysosomal degradation, protein degradation, and GFP-induced toxicity can improve transfection efficiency by three-fold. Application of the telecommunications model to nonviral gene delivery offers insight into the development of new gene delivery systems with therapeutically relevant transfection levels.

Guide to Alternative Mortgage Instruments. Teachers Instructional Packet, TIP No. 4, Spring 1985.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the various alternative mortgage instruments, including their major advantages and disadvantages. First, an evaluation form for the packet is presented. Next, a summary presentation on four basic…

Performance Evaluation of Multihop Packet Radio Networks by Simulation

DTIC Science & Technology

1987-03-01

Multihop Packet Radio Networks," Proc. IEEE, Vol. 75, No. 1, January 1987. [15] 1. Gitman , "On the Capacity of Slotted ALOHA Networks and Some Design...Networks in the Presence of Noise," Proc. Infocom, Washington D. C., April 1985 [40] H. Frank, I. Gitman and R. Van Slyke, " Packet Radio System

Sports Medicine. Clinical Rotation. Instructor's Packet and Student Study Packet.

ERIC Educational Resources Information Center

Texas Univ., Austin. Extension Instruction and Materials Center.

The materials in this packet are for a course designed to provide individualized classroom study for a specific area of clinical rotation--sports medicine. The instructor's manual describes the learning objectives together with a list of reference materials that should be provided for completion of the student worksheets, and lists suggested…

Tropical Animal Tour Packet. Metro.

ERIC Educational Resources Information Center

Metro Washington Park Zoo, Portland, OR. Educational Services Div.

This packet is designed to assist teachers in creating a tropical animals lesson plan that centers around a visit to the zoo. A teacher packet is divided into eight parts: (1) goals and objectives; (2) what to expect at the zoo; (3) student activities (preparatory activities, on-site activities, and follow-up activities); (4) background…

Understanding and Minimizing Staff Burnout. An Introductory Packet.

ERIC Educational Resources Information Center

California Univ., Los Angeles. Center for Mental Health Schools.

Staff who bring a mental health perspective to the schools can deal with problems of staff burnout. This packet is designed to help in beginning the process of minimizing burnout, a process that requires reducing environmental stressors, increasing personal capabilities, and enhancing job supports. The packet opens with brief discussions of "What…

In the Public Interest: Law, Government, and Media. Maryland Women's History Resource Packet--1986.

ERIC Educational Resources Information Center

Maryland State Commission for Women, Baltimore.

Designed to be used for National Women's History Week (March 2-8), this 1986 Maryland women's history resource packet centers around Maryland women who have made significant volunteer and career contributions in the areas of government, law, and the public interest media. The packet begins with suggested student activity lists and activity sheets…

Assessing To Address Barriers to Learning. An Introductory Packet.

ERIC Educational Resources Information Center

California Univ., Los Angeles. Center for Mental Health Schools.

Schools committed to the success of all children must have an array of activities designed to address barriers to learning. This introductory packet contains some aids to help school staff find new ways of thinking about how schools should assess barriers to learning. The following items are included in the packet: (1) a chart of "Barriers to…

Disk Operating System--DOS. Teacher Packet. Learning Activity Packets.

ERIC Educational Resources Information Center

Oklahoma State Dept. of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

The Learning Activity Packets (LAPs) contained in this manual are designed to assist the beginning user in understanding DOS (Disk Operating System). LAPs will not work with any version below DOS Version 3.0 and do not address the enhanced features of versions 4.0 or higher. These elementary activities cover only the DOS commands necessary to…

Accounting Clerk Guide, Test Packet--Part I.

ERIC Educational Resources Information Center

Foster, Brian; And Others

The test packet is part of an eight volume unit for grades 10, 11, and 12, designed for individualized progression in preparing students for entry into the occupation of accounting clerk. The test packet contains both pretests and post-tests for lessons 1 through 12. The unit is concerned with the basic accounting theory found in the accounting…

Learning Disabilities in the Workplace: A Professional Development Packet. Session 1 & 2.

ERIC Educational Resources Information Center

Corley, Mary Ann; Tibbetts, John

This field-tested training packet, which was designed for adult literacy providers, contains preparation materials, facilitator's notes, handout masters, and transparency masters for two 3-hour sessions on learning disabilities (LD) in the workplace. (At the end of the first session supported by the packet, participants will be able to do the…

Old as the Hills. Morrow Mountain State Park: An Environmental Education Learning Experience Designed for Grades 5-7.

ERIC Educational Resources Information Center

North Carolina State Dept. of Environment, Health, and Natural Resources, Raleigh. Div. of Parks and Recreation.

This curriculum packet was developed and designed to provide environmental education through a series of hands-on activities for the classroom and the outdoor setting of Morrow Mountain State Park, North Carolina to introduce students to the geology of the Uwharrie Mountains. Designed for grades 5 through 7, the packet meets the established…

Evaluation of a realtime, remote monitoring telemedicine system using the Bluetooth protocol and a mobile phone network.

PubMed

Jasemian, Yousef; Arendt-Nielsen, Lars

2005-01-01

A generic, realtime wireless telemedicine system has been developed that uses the Bluetooth protocol and the general packet radio service for mobile phones. The system was tested on 10 healthy volunteers, by continuous monitoring of their electrocardiograms (ECGs). Under realistic conditions, the system had 96.5% uptime, a data throughput of 3.3 kbit/s, a mean packet error rate of 8.5x10(-3) packet/s and a mean packet loss rate of 8.2x10(-3) packet/s. During 24 h testing, the total average downtime was 66 min and 90% of the periods of downtime were of only 1-3 min duration. Less than 10% of the ECGs were of unacceptable quality. Thus, the generic telemedicine system showed high reliability and performance, and the design may provide a foundation for realtime monitoring in clinical practice, for example in cardiology.

Event-driven charge-coupled device design and applications therefor

NASA Technical Reports Server (NTRS)

Doty, John P. (Inventor); Ricker, Jr., George R. (Inventor); Burke, Barry E. (Inventor); Prigozhin, Gregory Y. (Inventor)

2005-01-01

An event-driven X-ray CCD imager device uses a floating-gate amplifier or other non-destructive readout device to non-destructively sense a charge level in a charge packet associated with a pixel. The output of the floating-gate amplifier is used to identify each pixel that has a charge level above a predetermined threshold. If the charge level is above a predetermined threshold the charge in the triggering charge packet and in the charge packets from neighboring pixels need to be measured accurately. A charge delay register is included in the event-driven X-ray CCD imager device to enable recovery of the charge packets from neighboring pixels for accurate measurement. When a charge packet reaches the end of the charge delay register, control logic either dumps the charge packet, or steers the charge packet to a charge FIFO to preserve it if the charge packet is determined to be a packet that needs accurate measurement. A floating-diffusion amplifier or other low-noise output stage device, which converts charge level to a voltage level with high precision, provides final measurement of the charge packets. The voltage level is eventually digitized by a high linearity ADC.

A Taxonomy for Software Defined Networking, Man In The Middle Attacks

DTIC Science & Technology

2016-09-01

that separates it from the networks of today’s world . As Stallings (2013) describes, “current networks are vertically integrated, meaning that the data...cause overpopulation of flow tables increasing processing rate on the switch (Zarek, 2012). More specifically, premature evictions result 16 in...Mininet demonstrated our proof of concept but was not sufficient for real world implementation. Our overall goal was to grab an HTTP response packet

LEOPACK The integrated services communications system based on LEO satellites

NASA Astrophysics Data System (ADS)

Negoda, A.; Bunin, S.; Bushuev, E.; Dranovsky, V.

LEOPACK is yet another LEO satellite project which provides global integrated services for 'business' communications. It utilizes packet rather then circuit switching in both terrestrial and satellite chains as well as cellular approach for frequencies use. Original multiple access protocols and decentralized network control make it possible to organize regionally or logically independent and world-wide networks. Relatively small number of satellites (28) provides virtually global network coverage.

Sliding Mode Control for Discrete-Time Systems With Markovian Packet Dropouts.

PubMed

Song, Heran; Chen, Shih-Chi; Yam, Yeung

2017-11-01

This paper presents the design of a sliding mode controller for networked control systems subject to successive Markovian packet dropouts. This paper adopts the Gilbert-Elliott channel model to describe the temporal correlation among packet losses, and proposes an update scheme to select the assumed available states for use in a sliding mode control law. A technique used in the theory of discrete-time Markov jump linear systems is applied to tackle the effect of the packet losses. This involves introducing a couple of Lyapunov functions dependent on the indicator functions of the instantaneous packet loss, and proving that the sliding mode controller is able to drive the system state trajectories into the neighborhood of the designed integral sliding surface in mean-square sense given that the corresponding Lyapunov inequalities are satisfied. The system is guaranteed thereafter to remain inside the neighborhood of the sliding surface. Simulated case studies are presented to illustrate the effectiveness of the control law.

Easements in Texas. Teachers Instructional Packet, TIP No. 5, Spring 1985.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand public and private easements, which most commonly entail the right of a person (or the public) to use the land of another in a certain manner. Following an evaluation form for the packet, a…

Women's Studies for Teachers and Administrators: A Packet of Inservice Education Materials.

ERIC Educational Resources Information Center

Froschl, Merle, Ed.; And Others

This packet of materials is designed for elementary and secondary teachers and administrators who are engaged in inservice education and interested in the movement to eliminate sexism in schools. Two major purposes of the packet are to help a school district start an inservice course on sexism in education and to show the potential of such a…

Learning Activity Packets for High School Social Studies, American Studies, American History and Low Achieving Students. Course I.

ERIC Educational Resources Information Center

Seif, Elliott

The document presents student learning packets designed to provide an alternative social studies experience for high school students. The objective is to enable students to better understand themselves and their environment and other individuals and groups. Written at a junior high school reading level, the packets are intended to be used with low…

The United States History (Laotian Edition). [34 Self-Learning Packets for Laotian Students.

ERIC Educational Resources Information Center

Nhi, Do Dien; And Others

Designed primarily for Indochinese students in grades 9-12, 34 United States history self-learning packets are presented in eight sections. The publication could be used by mainstream teachers who have a number of limited English proficient (LEP) Laotian students in their classes or by parents to tutor their children. The packets were adapted from…

The United States History = Lich Su Hoa Ky. [34 Self-Learning Packets for Vietnamese Students.

ERIC Educational Resources Information Center

Nhi, Do Dien; And Others

Designed primarily for Indochinese students in grades 9-12, 34 United States history self-learning packets are presented in eight sections. The publication could be used by mainstream teachers who have a number of limited English proficient (LEP) Vietnamese students in their classes or by parents to tutor their children. The packets were adapted…

Design, development, and evaluation of printed educational materials for evidence-based practice dissemination.

PubMed

Williams, Jessica R; Caceda-Castro, Lizbeth E; Dusablon, Tracy; Stipa, Melissa

2016-06-01

Printed educational materials (PEMs) are one of the most common dissemination strategies for communicating information about evidence-based practices (EBPs) to healthcare professionals and organizations; however, evidence is conflicting regarding the conditions and circumstances in which PEMs are effective in achieving desired outcomes. The effectiveness of PEMs is largely dependent on the manner in which they are developed. This article reports on the findings from a comprehensive review of the literature regarding best practices for creating PEMs for health professionals and illustrates how these practices were used to design, develop, and evaluate an informational packet to disseminate information about motivational interviewing. The informational packet was disseminated to 92 community health organizations not currently implementing motivational interviewing. Evaluation surveys were completed by 212 healthcare directors and providers to examine quality and perceived helpfulness of the packets, intention to use information from the packet, and sharing of the packet with others. Associations between these and individual and organizational characteristics were also assessed. Overall, the packet was perceived as appropriate and helpful in making a decision to implement motivational interviewing. For example, 84.9% of participants stated that the content was 'about right'. Three-quarters (75.9%) of participants reported plans to use the information in the packet and almost half (46.7%) reported talking about the packet with others in the organizations. Higher levels of baseline interest in motivational interviewing adoption were significantly related to packet use and wanting to utilize additional resources presented in the packet. Positive attitudes toward EBPs were also significantly related to the desire to obtain resources in the packet. Perceptions of the packet did not differ by type of community health organization (i.e., community health center, community behavioral health organization) or whether the individual was a director or provider. Results indicated that PEMs can be a useful tool to disseminate EBP information to healthcare professionals particularly if they have a prior interest in the EBP and have general attitudes supportive of EBPs. Recommendations for the improvement of future PEMs are discussed.

A Novel Cross-Layer Routing Protocol Based on Network Coding for Underwater Sensor Networks.

PubMed

Wang, Hao; Wang, Shilian; Bu, Renfei; Zhang, Eryang

2017-08-08

Underwater wireless sensor networks (UWSNs) have attracted increasing attention in recent years because of their numerous applications in ocean monitoring, resource discovery and tactical surveillance. However, the design of reliable and efficient transmission and routing protocols is a challenge due to the low acoustic propagation speed and complex channel environment in UWSNs. In this paper, we propose a novel cross-layer routing protocol based on network coding (NCRP) for UWSNs, which utilizes network coding and cross-layer design to greedily forward data packets to sink nodes efficiently. The proposed NCRP takes full advantages of multicast transmission and decode packets jointly with encoded packets received from multiple potential nodes in the entire network. The transmission power is optimized in our design to extend the life cycle of the network. Moreover, we design a real-time routing maintenance protocol to update the route when detecting inefficient relay nodes. Substantial simulations in underwater environment by Network Simulator 3 (NS-3) show that NCRP significantly improves the network performance in terms of energy consumption, end-to-end delay and packet delivery ratio compared with other routing protocols for UWSNs.

Decoherence and surface hopping: When can averaging over initial conditions help capture the effects of wave packet separation?

NASA Astrophysics Data System (ADS)

Subotnik, Joseph E.; Shenvi, Neil

2011-06-01

Fewest-switches surface hopping (FSSH) is a popular nonadiabatic dynamics method which treats nuclei with classical mechanics and electrons with quantum mechanics. In order to simulate the motion of a wave packet as accurately as possible, standard FSSH requires a stochastic sampling of the trajectories over a distribution of initial conditions corresponding, e.g., to the Wigner distribution of the initial quantum wave packet. Although it is well-known that FSSH does not properly account for decoherence effects, there is some confusion in the literature about whether or not this averaging over a distribution of initial conditions can approximate some of the effects of decoherence. In this paper, we not only show that averaging over initial conditions does not generally account for decoherence, but also why it fails to do so. We also show how an apparent improvement in accuracy can be obtained for a fortuitous choice of model problems, even though this improvement is not possible, in general. For a basic set of one-dimensional and two-dimensional examples, we find significantly improved results using our recently introduced augmented FSSH algorithm.

Energy-saving scheme based on downstream packet scheduling in ethernet passive optical networks

NASA Astrophysics Data System (ADS)

Zhang, Lincong; Liu, Yejun; Guo, Lei; Gong, Xiaoxue

2013-03-01

With increasing network sizes, the energy consumption of Passive Optical Networks (PONs) has grown significantly. Therefore, it is important to design effective energy-saving schemes in PONs. Generally, energy-saving schemes have focused on sleeping the low-loaded Optical Network Units (ONUs), which tends to bring large packet delays. Further, the traditional ONU sleep modes are not capable of sleeping the transmitter and receiver independently, though they are not required to transmit or receive packets. Clearly, this approach contributes to wasted energy. Thus, in this paper, we propose an Energy-Saving scheme that is based on downstream Packet Scheduling (ESPS) in Ethernet PON (EPON). First, we design both an algorithm and a rule for downstream packet scheduling at the inter- and intra-ONU levels, respectively, to reduce the downstream packet delay. After that, we propose a hybrid sleep mode that contains not only ONU deep sleep mode but also independent sleep modes for the transmitter and the receiver. This ensures that the energy consumed by the ONUs is minimal. To realize the hybrid sleep mode, a modified GATE control message is designed that involves 10 time points for sleep processes. In ESPS, the 10 time points are calculated according to the allocated bandwidths in both the upstream and the downstream. The simulation results show that ESPS outperforms traditional Upstream Centric Scheduling (UCS) scheme in terms of energy consumption and the average delay for both real-time and non-real-time packets downstream. The simulation results also show that the average energy consumption of each ONU in larger-sized networks is less than that in smaller-sized networks; hence, our ESPS is better suited for larger-sized networks.

Operational Rations Current and Future of the Department of Defense

DTIC Science & Technology

1982-09-01

with Spiced Sauce Beefsteak Chicken and Noodles Chicken or Turkey, Boned Apricots Peaches Chocolate Nut Roll Cookies Grape MEATS Ham and...Sauce Tuna Fish Turkey Loaf Fruit Cocktail Peacan Cake Roll Pound Cake Orange Tomato 16 ACCESSORY ITEMS Instant Coffee Instant Tea or Tea... INSTANT ACCESSORY PACKET FOOD PACKET, IN-FLIGHT INDIVIDUAL SPOON EARLY VERSION VI FOOD PACKET, LONG-RANGE Designed for troops in operations

Salinity Changes in a Tidal River. A Learning Experience for Coastal and Oceanic Awareness Studies, No. 308. [Project COAST].

ERIC Educational Resources Information Center

Delaware Univ., Newark. Coll. of Education.

The materials in this packet are designed to aid teachers in the implementation of a science field studies unit concerning tidal rivers. The packet consists of the following: (1) background material for the teacher; (2) lab exercises; (3) field activities; and (4) classroom activities. The overall purpose of this packet is to provide information…

Improvements in Routing for Packet-Switched Networks

DTIC Science & Technology

1975-02-18

PROGRAM FOR COMPUTER SIMULATION . . 90 B.l Flow Diagram of Adaptive Routine 90 B.2 Progiam ARPSIM 93 B.3 Explanation of Variables...equa. 90 APPENDIX B ADAPTIVE ROUTING PROGRAM FOR COMPUTER SIMULA HON The computer simulation for adaptive routing was initially run on a DDP-24 small...TRANSMIT OVER AVAILABLE LINKS MESSAGES IN QUEUE COMPUTE Ni NUMBER OF ARRIVALS AT EACH NODE i AT TIME T Fig. Bla - Flow Diagram of Program Routine 92

Assured Information Flow Capping Architecture.

DTIC Science & Technology

1985-05-01

Air Control System Deployment, ESD-TR-71-371, AD 733 584, Electronic Systems Division, AFSC, Hanscom Air Force Base, MA, November 1971. 3. I. Gitman and...H. Frank, "Economic Analysis of Integrated Voice and Data Networks: A Case Study," Proceedings of the IEEE, November 1978. 4. H. Frank and I. Gitman ... Gitman , "Study Shows Packet Switching Best for Voice Traffic, Too," Data Communications, March 1979. ___ "Economic Analysis of Integrated Voice and

Aircraft Simulator: Multiple-Cockpit Combat Mission Trainer Network.

DTIC Science & Technology

1984-01-01

Force Human Resources Laboratory (AFHRL), the Air Force Office of Scientific Research (AFOSR), and the Southeastern Center for Electrical Engineering...New York: IEEE Press. Rapumno, R. A. , A Shimsaki, N. (1974). Synchronization of earth stations to satellite-switched sequences. Comunications ...Satellite Technology, 33 (Progress in Astronautics and Aeronautics) , 411-429. Tobagi, F. A. (1980). Multiaccess protocols in packet comunication systems. IEEE TMS. C". , 4 (vol. CO-28), 468-488. 27 ORR .0--000

Packet utilisation definitions for the ESA XMM mission

NASA Technical Reports Server (NTRS)

Nye, H. R.

1994-01-01

XMM, ESA's X-Ray Multi-Mirror satellite, due for launch at the end of 1999 will be the first ESA scientific spacecraft to implement the ESA packet telecommand and telemetry standards and will be the first ESOC-controlled science mission to take advantage of the new flight control system infrastructure development (based on object-oriented design and distributed-system architecture) due for deployment in 1995. The implementation of the packet standards is well defined at packet transport level. However, the standard relevant to the application level (the ESA Packet Utilization Standard) covers a wide range of on-board 'services' applicable in varying degrees to the needs of XMM. In defining which parts of the ESA PUS to implement, the XMM project first considered the mission objectives and the derived operations concept and went on to identify a minimum set of packet definitions compatible with these aspects. This paper sets the scene as above and then describes the services needed for XMM and the telecommand and telemetry packet types necessary to support each service.

Alpine Forest. Mount Mitchell State Park: An Environmental Education Learning Experience Designed for Grades 4-6.

ERIC Educational Resources Information Center

Bradley, Jack L., Jr.; Beazley, Lea J.; Cook, Carrie

This curriculum packet was developed to provide environmental education through a series of hands-on activities for the classroom and the outdoor setting of Mount Mitchell State Park, North Carolina. Designed for grades 3 through 6, the packet meets established curriculum objectives of the North Carolina Department of Public Instruction's Standard…

Africa: A Social Studies and Science Curriculum.

ERIC Educational Resources Information Center

Holboke, Kathy; And Others

This packet was designed to help teachers maximize a visit to a zoo's Africa exhibit. The packet provides two levels of activities, grades 3-5, and grades 6-8, for use before, during and after the visit. Activities are designed to enhance skills taught in science, social studies, language arts, reading, art, and math. A multi-grade background…

Experimental Packet Radio System Design Plan

DTIC Science & Technology

1974-03-13

specific design parameters (packet format, data rates, modulation type, spread factor, etc.) for the initial system configuration. c. Prototype...are described along with size, weight and power estimates, and projections of per- formance parameters . d. Measurement and Test. The plan...are presented covering the communications link, system parameters , and various levels of network operation and performance. This plan is a snapshot

"Sunday-start" OC regimen popular but may pose risk.

PubMed

1991-03-01

There is a controversy over the effectiveness of the "Sunday-Start" oral contraceptive packaging. Some clinicians believe that the Sunday-start pills are dangerously ineffective because up to 6 days after menses can elapse before a new packet is started. This is particularly risky for women beginning orals, or switching from a combined pill to a new triphasic. These clinicians consider them merely a successful marketing strategy. Most physicians consider the Sunday-start pills more effective because of improved compliance. The reasons cited are that women are too confused to remember to start pill packets on odd days, and that they like having their menses occur on weekdays. Arguments on this side are studies showing that the length of the pill-free interval does not affect the efficacy of that cycle. There are not data to resolve this debate other than a report from Ortho Pharmaceuticals that women prefer Sunday-start 3:1.

Accounting Clerk Guide, Instructor Packet--Part I. A Spec Unit for the 10th, 11th, or 12th Grade. A Career Education Unit (An Edited Developmental Draft).

ERIC Educational Resources Information Center

Foster, Brian; And Others

The instructor packet is part of an eight volume unit for grades 10, 11, and 12, designed for individualized progression in preparing students for entry into the occupation of accounting clerk. The instructor packet lists performance objectives, vocabulary, learning tasks, and supplemental activities for lessons 1 through 11. It also includes…

Combined Wavelet Video Coding and Error Control for Internet Streaming and Multicast

NASA Astrophysics Data System (ADS)

Chu, Tianli; Xiong, Zixiang

2003-12-01

This paper proposes an integrated approach to Internet video streaming and multicast (e.g., receiver-driven layered multicast (RLM) by McCanne) based on combined wavelet video coding and error control. We design a packetized wavelet video (PWV) coder to facilitate its integration with error control. The PWV coder produces packetized layered bitstreams that are independent among layers while being embedded within each layer. Thus, a lost packet only renders the following packets in the same layer useless. Based on the PWV coder, we search for a multilayered error-control strategy that optimally trades off source and channel coding for each layer under a given transmission rate to mitigate the effects of packet loss. While both the PWV coder and the error-control strategy are new—the former incorporates embedded wavelet video coding and packetization and the latter extends the single-layered approach for RLM by Chou et al.—the main distinction of this paper lies in the seamless integration of the two parts. Theoretical analysis shows a gain of up to 1 dB on a channel with 20% packet loss using our combined approach over separate designs of the source coder and the error-control mechanism. This is also substantiated by our simulations with a gain of up to 0.6 dB. In addition, our simulations show a gain of up to 2.2 dB over previous results reported by Chou et al.

Configuration development for ROMENET

NASA Astrophysics Data System (ADS)

Rhue, Lawrence

1989-10-01

A plan prepared by RJO Enterprises and BBN Communications Corporation (BBNCC) for the design of ROMENET, a DDN-like testbed for the Rome Air Development Center (RADC) Wide Area Networks (WAN) laboratory is presented. The ROMENET is intended to provide RADC with the ability to test and evaluate the performance and vulnerability of the Defense Data Network (DDN) technologies in support of specific Major Command programs and activities at RADC. It will also support experimentation with packet switched network technologies and includes facilities to analytically evaluate the performance of the network and its associated equipment and media. In addition, ROMENET will provide a simulation vehicle for controlled interference or jamming into the media for vulnerability assessment. Through interfaces with the RADC Battle Management Laboratory (BML), ROMENET will allow the Air Force to assess the restorative and performance characteristics of the network under stressed conditions. The closed environment of ROMENET makes it ideal for creating and testing routing algorithms and network control protocols.

A Design of a Network Model to the Electric Power Trading System Using Web Services

NASA Astrophysics Data System (ADS)

Maruo, Tomoaki; Matsumoto, Keinosuke; Mori, Naoki; Kitayama, Masashi; Izumi, Yoshio

Web services are regarded as a new application paradigm in the world of the Internet. On the other hand, many business models of a power trading system has been proposed to aim at load reduction by consumers cooperating with electric power suppliers in an electric power market. Then, we propose a network model of power trading system using Web service in this paper. The adaptability of Web services to power trading system was checked in the prototype of our network model and we got good results for it. Each server provides functions as a SOAP server, and it is coupled loosely with each other through SOAP. Storing SOAP message in HTTP packet can establish the penetration communication way that is not conscious of a firewall. Switching of a dynamic server is possible by means of rewriting the server point information on WSDL at the time of obstacle generating.

The Real Estate Inspector. Teachers Instructional Packet (TIP) No. 11, Spring 1986.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was designed to help real estate students understand legal requirements for real estate inspectors in Texas. The material is based on Section 18C of the Real Estate License Act, as amended by the 1985 Texas Legislature. Following a presentation on…

Jomeokee Geology. Pilot Mountain State Park: An Environmental Education Learning Experience Designed for Grades 9-12.

ERIC Educational Resources Information Center

Smith, Michael W.

This activity packet provides educators with a series of hands-on classroom and outdoor education activities for grades 9-12 that focus on geology using the Pilot Mountain State Park. The packet was designed to meet established curriculum objectives of the North Carolina Department of Public Instruction's Standard Course of Study. Three types of…

A Novel Cross-Layer Routing Protocol Based on Network Coding for Underwater Sensor Networks

PubMed Central

Wang, Hao; Wang, Shilian; Bu, Renfei; Zhang, Eryang

2017-01-01

Underwater wireless sensor networks (UWSNs) have attracted increasing attention in recent years because of their numerous applications in ocean monitoring, resource discovery and tactical surveillance. However, the design of reliable and efficient transmission and routing protocols is a challenge due to the low acoustic propagation speed and complex channel environment in UWSNs. In this paper, we propose a novel cross-layer routing protocol based on network coding (NCRP) for UWSNs, which utilizes network coding and cross-layer design to greedily forward data packets to sink nodes efficiently. The proposed NCRP takes full advantages of multicast transmission and decode packets jointly with encoded packets received from multiple potential nodes in the entire network. The transmission power is optimized in our design to extend the life cycle of the network. Moreover, we design a real-time routing maintenance protocol to update the route when detecting inefficient relay nodes. Substantial simulations in underwater environment by Network Simulator 3 (NS-3) show that NCRP significantly improves the network performance in terms of energy consumption, end-to-end delay and packet delivery ratio compared with other routing protocols for UWSNs. PMID:28786915

APC-PC Combined Scheme in Gilbert Two State Model: Proposal and Study

NASA Astrophysics Data System (ADS)

Bulo, Yaka; Saring, Yang; Bhunia, Chandan Tilak

2017-04-01

In an automatic repeat request (ARQ) scheme, a packet is retransmitted if it gets corrupted due to transmission errors caused by the channel. However, an erroneous packet may contain both erroneous bits and correct bits and hence it may still contain useful information. The receiver may be able to combine this information from multiple erroneous copies to recover the correct packet. Packet combining (PC) is a simple and elegant scheme of error correction in transmitted packet, in which two received copies are XORed to obtain the bit location of erroneous bits. Thereafter, the packet is corrected by bit inversion of bit located as erroneous. Aggressive packet combining (APC) is a logic extension of PC primarily designed for wireless communication with objective of correcting error with low latency. PC offers higher throughput than APC, but PC does not correct double bit errors if occur in same bit location of erroneous copies of the packet. A hybrid technique is proposed to utilize the advantages of both APC and PC while attempting to remove the limitation of both. In the proposed technique, applications of APC-PC on Gilbert two state model has been studied. The simulation results show that the proposed technique offers better throughput than the conventional APC and lesser packet error rate than PC scheme.

Multiple Path Static Routing Protocols for Packet Switched Networks.

DTIC Science & Technology

1983-09-01

model are: (1) Physical Layer (2) Data Link Layer (3) Network Layer (4) Transport Layer (5) Session Layer (6) Presentation Layer (7) pplication Layer The...The transport layer, also known as the host-host layer, accepts data from the session layer, splits it into smaller units if needed, passes these to...the network layer, and ensures that all the pieces arrive correctly at the other end. It creates a distinct network connection for each transport

Oak Ridge Environmental Information System (ORIES) site workstation information packet for OREIS V1.2. Environmental Restoration Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voorhees, L.D.; McCord, R.A.; Durfee, R.C.

1993-02-01

The OREIS site workstation information packet was developed to accompany the OREIS site workstations, which are being delivered to the Environmental Restoration programs at the five DOE-OR sites. The packet is written specifically for the Site ER program staff at each of the five Sites who have been designated the OREIS contact by their ER program manager, and is not intended for general distribution. The packet provides an overview of the components of OREIS, points to more detailed information provided in the accompanying vendor and OREIS developed manuals, and includes information on training opportunities and user support.

Oak Ridge Environmental Information System (ORIES) site workstation information packet for OREIS V1. 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voorhees, L.D.; McCord, R.A.; Durfee, R.C.

1993-02-01

The OREIS site workstation information packet was developed to accompany the OREIS site workstations, which are being delivered to the Environmental Restoration programs at the five DOE-OR sites. The packet is written specifically for the Site ER program staff at each of the five Sites who have been designated the OREIS contact by their ER program manager, and is not intended for general distribution. The packet provides an overview of the components of OREIS, points to more detailed information provided in the accompanying vendor and OREIS developed manuals, and includes information on training opportunities and user support.

Traffic-aware energy saving scheme with modularization supporting in TWDM-PON

NASA Astrophysics Data System (ADS)

Xiong, Yu; Sun, Peng; Liu, Chuanbo; Guan, Jianjun

2017-01-01

Time and wavelength division multiplexed passive optical network (TWDM-PON) is considered to be a primary solution for next-generation passive optical network stage 2 (NG-PON2). Due to the feature of multi-wavelength transmission of TWDM-PON, some of the transmitters/receivers at the optical line terminal (OLT) could be shut down to reduce the energy consumption. Therefore, a novel scheme called traffic-aware energy saving scheme with modularization supporting is proposed. Through establishing the modular energy consumption model of OLT, the wavelength transmitters/receivers at OLT could be switched on or shut down adaptively depending on sensing the status of network traffic load, thus the energy consumption of OLT will be effectively reduced. Furthermore, exploring the technology of optical network unit (ONU) modularization, each module of ONU could be switched to sleep or active mode independently in order to reduce the energy consumption of ONU. Simultaneously, the polling sequence of ONU could be changed dynamically via sensing the packet arrival time. In order to guarantee the delay performance of network traffic, the sub-cycle division strategy is designed to transmit the real-time traffic preferentially. Finally, simulation results verify that the proposed scheme is able to reduce the energy consumption of the network while maintaining the traffic delay performance.

Deep Packet/Flow Analysis using GPUs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Qian; Wu, Wenji; DeMar, Phil

Deep packet inspection (DPI) faces severe performance challenges in high-speed networks (40/100 GE) as it requires a large amount of raw computing power and high I/O throughputs. Recently, researchers have tentatively used GPUs to address the above issues and boost the performance of DPI. Typically, DPI applications involve highly complex operations in both per-packet and per-flow data level, often in real-time. The parallel architecture of GPUs fits exceptionally well for per-packet network traffic processing. However, for stateful network protocols such as TCP, their data stream need to be reconstructed in a per-flow level to deliver a consistent content analysis. Sincemore » the flow-centric operations are naturally antiparallel and often require large memory space for buffering out-of-sequence packets, they can be problematic for GPUs, whose memory is normally limited to several gigabytes. In this work, we present a highly efficient GPU-based deep packet/flow analysis framework. The proposed design includes a purely GPU-implemented flow tracking and TCP stream reassembly. Instead of buffering and waiting for TCP packets to become in sequence, our framework process the packets in batch and uses a deterministic finite automaton (DFA) with prefix-/suffix- tree method to detect patterns across out-of-sequence packets that happen to be located in different batches. In conclusion, evaluation shows that our code can reassemble and forward tens of millions of packets per second and conduct a stateful signature-based deep packet inspection at 55 Gbit/s using an NVIDIA K40 GPU.« less

Accounting Clerk Guide, Learner Packet--Part I. A Spec Unit for the 10th, 11th, or 12th Grade. A Career Education Unit (An Edited Developmental Draft).

ERIC Educational Resources Information Center

Foster, Brian; And Others

The learner packet is part of an eight volume unit for grades 10, 11, and 12, designed for individualized progression in preparing students for entry into the occupation of accounting clerk. Intended to be used on an individual basis at the student's own speed, the learner packet contains vocabulary, suggested lesson time, self-check keys, and…

Nonuniform traffic spots (NUTS) in multistage interconnection networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lang, T.; Kurisaki, L.

1990-09-01

The performance of multistage interconnection networks for multiprocessors is degraded when the traffic pattern produces nonuniform congestion in the blocking switches, that is, when there exist nonuniform traffic spots. For some specific patterns the authors evaluate this degradation in performance and propose modifications to the network organization and operation to reduce the degradation. Successful modifications are the use of diverting switches and the extension of the network with additional links. The use of these modifications makes the network more effective for a larger variety of traffic patterns. The authors also consider the case in which the network carries the superpositionmore » of two types of traffic. One type is the high throughput data and instruction traffic, while the other consists of control and I/O packets which are of low throughput but have severe real-time constraints. The authors conclude that diverting switches and networks with additional links are also suitable for assuring low latency for the real-time traffic, especially when using the displacing mode.« less

Attosecond vacuum UV coherent control of molecular dynamics

PubMed Central

Ranitovic, Predrag; Hogle, Craig W.; Rivière, Paula; Palacios, Alicia; Tong, Xiao-Ming; Toshima, Nobuyuki; González-Castrillo, Alberto; Martin, Leigh; Martín, Fernando; Murnane, Margaret M.; Kapteyn, Henry

2014-01-01

High harmonic light sources make it possible to access attosecond timescales, thus opening up the prospect of manipulating electronic wave packets for steering molecular dynamics. However, two decades after the birth of attosecond physics, the concept of attosecond chemistry has not yet been realized; this is because excitation and manipulation of molecular orbitals requires precisely controlled attosecond waveforms in the deep UV, which have not yet been synthesized. Here, we present a unique approach using attosecond vacuum UV pulse-trains to coherently excite and control the outcome of a simple chemical reaction in a deuterium molecule in a non-Born–Oppenheimer regime. By controlling the interfering pathways of electron wave packets in the excited neutral and singly ionized molecule, we unambiguously show that we can switch the excited electronic state on attosecond timescales, coherently guide the nuclear wave packets to dictate the way a neutral molecule vibrates, and steer and manipulate the ionization and dissociation channels. Furthermore, through advanced theory, we succeed in rigorously modeling multiscale electron and nuclear quantum control in a molecule. The observed richness and complexity of the dynamics, even in this very simplest of molecules, is both remarkable and daunting, and presents intriguing new possibilities for bridging the gap between attosecond physics and attochemistry. PMID:24395768

A Deadline-Aware Scheduling and Forwarding Scheme in Wireless Sensor Networks.

PubMed

Dao, Thi-Nga; Yoon, Seokhoon; Kim, Jangyoung

2016-01-05

Many applications in wireless sensor networks (WSNs) require energy consumption to be minimized and the data delivered to the sink within a specific delay. A usual solution for reducing energy consumption is duty cycling, in which nodes periodically switch between sleep and active states. By increasing the duty cycle interval, consumed energy can be reduced more. However, a large duty cycle interval causes a long end-to-end (E2E) packet delay. As a result, the requirement of a specific delay bound for packet delivery may not be satisfied. In this paper, we aim at maximizing the duty cycle while still guaranteeing that the packets arrive at the sink with the required probability, i.e., the required delay-constrained success ratio (DCSR) is achieved. In order to meet this objective, we propose a novel scheduling and forwarding scheme, namely the deadline-aware scheduling and forwarding (DASF) algorithm. In DASF, the E2E delay distribution with the given network model and parameters is estimated in order to determine the maximum duty cycle interval, with which the required DCSR is satisfied. Each node independently selects a wake-up time using the selected interval, and packets are forwarded to a node in the potential forwarding set, which is determined based on the distance between nodes and the sink. DASF does not require time synchronization between nodes, and a node does not need to maintain neighboring node information in advance. Simulation results show that the proposed scheme can satisfy a required delay-constrained success ratio and outperforms existing algorithms in terms of E2E delay and DCSR.

A Deadline-Aware Scheduling and Forwarding Scheme in Wireless Sensor Networks

PubMed Central

Dao, Thi-Nga; Yoon, Seokhoon; Kim, Jangyoung

2016-01-01

Many applications in wireless sensor networks (WSNs) require energy consumption to be minimized and the data delivered to the sink within a specific delay. A usual solution for reducing energy consumption is duty cycling, in which nodes periodically switch between sleep and active states. By increasing the duty cycle interval, consumed energy can be reduced more. However, a large duty cycle interval causes a long end-to-end (E2E) packet delay. As a result, the requirement of a specific delay bound for packet delivery may not be satisfied. In this paper, we aim at maximizing the duty cycle while still guaranteeing that the packets arrive at the sink with the required probability, i.e., the required delay-constrained success ratio (DCSR) is achieved. In order to meet this objective, we propose a novel scheduling and forwarding scheme, namely the deadline-aware scheduling and forwarding (DASF) algorithm. In DASF, the E2E delay distribution with the given network model and parameters is estimated in order to determine the maximum duty cycle interval, with which the required DCSR is satisfied. Each node independently selects a wake-up time using the selected interval, and packets are forwarded to a node in the potential forwarding set, which is determined based on the distance between nodes and the sink. DASF does not require time synchronization between nodes, and a node does not need to maintain neighboring node information in advance. Simulation results show that the proposed scheme can satisfy a required delay-constrained success ratio and outperforms existing algorithms in terms of E2E delay and DCSR. PMID:26742046

Development of the network architecture of the Canadian MSAT system

NASA Technical Reports Server (NTRS)

Davies, N. George; Shoamanesh, Alireza; Leung, Victor C. M.

1988-01-01

A description is given of the present concept for the Canadian Mobile Satellite (MSAT) System and the development of the network architecture which will accommodate the planned family of three categories of service: a mobile radio service (MRS), a mobile telephone service (MTS), and a mobile data service (MDS). The MSAT satellite will have cross-strapped L-band and Ku-band transponders to provide communications services between L-band mobile terminals and fixed base stations supporting dispatcher-type MRS, gateway stations supporting MTS interconnections to the public telephone network, data hub stations supporting the MDS, and the network control center. The currently perceived centralized architecture with demand assignment multiple access for the circuit switched MRS, MTS and permanently assigned channels for the packet switched MDS is discussed.

Development of the network architecture of the Canadian MSAT system

NASA Astrophysics Data System (ADS)

Davies, N. George; Shoamanesh, Alireza; Leung, Victor C. M.

1988-05-01

A description is given of the present concept for the Canadian Mobile Satellite (MSAT) System and the development of the network architecture which will accommodate the planned family of three categories of service: a mobile radio service (MRS), a mobile telephone service (MTS), and a mobile data service (MDS). The MSAT satellite will have cross-strapped L-band and Ku-band transponders to provide communications services between L-band mobile terminals and fixed base stations supporting dispatcher-type MRS, gateway stations supporting MTS interconnections to the public telephone network, data hub stations supporting the MDS, and the network control center. The currently perceived centralized architecture with demand assignment multiple access for the circuit switched MRS, MTS and permanently assigned channels for the packet switched MDS is discussed.

Implementation of the MSAT network in Canada

NASA Astrophysics Data System (ADS)

Roscoe, Orest S.

1991-10-01

MSAT will be launched into geostationary orbit at 106.5 degrees west longitude. It will have an aggregate EIRP in excess of 57 dBw, making it the highest powered mobile satellite launched or planned to date. The MSAT ground segment will comprise hundreds of thousands of mobile terminals, as well as numerous feederlink earth stations. This requires a large scale network control system which is unprecedented in a satellite environment. The network control system must support circuit-switched voice and data services and packet-switched data services. In addition to assignment of capacity on demand, the control system must be able to support a variety of service features required by customers, as well as record information for billing. It must operate in a multi-beam, multi-satellite environment as the system grows.

Protecting the Homeland Report of the Defense Science Board Task Force on Defensive Information Operations. 2000 Summer Study. Volume II

DTIC Science & Technology

2001-03-01

between attacks and other events such as accidents, system failures, or hacking by thrill-seekers. This challenge is exacerbated by the speed of events in...International Telegraph and Telephone (CCITT) international standards body and is referred to as Signaling System # 7 ( SS7 ). Commerc" I Intelligent...point to fixed infrastructure "" Signaling Transfer Point (STP) - Packet switch in CCITT#7 Network STP ... SS7 * System Data Bases i Network

Advances in Mechanisms Supporting Data Collection on Future Force Networks: Product Manager C4ISR On-the-Move

DTIC Science & Technology

2008-12-01

for Layer 3 data capture: NetPoll ncap tget Monitor session Radio System switch router User App interface box GPS This model applies to most fixed...developed a lightweight, custom implementation, termed ncap . As described in Section 3.1, the Ground Truth System provides a linkage between host...computer CPU time and GPS time, and ncap leverages this to perform highly precise (əmsec) time tagging of offered and received packets. Such

Packet Controller For Wireless Headset

NASA Technical Reports Server (NTRS)

Christensen, Kurt K.; Swanson, Richard J.

1993-01-01

Packet-message controller implements communications protocol of network of wireless headsets. Designed for headset application, readily adapted to other uses; slight modification enables controller to implement Integrated Services Digital Network (ISDN) X.25 protocol, giving far-reaching applications in telecommunications. Circuit converts continuous voice signals into digital packets of data and vice versa. Operates in master or slave mode. Controller reduced to single complementary metal oxide/semiconductor integrated-circuit chip. Occupies minimal space in headset and consumes little power, extending life of headset battery.

Design Report for the Synchronized Position, Velocity, and Time Code Generator

DTIC Science & Technology

2015-08-01

Stream Specification 4 2.3 Data Packet Format Specification 4 2.3.1 Individual Message Definition 5 3. MATLAB Parsing Software 6 4. Conclusions and...packet format structure ..................................................................4 Table 2 PPS time message definition ...5 Table 3 Position message definition ...................................................................5

Machine-Learning Based Channel Quality and Stability Estimation for Stream-Based Multichannel Wireless Sensor Networks.

PubMed

Rehan, Waqas; Fischer, Stefan; Rehan, Maaz

2016-09-12

Wireless sensor networks (WSNs) have become more and more diversified and are today able to also support high data rate applications, such as multimedia. In this case, per-packet channel handshaking/switching may result in inducing additional overheads, such as energy consumption, delays and, therefore, data loss. One of the solutions is to perform stream-based channel allocation where channel handshaking is performed once before transmitting the whole data stream. Deciding stream-based channel allocation is more critical in case of multichannel WSNs where channels of different quality/stability are available and the wish for high performance requires sensor nodes to switch to the best among the available channels. In this work, we will focus on devising mechanisms that perform channel quality/stability estimation in order to improve the accommodation of stream-based communication in multichannel wireless sensor networks. For performing channel quality assessment, we have formulated a composite metric, which we call channel rank measurement (CRM), that can demarcate channels into good, intermediate and bad quality on the basis of the standard deviation of the received signal strength indicator (RSSI) and the average of the link quality indicator (LQI) of the received packets. CRM is then used to generate a data set for training a supervised machine learning-based algorithm (which we call Normal Equation based Channel quality prediction (NEC) algorithm) in such a way that it may perform instantaneous channel rank estimation of any channel. Subsequently, two robust extensions of the NEC algorithm are proposed (which we call Normal Equation based Weighted Moving Average Channel quality prediction (NEWMAC) algorithm and Normal Equation based Aggregate Maturity Criteria with Beta Tracking based Channel weight prediction (NEAMCBTC) algorithm), that can perform channel quality estimation on the basis of both current and past values of channel rank estimation. In the end, simulations are made using MATLAB, and the results show that the Extended version of NEAMCBTC algorithm (Ext-NEAMCBTC) outperforms the compared techniques in terms of channel quality and stability assessment. It also minimizes channel switching overheads (in terms of switching delays and energy consumption) for accommodating stream-based communication in multichannel WSNs.

Machine-Learning Based Channel Quality and Stability Estimation for Stream-Based Multichannel Wireless Sensor Networks

PubMed Central

Rehan, Waqas; Fischer, Stefan; Rehan, Maaz

2016-01-01

Wireless sensor networks (WSNs) have become more and more diversified and are today able to also support high data rate applications, such as multimedia. In this case, per-packet channel handshaking/switching may result in inducing additional overheads, such as energy consumption, delays and, therefore, data loss. One of the solutions is to perform stream-based channel allocation where channel handshaking is performed once before transmitting the whole data stream. Deciding stream-based channel allocation is more critical in case of multichannel WSNs where channels of different quality/stability are available and the wish for high performance requires sensor nodes to switch to the best among the available channels. In this work, we will focus on devising mechanisms that perform channel quality/stability estimation in order to improve the accommodation of stream-based communication in multichannel wireless sensor networks. For performing channel quality assessment, we have formulated a composite metric, which we call channel rank measurement (CRM), that can demarcate channels into good, intermediate and bad quality on the basis of the standard deviation of the received signal strength indicator (RSSI) and the average of the link quality indicator (LQI) of the received packets. CRM is then used to generate a data set for training a supervised machine learning-based algorithm (which we call Normal Equation based Channel quality prediction (NEC) algorithm) in such a way that it may perform instantaneous channel rank estimation of any channel. Subsequently, two robust extensions of the NEC algorithm are proposed (which we call Normal Equation based Weighted Moving Average Channel quality prediction (NEWMAC) algorithm and Normal Equation based Aggregate Maturity Criteria with Beta Tracking based Channel weight prediction (NEAMCBTC) algorithm), that can perform channel quality estimation on the basis of both current and past values of channel rank estimation. In the end, simulations are made using MATLAB, and the results show that the Extended version of NEAMCBTC algorithm (Ext-NEAMCBTC) outperforms the compared techniques in terms of channel quality and stability assessment. It also minimizes channel switching overheads (in terms of switching delays and energy consumption) for accommodating stream-based communication in multichannel WSNs. PMID:27626429

Anti-Litter Curriculum Packet, Interdisciplinary, K-12.

ERIC Educational Resources Information Center

Tillis, Richard

This curriculum packet consists of 20 illustrated cards with 15 activities designed to create "positive feelings" about a clean environment. Activities range from picture coloring for younger students, to lessons such as the economic and health problems litter creates for older students. Objectives include encouraging anti-litter and…

Biological Diversity. Global Issues Education Packet.

ERIC Educational Resources Information Center

Holm, Amy E.

Biological diversity, also commonly called genetic diversity, refers to the variety of organisms on Earth. Scientists are concerned that many species will become extinct because of extensive development in the tropical regions. This packet is designed to increase student's awareness about direct and indirect causes of extinction, endangered…

Packet-Based Protocol Efficiency for Aeronautical and Satellite Communications

NASA Technical Reports Server (NTRS)

Carek, David A.

2005-01-01

This paper examines the relation between bit error ratios and the effective link efficiency when transporting data with a packet-based protocol. Relations are developed to quantify the impact of a protocol s packet size and header size relative to the bit error ratio of the underlying link. These relations are examined in the context of radio transmissions that exhibit variable error conditions, such as those used in satellite, aeronautical, and other wireless networks. A comparison of two packet sizing methodologies is presented. From these relations, the true ability of a link to deliver user data, or information, is determined. Relations are developed to calculate the optimal protocol packet size forgiven link error characteristics. These relations could be useful in future research for developing an adaptive protocol layer. They can also be used for sizing protocols in the design of static links, where bit error ratios have small variability.

Selective randomized load balancing and mesh networks with changing demands

NASA Astrophysics Data System (ADS)

Shepherd, F. B.; Winzer, P. J.

2006-05-01

We consider the problem of building cost-effective networks that are robust to dynamic changes in demand patterns. We compare several architectures using demand-oblivious routing strategies. Traditional approaches include single-hop architectures based on a (static or dynamic) circuit-switched core infrastructure and multihop (packet-switched) architectures based on point-to-point circuits in the core. To address demand uncertainty, we seek minimum cost networks that can carry the class of hose demand matrices. Apart from shortest-path routing, Valiant's randomized load balancing (RLB), and virtual private network (VPN) tree routing, we propose a third, highly attractive approach: selective randomized load balancing (SRLB). This is a blend of dual-hop hub routing and randomized load balancing that combines the advantages of both architectures in terms of network cost, delay, and delay jitter. In particular, we give empirical analyses for the cost (in terms of transport and switching equipment) for the discussed architectures, based on three representative carrier networks. Of these three networks, SRLB maintains the resilience properties of RLB while achieving significant cost reduction over all other architectures, including RLB and multihop Internet protocol/multiprotocol label switching (IP/MPLS) networks using VPN-tree routing.

Texas Wills. Teachers Instructional Packet, TIP No. 14, Spring 1987.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the different types of wills recognized in Texas, their preparation, provisions, and execution. First, information about wills is presented, including definitions of relevant terms and a…

Energy and the Environment.

ERIC Educational Resources Information Center

Fowler, J. M.; Mervine, K. W.

This booklet is the first in a series of Environmental Resource Packets designed to encourage college science teachers to become professionally competent in selected environmental areas of study. Produced unver a grant from the ESSO Education Foundation, each packet will consist of a review paper(s) and a selected and annotated bibliography which…

Constitutional and Non-Constitutional Governments...Similarities and Differences throughout History. Resource Packet.

ERIC Educational Resources Information Center

Pallasch, Brian Thomas

This civic education resource packet is designed to provide teachers, community leaders, and other civic educators with an understanding of the differences between constitutional and non-constitutional governments. Six papers discussing the topic are included: "The Differences bewteen Constitutional and Non-Constitutional Governments" (John…

Dissection & Science Fairs. [Information Packet.

ERIC Educational Resources Information Center

National Anti-Vivisection Society, Chicago, IL.

This collection of pamphlets and articles reprinted from other National Anti-Vivisection Society (NAVS) publications was compiled to address the issues of classroom laboratory dissection and the use of animals in science fair projects. Three of the pamphlets contained in this packet are student handbooks designed to help students of elementary,…

Mervyn's Moving Mission.

ERIC Educational Resources Information Center

2001

This teacher's resource packet includes a number of items designed to support teachers in the classroom before and after visiting Mervyn's Moving Mission. The packet includes eight sections: (1) welcome letter in English and Spanish; (2) summary timeline of California mission events in English and Spanish; (3) objectives and curriculum links; (4)…

Training Volunteers and Aides: An Inservice Teaching Packet.

ERIC Educational Resources Information Center

McBride, Deborah

This inservice packet is designed to guide teachers in training paraprofessionals to function in the school community. Complete lesson plans are included for six lessons of approximately 45 minutes to an hour. Specific measurable objectives are cited, and participant activities include: (1) discussing the value and use of paraprofessional…

Family Focus: Reading and Learning Together Packet.

ERIC Educational Resources Information Center

American Newspaper Publishers Association Foundation, Washington, DC.

Recognizing the crucial role played by parents and family in literacy development, a program called "Family Focus: Reading and Learning Together" has published this packet designed to teach parents ways to use the newspaper to reinforce reading skills in a relaxed home setting. It contains suggestions and materials for four 90-minute…

Schools Are for All Kids. Part II: School Site Implementation. Trainer's Packet.

ERIC Educational Resources Information Center

Roger, Blair; And Others

This trainer's packet, designed to be used in conjunction with the participant's manual, was prepared for a 2-day workshop to restructure schools to embrace all children, including those with disabilities. The trainer's materials include: program objectives; masters for overhead transparencies; and descriptions of learning activities, including…

AIME Copyright Information Packet. Revised.

ERIC Educational Resources Information Center

Association for Information Media and Equipment, Elkader, IA.

Designed to assist educators in developing or revising school/library copyright policy, this packet provides the following materials: (1) a viewer's guide for the film "Copyright Law: What Every School, College, and Public Library Should Know"; (2) a statement of the primary missions of the Association for Information Media and Equipment (AIME);…

Peninsula Humane Society Teacher's Packet. Secondary Level.

ERIC Educational Resources Information Center

Peninsula Humane Society, San Mateo, CA.

Activities in this teacher's packet are designed to familiarize secondary school students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons grouped under social studies, language arts, math, and health sciences. Activities focus on pet overpopulation, expressions of social responses in…

Student Problems. Adult Literacy Independent Learning Packet.

ERIC Educational Resources Information Center

Koefer, Ann M.

This independent learning packet, which is designed for administrators, teachers, counselors, and tutors in Pennsylvania's Region 7 Tri-Valley Literacy Staff Development area as well as for their adult students, examines the following seven problems encountered by students: the job market, child care, single parenting/parenting skills, divorce,…

High-Speed Ring Bus

NASA Technical Reports Server (NTRS)

Wysocky, Terry; Kopf, Edward, Jr.; Katanyoutananti, Sunant; Steiner, Carl; Balian, Harry

2010-01-01

The high-speed ring bus at the Jet Propulsion Laboratory (JPL) allows for future growth trends in spacecraft seen with future scientific missions. This innovation constitutes an enhancement of the 1393 bus as documented in the Institute of Electrical and Electronics Engineers (IEEE) 1393-1999 standard for a spaceborne fiber-optic data bus. It allows for high-bandwidth and time synchronization of all nodes on the ring. The JPL ring bus allows for interconnection of active units with autonomous operation and increased fault handling at high bandwidths. It minimizes the flight software interface with an intelligent physical layer design that has few states to manage as well as simplified testability. The design will soon be documented in the AS-1393 standard (Serial Hi-Rel Ring Network for Aerospace Applications). The framework is designed for "Class A" spacecraft operation and provides redundant data paths. It is based on "fault containment regions" and "redundant functional regions (RFR)" and has a method for allocating cables that completely supports the redundancy in spacecraft design, allowing for a complete RFR to fail. This design reduces the mass of the bus by incorporating both the Control Unit and the Data Unit in the same hardware. The standard uses ATM (asynchronous transfer mode) packets, standardized by ITU-T, ANSI, ETSI, and the ATM Forum. The IEEE-1393 standard uses the UNI form of the packet and provides no protection for the data portion of the cell. The JPL design adds optional formatting to this data portion. This design extends fault protection beyond that of the interconnect. This includes adding protection to the data portion that is contained within the Bus Interface Units (BIUs) and by adding to the signal interface between the Data Host and the JPL 1393 Ring Bus. Data transfer on the ring bus does not involve a master or initiator. Following bus protocol, any BIU may transmit data on the ring whenever it has data received from its host. There is no centralized arbitration or bus granting. The JPL design provides for autonomous synchronization of the nodes on the ring bus. An address-synchronous latency adjust buffer (LAB) has been designed that cannot get out of synchronization and needs no external input. Also, a priority-driven cable selection behavior has been programmed into each unit on the ring bus. This makes the bus able to connect itself up, according to a maximum redundancy priority system, without the need for computer intervention at startup. Switching around a failed or switched-off unit is also autonomous. The JPL bus provides a map of all the active units for the host computer to read and use for fault management. With regard to timing, this enhanced bus recognizes coordinated timing on a spacecraft as critical and addresses this with a single source of absolute and relative time, which is broadcast to all units on the bus with synchronization maintained to the tens of nanoseconds. Each BIU consists of up to five programmable triggers, which may be programmed for synchronization of events within the spacecraft of instrument. All JPL-formatted data transmitted on the ring bus are automatically time-stamped.

Fast packet switching algorithms for dynamic resource control over ATM networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsang, R.P.; Keattihananant, P.; Chang, T.

1996-12-01

Real-time continuous media traffic, such as digital video and audio, is expected to comprise a large percentage of the network load on future high speed packet switch networks such as ATM. A major feature which distinguishes high speed networks from traditional slower speed networks is the large amount of data the network must process very quickly. For efficient network usage, traffic control mechanisms are essential. Currently, most mechanisms for traffic control (such as flow control) have centered on the support of Available Bit Rate (ABR), i.e., non real-time, traffic. With regard to ATM, for ABR traffic, two major types ofmore » schemes which have been proposed are rate- control and credit-control schemes. Neither of these schemes are directly applicable to Real-time Variable Bit Rate (VBR) traffic such as continuous media traffic. Traffic control for continuous media traffic is an inherently difficult problem due to the time- sensitive nature of the traffic and its unpredictable burstiness. In this study, we present a scheme which controls traffic by dynamically allocating/de- allocating resources among competing VCs based upon their real-time requirements. This scheme incorporates a form of rate- control, real-time burst-level scheduling and link-link flow control. We show analytically potential performance improvements of our rate- control scheme and present a scheme for buffer dimensioning. We also present simulation results of our schemes and discuss the tradeoffs inherent in maintaining high network utilization and statistically guaranteeing many users` Quality of Service.« less

Quality of Service for Real-Time Applications Over Next Generation Data Networks

NASA Technical Reports Server (NTRS)

Ivancic, William; Atiquzzaman, Mohammed; Bai, Haowei; Su, Hongjun; Jain, Raj; Duresi, Arjan; Goyal, Mukyl; Bharani, Venkata; Liu, Chunlei; Kota, Sastri

2001-01-01

This project, which started on January 1, 2000, was funded by NASA Glenn Research Center for duration of one year. The deliverables of the project included the following tasks: Study of QoS mapping between the edge and core networks envisioned in the Next Generation networks will provide us with the QoS guarantees that can be obtained from next generation networks. Buffer management techniques to provide strict guarantees to real-time end-to-end applications through preferential treatment to packets belonging to real-time applications. In particular, use of ECN to help reduce the loss on high bandwidth-delay product satellite networks needs to be studied. Effect of Prioritized Packet Discard to increase goodput of the network and reduce the buffering requirements in the ATM switches. Provision of new IP circuit emulation services over Satellite IP backbones using MPLS will be studied. Determine the architecture and requirements for internetworking ATN and the Next Generation Internet for real-time applications.

Application of Frame Theory in Intelligent Packet-Based Communication Networks

NASA Astrophysics Data System (ADS)

Escobar-Moreira, León A.

2007-09-01

Frames are a stable and redundant representation of signals in a Hilbert space that have been used in signal processing because of their resilience to additive noise, quantization error, and their robustness to losses in packet-based networks [1,2]. Depending on the number of erasures (losses), there are some considerations to be taken into account in order to optimize the frame design. Further discussions will explain the innate characteristics of frames to include intelligence on the packet-based communication devices (routers) to increase their performance under different channel behaviors.

Integrated Collaborative Model in Research and Education with Emphasis on Small Satellite Technology

DTIC Science & Technology

1996-01-01

feedback; the number of iterations in a complete iteration is referred to as loop depth or iteration depth, g (i). A data packet or packet is data...loop depth, g (i)) is either a finite (constant or variable) or an infinite value. 1) Finite loop depth, variable number of iterations Some problems...design time. The time needed for the first packet to leave and a new initial data to be introduced to the iteration is min(R * ( g (k) * (N+I) + k-1

Campaign Safe & Sober. Youth & Generation X Planner.

ERIC Educational Resources Information Center

National Highway Traffic Safety Administration (DOT), Washington, DC.

This packet contains information on safe and sober driving for members of Generation X. The packet includes information on "Buckle Up America! Week 1998," which was designed to encourage everyone on the road to use seat belts and child safety seats and to use them properly. It also offers a safety city brochure and multiple program…

In Her Own Write: Maryland Women's History Resource Packet, 1989.

ERIC Educational Resources Information Center

Maryland State Commission for Women, Baltimore.

This packet is designed to raise precollege students' understanding and awareness of writing by women, to encourage women's studies in the curriculum, and to assist in identifying bias in language use and English/language arts curriculum materials. It can also be used by companies or community organizations interested in similar issues. It…

The Theory of Packet Broadcasting

DTIC Science & Technology

1976-01-01

34 IEEE Transactions on Communications, Vol. CCM-22, No. 5, May 1974, pp. 688-692. [27] FRANK, 1H., R.M. VAN SLYKE and I. GITMAN : "Packet Radio Network...423. [37] GITMAN , I.: "On the Capacity of Slotted ALOHA Networks and Some Design Problems," IEEE Transactions on Communications, Vol. COM-23, No. 3

The Maple Products: An Outdoor Education Unit.

ERIC Educational Resources Information Center

Yaple, Charles; And Others

Designed to take advantage of the spring season, this resource packet on maple products centers upon a field lesson in harvesting and making maple syrup. The resources in this packet include: a narrative on the origins of maple sugar; an illustrated description of "old time maple sugarin'"; suggestions for pre-trip activities (history of…

California's Water Problems.

ERIC Educational Resources Information Center

Wheatley, Judy; Sudman, Rita Schmidt, Ed.

This packet of instructional materials is designed to give social science students in grades 6-9 a first-hand experience in working out solutions to real-life problems involving the management of California's water. Students work in groups on one of three problems presented in the packet: (1) the management of the Sacramento-San Joaquin Delta that…

K-2 at the Zoo.

ERIC Educational Resources Information Center

Andrews, Lori; Andrews, Steve

This packet is designed to help teachers maximize a zoo visit for children ages 5 to 7. The packet provides activities for use before, during, and after the zoo visit. Activities are provided to enhance student skills in language arts, reading, art, science, and math, and are correlated to the Oregon Essentials Learning Skills Common Curriculum…

Exploring Classical Art at the Museum of Fine Arts, Boston.

ERIC Educational Resources Information Center

Burchenal, Margaret; Foote, Allison

This resource packet is designed to help teachers incorporate the study of ancient Greek and Roman art into junior and senior high school classrooms. The packet consists of four curriculum units based upon aspects of classical life or culture. These units are: "Daily Life; Mythology"; "Images of Power"; and "Echoes of…

Investing in Undeveloped Land. Teachers Instructional Packet, TIP No. 9, Spring 1986.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the opportunities and pitfalls associated with investments in undeveloped land, and ways to reduce the risk of ownership. A summary instructor's presentation is provided, which: (1) defines…

Building Trades II.

ERIC Educational Resources Information Center

Hamlin, Larry

This packet contains a curriculum guide, a set of lesson plans, a student manual, and a competency test packet for the Building Trades II course, the second year of a 2-year, 2-unit (350 hour) preemployment program for students in grades 11-12. This technical course is designed to develop the basic skills associated with builders. An additional…

No Deposit - No Return. The Management of Municipal Solid Wastes.

ERIC Educational Resources Information Center

Fowler, John M.; Mervine, Kathryn E.

This booklet is the second in a series of Environmental Resource Packets designed to encourage college science teachers to become professionally competent in selected environmental areas of study. Produced under a grant from the ESSO Education Foundation, each packet consists of a review paper(s) and a selected and annotated bibliography related…

Where To Get Resource Materials To Address Barriers to Learning. A Resource Packet.

ERIC Educational Resources Information Center

California Univ., Los Angeles. Center for Mental Health in Schools.

This resource aid is designed to provide a sampling of organizations and publishers that offer a variety of materials relevant to addressing students' psychosocial and mental concerns. Included is information about resources available upon request and/or purchase. The packet is divided into three sections. Section 1 identifies national…

Design and implementation of a random neural network routing engine.

PubMed

Kocak, T; Seeber, J; Terzioglu, H

2003-01-01

Random neural network (RNN) is an analytically tractable spiked neural network model that has been implemented in software for a wide range of applications for over a decade. This paper presents the hardware implementation of the RNN model. Recently, cognitive packet networks (CPN) is proposed as an alternative packet network architecture where there is no routing table, instead the RNN based reinforcement learning is used to route packets. Particularly, we describe implementation details for the RNN based routing engine of a CPN network processor chip: the smart packet processor (SPP). The SPP is a dual port device that stores, modifies, and interprets the defining characteristics of multiple RNN models. In addition to hardware design improvements over the software implementation such as the dual access memory, output calculation step, and reduced output calculation module, this paper introduces a major modification to the reinforcement learning algorithm used in the original CPN specification such that the number of weight terms are reduced from 2n/sup 2/ to 2n. This not only yields significant memory savings, but it also simplifies the calculations for the steady state probabilities (neuron outputs in RNN). Simulations have been conducted to confirm the proper functionality for the isolated SPP design as well as for the multiple SPP's in a networked environment.

A Study of the IEEE 802.16 MAC Layer and its Utility in Augmenting the ADNS Architecture to Provide Adaptable Intra-Strike Group High-Speed Packet Switched Data, Imagery, and Voice Communications

DTIC Science & Technology

2005-09-01

This research explores the need for a high throughput, high speed network for use in a network centric wartime environment and how commercial...Automated Digital Network System (ADNS). This research explores the need for a high-throughput, high-speed network for use in a network centric ...1 C. DEPARTMENT OF DEFENSE (DOD) DESIRED END STATE ..............2 1. DOD Transformation to Network Centric Warfare (NCW) Operations

DDN New User Guide, 3rd Edition

DTIC Science & Technology

1993-04-05

Network Security Officer) 38. 58 MILNET 1, 87, 88 contacts (CMMC, EMMC , PMMC) 71, 72 Packet-switched network 5 , 6 definition of 1. 7-9 Passwords 24, 28...2* `1CUMENTATION PAGE jA4 Nom 0704-41 AD A2 P’fo ~W. Uf ýto JI toot IPU ~ 409 -�.s~ I ~ 2.REPORT OAT[ 3. REPORT TYPE AND DATES COVERED 4- 5 -9 Draft...Systems Interconnection Profile (COSIP), and gateway, concentrators. BES 93 4- ý 0 APBLE COPY .93-07561 14. SUBJECT TERMS NIC, TAG, WIIOIS, DDN, MILNET

Proceedings of a Conference on Telecommunication Technologies, Networkings and Libraries

NASA Astrophysics Data System (ADS)

Knight, N. K.

1981-12-01

Current and developing technologies for digital transmission of image data likely to have an impact on the operations of libraries and information centers or provide support for information networking are reviewed. Technologies reviewed include slow scan television, teleconferencing, and videodisc technology and standards development for computer network interconnection through hardware and software, particularly packet switched networks computer network protocols for library and information service applications, the structure of a national bibliographic telecommunications network; and the major policy issues involved in the regulation or deregulation of the common communications carriers industry.

Simple online recognition of optical data strings based on conservative optical logic

NASA Astrophysics Data System (ADS)

Caulfield, H. John; Shamir, Joseph; Zavalin, Andrey I.; Silberman, Enrique; Qian, Lei; Vikram, Chandra S.

2006-06-01

Optical packet switching relies on the ability of a system to recognize header information on an optical signal. Unless the headers are very short with large Hamming distances, optical correlation fails and optical logic becomes attractive because it can handle long headers with Hamming distances as low as 1. Unfortunately, the only optical logic gates fast enough to keep up with current communication speeds involve semiconductor optical amplifiers and do not lend themselves to the incorporation of large numbers of elements for header recognition and would consume a lot of power as well. The ideal system would operate at any bandwidth with no power consumption. We describe how to design and build such a system by using passive optical logic. This too leads to practical problems that we discuss. We show theoretically various ways to use optical interferometric logic for reliable recognition of long data streams such as headers in optical communication. In addition, we demonstrate one particularly simple experimental approach using interferometric coinc gates.

Load-adaptive practical multi-channel communications in wireless sensor networks.

PubMed

Islam, Md Shariful; Alam, Muhammad Mahbub; Hong, Choong Seon; Lee, Sungwon

2010-01-01

In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs). In this paper, we present a multi-channel communications system for WSNs that is referred to as load-adaptive practical multi-channel communications (LPMC). LPMC estimates the active load of a channel at the sink since it has a more comprehensive view of the network behavior, and dynamically adds or removes channels based on the estimated load. LPMC updates the routing path to balance the loads of the channels. The nodes in a path use the same channel; therefore, they do not need to switch channels to receive or forward packets. LPMC has been evaluated through extensive simulations, and the results demonstrate that it can effectively increase the delivery ratio, network throughput, and channel utilization, and that it can decrease the end-to-end delay and energy consumption.

Real-time video streaming using H.264 scalable video coding (SVC) in multihomed mobile networks: a testbed approach

NASA Astrophysics Data System (ADS)

Nightingale, James; Wang, Qi; Grecos, Christos

2011-03-01

Users of the next generation wireless paradigm known as multihomed mobile networks expect satisfactory quality of service (QoS) when accessing streamed multimedia content. The recent H.264 Scalable Video Coding (SVC) extension to the Advanced Video Coding standard (AVC), offers the facility to adapt real-time video streams in response to the dynamic conditions of multiple network paths encountered in multihomed wireless mobile networks. Nevertheless, preexisting streaming algorithms were mainly proposed for AVC delivery over multipath wired networks and were evaluated by software simulation. This paper introduces a practical, hardware-based testbed upon which we implement and evaluate real-time H.264 SVC streaming algorithms in a realistic multihomed wireless mobile networks environment. We propose an optimised streaming algorithm with multi-fold technical contributions. Firstly, we extended the AVC packet prioritisation schemes to reflect the three-dimensional granularity of SVC. Secondly, we designed a mechanism for evaluating the effects of different streamer 'read ahead window' sizes on real-time performance. Thirdly, we took account of the previously unconsidered path switching and mobile networks tunnelling overheads encountered in real-world deployments. Finally, we implemented a path condition monitoring and reporting scheme to facilitate the intelligent path switching. The proposed system has been experimentally shown to offer a significant improvement in PSNR of the received stream compared with representative existing algorithms.

Laser control of electronic transitions of wave packet by using quadratically chirped pulses.

PubMed

Zou, Shiyang; Kondorskiy, Alexey; Mil'nikov, Gennady; Nakamura, Hiroki

2005-02-22

An effective scheme is proposed for the laser control of wave packet dynamics. It is demonstrated that by using specially designed quadratically chirped pulses, fast and nearly complete excitation of wave packet can be achieved without significant distortion of its shape. The parameters of the laser pulse can be estimated analytically from the Zhu-Nakamura theory of nonadiabatic transition. If the wave packet is not too narrow or not too broad, then the scheme is expected to be utilizable for multidimensional systems. The scheme is applicable to various processes such as simple electronic excitation, pump-dump, and selective bond breaking, and it is actually numerically demonstrated to work well by taking diatomic and triatomic molecules (LiH, NaK, H(2)O) as examples.

Laser control of electronic transitions of wave packet by using quadratically chirped pulses

NASA Astrophysics Data System (ADS)

Zou, Shiyang; Kondorskiy, Alexey; Mil'nikov, Gennady; Nakamura, Hiroki

2005-02-01

An effective scheme is proposed for the laser control of wave packet dynamics. It is demonstrated that by using specially designed quadratically chirped pulses, fast and nearly complete excitation of wave packet can be achieved without significant distortion of its shape. The parameters of the laser pulse can be estimated analytically from the Zhu-Nakamura theory of nonadiabatic transition. If the wave packet is not too narrow or not too broad, then the scheme is expected to be utilizable for multidimensional systems. The scheme is applicable to various processes such as simple electronic excitation, pump-dump, and selective bond breaking, and it is actually numerically demonstrated to work well by taking diatomic and triatomic molecules (LiH, NaK, H2O) as examples.

Experimentation and evaluation of advanced integrated system concepts

NASA Astrophysics Data System (ADS)

Ross, M.; Garrigus, K.; Gottschalck, J.; Rinearson, L.; Longee, E.

1980-09-01

This final report examines the implementation of a time-phased test bed for experimentation and evaluation of advanced system concepts relative to the future Defense Switched Network (DSN). After identifying issues pertinent to the DSN, a set of experiments which address these issues are developed. Experiments are ordered based on their immediacy and relative importance to DSN development. The set of experiments thus defined allows requirements for a time phased implementation of a test bed to be identified, and several generic test bed architectures which meet these requirements are examined. Specific architecture implementations are costed and cost/schedule profiles are generated as a function of experimental capability. The final recommended system consists of two separate test beds: a circuit switch test bed, configured around an off-the-shelf commercial switch, and directed toward the examination of nearer term and transitional issues raised by the evolving DSN; and a packet/hybrid test bed, featuring a discrete buildup of new hardware and software modules, and directed toward examination of the more advanced integrated voice and data telecommunications issues and concepts.

Advanced teleprocessing systems

NASA Astrophysics Data System (ADS)

Kleinrock, L.; Gerla, M.

1983-03-01

This Semi-Annual Technical Report covers research covering the period from October 1, 1982 to March 31, 1983. This contract has three primary designated research areas: packet radio systems, resource sharing and allocation, and distributed processing and control. This report contains abstracts of publications which summarize research results in these areas followed by the main body of the report which is devoted to a treatment of single- and multi-hop packet radio systems. In particular, the main body consists of a Ph.D. dissertation, Analysis of Throughput and Delay for Single- and Multi-Hop Packet Radio Networks. The work presents a new approach to evaluating the performance of multi-hop packet radio networks, namely, a study of the times between successful transmissions. Also studied is the behavior of packets in a multi-hop system when a fixed transmission radius is specified and this radius is then optimized for throughput. A Markov chain model is also introduced and solved numerically to evaluate transmission and flow control strategies in these systems.

Optimization of OSPF Routing in IP Networks

NASA Astrophysics Data System (ADS)

Bley, Andreas; Fortz, Bernard; Gourdin, Eric; Holmberg, Kaj; Klopfenstein, Olivier; Pióro, Michał; Tomaszewski, Artur; Ümit, Hakan

The Internet is a huge world-wide packet switching network comprised of more than 13,000 distinct subnetworks, referred to as Autonomous Systems (ASs) autonomous system AS . They all rely on the Internet Protocol (IP) internet protocol IP for transport of packets across the network. And most of them use shortest path routing protocols shortest path routing!protocols , such as OSPF or IS-IS, to control the routing of IP packets routing!of IP packets within an AS. The idea of the routing is extremely simple — every packet is forwarded on IP links along the shortest route between its source and destination nodes of the AS. The AS network administrator can manage the routing of packets in the AS by supplying the so-called administrative weights of IP links, which specify the link lengths that are used by the routing protocols for their shortest path computations. The main advantage of the shortest path routing policy is its simplicity, allowing for little administrative overhead. From the network engineering perspective, however, shortest path routing can pose problems in achieving satisfactory traffic handling efficiency. As all routing paths depend on the same routing metric routing!metric , it is not possible to configure the routing paths for the communication demands between different pairs of nodes explicitly or individually; the routing can be controlled only indirectly and only as a whole by modifying the routing metric. Thus, one of the main tasks when planning such networks is to find administrative link weights that induce a globally efficient traffic routing traffic!routing configuration of an AS. It turns out that this task leads to very difficult mathematical optimization problems. In this chapter, we discuss and describe exact integer programming models and solution approaches as well as practically efficient smart heuristics for such shortest path routing problems shortest path routing!problems .

SpaceWire Protocol ID: What Does It Mean To You?

NASA Technical Reports Server (NTRS)

Rakow, Glenn; Schnurr, Richard; Gilley, Daniel; Parks, Steve

2006-01-01

Spacewire is becoming a popular solution for satellite high-speed data buses because it is a simple standard that provides great flexibility for a wide range of system requirements. It is simple in packet format and protocol, allowing users to easily tailor their implementation for their specific application. Some of the attractive aspects of Spacewire that make it easy to implement also make it hard for future reuse. Protocol reuse is difficult because Spacewire does not have a defined mechanism to communicate with the higher layers of the protocol stack. This has forced users of Spacewire to define unique packet formats and define how these packets are to be processed. Each mission writes their own Interface Control Document (ICD) and tailors Spacewire for their specific requirements making reuse difficult. Part of the reason for this habit may be because engineers typically optimize designs for their own requirements in the absence of a standard. This is an inefficient use of project resources and costs more to develop missions. A new packet format for Spacewire has been defined as a solution for this problem. This new packet format is a compliment to the Spacewire standard that will support protocol development upon Spacewire. The new packet definition does not replace the current packet structure, i.e., does not make the standard obsolete, but merely extends the standard for those who want to develop protocols over Spacewire. The Spacewire packet is defined with the first part being the Destination Address, which may be one or more bytes. This is followed by the packet cargo, which is user defined. The cargo is truncated with an End-Of-Packet (EOP) marker. This packet structure offers low packet overhead and allows the user to define how the contents are to be formatted. It also provides for many different addressing schemes, which provide flexibility in the system. This packet flexibility is typically an attractive part of the Spacewire. The new extended packet format adds one new field to the packet that greatly enhances the capability of Spacewire. This new field called the Protocol Identifier (ID) is used to identify the packet contents and the associated processing for the packet. This feature along with the restriction in the packet format that uses the Protocol ID, allows a deterministic method of decoding packets that was not before possible. The first part of the packet is still the Destination Address, which still conforms to the original standard but with one restriction. The restriction is that the first byte seen at the destination by the user needs to be a logical address, independent of the addressing scheme used. The second field is defined as the Protocol ID, which is usually one byte in length. The packet cargo (user defined) follows the Protocol ID. After the packet cargo is the EOP, which defines the end of packet. The value of the Protocol ID is assigned by the Spacewire working group and the protocol description published for others to use. The development of Protocols for Spacewire is currently the area of greatest activity by the Spacewire working group. The first protocol definition by the working group has been completed and is now in the process of formal standardization. There are many other protocols in development for missions that have not yet received formal Protocol ID assignment, but even if the protocols are not formally assigned a value, this effort will provide synergism for future developments.

Design of EPON far-end equipment based on FTTH

NASA Astrophysics Data System (ADS)

Feng, Xiancheng; Yun, Xiang

2008-12-01

Now, most favors fiber access is mainly the EPON fiber access system. Inheriting from the low cost of Ethernet, usability and bandwidth of optical network, EPON technology is one of the best technologies in fiber access and is adopted by the carriers all over the world widely. According to the scheme analysis to FTTH fan-end equipment, hardware design of ONU is proposed in this paper. The FTTH far-end equipment software design deference modulation design concept, it divides the software designment into 5 function modules: the module of low-layer driver, the module of system management, the module of master/slave communication, and the module of main/Standby switch and the module of command line. The software flow of the host computer is also analyzed. Finally, test is made for Ethernet service performance of FTTH far-end equipment, E1 service performance and the optical path protection switching, and so on. The results of test indicates that all the items are accordance with technical request of far-end ONU equipment and possess good quality and fully reach the requirement of telecommunication level equipment. The far-end equipment of FTTH divides into several parts based on the function: the control module, the exchange module, the UNI interface module, the ONU module, the EPON interface module, the network management debugging module, the voice processing module, the circuit simulation module, the CATV module. In the downstream direction, under the protect condition, we design 2 optical modules. The system can set one group optical module working and another group optical module closure when it is initialized. When the optical fiber line is cut off, the LOS warning comes out. It will cause MUX to replace another group optical module, simultaneously will reset module 3701/3711 and will make it again test the distance, and will give the plug board MPC850 report through the GPIO port. During normal mode, the downstream optical signal is transformed into the electrical signal by the optical module. In the upstream direction, the upstream Ethernet data is retransmitted through the exchange chip BCM5380 to the GMII/MII in module 3701/3711, and then is transmitted to EPON port. The 2MB data are transformed the Ethernet data packet in the plug board TDM, then it's transmitted to the interface MII of the module 3701/3711. The software design of FTTH far-end equipment compiles with modulation design concept. According to the system realization duty, the software is divided into 5 function modules: low-level driver module, system management module, master/slave communication module, the man/Standby switch module and the command line module. The FTTH far-end equipment test, is mainly the Ethernet service performance test, E1 service performance test and the optical path protection switching test and so on the key specification test.

High speed packet switching

NASA Technical Reports Server (NTRS)

1991-01-01

This document constitutes the final report prepared by Proteon, Inc. of Westborough, Massachusetts under contract NAS 5-30629 entitled High-Speed Packet Switching (SBIR 87-1, Phase 2) prepared for NASA-Greenbelt, Maryland. The primary goal of this research project is to use the results of the SBIR Phase 1 effort to develop a sound, expandable hardware and software router architecture capable of forwarding 25,000 packets per second through the router and passing 300 megabits per second on the router's internal busses. The work being delivered under this contract received its funding from three different sources: the SNIPE/RIG contract (Contract Number F30602-89-C-0014, CDRL Sequence Number A002), the SBIR contract, and Proteon. The SNIPE/RIG and SBIR contracts had many overlapping requirements, which allowed the research done under SNIPE/RIG to be applied to SBIR. Proteon funded all of the work to develop new router interfaces other than FDDI, in addition to funding the productization of the router itself. The router being delivered under SBIR will be a fully product-quality machine. The work done during this contract produced many significant findings and results, summarized here and explained in detail in later sections of this report. The SNIPE/RIG contract was completed. That contract had many overlapping requirements with the SBIR contract, and resulted in the successful demonstration and delivery of a high speed router. The development that took place during the SNIPE/RIG contract produced findings that included the choice of processor and an understanding of the issues surrounding inter processor communications in a multiprocessor environment. Many significant speed enhancements to the router software were made during that time. Under the SBIR contract (and with help from Proteon-funded work), it was found that a single processor router achieved a throughput significantly higher than originally anticipated. For this reason, a single processor router was developed and the final delivery under this contract will include a single processor CNX-500 router. The router and its interface boards (2 FDDIs and 2 dual-ethernets) are all product-quality components.

Laser control of reactions of photoswitching functional molecules.

PubMed

Tamura, Hiroyuki; Nanbu, Shinkoh; Ishida, Toshimasa; Nakamura, Hiroki

2006-07-21

Laser control schemes of reactions of photoswitching functional molecules are proposed based on the quantum mechanical wave-packet dynamics and the design of laser parameters. The appropriately designed quadratically chirped laser pulses can achieve nearly complete transitions of wave packet among electronic states. The laser parameters can be optimized by using the Zhu-Nakamura theory of nonadiabatic transition. This method is effective not only for the initial photoexcitation process but also for the pump and dump scheme in the middle of the overall photoswitching process. The effects of momentum of the wave packet crossing a conical intersection on the branching ratio of products have also been clarified. These control schemes mentioned above are successfully applied to the cyclohexadiene/hexatriene photoisomerization (ring-opening) process which is the reaction center of practical photoswitching molecules such as diarylethenes. The overall efficiency of the ring opening can be appreciably increased by using the appropriately designed laser pulses compared to that of the natural photoisomerization without any control schemes.

Path Diversity Improved Opportunistic Routing for Underwater Sensor Networks

PubMed Central

Wang, Haiyan; He, Ke

2018-01-01

The packets carried along a pre-defined route in underwater sensor networks are very vulnerble. Node mobility or intermittent channel availability easily leads to unreachable routing. Opportunistic routing has been proven to be a promising paradigm to design routing protocols for underwater sensor networks. It takes advantage of the broadcast nature of the wireless medium to combat packet losses and selects potential paths on the fly. Finding an appropriate forwarding candidate set is a key issue in opportunistic routing. Many existing solutions ignore the impact of candidates location distribution on packet forwarding. In this paper, a path diversity improved candidate selection strategy is applied in opportunistic routing to improve packet forwarding efficiency. It not only maximizes the packet forwarding advancements but also takes the candidate’s location distribution into account. Based on this strategy, we propose two effective routing protocols: position improved candidates selection (PICS) and position random candidates selection (PRCS). PICS employs two-hop neighbor information to make routing decisions. PRCS only uses one-hop neighbor information. Simulation results show that both PICS and PRCS can significantly improve network performance when compared with the previous solutions, in terms of packet delivery ratio, average energy consumption and end-to-end delay. PMID:29690621

Path Diversity Improved Opportunistic Routing for Underwater Sensor Networks.

PubMed

Bai, Weigang; Wang, Haiyan; He, Ke; Zhao, Ruiqin

2018-04-23

The packets carried along a pre-defined route in underwater sensor networks are very vulnerble. Node mobility or intermittent channel availability easily leads to unreachable routing. Opportunistic routing has been proven to be a promising paradigm to design routing protocols for underwater sensor networks. It takes advantage of the broadcast nature of the wireless medium to combat packet losses and selects potential paths on the fly. Finding an appropriate forwarding candidate set is a key issue in opportunistic routing. Many existing solutions ignore the impact of candidates location distribution on packet forwarding. In this paper, a path diversity improved candidate selection strategy is applied in opportunistic routing to improve packet forwarding efficiency. It not only maximizes the packet forwarding advancements but also takes the candidate’s location distribution into account. Based on this strategy, we propose two effective routing protocols: position improved candidates selection (PICS) and position random candidates selection (PRCS). PICS employs two-hop neighbor information to make routing decisions. PRCS only uses one-hop neighbor information. Simulation results show that both PICS and PRCS can significantly improve network performance when compared with the previous solutions, in terms of packet delivery ratio, average energy consumption and end-to-end delay.

A source-controlled data center network model.

PubMed

Yu, Yang; Liang, Mangui; Wang, Zhe

2017-01-01

The construction of data center network by applying SDN technology has become a hot research topic. The SDN architecture has innovatively separated the control plane from the data plane which makes the network more software-oriented and agile. Moreover, it provides virtual multi-tenancy, effective scheduling resources and centralized control strategies to meet the demand for cloud computing data center. However, the explosion of network information is facing severe challenges for SDN controller. The flow storage and lookup mechanisms based on TCAM device have led to the restriction of scalability, high cost and energy consumption. In view of this, a source-controlled data center network (SCDCN) model is proposed herein. The SCDCN model applies a new type of source routing address named the vector address (VA) as the packet-switching label. The VA completely defines the communication path and the data forwarding process can be finished solely relying on VA. There are four advantages in the SCDCN architecture. 1) The model adopts hierarchical multi-controllers and abstracts large-scale data center network into some small network domains that has solved the restriction for the processing ability of single controller and reduced the computational complexity. 2) Vector switches (VS) developed in the core network no longer apply TCAM for table storage and lookup that has significantly cut down the cost and complexity for switches. Meanwhile, the problem of scalability can be solved effectively. 3) The SCDCN model simplifies the establishment process for new flows and there is no need to download flow tables to VS. The amount of control signaling consumed when establishing new flows can be significantly decreased. 4) We design the VS on the NetFPGA platform. The statistical results show that the hardware resource consumption in a VS is about 27% of that in an OFS.

A source-controlled data center network model

PubMed Central

Yu, Yang; Liang, Mangui; Wang, Zhe

2017-01-01

The construction of data center network by applying SDN technology has become a hot research topic. The SDN architecture has innovatively separated the control plane from the data plane which makes the network more software-oriented and agile. Moreover, it provides virtual multi-tenancy, effective scheduling resources and centralized control strategies to meet the demand for cloud computing data center. However, the explosion of network information is facing severe challenges for SDN controller. The flow storage and lookup mechanisms based on TCAM device have led to the restriction of scalability, high cost and energy consumption. In view of this, a source-controlled data center network (SCDCN) model is proposed herein. The SCDCN model applies a new type of source routing address named the vector address (VA) as the packet-switching label. The VA completely defines the communication path and the data forwarding process can be finished solely relying on VA. There are four advantages in the SCDCN architecture. 1) The model adopts hierarchical multi-controllers and abstracts large-scale data center network into some small network domains that has solved the restriction for the processing ability of single controller and reduced the computational complexity. 2) Vector switches (VS) developed in the core network no longer apply TCAM for table storage and lookup that has significantly cut down the cost and complexity for switches. Meanwhile, the problem of scalability can be solved effectively. 3) The SCDCN model simplifies the establishment process for new flows and there is no need to download flow tables to VS. The amount of control signaling consumed when establishing new flows can be significantly decreased. 4) We design the VS on the NetFPGA platform. The statistical results show that the hardware resource consumption in a VS is about 27% of that in an OFS. PMID:28328925

Working Together: From School-Based Collaborative Teams to School-Community-Higher Education Connections. An Introductory Packet.

ERIC Educational Resources Information Center

California Univ., Los Angeles. Center for Mental Health Schools.

This packet is designed to help in the development of collaborative efforts for educational improvement. "Working Together with Others To Enhance Programs and Resources" (from the Center for Mental Health in Schools) is the first selection. This discussion emphasizes that effectiveness is the real point of collaboration, and it explores the…

French-Canadians, Acadians and the French in New England. A Learning Activity Packet.

ERIC Educational Resources Information Center

Maine Univ., Orono. New England - Atlantic Provinces - Quebec Center.

The history of the French-Canadians from their beginnings to the present time is the topic of this Learning Activity Packet (LAP). Designed to acquaint students with the French, Canada's earliest permanent settlers following the Indians, the unit is divided into six objectives which include learning activities for each. Students are expected to…

Plant Galls and Ecological Concepts: A Multidisciplinary Outdoor Education Teaching Resource Packet.

ERIC Educational Resources Information Center

Matthews, Bruce; And Others

Designed for adaptation in primary through high school classes, the lessons in this resource packet use the development of plant galls (plant growths caused by irritation of the plant tissue) as a focus for outdoor education studies and activities. Emphasis is on science and ecology, though other disciplines are represented. Illustrations and…

The Texas Real Estate Licensee 1984: A Profile. Teachers Instructional Packet, TIP No. 13, Spring 1987.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the characteristics of Texas real estate licensees based on a 1984 state survey which focused on the demographic, educational, business, career, income, and job specialization characteristics of a…

A Profile of 1984 Homebuyers. Teachers Instructional Packet, TIP-2A, Spring 1987.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the characteristics of Texas homebuyers. First, a summary profile of homebuyers is presented, indicating that: (1) the typical 1984 Texas homebuyer was married, was between 25 and 34 years old,…

Intermediate SCDC Spanish Curricula Units. Social Science, Unit 1, Kits 1-4, Supplement & Ditto Packet.

ERIC Educational Resources Information Center

Spanish Curricula Development Center, Miami Beach, FL.

Designed for use with the teacher's guide to the intermediate social science unit, the supplement and ditto packet provides visual aids and worksheets for class activities and seatwork for individual students. Visual materials are provided to help stimulate oral language and conceptual development. The worksheets are to be presented under…

Teen Pregnancy Prevention and Support. An Introductory Packet.

ERIC Educational Resources Information Center

California Univ., Los Angeles. Center for Mental Health Schools.

This introductory packet is designed to help those with an interest in preventing teen pregnancy. It opens with "A Brief Introduction to Teen Pregnancy Prevention and Support," an essay by the Center for Mental Health in Schools of the University of California, Los Angeles, that outlines the dimensions of the problem. "A Quick Overview of Some…

Ecologia: Spanish Ecology Packet Resource Units and Materials for Intermediate and Advanced Spanish Classes.

ERIC Educational Resources Information Center

Bell, Mozelle Sawyer; Arribas, E. Jaime

This Spanish ecology packet contains resource units and materials for intermediate and advanced Spanish classes. It is designed to be used for individual and small-group instruction in the senior high school to supplement the Spanish language curriculum. Included are articles, pictures, and cartoons from Spanish-language newspapers and magazines…

Issues and Images: New Yorkers during the Thirties. A Teaching Packet of Historical Documents.

ERIC Educational Resources Information Center

New York State Education Dept., Albany. Cultural Education Center.

Derived from an exhibit produced cooperatively by the New York State Archives and the New York State Museum for the Franklin D. Roosevelt Centennial, and designed to provide secondary students with first-hand exposure to New York during the Great Depression, this packet contains a teacher's guide and 22 facsimile documents, including historic…

Iowa's Clean Solid Waste Environmental Education Project (SWEEP).

ERIC Educational Resources Information Center

Eells, Jean Crim; And Others

The Iowa Clean SWEEP program is designed to provide educators, K-12, with a series of activities focusing upon critical concepts related to Iowa's solid waste problem. This activity packet contains 19 activities for grades K-6, and 25 activities for grades 7-12. Key concepts addressed throughout the activity packet include: (1) an overview, the…

Tools and Techniques for Simplifying the Analysis of Captured Packet Data

ERIC Educational Resources Information Center

Cavaiani, Thomas P.

2008-01-01

Students acquire an understanding of the differences between TCP and UDP (connection-oriented vs. connection-less) data transfers as they analyze network packet data collected during one of a series of labs designed for an introductory network essentials course taught at Boise State University. The learning emphasis of the lab is not on the…

The United States History (Khmer Edition). [34 Self-Learning Packets for Khmer Students.

ERIC Educational Resources Information Center

Nhi, Do Dien; And Others

Designed primarily for Indochinese students in grades 9-12, 34 United States history self-learning packets Materials produced as a joint effort between George Mason University, in eight sections. The publication could be used by mainstream teachers who have a number of limited English proficient (LEP) Khmer students in their classes or by parents…

Experimental demonstration of time- and mode-division multiplexed passive optical network

NASA Astrophysics Data System (ADS)

Ren, Fang; Li, Juhao; Tang, Ruizhi; Hu, Tao; Yu, Jinyi; Mo, Qi; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

2017-07-01

A time- and mode-division multiplexed passive optical network (TMDM-PON) architecture is proposed, in which each optical network unit (ONU) communicates with the optical line terminal (OLT) independently utilizing both different time slots and switched optical linearly polarized (LP) spatial modes. Combination of a mode multiplexer/demultiplexer (MUX/DEUX) and a simple N × 1 optical switch is employed to select the specific LP mode in each ONU. A mode-insensitive power splitter is used for signal broadcast/combination between OLT and ONUs. We theoretically propose a dynamic mode and time slot assignment scheme for TMDM-PON based on inter-ONU priority rating, in which the time delay and packet loss ratio's variation tendency are investigated by simulation. Moreover, we experimentally demonstrate 2-mode TMDM-PON transmission over 10 km FMF with 10-Gb/s on-off keying (OOK) signal and direct detection.

GLOBECOM '85 - Global Telecommunications Conference, New Orleans, LA, December 2-5, 1985, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

Various papers on global telecommunications are presented. The general topics addressed include: multiservice integration with optical fibers, multicompany owned telecommunication networks, softworks quality and reliability, advanced on-board processing, impact of new services and systems on operations and maintenance, analytical studies of protocols for data communication networks, topics in packet radio networking, CCITT No. 7 to support new services, document processing and communication, antenna technology and system aspects in satellite communications. Also considered are: communication systems modelling methodology, experimental integrated local area voice/data nets, spread spectrum communications, motion video at the DS-0 rate, optical and data communications, intelligent work stations, switch performance analysis, novel radio communication systems, wireless local networks, ISDN services, LAN communication protocols, user-system interface, radio propagation and performance, mobile satellite system, software for computer networks, VLSI for ISDN terminals, quality management, man-machine interfaces in switching, and local area network performance.

ICC '86; Proceedings of the International Conference on Communications, Toronto, Canada, June 22-25, 1986, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

Papers are presented on ISDN, mobile radio systems and techniques for digital connectivity, centralized and distributed algorithms in computer networks, communications networks, quality assurance and impact on cost, adaptive filters in communications, the spread spectrum, signal processing, video communication techniques, and digital satellite services. Topics discussed include performance evaluation issues for integrated protocols, packet network operations, the computer network theory and multiple-access, microwave single sideband systems, switching architectures, fiber optic systems, wireless local communications, modulation, coding, and synchronization, remote switching, software quality, transmission, and expert systems in network operations. Consideration is given to wide area networks, image and speech processing, office communications application protocols, multimedia systems, customer-controlled network operations, digital radio systems, channel modeling and signal processing in digital communications, earth station/on-board modems, computer communications system performance evaluation, source encoding, compression, and quantization, and adaptive communications systems.

Performance analysis of cross-layer design with average PER constraint over MIMO fading channels

NASA Astrophysics Data System (ADS)

Dang, Xiaoyu; Liu, Yan; Yu, Xiangbin

2015-12-01

In this article, a cross-layer design (CLD) scheme for multiple-input and multiple-output system with the dual constraints of imperfect feedback and average packet error rate (PER) is presented, which is based on the combination of the adaptive modulation and the automatic repeat request protocols. The design performance is also evaluated over wireless Rayleigh fading channel. With the constraint of target PER and average PER, the optimum switching thresholds (STs) for attaining maximum spectral efficiency (SE) are developed. An effective iterative algorithm for finding the optimal STs is proposed via Lagrange multiplier optimisation. With different thresholds available, the analytical expressions of the average SE and PER are provided for the performance evaluation. To avoid the performance loss caused by the conventional single estimate, multiple outdated estimates (MOE) method, which utilises multiple previous channel estimation information, is presented for CLD to improve the system performance. It is shown that numerical simulations for average PER and SE are in consistent with the theoretical analysis and that the developed CLD with average PER constraint can meet the target PER requirement and show better performance in comparison with the conventional CLD with instantaneous PER constraint. Especially, the CLD based on the MOE method can obviously increase the system SE and reduce the impact of feedback delay greatly.

Nationwide SIP Telephony Network Design to Prevent Congestion Caused by Disaster

NASA Astrophysics Data System (ADS)

Satoh, Daisuke; Ashitagawa, Kyoko

We present a session initiation protocol (SIP) network design for a voice-over-IP network to prevent congestion caused by people calling friends and family after a disaster. The design increases the capacity of SIP servers in a network by using all of the SIP servers equally. It takes advantage of the fact that equipment for voice data packets is different from equipment for signaling packets in SIP networks. Furthermore, the design achieves simple routing on the basis of telephone numbers. We evaluated the performance of our design in preventing congestion through simulation. We showed that the proposed design has roughly 20 times more capacity, which is 57 times the normal load, than the conventional design if a disaster were to occur in Niigata Prefecture struck by the Chuetsu earthquake in 2004.

Toward fidelity between specification and implementation

NASA Technical Reports Server (NTRS)

Callahan, John R.; Montgomery, Todd L.; Morrison, Jeff; Wu, Yunqing

1994-01-01

This paper describes the methods used to specify and implement a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally by two complementary teams using a combination of formal and informal techniques in an attempt to ensure the correctness of the protocol implementation. The first team, called the Design team, initially specified protocol requirements using a variant of SCR requirements tables and implemented a prototype solution. The second team, called the V&V team, developed a state model based on the requirements tables and derived test cases from these tables to exercise the implementation. In a series of iterative steps, the Design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation through testing. Test cases derived from state transition paths in the formal model formed the dialogue between teams during development and served as the vehicles for keeping the model and implementation in fidelity with each other. This paper describes our experiences in developing our process model, details of our approach, and some example problems found during the development of RMP.

Verification and validation of a reliable multicast protocol

NASA Technical Reports Server (NTRS)

Callahan, John R.; Montgomery, Todd L.

1995-01-01

This paper describes the methods used to specify and implement a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally by two complementary teams using a combination of formal and informal techniques in an attempt to ensure the correctness of the protocol implementation. The first team, called the Design team, initially specified protocol requirements using a variant of SCR requirements tables and implemented a prototype solution. The second team, called the V&V team, developed a state model based on the requirements tables and derived test cases from these tables to exercise the implementation. In a series of iterative steps, the Design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation through testing. Test cases derived from state transition paths in the formal model formed the dialogue between teams during development and served as the vehicles for keeping the model and implementation in fidelity with each other. This paper describes our experiences in developing our process model, details of our approach, and some example problems found during the development of RMP.

Multi-wavelength transceiver integration on SOI for high-performance computing system applications

NASA Astrophysics Data System (ADS)

Aalto, Timo; Harjanne, Mikko; Ylinen, Sami; Kapulainen, Markku; Vehmas, Tapani; Cherchi, Matteo; Neumeyr, Christian; Ortsiefer, Markus; Malacarne, Antonio

2015-03-01

We present a vision for transceiver integration on a 3 μm SOI waveguide platform for systems scalable to Pb/s. We also present experimental results from the first building blocks developed in the EU-funded RAPIDO project. At 1.3 μm wavelength 80 Gb/s per wavelength is to be achieved using hybrid integration of III-V optoelectronics on SOI. Goals include athermal operation, low-loss I/O coupling, advanced modulation formats and packet switching. An example of the design results is an interposer chip that consists of 12 μm thick SOI waveguides locally tapered down to 3 μm to provide low-loss coupling between an optical single-mode fiber array and the 3 μm SOI chip. First example of experimental results is a 4x4 cyclic AWGs with 5 nm channel spacing, 0.4 dB/facet fiber coupling loss, 3.5 dB center-tocenter loss, and -23 dB adjacent channel crosstalk in 3.5x1.5 mm2 footprint. The second example result is a new VCSEL design that was demonstrated to have up to 40 Gb/s operation at 1.55 μm.

Event-triggered resilient filtering with stochastic uncertainties and successive packet dropouts via variance-constrained approach

NASA Astrophysics Data System (ADS)

Jia, Chaoqing; Hu, Jun; Chen, Dongyan; Liu, Yurong; Alsaadi, Fuad E.

2018-07-01

In this paper, we discuss the event-triggered resilient filtering problem for a class of time-varying systems subject to stochastic uncertainties and successive packet dropouts. The event-triggered mechanism is employed with hope to reduce the communication burden and save network resources. The stochastic uncertainties are considered to describe the modelling errors and the phenomenon of successive packet dropouts is characterized by a random variable obeying the Bernoulli distribution. The aim of the paper is to provide a resilient event-based filtering approach for addressed time-varying systems such that, for all stochastic uncertainties, successive packet dropouts and filter gain perturbation, an optimized upper bound of the filtering error covariance is obtained by designing the filter gain. Finally, simulations are provided to demonstrate the effectiveness of the proposed robust optimal filtering strategy.

Implementing MANETS in Android based environment using Wi-Fi direct

NASA Astrophysics Data System (ADS)

Waqas, Muhammad; Babar, Mohammad Inayatullah Khan; Zafar, Mohammad Haseeb

2015-05-01

Packet loss occurs in real-time voice transmission over wireless broadcast Ad-hoc network which creates disruptions in sound. Basic objective of this research is to design a wireless Ad-hoc network based on two Android devices by using the Wireless Fidelity (WIFI) Direct Application Programming Interface (API) and apply the Network Codec, Reed Solomon Code. The network codec is used to encode the data of a music wav file and recover the lost packets if any, packets are dropped using a loss module at the transmitter device to analyze the performance with the objective of retrieving the original file at the receiver device using the network codec. This resulted in faster transmission of the files despite dropped packets. In the end both files had the original formatted music files with complete performance analysis based on the transmission delay.

Design and implement of pack filter module base on embedded firewall

NASA Astrophysics Data System (ADS)

Tian, Libo; Wang, Chen; Yang, Shunbo

2011-10-01

In the traditional security solution conditions, software firewall cannot intercept and respond the invasion before being attacked. And because of the high cost, the hardware firewall does not apply to the security strategy of the end nodes, so we have designed a kind of solution of embedded firewall with hardware and software. With ARM embedding Linux operating system, we have designed packet filter module and intrusion detection module to implement the basic function of firewall. Experiments and results show that that firewall has the advantages of low cost, high processing speed, high safety and the application of the computer terminals. This paper focuses on packet filtering module design and implementation.

A Bernoulli Gaussian Watermark for Detecting Integrity Attacks in Control Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weerakkody, Sean; Ozel, Omur; Sinopoli, Bruno

We examine the merit of Bernoulli packet drops in actively detecting integrity attacks on control systems. The aim is to detect an adversary who delivers fake sensor measurements to a system operator in order to conceal their effect on the plant. Physical watermarks, or noisy additive Gaussian inputs, have been previously used to detect several classes of integrity attacks in control systems. In this paper, we consider the analysis and design of Gaussian physical watermarks in the presence of packet drops at the control input. On one hand, this enables analysis in a more general network setting. On the othermore » hand, we observe that in certain cases, Bernoulli packet drops can improve detection performance relative to a purely Gaussian watermark. This motivates the joint design of a Bernoulli-Gaussian watermark which incorporates both an additive Gaussian input and a Bernoulli drop process. We characterize the effect of such a watermark on system performance as well as attack detectability in two separate design scenarios. Here, we consider a correlation detector for attack recognition. We then propose efficiently solvable optimization problems to intelligently select parameters of the Gaussian input and the Bernoulli drop process while addressing security and performance trade-offs. Finally, we provide numerical results which illustrate that a watermark with packet drops can indeed outperform a Gaussian watermark.« less

SCDC Spanish Curricula Units. Spanish SL, Unit 5, Grade 2, Supplement & Ditto Packet.

ERIC Educational Resources Information Center

Spanish Curricula Development Center, Miami Beach, FL.

The supplement and ditto packet to the Spanish SL strand of unit five for second graders provides visual materials for kits 17-20. Linguistic content of the unit was determined by its relation to the basic theme of the school as a community. Each kit treats a spiraling question. Illustrations are designed to implement oral language and conceptual…

Viva Nuestra Amistad IV: Spanish Activity Packet (Long Live our Friendship).

ERIC Educational Resources Information Center

Cobb, Hubert

This Spanish activity packet was designed to be used with the map study portion of each of twelve units in a second year course in Spanish. Each unit deals with a different Spanish-speaking country or place, such as Puerto Rico, Colombia, Venezuela, or Peru. Included here are worksheets, games, map outlines, crossword puzzles, skits, and cultural…

The Identification of Major Factors in the Deployment of a Science DMZ at Small Institutions

ERIC Educational Resources Information Center

Valcourt, Scott A.

2017-01-01

The Science DMZ is a network research tool offering superior large science data transmission between two locations. Through a network design that places the Science DMZ at the edge of the campus network, the Science DMZ defines a network path that avoids packet inspecting devices (firewalls, packet shapers) and produces near line-rate transmission…

SCDC Spanish Curricula Units. Science/Math Strand, Unit 6, Grade 2, Supplement & Ditto Packet.

ERIC Educational Resources Information Center

Spanish Curricula Development Center, Miami Beach, FL.

The supplement and ditto packet to the science-math strand of unit six for second graders features visual materials to help the teacher carry out the instructional and assessment activities for the unit's four kits. Illustrations are provided to help stimulate oral language and conceptual development. Some are designed to be cut out for…

Negotiating an Oil and Gas Lease. Teachers Instructional Packet, TIP No. 6, Spring 1985.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the more common provisions and the legal significance of an oil and gas lease, as well as some provisions landowners may wish to insert for personal benefit and protection. Following an evaluation…

Characteristics of the High Performance Real Estate Salesperson. Teachers Instructional Packet, TIP No. 12, Spring 1987.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Texas Real Estate Research Center.

Part of a series of classroom aids designed for real estate instructors, this instructional packet was developed to help real estate students understand the characteristics of Texas real estate salespersons based on a 1983 state survey. First, questions for class discussion are presented, followed by a summary presentation on the survey findings,…

Thinking about Our Future: War, Society, and the Environment. A Series of Lesson Plans.

ERIC Educational Resources Information Center

Harik, Ramsay M.

This packet of 11 lesson plans is designed to help high school social studies classes examine socio-political issues facing the post-Cold War world. Though its multi-disciplinary approach touches upon a number of current topics, the packet's particular focus is on the wide-ranging impact of war and militarism on the planet's growing ecological…

Discover New Windsor Cantonment, The Last Encampment of Washington's Army. An Activities Learning Packet.

ERIC Educational Resources Information Center

New Windsor Cantonment State Historic Site, Vails Gate, NY.

The activities in this learning packet are designed to provide background information on the significance of New Windsor Cantonment to local, state, and U.S. history. The New Windsor Cantonment was the final winter encampment of the Continental Army during the Revolutionary War and the site where the cessation of hostilities was announced in April…

Intermediate SCDC Spanish Curricula Units. Science/Health, Unit 1, Kits 1-4, Supplement & Ditto Packet.

ERIC Educational Resources Information Center

Spanish Curricula Development Center, Miami Beach, FL.

Visual aids and ditto masters for the first unit of a science/health curriculum for the intermediate level are included in this supplement and ditto packet. The visual aids are designed to help stimulate oral language and conceptual development through group activities and individual seatwork. Intended to help the teacher successfully carry out…

SCDC Spanish Curricula Units. Science/Math Strand, Unit 4, Grade 2, Supplements & Ditto Packet.

ERIC Educational Resources Information Center

Spanish Curricula Development Center, Miami Beach, FL.

Designed for use with unit four of the science/math strand for second graders, the supplement and ditto packet contain visuals, worksheets, and instructional aids referred to in the teacher's guide corresponding to this unit. The brief introductions to kits 13-16 are written in both English and Spanish; all classroom materials for students are in…

An Underlay Communication Channel for 5G Cognitive Mesh Networks: Packet Design, Implementation, Analysis, and Experimental Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tarek Haddadin; Stephen Andrew Laraway; Arslan Majid

This paper proposes and presents the design and implementation of an underlay communication channel (UCC) for 5G cognitive mesh networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MCSS) signaling. The use of this novel spread spectrum signaling allows the device-to-device (D2D) user equipments (UEs) to communicate at a level well below noise temperature and hence, minimize taxation on macro-cell/small-cell base stations and their UEs in 5G wireless systems. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by macro-cell and small-cell users. Hence, both D2D-to-cellularmore » and cellular-to-D2D interference will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present the detail of an implementation of the proposed transceiver on a software radio platform and compare our experimental results with those from a theoretical analysis of our packet detection algorithm.« less

Ethernet-Enabled Power and Communication Module for Embedded Processors

NASA Technical Reports Server (NTRS)

Perotti, Jose; Oostdyk, Rebecca

2010-01-01

The power and communications module is a printed circuit board (PCB) that has the capability of providing power to an embedded processor and converting Ethernet packets into serial data to transfer to the processor. The purpose of the new design is to address the shortcomings of previous designs, including limited bandwidth and program memory, lack of control over packet processing, and lack of support for timing synchronization. The new design of the module creates a robust serial-to-Ethernet conversion that is powered using the existing Ethernet cable. This innovation has a small form factor that allows it to power processors and transducers with minimal space requirements.

A decision support system for telemedicine through the mobile telecommunications platform.

PubMed

Eren, Ali; Subasi, Abdulhamit; Coskun, Osman

2008-02-01

In this paper we have discussed the application of artificial intelligence in telemedicine using mobile device. The main goal of our research is to develop methods and systems to collect, analyze, distribute and use medical diagnostics information from multiple knowledge sources and areas of expertise. Physicians may collect and analyze information obtained from experts worldwide with the help of a medical decision support system. In this information retrieval system, modern communication tools such as computers and mobile phones can be used efficiently. In this work we propose a medical decision support system using the general packet radio service (GPRS). GPRS, a data extension of the mobile telephony standard Global system for mobile communications (GSM) is emerging as the first true packet-switched architecture to allow mobile subscribers to benefit from high-speed transmission rates and run JAVA based applications from their mobile terminals. An academic prototype of a medical decision support system using mobile device was implemented. The results reveal that the system could find acceptance from the medical community and it could be an effective means of providing quality health care in developing countries.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishihara, T

Currently, the problem at hand is in distributing identical copies of OEP and filter software to a large number of farm nodes. One of the common methods used to transfer these softwares is through unicast. Unicast protocol faces the problem of repetitiously sending the same data over the network. Since the sending rate is limited, this process poses to be a bottleneck. Therefore, one possible solution to this problem lies in creating a reliable multicast protocol. A specific type of multicast protocol is the Bulk Multicast Protocol [4]. This system consists of one sender distributing data to many receivers. Themore » sender delivers data at a given rate of data packets. In response to that, the receiver replies to the sender with a status packet which contains information about the packet loss in terms of Negative Acknowledgment. The probability of the status packet sent back to the sender is+, where N is the number of receivers. The protocol is designed to have approximately 1 status packet for each data packet sent. In this project, we were able to show that the time taken for the complete transfer of a file to multiple receivers was about 12 times faster with multicast than by the use of unicast. The implementation of this experimental protocol shows remarkable improvement in mass data transfer to a large number of farm machines.« less

Digital transceiver implementation for wavelet packet modulation

NASA Astrophysics Data System (ADS)

Lindsey, Alan R.; Dill, Jeffrey C.

1998-03-01

Current transceiver designs for wavelet-based communication systems are typically reliant on analog waveform synthesis, however, digital processing is an important part of the eventual success of these techniques. In this paper, a transceiver implementation is introduced for the recently introduced wavelet packet modulation scheme which moves the analog processing as far as possible toward the antenna. The transceiver is based on the discrete wavelet packet transform which incorporates level and node parameters for generalized computation of wavelet packets. In this transform no particular structure is imposed on the filter bank save dyadic branching, and a maximum level which is specified a priori and dependent mainly on speed and/or cost considerations. The transmitter/receiver structure takes a binary sequence as input and, based on the desired time- frequency partitioning, processes the signal through demultiplexing, synthesis, analysis, multiplexing and data determination completely in the digital domain - with exception of conversion in and out of the analog domain for transmission.

Performance evaluation of NASA/KSC CAD/CAE graphics local area network

NASA Technical Reports Server (NTRS)

Zobrist, George

1988-01-01

This study had as an objective the performance evaluation of the existing CAD/CAE graphics network at NASA/KSC. This evaluation will also aid in projecting planned expansions, such as the Space Station project on the existing CAD/CAE network. The objectives were achieved by collecting packet traffic on the various integrated sub-networks. This included items, such as total number of packets on the various subnetworks, source/destination of packets, percent utilization of network capacity, peak traffic rates, and packet size distribution. The NASA/KSC LAN was stressed to determine the useable bandwidth of the Ethernet network and an average design station workload was used to project the increased traffic on the existing network and the planned T1 link. This performance evaluation of the network will aid the NASA/KSC network managers in planning for the integration of future workload requirements into the existing network.

All optical logic for optical pattern recognition and networking applications

NASA Astrophysics Data System (ADS)

Khoury, Jed

2017-05-01

In this paper, we propose architectures for the implementation 16 Boolean optical gates from two inputs using externally pumped phase- conjugate Michelson interferometer. Depending on the gate to be implemented, some require single stage interferometer and others require two stages interferometer. The proposed optical gates can be used in several applications in optical networks including, but not limited to, all-optical packet routers switching, and all-optical error detection. The optical logic gates can also be used in recognition of noiseless rotation and scale invariant objects such as finger prints for home land security applications.

Linking: Today's Libraries, Tomorrow's Technologies. Report of the Bibliographic and Communications Network Pilot Project. Canadian Network Papers Number 7 = Le Lien entre les Bibliotheques d'Aujourd'hui et les Technologies de Demain. Rapport du Projet Pilote du Reseau de Services Bibliographiques et de Communications. Documents sur les Reseaux Canadiens Numero 7.

ERIC Educational Resources Information Center

National Library of Canada, Ottawa (Ontario).

A pilot project was conducted from May 1980 to November 1983 to test the application of iNet--a decentralized, packet-switched telecommunications network--to bibliographic data interchange in Canada. The principal components of the project were participation of the Bibliographic Common Interest Group (BCIP), a group of libraries with stand-alone,…

Priority-based methods for reducing the impact of packet loss on HEVC encoded video streams

NASA Astrophysics Data System (ADS)

Nightingale, James; Wang, Qi; Grecos, Christos

2013-02-01

The rapid growth in the use of video streaming over IP networks has outstripped the rate at which new network infrastructure has been deployed. These bandwidth-hungry applications now comprise a significant part of all Internet traffic and present major challenges for network service providers. The situation is more acute in mobile networks where the available bandwidth is often limited. Work towards the standardisation of High Efficiency Video Coding (HEVC), the next generation video coding scheme, is currently on track for completion in 2013. HEVC offers the prospect of a 50% improvement in compression over the current H.264 Advanced Video Coding standard (H.264/AVC) for the same quality. However, there has been very little published research on HEVC streaming or the challenges of delivering HEVC streams in resource-constrained network environments. In this paper we consider the problem of adapting an HEVC encoded video stream to meet the bandwidth limitation in a mobile networks environment. Video sequences were encoded using the Test Model under Consideration (TMuC HM6) for HEVC. Network abstraction layers (NAL) units were packetized, on a one NAL unit per RTP packet basis, and transmitted over a realistic hybrid wired/wireless testbed configured with dynamically changing network path conditions and multiple independent network paths from the streamer to the client. Two different schemes for the prioritisation of RTP packets, based on the NAL units they contain, have been implemented and empirically compared using a range of video sequences, encoder configurations, bandwidths and network topologies. In the first prioritisation method the importance of an RTP packet was determined by the type of picture and the temporal switching point information carried in the NAL unit header. Packets containing parameter set NAL units and video coding layer (VCL) NAL units of the instantaneous decoder refresh (IDR) and the clean random access (CRA) pictures were given the highest priority followed by NAL units containing pictures used as reference pictures from which others can be predicted. The second method assigned a priority to each NAL unit based on the rate-distortion cost of the VCL coding units contained in the NAL unit. The sum of the rate-distortion costs of each coding unit contained in a NAL unit was used as the priority weighting. The preliminary results of extensive experiments have shown that all three schemes offered an improvement in PSNR, when comparing original and decoded received streams, over uncontrolled packet loss. Using the first method consistently delivered a significant average improvement of 0.97dB over the uncontrolled scenario while the second method provided a measurable, but less consistent, improvement across the range of testing conditions and encoder configurations.

Back Pack: Parent and Child Kits. Actividades para la Familia: Octubre. The Best of BES--Basic Educational Skills Materials.

ERIC Educational Resources Information Center

Southwest Educational Development Lab., Austin, TX.

One of a series of documents produced by a nationwide network of early childhood education specialists, teachers, parents, and Head Start staff, the document presents a packet of over 52 home activities in both Spanish and English. Designed for teachers and parents of kindergarteners, the packet was intended to help teachers facilitate the…

Hokule'a: A Field Trip. A Guide for Upper-Elementary Teachers.

ERIC Educational Resources Information Center

Larson, R. Bruce

This document is a packet designed to be used in conjunction with a visit to the Hokule'a, a famous voyaging canoe that is usually docked at the Hawaii Maritime Center in Honolulu Harbor. The material focuses on the canoe itself and on the skills needed to sail it. The packet includes background information on the Hokule'a, basic terms,…

Contemporary World Classics in Literature and Film. Fall, 1998. Fulbright-Hays Summer Seminars Abroad 1998 (India).

ERIC Educational Resources Information Center

Altman, Leslie J.

This packet includes the syllabus of a trimester-long senior elective course on India, designed to begin with two writers of Indian descent, Salman Rushdie and Bharati Mukherjee. The packet contains the daily assignments for the first half of the trimester, which include all of the reading assignments from Rushdie and Mukherjee, as well as the…

Rock around the Clock: Hanging Rock State Park. An Environmental Education Learning Experience. Designed for Grade 5.

ERIC Educational Resources Information Center

Dow, Jaye

This learning packet was developed for grade 5 to teach about the geology of a park. Sections include: (1) Introduction, which introduces the North Carolina State Park System, Hanging Rock State Park, the park's activity packet, and the geology of the park; (2) Summary, a brief summary of the activity outlines including major concepts and…

Architectures and Design for Next-Generation Hybrid Circuit/Packet Networks

NASA Astrophysics Data System (ADS)

Vadrevu, Sree Krishna Chaitanya

Internet traffic is increasing rapidly at an annual growth rate of 35% with aggregate traffic exceeding several Exabyte's per month. The traffic is also becoming heterogeneous in bandwidth and quality-of-service (QoS) requirements with growing popularity of cloud computing, video-on-demand (VoD), e-science, etc. Hybrid circuit/packet networks which can jointly support circuit and packet services along with the adoption of high-bit-rate transmission systems form an attractive solution to address the traffic growth. 10 Gbps and 40 Gbps transmission systems are widely deployed in telecom backbone networks such as Comcast, AT&T, etc., and network operators are considering migration to 100 Gbps and beyond. This dissertation proposes robust architectures, capacity migration strategies, and novel service frameworks for next-generation hybrid circuit/packet architectures. In this dissertation, we study two types of hybrid circuit/packet networks: a) IP-over-WDM networks, in which the packet (IP) network is overlaid on top of the circuit (optical WDM) network and b) Hybrid networks in which the circuit and packet networks are deployed side by side such as US DoE's ESnet. We investigate techniques to dynamically migrate capacity between the circuit and packet sections by exploiting traffic variations over a day, and our methods show that significant bandwidth savings can be obtained with improved reliability of services. Specifically, we investigate how idle backup circuit capacity can be used to support packet services in IP-over-WDM networks, and similarly, excess capacity in packet network to support circuit services in ESnet. Control schemes that enable our mechanisms are also discussed. In IP-over-WDM networks, with upcoming 100 Gbps and beyond, dedicated protection will induce significant under-utilization of backup resources. We investigate design strategies to loan idle circuit backup capacity to support IP/packet services. However, failure of backup circuits will preempt IP services routed over them, and thus it is important to ensure IP topology survivability to successfully re-route preempted IP services. Integer-linear-program (ILP) and heuristic solutions have been developed and network cost reduction up to 60% has been observed. In ESnet, we study loaning packet links to support circuit services. Mixed-line-rate (MLR) networks supporting 10/40/100 Gbps on the same fiber are becoming increasingly popular. Services that accept degradation in bandwidth, latency, jitter, etc. under failure scenarios for lower cost are known as degraded services. We study degradation in bandwidth for lower cost under failure scenarios, a concept called partial protection, in the context of MLR networks. We notice partial protection enables significant cost savings compared to full protection. To cope with traffic growth, network operators need to deploy equipment at periodic time intervals, and this is known as the multi-period planning and upgrade problem. We study three important multi-period planning approaches, namely incremental planning, all-period planning, and two-period planning with mixed line rates. Our approaches predict the network equipment that needs to be deployed optimally at which nodes and at which time periods in the network to meet QoS requirements.

MPEG-compliant joint source/channel coding using discrete cosine transform and substream scheduling for visual communication over packet networks

NASA Astrophysics Data System (ADS)

Kim, Seong-Whan; Suthaharan, Shan; Lee, Heung-Kyu; Rao, K. R.

2001-01-01

Quality of Service (QoS)-guarantee in real-time communication for multimedia applications is significantly important. An architectural framework for multimedia networks based on substreams or flows is effectively exploited for combining source and channel coding for multimedia data. But the existing frame by frame approach which includes Moving Pictures Expert Group (MPEG) cannot be neglected because it is a standard. In this paper, first, we designed an MPEG transcoder which converts an MPEG coded stream into variable rate packet sequences to be used for our joint source/channel coding (JSCC) scheme. Second, we designed a classification scheme to partition the packet stream into multiple substreams which have their own QoS requirements. Finally, we designed a management (reservation and scheduling) scheme for substreams to support better perceptual video quality such as the bound of end-to-end jitter. We have shown that our JSCC scheme is better than two other two popular techniques by simulation and real video experiments on the TCP/IP environment.

A novel 6-DOF parallel robot and its pose errors compensation

NASA Astrophysics Data System (ADS)

Shi, Zhixin; Ye, Meiyan; Luo, Yufeng

2011-10-01

In the traditional security solution conditions, software firewall cannot intercept and respond the invasion before being attacked. And because of the high cost, the hardware firewall does not apply to the security strategy of the end nodes, so we have designed a kind of solution of embedded firewall with hardware and software. With ARM embedding Linux operating system, we have designed packet filter module and intrusion detection module to implement the basic function of firewall. Experiments and results show that that firewall has the advantages of low cost, high processing speed, high safety and the application of the computer terminals. This paper focuses on packet filtering module design and implementation.

Rock Around the Clock. Hanging Rock State Park: An Environmental Education Learning Experience Designed for Grade 5.

ERIC Educational Resources Information Center

Dow, Jaye

This learning packet, one in a series of eight, was developed by the Hanging Roek State Park in North Carolina for grade 5 to teach about the geology of the park. Loose-leaf pages are presented in nine sections that contain: (1) introductions to the North Carolina State Park System, the Hanging Rock State Park, the park's activity packet, and to…

Monitor Network Traffic with Packet Capture (pcap) on an Android Device

DTIC Science & Technology

2015-09-01

administrative privileges . Under the current design Android development requirement, an Android Graphical User Interface (GUI) application cannot directly...build an Android application to monitor network traffic using open source packet capture (pcap) libraries. 15. SUBJECT TERMS ELIDe, Android , pcap 16...Building Application with Native Codes 5 8.1 Calling Native Codes Using JNI 5 8.2 Calling Native Codes from an Android Application 8 9. Retrieve Live

Plants that Bite Back. Carolina Beach State Park: An Environmental Education Learning Experience Designed for the Middle Grades.

ERIC Educational Resources Information Center

Wahab, Phoebe

This learning packet, one in a series of eight, was developed by the Carolina Beach State Park in North Carolina for the middle grades to teach about carnivorous plants. Loose-leaf pages are presented in 10 sections that contain: (1) introductions to the North Carolina State Park System, the Carolina Beach State Park, the park's activity packet,…

Distributed fault detection over sensor networks with Markovian switching topologies

NASA Astrophysics Data System (ADS)

Ge, Xiaohua; Han, Qing-Long

2014-05-01

This paper deals with the distributed fault detection for discrete-time Markov jump linear systems over sensor networks with Markovian switching topologies. The sensors are scatteredly deployed in the sensor field and the fault detectors are physically distributed via a communication network. The system dynamics changes and sensing topology variations are modeled by a discrete-time Markov chain with incomplete mode transition probabilities. Each of these sensor nodes firstly collects measurement outputs from its all underlying neighboring nodes, processes these data in accordance with the Markovian switching topologies, and then transmits the processed data to the remote fault detector node. Network-induced delays and accumulated data packet dropouts are incorporated in the data transmission between the sensor nodes and the distributed fault detector nodes through the communication network. To generate localized residual signals, mode-independent distributed fault detection filters are proposed. By means of the stochastic Lyapunov functional approach, the residual system performance analysis is carried out such that the overall residual system is stochastically stable and the error between each residual signal and the fault signal is made as small as possible. Furthermore, a sufficient condition on the existence of the mode-independent distributed fault detection filters is derived in the simultaneous presence of incomplete mode transition probabilities, Markovian switching topologies, network-induced delays, and accumulated data packed dropouts. Finally, a stirred-tank reactor system is given to show the effectiveness of the developed theoretical results.

Energy and Information Transfer Via Coherent Exciton Wave Packets

NASA Astrophysics Data System (ADS)

Zang, Xiaoning

Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The associated excitations were dubbed twisted excitons. Twisted exciton packets can be manipulated as they travel down molecular chains, and this has applications in quantum information science as well. In each setting considered, exciton dynamics were initially studied using a simple tight-binding formalism. This misses the actual many-body interactions and multiple energy levels associated real systems. To remedy this, I adapted an existing time-domain Density Functional Theory code and applied it to study the dynamics of exciton wave packets on quasi-one-dimensional systems. This required the use of high-performance computing and the construction of a number of key auxiliary codes. Establishing the requisite methodology constituted a substantial part of the entire thesis. Surprisingly, this effort uncovered a computational issue associated with Rabi oscillations that had been incorrectly characterized in the literature. My research elucidated the actual problem and a solution was found. This new methodology was an integral part of the overall computational analysis. The thesis then takes up the a detailed consideration of the prospect for creating systems that support a strong measure of transport coherence. While physical implementations include molecular assemblies, solid-state superlattices, and even optical lattices, I decided to focus on assemblies of nanometer-sized silicon quantum dots. First principles computational analysis was used to quantify reorganization within individual dots and excitonic coupling between dots. Quantum dot functionalizations were identified that make it plausible to maintain a measure of excitonic coherence even at room temperatures. Attention was then turned to the use of covalently bonded bridge material to join quantum dots in a way that facilitates efficient exciton transfer. Both carbon and silicon structures were considered by considering the way in which subunits might be best brought together. This resulted in a set of design criteria which were then evaluated using first-principles, excited state analyses. It was found that efficient exciton transfer is indeed possible. When coupled to the previous quantum dot functionalizations, the notion that quantum dot materials could support partially coherent exciton wave packets was determined to be quite reasonable.

GLOBECOM '87 - Global Telecommunications Conference, Tokyo, Japan, Nov. 15-18, 1987, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

The present conference on global telecommunications discusses topics in the fields of Integrated Services Digital Network (ISDN) technology field trial planning and results to date, motion video coding, ISDN networking, future network communications security, flexible and intelligent voice/data networks, Asian and Pacific lightwave and radio systems, subscriber radio systems, the performance of distributed systems, signal processing theory, satellite communications modulation and coding, and terminals for the handicapped. Also discussed are knowledge-based technologies for communications systems, future satellite transmissions, high quality image services, novel digital signal processors, broadband network access interface, traffic engineering for ISDN design and planning, telecommunications software, coherent optical communications, multimedia terminal systems, advanced speed coding, portable and mobile radio communications, multi-Gbit/second lightwave transmission systems, enhanced capability digital terminals, communications network reliability, advanced antimultipath fading techniques, undersea lightwave transmission, image coding, modulation and synchronization, adaptive signal processing, integrated optical devices, VLSI technologies for ISDN, field performance of packet switching, CSMA protocols, optical transport system architectures for broadband ISDN, mobile satellite communications, indoor wireless communication, echo cancellation in communications, and distributed network algorithms.

Concurrent communication among multi-transceiver stations over shared media. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Birk, Yitzhak

1987-01-01

In order to increase a local-area network's throughput beyond a single bus data rate without using dedicated switching nodes, multiple buses and multitransceiver stations are required. The design space of single-hop interconnections is explored among such stations. Interconnections are presented whose throughput can grow quadratically with the number of transmitters and receivers per station. These are referred to as selective broadcast interconnections (SBIs). The performance of various SBIs are studied. A spread-spectrum channel can accommodate several current successful transmission, and a single-transceiver node can thus utilize only a small fraction of the channel capacity. In order to allocate the appropriate fraction of capacity to a busy node, it is proposed to equip it with several transmitters and receivers, thereby turning it into a supernode. Several architectures and operation policies for supernodes are suggested and compared. It is shown that a supernode can significantly outperform a collection of independent conventional nodes with the same total numbers of transmitters and receivers. Packet-radio networks with half-duplex nodes, as well as networks with full-duplex nodes, are considered.

CATO: a CAD tool for intelligent design of optical networks and interconnects

NASA Astrophysics Data System (ADS)

Chlamtac, Imrich; Ciesielski, Maciej; Fumagalli, Andrea F.; Ruszczyk, Chester; Wedzinga, Gosse

1997-10-01

Increasing communication speed requirements have created a great interest in very high speed optical and all-optical networks and interconnects. The design of these optical systems is a highly complex task, requiring the simultaneous optimization of various parts of the system, ranging from optical components' characteristics to access protocol techniques. Currently there are no computer aided design (CAD) tools on the market to support the interrelated design of all parts of optical communication systems, thus the designer has to rely on costly and time consuming testbed evaluations. The objective of the CATO (CAD tool for optical networks and interconnects) project is to develop a prototype of an intelligent CAD tool for the specification, design, simulation and optimization of optical communication networks. CATO allows the user to build an abstract, possible incomplete, model of the system, and determine its expected performance. Based on design constraints provided by the user, CATO will automatically complete an optimum design, using mathematical programming techniques, intelligent search methods and artificial intelligence (AI). Initial design and testing of a CATO prototype (CATO-1) has been completed recently. The objective was to prove the feasibility of combining AI techniques, simulation techniques, an optical device library and a graphical user interface into a flexible CAD tool for obtaining optimal communication network designs in terms of system cost and performance. CATO-1 is an experimental tool for designing packet-switching wavelength division multiplexing all-optical communication systems using a LAN/MAN ring topology as the underlying network. The two specific AI algorithms incorporated are simulated annealing and a genetic algorithm. CATO-1 finds the optimal number of transceivers for each network node, using an objective function that includes the cost of the devices and the overall system performance.

Simultaneous spectrophotometric determination of four metals by two kinds of partial least squares methods

NASA Astrophysics Data System (ADS)

Gao, Ling; Ren, Shouxin

2005-10-01

Simultaneous determination of Ni(II), Cd(II), Cu(II) and Zn(II) was studied by two methods, kernel partial least squares (KPLS) and wavelet packet transform partial least squares (WPTPLS), with xylenol orange and cetyltrimethyl ammonium bromide as reagents in the medium pH = 9.22 borax-hydrochloric acid buffer solution. Two programs, PKPLS and PWPTPLS, were designed to perform the calculations. Data reduction was performed using kernel matrices and wavelet packet transform, respectively. In the KPLS method, the size of the kernel matrix is only dependent on the number of samples, thus the method was suitable for the data matrix with many wavelengths and fewer samples. Wavelet packet representations of signals provide a local time-frequency description, thus in the wavelet packet domain, the quality of the noise removal can be improved. In the WPTPLS by optimization, wavelet function and decomposition level were selected as Daubeches 12 and 5, respectively. Experimental results showed both methods to be successful even where there was severe overlap of spectra.

Design and application of discrete wavelet packet transform based multiresolution controller for liquid level system.

PubMed

Paul, Rimi; Sengupta, Anindita

2017-11-01

A new controller based on discrete wavelet packet transform (DWPT) for liquid level system (LLS) has been presented here. This controller generates control signal using node coefficients of the error signal which interprets many implicit phenomena such as process dynamics, measurement noise and effect of external disturbances. Through simulation results on LLS problem, this controller is shown to perform faster than both the discrete wavelet transform based controller and conventional proportional integral controller. Also, it is more efficient in terms of its ability to provide better noise rejection. To overcome the wind up phenomenon by considering the saturation due to presence of actuator, anti-wind up technique is applied to the conventional PI controller and compared to the wavelet packet transform based controller. In this case also, packet controller is found better than the other ones. This similar work has been extended for analogous first order RC plant as well as second order plant also. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

System services and architecture of the TMI satellite mobile data system

NASA Technical Reports Server (NTRS)

Gokhale, D.; Agarwal, A.; Guibord, A.

1993-01-01

The North American Mobile Satellite Service (MSS) system being developed by AMSC/TMI and scheduled to go into service in early 1995 will include the provision for real time packet switched services (mobile data service - MDS) and circuit switched services (mobile telephony service - MTS). These services will utilize geostationary satellites which provide access to mobile terminals (MT's) through L-band beams. The MDS system utilizes a star topology with a centralized data hub (DH) and will support a large number of mobile terminals. The DH, which accesses the satellite via a single Ku band beam, is responsible for satellite resource management, for providing mobile users with access to public and private data networks, and for comprehensive network management of the system. This paper describes the various MDS services available for the users, the ground segment elements involved in the provisioning of these services, and a summary description of the channel types, protocol architecture, and network management capabilities provided within the system.

Studies in integrated line-and packet-switched computer communication systems

NASA Astrophysics Data System (ADS)

Maglaris, B. S.

1980-06-01

The problem of efficiently allocating the bandwidth of a trunk to both types of traffic is handled for various system and traffic models. A performance analysis is carried out both for variable and fixed frame schemes. It is shown that variable frame schemes, adjusting the frame length according to the traffic variations, offer better trunk utilization at the cost of the additional hardware and software complexity needed because of the lack of synchronization. An optimization study on the fixed frame schemes follows. The problem of dynamically allocating the fixed frame to both types of traffic is formulated as a Markovian Decision process. It is shown that the movable boundary scheme, suggested for commercial implementations of integrated multiplexors, offers optimal or near optimal performance and simplicity of implementation. Finally, the behavior of the movable boundary integrated scheme is studied for tandem link connections. Under the assumptions made for the line-switched traffic, the forward allocation technique is found to offer the best alternative among different path set-up strategies.

Adjustable Trajectory Design Based on Node Density for Mobile Sink in WSNs

PubMed Central

Yang, Guisong; Liu, Shuai; He, Xingyu; Xiong, Naixue; Wu, Chunxue

2016-01-01

The design of movement trajectories for mobile sink plays an important role in data gathering for Wireless Sensor Networks (WSNs), as it affects the network coverage, and packet delivery ratio, as well as the network lifetime. In some scenarios, the whole network can be divided into subareas where the nodes are randomly deployed. The node densities of these subareas are quite different, which may result in a decreased packet delivery ratio and network lifetime if the movement trajectory of the mobile sink cannot adapt to these differences. To address these problems, we propose an adjustable trajectory design method based on node density for mobile sink in WSNs. The movement trajectory of the mobile sink in each subarea follows the Hilbert space-filling curve. Firstly, the trajectory is constructed based on network size. Secondly, the adjustable trajectory is established based on node density in specific subareas. Finally, the trajectories in each subarea are combined to acquire the whole network’s movement trajectory for the mobile sink. In addition, an adaptable power control scheme is designed to adjust nodes’ transmitting range dynamically according to the movement trajectory of the mobile sink in each subarea. The simulation results demonstrate that the proposed trajectories can adapt to network changes flexibly, thus outperform both in packet delivery ratio and in energy consumption the trajectories designed only based on the network size and the whole network node density. PMID:27941662

Reconfigurable signal processor designs for advanced digital array radar systems

NASA Astrophysics Data System (ADS)

Suarez, Hernan; Zhang, Yan (Rockee); Yu, Xining

2017-05-01

The new challenges originated from Digital Array Radar (DAR) demands a new generation of reconfigurable backend processor in the system. The new FPGA devices can support much higher speed, more bandwidth and processing capabilities for the need of digital Line Replaceable Unit (LRU). This study focuses on using the latest Altera and Xilinx devices in an adaptive beamforming processor. The field reprogrammable RF devices from Analog Devices are used as analog front end transceivers. Different from other existing Software-Defined Radio transceivers on the market, this processor is designed for distributed adaptive beamforming in a networked environment. The following aspects of the novel radar processor will be presented: (1) A new system-on-chip architecture based on Altera's devices and adaptive processing module, especially for the adaptive beamforming and pulse compression, will be introduced, (2) Successful implementation of generation 2 serial RapidIO data links on FPGA, which supports VITA-49 radio packet format for large distributed DAR processing. (3) Demonstration of the feasibility and capabilities of the processor in a Micro-TCA based, SRIO switching backplane to support multichannel beamforming in real-time. (4) Application of this processor in ongoing radar system development projects, including OU's dual-polarized digital array radar, the planned new cylindrical array radars, and future airborne radars.

HNET - A National Computerized Health Network

PubMed Central

Casey, Mark; Hamilton, Richard

1988-01-01

The HNET system demonstrated conceptually and technically a national text (and limited bit mapped graphics) computer network for use between innovative members of the health care industry. The HNET configuration of a leased high speed national packet switching network connecting any number of mainframe, mini, and micro computers was unique in it's relatively low capital costs and freedom from obsolescence. With multiple simultaneous conferences, databases, bulletin boards, calendars, and advanced electronic mail and surveys, it is marketable to innovative hospitals, clinics, physicians, health care associations and societies, nurses, multisite research projects libraries, etc.. Electronic publishing and education capabilities along with integrated voice and video transmission are identified as future enhancements.

A communications model for an ISAS to NASA span link

NASA Technical Reports Server (NTRS)

Green, James L.; Mcguire, Robert E.; Lopez-Swafford, Brian

1987-01-01

The authors propose that an initial computer-to-computer communication link use the public packet switched networks (PPSN) Venus-P in Japan and TELENET in the U.S. When the traffic warrants it, this link would then be upgraded to a dedicated leased line that directly connects into the Space Physics Analysis Network (SPAN). The proposed system of hardware and software will easily support migration to such a dedicated link. It therefore provides a cost effective approach to the network problem. Once a dedicated line becomes operation it is suggested that the public networks link and continue to coexist, providing a backup capability.

Regional-specific Stochastic Simulation of Spatially-distributed Ground-motion Time Histories using Wavelet Packet Analysis

NASA Astrophysics Data System (ADS)

Huang, D.; Wang, G.

2014-12-01

Stochastic simulation of spatially distributed ground-motion time histories is important for performance-based earthquake design of geographically distributed systems. In this study, we develop a novel technique to stochastically simulate regionalized ground-motion time histories using wavelet packet analysis. First, a transient acceleration time history is characterized by wavelet-packet parameters proposed by Yamamoto and Baker (2013). The wavelet-packet parameters fully characterize ground-motion time histories in terms of energy content, time- frequency-domain characteristics and time-frequency nonstationarity. This study further investigates the spatial cross-correlations of wavelet-packet parameters based on geostatistical analysis of 1500 regionalized ground motion data from eight well-recorded earthquakes in California, Mexico, Japan and Taiwan. The linear model of coregionalization (LMC) is used to develop a permissible spatial cross-correlation model for each parameter group. The geostatistical analysis of ground-motion data from different regions reveals significant dependence of the LMC structure on regional site conditions, which can be characterized by the correlation range of Vs30 in each region. In general, the spatial correlation and cross-correlation of wavelet-packet parameters are stronger if the site condition is more homogeneous. Using the regional-specific spatial cross-correlation model and cokriging technique, wavelet packet parameters at unmeasured locations can be best estimated, and regionalized ground-motion time histories can be synthesized. Case studies and blind tests demonstrated that the simulated ground motions generally agree well with the actual recorded data, if the influence of regional-site conditions is considered. The developed method has great potential to be used in computational-based seismic analysis and loss estimation in a regional scale.

Validation of a real-time wireless telemedicine system, using bluetooth protocol and a mobile phone, for remote monitoring patient in medical practice.

PubMed

Yousef, Jasemian; Lars, A N

2005-06-22

This paper validates the integration of a generic real-time wireless telemedicine system utilising Global System for Mobile Communications (GSM), BLUETOOTH protocol and General Packet Radio Service (GPRS) for cellular network in clinical practice. In the first experiment, the system was tested on 24 pacemaker patients at Aalborg Hospital (Denmark), in order to see if the pacemaker implant would be affected by the system. I the second experiment, the system was tested on 15 non risky arrhythmia heart patients, in order to evaluate and validate the system application in clinical practice, for patient monitoring. Electrocardiograms were selected as the continuously monitored parameter in the present study. The results showed that the system had no negative effects on the pacemaker implants. The experiment results showed, that in a realistic environment for the patients, the system had 96.1 % up-time, 3.2 (kbps) throughput, 10(-3) (packet/s) Packet Error Rate and 10(-3) (packet/s) Packet Lost Rate. During 24 hours test the network did not respond for 57 minutes, from which 83.1 % was in the range of 0-3 minutes, 15.4 % was in the range of 3-5 minutes, and only 0.7 % of the down-time was > or = 5 and < or = 6 minutes. By a subjective evaluation, it was demonstrated that the system is applicable and the patients as well as the healthcare personals were highly confident with the system. Moreover, the patients had high degree of mobility and freedom, employing the system. In conclusion, this generic telemedicine system showed a high reliability, quality and performance, and the design can provide a basic principle for real-time wireless remote monitoring systems used in clinical practice.

A novel all-optical label processing for OPS networks based on multiple OOC sequences from multiple-groups OOC

NASA Astrophysics Data System (ADS)

Qiu, Kun; Zhang, Chongfu; Ling, Yun; Wang, Yibo

2007-11-01

This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS) for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is performed. These analysis and results show that the proposed scheme can overcome the lack of available optical orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short code length, and indicate that the MOOCS-OPS scheme is feasible.

New Scheduling Algorithms for Agile All-Photonic Networks

NASA Astrophysics Data System (ADS)

Mehri, Mohammad Saleh; Ghaffarpour Rahbar, Akbar

2017-12-01

An optical overlaid star network is a class of agile all-photonic networks that consists of one or more core node(s) at the center of the star network and a number of edge nodes around the core node. In this architecture, a core node may use a scheduling algorithm for transmission of traffic through the network. A core node is responsible for scheduling optical packets that arrive from edge nodes and switching them toward their destinations. Nowadays, most edge nodes use virtual output queue (VOQ) architecture for buffering client packets to achieve high throughput. This paper presents two efficient scheduling algorithms called discretionary iterative matching (DIM) and adaptive DIM. These schedulers find maximum matching in a small number of iterations and provide high throughput and incur low delay. The number of arbiters in these schedulers and the number of messages exchanged between inputs and outputs of a core node are reduced. We show that DIM and adaptive DIM can provide better performance in comparison with iterative round-robin matching with SLIP (iSLIP). SLIP means the act of sliding for a short distance to select one of the requested connections based on the scheduling algorithm.

Design and Implementation of the MARG Human Body Motion Tracking System

DTIC Science & Technology

2004-10-01

7803-8463-6/041$20.00 ©:!004 IEEE 625 OPTOTRAK from Northern Digital Inc. is a typical example of a marker-based system [I 0]. Another is the...technique called tunneling is :used to overcome this problem. Tunneling is a software solution that runs on the end point routers/computers and allows...multicast packets to traverse the network by putting them into unicast packets. MUTUP overcomes the tunneling problem using shared memory in the

Bandwidth and Detection of Packet Length Covert Channels

DTIC Science & Technology

2011-03-01

Shared Resource Matrix ( SRM ): Develop a matrix of all resources on one side and on the other all the processes. Then, determine which process uses which...system calls. This method is similar to that of the SRM . Covert channels have also been created by modulating packet timing, data and headers of net- work...analysis, noninterference analysis, SRM method, and the covert flow tree method [4]. These methods can be used during the design phase of a system. Less

Performance Characteristics of a Kernel-Space Packet Capture Module

DTIC Science & Technology

2010-03-01

Defense, or the United States Government . AFIT/GCO/ENG/10-03 PERFORMANCE CHARACTERISTICS OF A KERNEL-SPACE PACKET CAPTURE MODULE THESIS Presented to the...3.1.2.3 Prototype. The proof of concept for this research is the design, development, and comparative performance analysis of a kernel level N2d capture...changes to kernel code 5. Can be used for both user-space and kernel-space capture applications in order to control comparative performance analysis to

PcapDB: Search Optimized Packet Capture, Version 0.1.0.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrell, Paul; Steinfadt, Shannon

PcapDB is a packet capture system designed to optimize the captured data for fast search in the typical (network incident response) use case. The technology involved in this software has been submitted via the IDEAS system and has been filed as a provisional patent. It includes the following primary components: capture: The capture component utilizes existing capture libraries to retrieve packets from network interfaces. Once retrieved the packets are passed to additional threads for sorting into flows and indexing. The sorted flows and indexes are passed to other threads so that they can be written to disk. These components aremore » written in the C programming language. search: The search components provide a means to find relevant flows and the associated packets. A search query is parsed and represented as a search tree. Various search commands, written in C, are then used resolve this tree into a set of search results. The tree generation and search execution management components are written in python. interface: The PcapDB web interface is written in Python on the Django framework. It provides a series of pages, API's, and asynchronous tasks that allow the user to manage the capture system, perform searches, and retrieve results. Web page components are written in HTML,CSS and Javascript.« less

Apply network coding for H.264/SVC multicasting

NASA Astrophysics Data System (ADS)

Wang, Hui; Kuo, C.-C. Jay

2008-08-01

In a packet erasure network environment, video streaming benefits from error control in two ways to achieve graceful degradation. The first approach is application-level (or the link-level) forward error-correction (FEC) to provide erasure protection. The second error control approach is error concealment at the decoder end to compensate lost packets. A large amount of research work has been done in the above two areas. More recently, network coding (NC) techniques have been proposed for efficient data multicast over networks. It was shown in our previous work that multicast video streaming benefits from NC for its throughput improvement. An algebraic model is given to analyze the performance in this work. By exploiting the linear combination of video packets along nodes in a network and the SVC video format, the system achieves path diversity automatically and enables efficient video delivery to heterogeneous receivers in packet erasure channels. The application of network coding can protect video packets against the erasure network environment. However, the rank defficiency problem of random linear network coding makes the error concealment inefficiently. It is shown by computer simulation that the proposed NC video multicast scheme enables heterogenous receiving according to their capacity constraints. But it needs special designing to improve the video transmission performance when applying network coding.

CHEETAH: circuit-switched high-speed end-to-end transport architecture

NASA Astrophysics Data System (ADS)

Veeraraghavan, Malathi; Zheng, Xuan; Lee, Hyuk; Gardner, M.; Feng, Wuchun

2003-10-01

Leveraging the dominance of Ethernet in LANs and SONET/SDH in MANs and WANs, we propose a service called CHEETAH (Circuit-switched High-speed End-to-End Transport ArcHitecture). The service concept is to provide end hosts with high-speed, end-to-end circuit connectivity on a call-by-call shared basis, where a "circuit" consists of Ethernet segments at the ends that are mapped into Ethernet-over-SONET long-distance circuits. This paper focuses on the file-transfer application for such circuits. For this application, the CHEETAH service is proposed as an add-on to the primary Internet access service already in place for enterprise hosts. This allows an end host that is sending a file to first attempt setting up an end-to-end Ethernet/EoS circuit, and if rejected, fall back to the TCP/IP path. If the circuit setup is successful, the end host will enjoy a much shorter file-transfer delay than on the TCP/IP path. To determine the conditions under which an end host with access to the CHEETAH service should attempt circuit setup, we analyze mean file-transfer delays as a function of call blocking probability in the circuit-switched network, probability of packet loss in the IP network, round-trip times, link rates, and so on.

Ground equipment for the support of packet telemetry and telecommand

NASA Technical Reports Server (NTRS)

Hell, Wolfgang

1994-01-01

This paper describes ground equipment for packet telemetry and telecommand which has been recently developed by industry for the European Space Agency. The architectural concept for this type of equipment is outlined and the actual implementation is presented. Focus is put on issues related to cross support and telescience as far as they affect the design of the interfaces to the users of the services provided by the equipment and to the management entities in charge of equipment control and monitoring.

Composable Flexible Real-time Packet Scheduling for Networks on-Chip

DTIC Science & Technology

2012-05-16

unclassified b . ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Copyright © 2012...words, real-time flows need to be composable. We set this as the design goal for our packet scheduling discipline developed in this paper. B . Motivating...with closest deadline is chosen to forward to the next router. B . Traffic Model We assume a traffic model for real-time flows similar to the one used

Can We Talk? Helping Families Talk about Self-Esteem, Sex, and Peer Pressure. Training Package = Conversamos? Ayudando a Familias a Hablar sobre la Autoestima, el Sexo, y la Presion de los Amigos. Paquete de Capacitacion.

ERIC Educational Resources Information Center

Cappello, Dominic; Newberry, Jerald

This English and Spanish language multimedia packet comprises an educational curriculum designed to help families talk about self-esteem, sex, and peer pressure with their children in grades 4 through 8. The packet consists of a planning and training manuals, family activity books, and a videotape. The curriculum is comprised of four parent…

Design of a digital, ultra-broadband electro-optic switch for reconfigurable optical networks-on-chip.

PubMed

Van Campenhout, Joris; Green, William M J; Vlasov, Yurii A

2009-12-21

We present a novel design for a noise-tolerant, ultra-broadband electro-optic switch, based on a Mach-Zehnder lattice (MZL) interferometer. We analyze the switch performance through rigorous optical simulations, for devices implemented in silicon-on-insulator with carrier-injection-based phase shifters. We show that such a MZL switch can be designed to have a step-like switching response, resulting in improved tolerance to drive-voltage noise and temperature variations as compared to a single-stage Mach-Zehnder switch. Furthermore, we show that degradation in switching crosstalk and insertion loss due to free-carrier absorption can be largely overcome by a MZL switch design. Finally, MZL switches can be designed for having an ultra-wide, temperature-insensitive optical bandwidth of more than 250 nm. The proposed device shows good potential as a broadband optical switch in reconfigurable optical networks-on-chip.

Packet Randomized Experiments for Eliminating Classes of Confounders

PubMed Central

Pavela, Greg; Wiener, Howard; Fontaine, Kevin R.; Fields, David A.; Voss, Jameson D.; Allison, David B.

2014-01-01

Background Although randomization is considered essential for causal inference, it is often not possible to randomize in nutrition and obesity research. To address this, we develop a framework for an experimental design—packet randomized experiments (PREs), which improves causal inferences when randomization on a single treatment variable is not possible. This situation arises when subjects are randomly assigned to a condition (such as a new roommate) which varies in one characteristic of interest (such as weight), but also varies across many others. There has been no general discussion of this experimental design, including its strengths, limitations, and statistical properties. As such, researchers are left to develop and apply PREs on an ad hoc basis, limiting its potential to improve causal inferences among nutrition and obesity researchers. Methods We introduce PREs as an intermediary design between randomized controlled trials and observational studies. We review previous research that used the PRE design and describe its application in obesity-related research, including random roommate assignments, heterochronic parabiosis, and the quasi-random assignment of subjects to geographic areas. We then provide a statistical framework to control for potential packet-level confounders not accounted for by randomization. Results PREs have successfully been used to improve causal estimates of the effect of roommates, altitude, and breastfeeding on weight outcomes. When certain assumptions are met, PREs can asymptotically control for packet-level characteristics. This has the potential to statistically estimate the effect of a single treatment even when randomization to a single treatment did not occur. Conclusions Applying PREs to obesity-related research will improve decisions about clinical, public health, and policy actions insofar as it offers researchers new insight into cause and effect relationships among variables. PMID:25444088

Bluetooth and security

NASA Astrophysics Data System (ADS)

Ivo, Penn

2004-04-01

Bluetooth is the new emerging technology for wireless communication. It can be used to connect almost any device to another device. The traditional example is to link a Personal Digital Assistant (PDA) or a laptop to a mobile phone. That way you can easily take remote connections with your PDA or laptop without getting your mobile phone from your pocket or messing around with cables. A Class 3 Bluetooth device has range of 0,1 - 10 meters. The architecture of Bluetooth is formed by the radio, the base frequency part and the Link Manager. Bluetooth uses the radio range of 2.45 GHz. The theoretical maximum bandwidth is 1 Mb/s, which is slowed down a bit by Forward Error Correction (FEC). Bluetooth specification designates the frequency hopping to be implemented with Gaussian Frequency Shift Keying (GFSK). The base frequency part of the Bluetooth architecture uses a combination of circuit and packet switching technologies. Bluetooth can support either one asynchronous data channel and up to three simultaneous synchronous speech channels, or one channel that transfers asynchronous data and synchronous speech simultaneously. The Link Manager is an essential part of the Bluetooth architecture. It uses Link Manager Protocol (LMP) to configure, authenticate and handle the connections between Bluetooth devices. Several Bluetooth devices can form an ad hoc network. In these piconets, one of the Bluetooth devices will act as a master and the others are slaves. The master sets the frequency-hopping behavior of the piconet. It is also possible to connect up to 10 piconets to each other to form so-called scatternets. Bluetooth has been designed to operate in noisy radio frequency environments, and uses a fast acknowledgement and frequency-hopping scheme to make the link robust, communication-wise. Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a packet. Compared with other systems operating in the same frequency band, the Bluetooth radio typically hops faster and uses shorter packets. This is because short packages and fast hopping limit the impact of microwave ovens and other sources of disturbances. Use of Forward Error Correction (FEC) limits the impact of random noise on long-distance links. Bluetooth transmissions are secure in a business and home environment. Bluetooth has built in sufficient encryption and authentication and is thus very secure in any environment. In addition to this, a frequency-hopping scheme with 1600 hops/sec. is employed. This is far quicker than any other competing system. This, together with an automatic output power adaption to reduce the range exactly to requirement, makes the system extremely difficult to eavesdrop. Information Integrity in Bluetooth has these components: Random Number Generation, Encryption, Encryption Key Management and Authentication.

On Maximizing the Throughput of Packet Transmission under Energy Constraints.

PubMed

Wu, Weiwei; Dai, Guangli; Li, Yan; Shan, Feng

2018-06-23

More and more Internet of Things (IoT) wireless devices have been providing ubiquitous services over the recent years. Since most of these devices are powered by batteries, a fundamental trade-off to be addressed is the depleted energy and the achieved data throughput in wireless data transmission. By exploiting the rate-adaptive capacities of wireless devices, most existing works on energy-efficient data transmission try to design rate-adaptive transmission policies to maximize the amount of transmitted data bits under the energy constraints of devices. Such solutions, however, cannot apply to scenarios where data packets have respective deadlines and only integrally transmitted data packets contribute. Thus, this paper introduces a notion of weighted throughput, which measures how much total value of data packets are successfully and integrally transmitted before their own deadlines. By designing efficient rate-adaptive transmission policies, this paper aims to make the best use of the energy and maximize the weighted throughput. What is more challenging but with practical significance, we consider the fading effect of wireless channels in both offline and online scenarios. In the offline scenario, we develop an optimal algorithm that computes the optimal solution in pseudo-polynomial time, which is the best possible solution as the problem undertaken is NP-hard. In the online scenario, we propose an efficient heuristic algorithm based on optimal properties derived for the optimal offline solution. Simulation results validate the efficiency of the proposed algorithm.

Directional MAC approach for wireless body area networks.

PubMed

Hussain, Md Asdaque; Alam, Md Nasre; Kwak, Kyung Sup

2011-01-01

Wireless Body Area Networks (WBANs) designed for medical, sports, and entertainment applications, have drawn the attention of academia and industry alike. A WBAN is a special purpose network, designed to operate autonomously to connect various medical sensors and appliances, located inside and/or outside of a human body. This network enables physicians to remotely monitor vital signs of patients and provide real time feedback for medical diagnosis and consultations. The WBAN system can offer two significant advantages: patient mobility due to their use of portable monitoring devices and a location independent monitoring facility. With its appealing dimensions, it brings about a new set of challenges, which we do not normally consider in such small sensor networks. It requires a scalable network in terms of heterogeneous data traffic, low power consumption of sensor nodes, integration in and around the body networking and coexistence. This work presents a medium access control protocol for WBAN which tries to overcome the aforementioned challenges. We consider the use of multiple beam adaptive arrays (MBAA) at BAN Coordinator (BAN_C) node. When used as a BAN_C, an MBAA can successfully receive two or more overlapping packets at the same time. Each beam captures a different packet by automatically pointing its pattern toward one packet while annulling other contending packets. This paper describes how an MBAA can be integrated into a single hope star topology as a BAN_C. Simulation results show the performance of our proposed protocol.

Design of RF MEMS switches without pull-in instability

NASA Astrophysics Data System (ADS)

Proctor, W. Cyrus; Richards, Gregory P.; Shen, Chongyi; Skorczewski, Tyler; Wang, Min; Zhang, Jingyan; Zhong, Peng; Massad, Jordan E.; Smith, Ralph

2010-04-01

Micro-electro-mechanical systems (MEMS) switches for radio-frequency (RF) signals have certain advantages over solid-state switches, such as lower insertion loss, higher isolation, and lower static power dissipation. Mechanical dynamics can be a determining factor for the reliability of RF MEMS. The RF MEMS ohmic switch discussed in this paper consists of a plate suspended over an actuation pad by four double-cantilever springs. Closing the switch with a simple step actuation voltage typically causes the plate to rebound from its electrical contacts. The rebound interrupts the signal continuity and degrades the performance, reliability and durability of the switch. The switching dynamics are complicated by a nonlinear, electrostatic pull-in instability that causes high accelerations. Slow actuation and tailored voltage control signals can mitigate switch bouncing and effects of the pull-in instability; however, slow switching speed and overly-complex input signals can significantly penalize overall system-level performance. Examination of a balanced and optimized alternative switching solution is sought. A step toward one solution is to consider a pull-in-free switch design. In this paper, determine how simple RC-circuit drive signals and particular structural properties influence the mechanical dynamics of an RF MEMS switch designed without a pull-in instability. The approach is to develop a validated modeling capability and subsequently study switch behavior for variable drive signals and switch design parameters. In support of project development, specifiable design parameters and constraints will be provided. Moreover, transient data of RF MEMS switches from laser Doppler velocimetry will be provided for model validation tasks. Analysis showed that a RF MEMS switch could feasibly be designed with a single pulse waveform and no pull-in instability and achieve comparable results to previous waveform designs. The switch design could reliably close in a timely manner, with small contact velocity, usually with little to no rebound even when considering manufacturing variability.

Taking the Politics Out of Satellite and Space-Based Communications Protocols

NASA Technical Reports Server (NTRS)

Ivancic, William D.

2006-01-01

After many years of studies, experimentation, and deployment, large amounts of misinformation and misconceptions remain regarding applicability of various communications protocols for use in satellite and space-based networks. This paper attempts to remove much of the politics, misconceptions, and misinformation that have plagued spacebased communications protocol development and deployment. This paper provides a common vocabulary for communications; a general discussion of the requirements for various communication environments; an evaluation of tradeoffs between circuit and packet-switching technologies, and the pros and cons of various link, network, transport, application, and security protocols. Included is the applicability of protocol enhancing proxies to NASA, Department of Defense (DOD), and commercial space communication systems.

Design and Development of the SMAP Microwave Radiometer Electronics

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Medeiros, James J.; Horgan, Kevin A.; Brambora, Clifford K.; Estep, Robert H.

2014-01-01

The SMAP microwave radiometer will measure land surface brightness temperature at L-band (1413 MHz) in the presence of radio frequency interference (RFI) for soil moisture remote sensing. The radiometer design was driven by the requirements to incorporate internal calibration, to operate synchronously with the SMAP radar, and to mitigate the deleterious effects of RFI. The system design includes a highly linear super-heterodyne microwave receiver with internal reference loads and noise sources for calibration and an innovative digital signal processor and detection system. The front-end comprises a coaxial cable-based feed network, with a pair of diplexers and a coupled noise source, and radiometer front-end (RFE) box. Internal calibration is provided by reference switches and a common noise source inside the RFE. The RF back-end (RBE) downconverts the 1413 MHz channel to an intermediate frequency (IF) of 120 MHz. The IF signals are then sampled and quantized by high-speed analog-to-digital converters in the radiometer digital electronics (RDE) box. The RBE local oscillator and RDE sampling clocks are phase-locked to a common reference to ensure coherency between the signals. The RDE performs additional filtering, sub-band channelization, cross-correlation for measuring third and fourth Stokes parameters, and detection and integration of the first four raw moments of the signals. These data are packetized and sent to the ground for calibration and further processing. Here we discuss the novel features of the radiometer hardware particularly those influenced by the need to mitigate RFI.

Design Concepts. Teacher Edition. Marketing Education LAPs.

ERIC Educational Resources Information Center

Hawley, Jana

This learning activity packet is designed to help prepare students to acquire a competency: how to use design concepts in preparation for a career in the fashion industry. The unit consists of the competency, four objectives, suggested learning activities, transparency masters, and a pretest/posttest with answer keys. Activities include a…

Design for Visual Arts.

ERIC Educational Resources Information Center

Skeries, Larry

Experiences suggested within this visual arts packet provide high school students with awareness of visual expression in graphic design, product design, architecture, and crafts. The unit may be used in whole or in part and includes information about art careers and art-related jobs found in major occupational fields. Specific lesson topics…

Packet Fragmentation and Reassembly in Molecular Communication.

PubMed

Furubayashi, Taro; Nakano, Tadashi; Eckford, Andrew; Okaie, Yutaka; Yomo, Tetsuya

2016-04-01

This paper describes packet fragmentation and reassembly to achieve reliable molecular communication among bionanomachines. In the molecular communication described in this paper, a sender bionanomachine performs packet fragmentation, dividing a large molecular message into smaller pieces and embedding into smaller molecular packets, so that molecular packets have higher diffusivity to reach the receiver bionanomachine. The receiver bionanomachine then performs packet reassembly to retrieve the original molecular message from a set of molecular packets that it receives. To examine the effect of packet fragmentation and reassembly, we develop analytical models and conduct numerical experiments. Numerical results show that packet fragmentation and reassembly can improve the message delivery performance. Numerical results also indicate that packet fragmentation and reassembly may degrade the performance in the presence of drift in the environment.

A novel lost packets recovery scheme based on visual secret sharing

NASA Astrophysics Data System (ADS)

Lu, Kun; Shan, Hong; Li, Zhi; Niu, Zhao

2017-08-01

In this paper, a novel lost packets recovery scheme which encrypts the effective parts of an original packet into two shadow packets based on (2, 2)-threshold XOR-based visual Secret Sharing (VSS) is proposed. The two shadow packets used as watermarks would be embedded into two normal data packets with digital watermarking embedding technology and then sent from one sensor node to another. Each shadow packet would reveal no information of the original packet, which can improve the security of original packet delivery greatly. The two shadow packets which can be extracted from the received two normal data packets delivered from a sensor node can recover the original packet lossless based on XOR-based VSS. The Performance analysis present that the proposed scheme provides essential services as long as possible in the presence of selective forwarding attack. The proposed scheme would not increase the amount of additional traffic, namely, lower energy consumption, which is suitable for Wireless Sensor Network (WSN).

New mode switching algorithm for the JPL 70-meter antenna servo controller

NASA Technical Reports Server (NTRS)

Nickerson, J. A.

1988-01-01

The design of control mode switching algorithms and logic for JPL's 70 m antenna servo controller are described. The old control mode switching logic was reviewed and perturbation problems were identified. Design approaches for mode switching are presented and the final design is described. Simulations used to compare old and new mode switching algorithms and logic show that the new mode switching techniques will significantly reduce perturbation problems.

Spacecraft in switch matrix for wide band service applicatons in 30/20 GHz communications satellite systems

NASA Technical Reports Server (NTRS)

Cory, B. J.

1982-01-01

Bandwidth, switching speed, off-state isolation, and reliability over a ten-year mission were factors in determining the optimum available technology for satellite communications switching in 1982. A proof of concept model for a 20 x 20 coupled crossbar switch matrix designed with FET devices for microwave switching and with high speed CMOS LIS for switch crosspoint addressing was fabricated and tested. Results show the design is feasible for application in a multichannel SS-TDMA communications system. Expandibility can readily be achieved with this design. A conceptual design study for a 100 x 100 switch matrix utilizing a coupled crossbar architecture implemented with a monolithic microwave integrated circuits revealed technology needs for high capacity switch matrices.

Extensible packet processing architecture

DOEpatents

Robertson, Perry J.; Hamlet, Jason R.; Pierson, Lyndon G.; Olsberg, Ronald R.; Chun, Guy D.

2013-08-20

A technique for distributed packet processing includes sequentially passing packets associated with packet flows between a plurality of processing engines along a flow through data bus linking the plurality of processing engines in series. At least one packet within a given packet flow is marked by a given processing engine to signify by the given processing engine to the other processing engines that the given processing engine has claimed the given packet flow for processing. A processing function is applied to each of the packet flows within the processing engines and the processed packets are output on a time-shared, arbitered data bus coupled to the plurality of processing engines.

Dynamic optical resource allocation for mobile core networks with software defined elastic optical networking.

PubMed

Zhao, Yongli; Chen, Zhendong; Zhang, Jie; Wang, Xinbo

2016-07-25

Driven by the forthcoming of 5G mobile communications, the all-IP architecture of mobile core networks, i.e. evolved packet core (EPC) proposed by 3GPP, has been greatly challenged by the users' demands for higher data rate and more reliable end-to-end connection, as well as operators' demands for low operational cost. These challenges can be potentially met by software defined optical networking (SDON), which enables dynamic resource allocation according to the users' requirement. In this article, a novel network architecture for mobile core network is proposed based on SDON. A software defined network (SDN) controller is designed to realize the coordinated control over different entities in EPC networks. We analyze the requirement of EPC-lightpath (EPCL) in data plane and propose an optical switch load balancing (OSLB) algorithm for resource allocation in optical layer. The procedure of establishment and adjustment of EPCLs is demonstrated on a SDON-based EPC testbed with extended OpenFlow protocol. We also evaluate the OSLB algorithm through simulation in terms of bandwidth blocking ratio, traffic load distribution, and resource utilization ratio compared with link-based load balancing (LLB) and MinHops algorithms.

Comparison of technique errors of intraoral radiographs taken on film v photostimulable phosphor (PSP) plates.

PubMed

Zhang, Wenjian; Huynh, Carolyn P; Abramovitch, Kenneth; Leon, Inga-Lill K; Arvizu, Liliana

2012-06-01

The objective of this study was to compare the technical errors of intraoral radiographs exposed on film v photostimulable phosphor (PSP) plates. The intraoral radiographic images exposed on phantoms from preclinical practical exams of dental and dental hygiene students were used. Each exam consisted of 10 designated periapical and bitewing views. A total of 107 film sets and 122 PSP sets were evaluated for technique errors, including placement, elongation, foreshortening, overlapping, cone cut, receptor bending, density, mounting, dot in apical area, and others. Some errors were further subcategorized as minor, major, or remake depending on the severity. The percentages of radiographs with various errors were compared between film and PSP by the Fisher's Exact Test. Compared with film, there was significantly less PSP foreshortening, elongation, and bending errors, but significantly more placement and overlapping errors. Using a wrong sized receptor due to the similarity of the color of the package sleeves is a unique PSP error. Optimum image quality is attainable with PSP plates as well as film. When switching from film to a PSP digital environment, more emphasis is necessary for placing the PSP plates, especially those with excessive packet edge, and then correcting the corresponding angulation for the beam alignment. Better design for improving intraoral visibility and easy identification of different sized PSP will improve the clinician's technical performance with this receptor.

Quality of Service for Real-Time Applications Over Next Generation Data Networks

NASA Technical Reports Server (NTRS)

Atiquzzaman, Mohammed; Jain, Raj

2001-01-01

This project, which started on January 1, 2000, was funded by the NASA Glenn Research Center for duration of one year. The deliverables of the project included the following tasks: (1) Study of QoS mapping between the edge and core networks envisioned in the Next Generation networks will provide us with the QoS guarantees that can be obtained from next generation networks; (2) Buffer management techniques to provide strict guarantees to real-time end-to-end applications through preferential treatment to packets belonging to real-time applications. In particular, use of ECN to help reduce the loss on high bandwidth-delay product satellite networks needs to be studied; (3) Effect of Prioritized Packet Discard to increase goodput of the network and reduce the buffering requirements in the ATM switches; (4) Provision of new IP circuit emulation services over Satellite IP backbones using MPLS will be studied; and (5) Determine the architecture and requirements for internetworking ATN and the Next Generation Internet for real-time applications. The project has been completed on time. All the objectives and deliverables of the project have been completed. Research results obtained from this project have been published in a number of papers in journals, conferences, and technical reports, included in this document.

Models for IP/MPLS routing performance: convergence, fast reroute, and QoS impact

NASA Astrophysics Data System (ADS)

Choudhury, Gagan L.

2004-09-01

We show how to model the black-holing and looping of traffic during an Interior Gateway Protocol (IGP) convergence event at an IP network and how to significantly improve both the convergence time and packet loss duration through IGP parameter tuning and algorithmic improvement. We also explore some congestion avoidance and congestion control algorithms that can significantly improve stability of networks in the face of occasional massive control message storms. Specifically we show the positive impacts of prioritizing Hello and Acknowledgement packets and slowing down LSA generation and retransmission generation on detecting congestion in the network. For some types of video, voice signaling and circuit emulation applications it is necessary to reduce traffic loss durations following a convergence event to below 100 ms and we explore that using Fast Reroute algorithms based on Multiprotocol Label Switching Traffic Engineering (MPLS-TE) that effectively bypasses IGP convergence. We explore the scalability of primary and backup MPLS-TE tunnels where MPLS-TE domain is in the backbone-only or edge-to-edge. We also show how much extra backbone resource is needed to support Fast Reroute and how can that be reduced by taking advantage of Constrained Shortest Path (CSPF) routing of MPLS-TE and by reserving less than 100% of primary tunnel bandwidth during Fast Reroute.

Generation and evolution of mode-locked noise-like square-wave pulses in a large-anomalous-dispersion Er-doped ring fiber laser.

PubMed

Liu, Jun; Chen, Yu; Tang, Pinghua; Xu, Changwen; Zhao, Chujun; Zhang, Han; Wen, Shuangchun

2015-03-09

In a passively mode-locked Erbium-doped fiber laser with large anomalous-dispersion, we experimentally demonstrate the formation of noise-like square-wave pulse, which shows quite different features from conventional dissipative soliton resonance (DSR). The corresponding temporal and spectral characteristics of a variety of operation states, including Q-switched mode-locking, continuous-wave mode-locking and Raman-induced noise-like pulse near the lasing threshold, are also investigated. Stable noise-like square-wave mode-locked pulses can be obtained at a fundamental repetition frequency of 195 kHz, with pulse packet duration tunable from 15 ns to 306 ns and per-pulse energy up to 200 nJ. By reducing the linear cavity loss, stable higher-order harmonic mode-locking had also been observed, with pulse duration ranging from 37 ns at the 21st order harmonic wave to 320 ns at the fundamental order. After propagating along a piece of long telecom fiber, the generated square-wave pulses do not show any obvious change, indicating that the generated noise-like square-wave pulse can be considered as high-energy pulse packet for some promising applications. These experimental results should shed some light on the further understanding of the mechanism and characteristics of noise-like square-wave pulses.

Design Patterns for Learning and Assessment: Facilitating the Introduction of a Complex Simulation-Based Learning Environment into a Community of Instructors

NASA Astrophysics Data System (ADS)

Frezzo, Dennis C.; Behrens, John T.; Mislevy, Robert J.

2010-04-01

Simulation environments make it possible for science and engineering students to learn to interact with complex systems. Putting these capabilities to effective use for learning, and assessing learning, requires more than a simulation environment alone. It requires a conceptual framework for the knowledge, skills, and ways of thinking that are meant to be developed, in order to design activities that target these capabilities. The challenges of using simulation environments effectively are especially daunting in dispersed social systems. This article describes how these challenges were addressed in the context of the Cisco Networking Academies with a simulation tool for computer networks called Packet Tracer. The focus is on a conceptual support framework for instructors in over 9,000 institutions around the world for using Packet Tracer in instruction and assessment, by learning to create problem-solving scenarios that are at once tuned to the local needs of their students and consistent with the epistemic frame of "thinking like a network engineer." We describe a layered framework of tools and interfaces above the network simulator that supports the use of Packet Tracer in the distributed community of instructors and students.

Method and Apparatus for Processing UDP Data Packets

NASA Technical Reports Server (NTRS)

Murphy, Brandon M. (Inventor)

2017-01-01

A method and apparatus for processing a plurality of data packets. A data packet is received. A determination is made as to whether a portion of the data packet follows a selected digital recorder standard protocol based on a header of the data packet. Raw data in the data packet is converted into human-readable information in response to a determination that the portion of the data packet follows the selected digital recorder standard protocol.

Distributed reservation control protocols for random access broadcasting channels

NASA Technical Reports Server (NTRS)

Greene, E. P.; Ephremides, A.

1981-01-01

Attention is given to a communication network consisting of an arbitrary number of nodes which can communicate with each other via a time-division multiple access (TDMA) broadcast channel. The reported investigation is concerned with the development of efficient distributed multiple access protocols for traffic consisting primarily of single packet messages in a datagram mode of operation. The motivation for the design of the protocols came from the consideration of efficient multiple access utilization of moderate to high bandwidth (4-40 Mbit/s capacity) communication satellite channels used for the transmission of short (1000-10,000 bits) fixed length packets. Under these circumstances, the ratio of roundtrip propagation time to packet transmission time is between 100 to 10,000. It is shown how a TDMA channel can be adaptively shared by datagram traffic and constant bandwidth users such as in digital voice applications. The distributed reservation control protocols described are a hybrid between contention and reservation protocols.

Performance analysis of Aloha networks with power capture and near/far effect

NASA Astrophysics Data System (ADS)

McCartin, Joseph T.

1989-06-01

An analysis is presented for the throughput characteristics for several classes of Aloha packet networks. Specifically, the throughput for variable packet length Aloha utilizing multiple power levels to induce receiver capture is derived. The results are extended to an analysis of a selective-repeat ARQ Aloha network. Analytical results are presented which indicate a significant increase in throughput for a variable packet network implementing a random two power level capture scheme. Further research into the area of the near/far effect on Aloha networks is included. Improvements in throughput for mobile radio Aloha networks which are subject to the near/far effect are presented. Tactical Command, Control and Communications (C3) systems of the future will rely on Aloha ground mobile data networks. The incorporation of power capture and the near/far effect into future tactical networks will result in improved system analysis, design, and performance.

The EURECA telecommanding chain: Experience with packet telecommand and telemetry systems

NASA Technical Reports Server (NTRS)

Mueller, C.; Bater, R.; Sorensen, E. M.

1993-01-01

The European Retrieval Carrier (EURECA) was launched on its first flight on the 31st July 1992 by the Space Shuttle Atlantis. EURECA is characterized by several new on-board features, most notable Packet Telemetry and a partial implementation of Packet Telecommanding using an early version of the Command Operation Procedure (COP-1) protocol. EURECA has also very low contact time with its Ground Station, with a consequent high number of out-of-visibility onboard operations. This paper concentrates on the implementation and operational experience with the COP-1 Protocol and the effect the short ground contact time has on the design of the Commanding System. Another interesting feature is that the COP-1 is implemented at the control center rather than at the ground station. The COP-1 protocol also successfully supported the mission during the launch where commands were sent via NASCOM and the Shuttle.

Use of CCSDS Packets Over SpaceWire to Control Hardware

NASA Technical Reports Server (NTRS)

Haddad, Omar; Blau, Michael; Haghani, Noosha; Yuknis, William; Albaijes, Dennis

2012-01-01

For the Lunar Reconnaissance Orbiter, the Command and Data Handling subsystem consisted of several electronic hardware assemblies that were connected with SpaceWire serial links. Electronic hardware would be commanded/controlled and telemetry data was obtained using the SpaceWire links. Prior art focused on parallel data buses and other types of serial buses, which were not compatible with the SpaceWire and the core flight executive (CFE) software bus. This innovation applies to anything that utilizes both SpaceWire networks and the CFE software. The CCSDS (Consultative Committee for Space Data Systems) packet contains predetermined values in its payload fields that electronic hardware attached at the terminus of the SpaceWire node would decode, interpret, and execute. The hardware s interpretation of the packet data would enable the hardware to change its state/configuration (command) or generate status (telemetry). The primary purpose is to provide an interface that is compatible with the hardware and the CFE software bus. By specifying the format of the CCSDS packet, it is possible to specify how the resulting hardware is to be built (in terms of digital logic) that results in a hardware design that can be controlled by the CFE software bus in the final application

Optimal laser pulse design for transferring the coherent nuclear wave packet of H+2

NASA Astrophysics Data System (ADS)

Zhang, Jun; He, Guang-Qiang; He, Feng

2014-07-01

Within the Franck-Condon approximation, the single ionisation of H2 leaves H+2 in a coherent superposition of 19 nuclear vibrational states. We numerically design an optimal laser pulse train to transfer such a coherent nuclear wave packet to the ground vibrational state of H+2. Frequency analysis of the designed optimal pulse reveals that the transfer principle is mainly an anti-Stokes transition, i.e. the H+2 in 1sσg with excited nuclear vibrational states is first pumped to 2pσg state by the pulse at an appropriate time, and then dumped back to 1sσg with lower excited or ground vibrational states. The simulation results show that the population of the ground state after the transfer is more than 91%. To the best of our knowledge, this is the highest transition probability when the driving laser field is dozens of femtoseconds.

Packet flow monitoring tool and method

DOEpatents

Thiede, David R [Richland, WA

2009-07-14

A system and method for converting packet streams into session summaries. Session summaries are a group of packets each having a common source and destination internet protocol (IP) address, and, if present in the packets, common ports. The system first captures packets from a transport layer of a network of computer systems, then decodes the packets captured to determine the destination IP address and the source IP address. The system then identifies packets having common destination IP addresses and source IP addresses, then writes the decoded packets to an allocated memory structure as session summaries in a queue.

I/O routing in a multidimensional torus network

DOEpatents

Chen, Dong; Eisley, Noel A.; Heidelberger, Philip

2017-02-07

A method, system and computer program product are disclosed for routing data packet in a computing system comprising a multidimensional torus compute node network including a multitude of compute nodes, and an I/O node network including a plurality of I/O nodes. In one embodiment, the method comprises assigning to each of the data packets a destination address identifying one of the compute nodes; providing each of the data packets with a toio value; routing the data packets through the compute node network to the destination addresses of the data packets; and when each of the data packets reaches the destination address assigned to said each data packet, routing said each data packet to one of the I/O nodes if the toio value of said each data packet is a specified value. In one embodiment, each of the data packets is also provided with an ioreturn value used to route the data packets through the compute node network.

I/O routing in a multidimensional torus network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dong; Eisley, Noel A.; Heidelberger, Philip

A method, system and computer program product are disclosed for routing data packet in a computing system comprising a multidimensional torus compute node network including a multitude of compute nodes, and an I/O node network including a plurality of I/O nodes. In one embodiment, the method comprises assigning to each of the data packets a destination address identifying one of the compute nodes; providing each of the data packets with a toio value; routing the data packets through the compute node network to the destination addresses of the data packets; and when each of the data packets reaches the destinationmore » address assigned to said each data packet, routing said each data packet to one of the I/O nodes if the toio value of said each data packet is a specified value. In one embodiment, each of the data packets is also provided with an ioreturn value used to route the data packets through the compute node network.« less

Estimating TCP Packet Loss Ratio from Sampled ACK Packets

NASA Astrophysics Data System (ADS)

Yamasaki, Yasuhiro; Shimonishi, Hideyuki; Murase, Tutomu

The advent of various quality-sensitive applications has greatly changed the requirements for IP network management and made the monitoring of individual traffic flows more important. Since the processing costs of per-flow quality monitoring are high, especially in high-speed backbone links, packet sampling techniques have been attracting considerable attention. Existing sampling techniques, such as those used in Sampled NetFlow and sFlow, however, focus on the monitoring of traffic volume, and there has been little discussion of the monitoring of such quality indexes as packet loss ratio. In this paper we propose a method for estimating, from sampled packets, packet loss ratios in individual TCP sessions. It detects packet loss events by monitoring duplicate ACK events raised by each TCP receiver. Because sampling reveals only a portion of the actual packet loss, the actual packet loss ratio is estimated statistically. Simulation results show that the proposed method can estimate the TCP packet loss ratio accurately from a 10% sampling of packets.

Packet based serial link realized in FPGA dedicated for high resolution infrared image transmission

NASA Astrophysics Data System (ADS)

Bieszczad, Grzegorz

2015-05-01

In article the external digital interface specially designed for thermographic camera built in Military University of Technology is described. The aim of article is to illustrate challenges encountered during design process of thermal vision camera especially related to infrared data processing and transmission. Article explains main requirements for interface to transfer Infra-Red or Video digital data and describes the solution which we elaborated based on Low Voltage Differential Signaling (LVDS) physical layer and signaling scheme. Elaborated link for image transmission is built using FPGA integrated circuit with built-in high speed serial transceivers achieving up to 2500Gbps throughput. Image transmission is realized using proprietary packet protocol. Transmission protocol engine was described in VHDL language and tested in FPGA hardware. The link is able to transmit 1280x1024@60Hz 24bit video data using one signal pair. Link was tested to transmit thermal-vision camera picture to remote monitor. Construction of dedicated video link allows to reduce power consumption compared to solutions with ASIC based encoders and decoders realizing video links like DVI or packed based Display Port, with simultaneous reduction of wires needed to establish link to one pair. Article describes functions of modules integrated in FPGA design realizing several functions like: synchronization to video source, video stream packeting, interfacing transceiver module and dynamic clock generation for video standard conversion.

Computer Aided Design: Instructional Manual. The North Dakota High Technology Mobile Laboratory Project.

ERIC Educational Resources Information Center

Cheng, Wan-Lee

This instructional manual contains 12 learning activity packets for use in a workshop in computer-aided design and drafting (CADD). The lessons cover the following topics: introduction to computer graphics and computer-aided design/drafting; coordinate systems; advance space graphics hardware configuration and basic features of the IBM PC…

An integrated Ka/Ku-band payload for personal, mobile and private business communications

NASA Technical Reports Server (NTRS)

Hayes, Edward J.; Keelty, J. Malcolm

1991-01-01

The Canadian Department of Communications has been studying options for a government-sponsored demonstration payload to be launched before the end of the century. A summary of the proposed system concepts and network architectures for providing an advanced private business network service at Ku-band and personal and mobile communications at Ka-band is presented. The system aspects addressed include coverage patterns, traffic capacity, and grade of service, multiple access options as well as special problems, such as Doppler in mobile applications. Earth terminal types and the advanced payload concept proposed in a feasibility study for the demonstration mission are described. This concept is a combined Ka-band/Ku-band payload which incorporates a number of advanced satellite technologies including a group demodulator to convert single-channel-per-carrier frequency division multiple access uplink signals to a time division multiplex downlink, on-board signal regeneration, and baseband switching to support packet switched data operation. The on-board processing capability of the payload provides a hubless VSAT architecture which permits single-hop full mesh interconnectivity. The Ka-band and Ku-band portions of the payload are fully integrated through an on-board switch, thereby providing the capability for fully integrated services, such as using the Ku-band VSAT terminals as gateway stations for the Ka-band personal and mobile communications services.

Gigabit ATM: another technical mistake?

NASA Astrophysics Data System (ADS)

Christ, Paul

1998-09-01

Once upon a time, or more precisely during February 1988 at the CCITT Seoul plenary, and definitely arriving as a revolution, ATM hit the hard-core B-ISDN circuit-switching gang. Initiated by the Telecoms' camp, but, surprisingly, soon to be pushed by computer minded people, ATM's generic technological history is somewhat richer than single-sided stories. Here are two classical elements of that history: Firstly, together with X.25, ATM suffers from the connection versus datagram dichotomy, well known for more than twenty years. Secondly, and lesser known, ATM's use of cells in support of the 'I' of B-ISDN was questioned from the very beginning by the packet switching camp. Furthermore, in this context, there are two other essential elements to be considered: Firstly, the exponential growth of the Internet and later intranets, using Internet technology, sparked by the success of the Web and the WINTEL alliance, resulted in a corresponding demand for both aggregate and end-system network bandwidth. Secondly, servers, historically restricted to the exclusive club of HIPPI-equipped supercomputers, suddenly become ordinary high-end PCs with 64-bit wide PCI busses -- definitely aiming at the Gigabit. Here, if your aim is for Gigabit ATM with 5000-transactions per second classical supercomputers, a 65K ATM MTU -- as implemented by Cray -- might be okay. Following Clark and others, another part of the story is the adoption and redefinition, by the IETF, of the Telecoms' notion of 'Integrated Services' and QoS mechanisms. The quest for low-delay IP packet forwarding, perhaps possible over ATM cut-throughs, has resulted in the switching versus/or integrated-with-routing movement. However, a blow for ATM may be the recent results concerning fast routing table lookup algorithms. This, by making Gigabit routing possible using ordinary Pentium processors may eventually render the much prophesized ATM switching performance unnecessary. Recently, with the rise of Gigabit Ethernet, many of the elements mentioned above are now being presented by standard 'Gigabit Ethernet and Gigabit ATM -- friends or foes' conferences. In- depth analyses are given concerning the canonical elements of such a setting: legacy, new use requirements, manageability, security LAN-WAN, architectures, standards, technologies and products, complexity, evolution-transition strategies, manufacturers, player organizations etc. Often in such conferences, Fiber Channel, being one of Gigabit Ethernet's physical media, is presented as the only other Gigabit LAN technology. In an attempt to sum up: Given the present state of ATM deployment measured in terms of functionalities and sophistication, after ten years of CCCITT/ITU and almost as many years of ATM Forum effort, does the question still being asked now represent the answer -- ATM is or was a mistake there some elements still missing? Here's a technical and a political example:

Random access with adaptive packet aggregation in LTE/LTE-A.

PubMed

Zhou, Kaijie; Nikaein, Navid

While random access presents a promising solution for efficient uplink channel access, the preamble collision rate can significantly increase when massive number of devices simultaneously access the channel. To address this issue and improve the reliability of the random access, an adaptive packet aggregation method is proposed. With the proposed method, a device does not trigger a random access for every single packet. Instead, it starts a random access when the number of aggregated packets reaches a given threshold. This method reduces the packet collision rate at the expense of an extra latency, which is used to accumulate multiple packets into a single transmission unit. Therefore, the tradeoff between packet loss rate and channel access latency has to be carefully selected. We use semi-Markov model to derive the packet loss rate and channel access latency as functions of packet aggregation number. Hence, the optimal amount of aggregated packets can be found, which keeps the loss rate below the desired value while minimizing the access latency. We also apply for the idea of packet aggregation for power saving, where a device aggregates as many packets as possible until the latency constraint is reached. Simulations are carried out to evaluate our methods. We find that the packet loss rate and/or power consumption are significantly reduced with the proposed method.

Error recovery to enable error-free message transfer between nodes of a computer network

DOEpatents

Blumrich, Matthias A.; Coteus, Paul W.; Chen, Dong; Gara, Alan; Giampapa, Mark E.; Heidelberger, Philip; Hoenicke, Dirk; Takken, Todd; Steinmacher-Burow, Burkhard; Vranas, Pavlos M.

2016-01-26

An error-recovery method to enable error-free message transfer between nodes of a computer network. A first node of the network sends a packet to a second node of the network over a link between the nodes, and the first node keeps a copy of the packet on a sending end of the link until the first node receives acknowledgment from the second node that the packet was received without error. The second node tests the packet to determine if the packet is error free. If the packet is not error free, the second node sets a flag to mark the packet as corrupt. The second node returns acknowledgement to the first node specifying whether the packet was received with or without error. When the packet is received with error, the link is returned to a known state and the packet is sent again to the second node.

30 CFR 57.12041 - Design of switches and starting boxes.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Design of switches and starting boxes. 57.12041 Section 57.12041 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12041 Design of switches and starting boxes. Switches and starting...

30 CFR 57.12041 - Design of switches and starting boxes.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Design of switches and starting boxes. 57.12041 Section 57.12041 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12041 Design of switches and starting boxes. Switches and starting...

30 CFR 57.12041 - Design of switches and starting boxes.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Design of switches and starting boxes. 57.12041 Section 57.12041 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12041 Design of switches and starting boxes. Switches and starting...

30 CFR 57.12041 - Design of switches and starting boxes.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Design of switches and starting boxes. 57.12041 Section 57.12041 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12041 Design of switches and starting boxes. Switches and starting...

30 CFR 57.12041 - Design of switches and starting boxes.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Design of switches and starting boxes. 57.12041 Section 57.12041 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12041 Design of switches and starting boxes. Switches and starting...

Automated design of genetic toggle switches with predetermined bistability.

PubMed

Chen, Shuobing; Zhang, Haoqian; Shi, Handuo; Ji, Weiyue; Feng, Jingchen; Gong, Yan; Yang, Zhenglin; Ouyang, Qi

2012-07-20

Synthetic biology aims to rationally construct biological devices with required functionalities. Methods that automate the design of genetic devices without post-hoc adjustment are therefore highly desired. Here we provide a method to predictably design genetic toggle switches with predetermined bistability. To accomplish this task, a biophysical model that links ribosome binding site (RBS) DNA sequence to toggle switch bistability was first developed by integrating a stochastic model with RBS design method. Then, to parametrize the model, a library of genetic toggle switch mutants was experimentally built, followed by establishing the equivalence between RBS DNA sequences and switch bistability. To test this equivalence, RBS nucleotide sequences for different specified bistabilities were in silico designed and experimentally verified. Results show that the deciphered equivalence is highly predictive for the toggle switch design with predetermined bistability. This method can be generalized to quantitative design of other probabilistic genetic devices in synthetic biology.

Designing Meaningful Developmental Reform. Research Overview

ERIC Educational Resources Information Center

Jaggars, Shanna Smith; Hodara, Michelle; Stacey, Georgia West

2013-01-01

This practitioner packet is designed to help community college administrators implement reforms to developmental education at their colleges. It reviews common impediments to developmental reform and presents data that supports directions colleges can take to create a system of developmental education that might serve students more effectively.…

Standardised (plain) cigarette packaging increases attention to both text-based and graphical health warnings: experimental evidence.

PubMed

Shankleman, M; Sykes, C; Mandeville, K L; Di Costa, S; Yarrow, K

2015-01-01

To investigate whether standardised cigarette packaging increases the time spent looking at health warnings, regardless of the format of those warnings. A factorial (two pack styles x three warning types) within-subject experiment, with participants randomised to different orders of conditions, completed at a university in London, UK. Mock-ups of cigarette packets were presented to participants with their branded portion in either standardised (plain) or manufacturer-designed (branded) format. Health warnings were present on all packets, representing all three types currently in use in the UK: black & white text, colour text, or colour images with accompanying text. Gaze position was recorded using a specialised eye tracker, providing the main outcome measure, which was the mean proportion of a five-second viewing period spent gazing at the warning-label region of the packet. An opportunity sample of 30 (six male, mean age = 23) young adults met the following inclusion criteria: 1) not currently a smoker; 2) <100 lifetime cigarettes smoked; 3) gaze position successfully tracked for > 50% viewing time. These participants spent a greater proportion of the available time gazing at the warning-label region when the branded section of the pack was standardised (following current Australian guidelines) rather than containing the manufacturer's preferred design (mean difference in proportions = 0.078, 95% confidence interval 0.049 to 0.106, p < 0.001). There was no evidence that this effect varied based on the type of warning label (black & white text vs. colour text vs. colour image & text; interaction p = 0.295). During incidental viewing of cigarette packets, young adult never-smokers are likely to spend more time looking at health warnings if manufacturers are compelled to use standardised packaging, regardless of the warning design. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Remote Memory Access Protocol Target Node Intellectual Property

NASA Technical Reports Server (NTRS)

Haddad, Omar

2013-01-01

The MagnetoSpheric Multiscale (MMS) mission had a requirement to use the Remote Memory Access Protocol (RMAP) over its SpaceWire network. At the time, no known intellectual property (IP) cores were available for purchase. Additionally, MMS preferred to implement the RMAP functionality with control over the low-level details of the design. For example, not all the RMAP standard functionality was needed, and it was desired to implement only the portions of the RMAP protocol that were needed. RMAP functionality had been previously implemented in commercial off-the-shelf (COTS) products, but the IP core was not available for purchase. The RMAP Target IP core is a VHDL (VHSIC Hardware Description Language description of a digital logic design suitable for implementation in an FPGA (field-programmable gate array) or ASIC (application-specific integrated circuit) that parses SpaceWire packets that conform to the RMAP standard. The RMAP packet protocol allows a network host to access and control a target device using address mapping. This capability allows SpaceWire devices to be managed in a standardized way that simplifies the hardware design of the device, as well as the development of the software that controls the device. The RMAP Target IP core has some features that are unique and not specified in the RMAP standard. One such feature is the ability to automatically abort transactions if the back-end logic does not respond to read/write requests within a predefined time. When a request times out, the RMAP Target IP core automatically retracts the request and returns a command response with an appropriate status in the response packet s header. Another such feature is the ability to control the SpaceWire node or router using RMAP transactions in the extended address range. This allows the SpaceWire network host to manage the SpaceWire network elements using RMAP packets, which reduces the number of protocols that the network host needs to support.

Old Time Apple Cider Makin': An Outdoor Education Unit.

ERIC Educational Resources Information Center

Matthews, Bruce E.; Oakes, David B.

An illustrated, self-contained packet, the resource materials contained in this guide are designed for adaptation to K-8. The resources and ideas presented here are designed to encourage utilization of the outdoors as a learning resource. While intrinsically multidisciplinary, the activities are particularly adaptable to social studies, science,…

Police Patrol Game Kit.

ERIC Educational Resources Information Center

Clark, Todd, Ed.

A packet of game materials, designed to help young people better understand what the law is, what the police officer's duties are, and what pressures and fears the police officers experience daily, is presented. The game, designed for a group of 20 to 35 students, contains: Teacher's Manual, Attitude Survey Master, Observer Evaluation Master,…

Textiles. Teacher Edition. Marketing Education LAPs.

ERIC Educational Resources Information Center

Hawley, Jana

This learning activity packet is designed to help students to acquire a competency: how to use knowledge of textile design to gain expertise in preparation for a career in the fashion industry. The unit consists of the competency, four objectives, suggested learning activities, transparency masters, and a pretest/posttest with answer keys.…

Research in network management techniques for tactical data communications networks

NASA Astrophysics Data System (ADS)

Boorstyn, R.; Kershenbaum, A.; Maglaris, B.; Sarachik, P.

1982-09-01

This is the final technical report for work performed on network management techniques for tactical data networks. It includes all technical papers that have been published during the control period. Research areas include Packet Network modelling, adaptive network routing, network design algorithms, network design techniques, and local area networks.

Design concept for pressure switch calibrator

NASA Technical Reports Server (NTRS)

Slingerland, M. G.

1966-01-01

Calibrator and switch design enables pressure switches to operate under 150 g shock loads. The design employs a saturated liquid-to-vapor phase transition at constant pressure to produce a known force independent of displacement over a usable range.

Synchronization Control for a Class of Discrete-Time Dynamical Networks With Packet Dropouts: A Coding-Decoding-Based Approach.

PubMed

Wang, Licheng; Wang, Zidong; Han, Qing-Long; Wei, Guoliang

2017-09-06

The synchronization control problem is investigated for a class of discrete-time dynamical networks with packet dropouts via a coding-decoding-based approach. The data is transmitted through digital communication channels and only the sequence of finite coded signals is sent to the controller. A series of mutually independent Bernoulli distributed random variables is utilized to model the packet dropout phenomenon occurring in the transmissions of coded signals. The purpose of the addressed synchronization control problem is to design a suitable coding-decoding procedure for each node, based on which an efficient decoder-based control protocol is developed to guarantee that the closed-loop network achieves the desired synchronization performance. By applying a modified uniform quantization approach and the Kronecker product technique, criteria for ensuring the detectability of the dynamical network are established by means of the size of the coding alphabet, the coding period and the probability information of packet dropouts. Subsequently, by resorting to the input-to-state stability theory, the desired controller parameter is obtained in terms of the solutions to a certain set of inequality constraints which can be solved effectively via available software packages. Finally, two simulation examples are provided to demonstrate the effectiveness of the obtained results.

A Simulation Study of Paced TCP

NASA Technical Reports Server (NTRS)

Kulik, Joanna; Coulter, Robert; Rockwell, Dennis; Partridge, Craig

2000-01-01

In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

Wavelet-based Encoding Scheme for Controlling Size of Compressed ECG Segments in Telecardiology Systems.

PubMed

Al-Busaidi, Asiya M; Khriji, Lazhar; Touati, Farid; Rasid, Mohd Fadlee; Mnaouer, Adel Ben

2017-09-12

One of the major issues in time-critical medical applications using wireless technology is the size of the payload packet, which is generally designed to be very small to improve the transmission process. Using small packets to transmit continuous ECG data is still costly. Thus, data compression is commonly used to reduce the huge amount of ECG data transmitted through telecardiology devices. In this paper, a new ECG compression scheme is introduced to ensure that the compressed ECG segments fit into the available limited payload packets, while maintaining a fixed CR to preserve the diagnostic information. The scheme automatically divides the ECG block into segments, while maintaining other compression parameters fixed. This scheme adopts discrete wavelet transform (DWT) method to decompose the ECG data, bit-field preserving (BFP) method to preserve the quality of the DWT coefficients, and a modified running-length encoding (RLE) scheme to encode the coefficients. The proposed dynamic compression scheme showed promising results with a percentage packet reduction (PR) of about 85.39% at low percentage root-mean square difference (PRD) values, less than 1%. ECG records from MIT-BIH Arrhythmia Database were used to test the proposed method. The simulation results showed promising performance that satisfies the needs of portable telecardiology systems, like the limited payload size and low power consumption.

An Approach to Verification and Validation of a Reliable Multicasting Protocol

NASA Technical Reports Server (NTRS)

Callahan, John R.; Montgomery, Todd L.

1994-01-01

This paper describes the process of implementing a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally using a combination of formal and informal techniques in an attempt to ensure the correctness of its implementation. Our development process involved three concurrent activities: (1) the initial construction and incremental enhancement of a formal state model of the protocol machine; (2) the initial coding and incremental enhancement of the implementation; and (3) model-based testing of iterative implementations of the protocol. These activities were carried out by two separate teams: a design team and a V&V team. The design team built the first version of RMP with limited functionality to handle only nominal requirements of data delivery. In a series of iterative steps, the design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation. This was done by generating test cases based on suspected errant or offnominal behaviors predicted by the current model. If the execution of a test was different between the model and implementation, then the differences helped identify inconsistencies between the model and implementation. The dialogue between both teams drove the co-evolution of the model and implementation. Testing served as the vehicle for keeping the model and implementation in fidelity with each other. This paper describes (1) our experiences in developing our process model; and (2) three example problems found during the development of RMP.

An approach to verification and validation of a reliable multicasting protocol

NASA Technical Reports Server (NTRS)

Callahan, John R.; Montgomery, Todd L.

1995-01-01

This paper describes the process of implementing a complex communications protocol that provides reliable delivery of data in multicast-capable, packet-switching telecommunication networks. The protocol, called the Reliable Multicasting Protocol (RMP), was developed incrementally using a combination of formal and informal techniques in an attempt to ensure the correctness of its implementation. Our development process involved three concurrent activities: (1) the initial construction and incremental enhancement of a formal state model of the protocol machine; (2) the initial coding and incremental enhancement of the implementation; and (3) model-based testing of iterative implementations of the protocol. These activities were carried out by two separate teams: a design team and a V&V team. The design team built the first version of RMP with limited functionality to handle only nominal requirements of data delivery. In a series of iterative steps, the design team added new functionality to the implementation while the V&V team kept the state model in fidelity with the implementation. This was done by generating test cases based on suspected errant or off-nominal behaviors predicted by the current model. If the execution of a test was different between the model and implementation, then the differences helped identify inconsistencies between the model and implementation. The dialogue between both teams drove the co-evolution of the model and implementation. Testing served as the vehicle for keeping the model and implementation in fidelity with each other. This paper describes (1) our experiences in developing our process model; and (2) three example problems found during the development of RMP.

The Space Telescope SI C&DH system. [Scientific Instrument Control and Data Handling Subsystem

NASA Technical Reports Server (NTRS)

Gadwal, Govind R.; Barasch, Ronald S.

1990-01-01

The Hubble Space Telescope Scientific Instrument Control and Data Handling Subsystem (SI C&DH) is designed to interface with five scientific instruments of the Space Telescope to provide ground and autonomous control and collect health and status information using the Standard Telemetry and Command Components (STACC) multiplex data bus. It also formats high throughput science data into packets. The packetized data is interleaved and Reed-Solomon encoded for error correction and Pseudo Random encoded. An inner convolutional coding with the outer Reed-Solomon coding provides excellent error correction capability. The subsystem is designed with the capacity for orbital replacement in order to meet a mission life of fifteen years. The spacecraft computer and the SI C&DH computer coordinate the activities of the spacecraft and the scientific instruments to achieve the mission objectives.

Design and application of gas-gap heat switches

NASA Technical Reports Server (NTRS)

Chan, C. K.; Ross, R. G., Jr.

1990-01-01

Gas-gap heat switches can serve as an effective means of thermally disconnecting a standby cryocooler when the primary (operating) cooler is connected and vice versa. The final phase of the development and test of a cryogenic heat switch designed for loads ranging from 2 watts at 8 K, to 100 watts at 80 K are described. Achieved heat-switch on/off conductance ratio ranged from 11,000 at 8 K to 2200 at 80 K. A particularly challenging element of heat-switch design is achieving satisfactory operation when large temperatures differentials exist across the switch. A special series of tests and analyses was conducted and used in this Phase-2 activity to evaluate the developed switches for temperature differentials ranging up to 200 K. Problems encountered at the maximum levels are described and analyzed, and means of avoiding the problems in the future are presented. A comprehensive summary of the overall heat-switch design methodology is also presented with special emphasis on lessons learned over the course of the 4-year development effort.

40-Gbps optical backbone network deep packet inspection based on FPGA

NASA Astrophysics Data System (ADS)

Zuo, Yuan; Huang, Zhiping; Su, Shaojing

2014-11-01

In the era of information, the big data, which contains huge information, brings about some problems, such as high speed transmission, storage and real-time analysis and process. As the important media for data transmission, the Internet is the significant part for big data processing research. With the large-scale usage of the Internet, the data streaming of network is increasing rapidly. The speed level in the main fiber optic communication of the present has reached 40Gbps, even 100Gbps, therefore data on the optical backbone network shows some features of massive data. Generally, data services are provided via IP packets on the optical backbone network, which is constituted with SDH (Synchronous Digital Hierarchy). Hence this method that IP packets are directly mapped into SDH payload is named POS (Packet over SDH) technology. Aiming at the problems of real time process of high speed massive data, this paper designs a process system platform based on ATCA for 40Gbps POS signal data stream recognition and packet content capture, which employs the FPGA as the CPU. This platform offers pre-processing of clustering algorithms, service traffic identification and data mining for the following big data storage and analysis with high efficiency. Also, the operational procedure is proposed in this paper. Four channels of 10Gbps POS signal decomposed by the analysis module, which chooses FPGA as the kernel, are inputted to the flow classification module and the pattern matching component based on TCAM. Based on the properties of the length of payload and net flows, buffer management is added to the platform to keep the key flow information. According to data stream analysis, DPI (deep packet inspection) and flow balance distribute, the signal is transmitted to the backend machine through the giga Ethernet ports on back board. Practice shows that the proposed platform is superior to the traditional applications based on ASIC and NP.

Region-Based Collision Avoidance Beaconless Geographic Routing Protocol in Wireless Sensor Networks.

PubMed

Lee, JeongCheol; Park, HoSung; Kang, SeokYoon; Kim, Ki-Il

2015-06-05

Due to the lack of dependency on beacon messages for location exchange, the beaconless geographic routing protocol has attracted considerable attention from the research community. However, existing beaconless geographic routing protocols are likely to generate duplicated data packets when multiple winners in the greedy area are selected. Furthermore, these protocols are designed for a uniform sensor field, so they cannot be directly applied to practical irregular sensor fields with partial voids. To prevent the failure of finding a forwarding node and to remove unnecessary duplication, in this paper, we propose a region-based collision avoidance beaconless geographic routing protocol to increase forwarding opportunities for randomly-deployed sensor networks. By employing different contention priorities into the mutually-communicable nodes and the rest of the nodes in the greedy area, every neighbor node in the greedy area can be used for data forwarding without any packet duplication. Moreover, simulation results are given to demonstrate the increased packet delivery ratio and shorten end-to-end delay, rather than well-referred comparative protocols.

Region-Based Collision Avoidance Beaconless Geographic Routing Protocol in Wireless Sensor Networks

PubMed Central

Lee, JeongCheol; Park, HoSung; Kang, SeokYoon; Kim, Ki-Il

2015-01-01

Due to the lack of dependency on beacon messages for location exchange, the beaconless geographic routing protocol has attracted considerable attention from the research community. However, existing beaconless geographic routing protocols are likely to generate duplicated data packets when multiple winners in the greedy area are selected. Furthermore, these protocols are designed for a uniform sensor field, so they cannot be directly applied to practical irregular sensor fields with partial voids. To prevent the failure of finding a forwarding node and to remove unnecessary duplication, in this paper, we propose a region-based collision avoidance beaconless geographic routing protocol to increase forwarding opportunities for randomly-deployed sensor networks. By employing different contention priorities into the mutually-communicable nodes and the rest of the nodes in the greedy area, every neighbor node in the greedy area can be used for data forwarding without any packet duplication. Moreover, simulation results are given to demonstrate the increased packet delivery ratio and shorten end-to-end delay, rather than well-referred comparative protocols. PMID:26057037

Wireless Avionics Packet to Support Fault Tolerance for Flight Applications

NASA Technical Reports Server (NTRS)

Block, Gary L.; Whitaker, William D.; Dillon, James W.; Lux, James P.; Ahmad, Mohammad

2009-01-01

In this protocol and packet format, data traffic is monitored by all network interfaces to determine the health of transmitter and subsystems. When failures are detected, the network inter face applies its recover y policies to provide continued service despite the presence of faults. The protocol, packet format, and inter face are independent of the data link technology used. The current demonstration system supports both commercial off-the-shelf wireless connections and wired Ethernet connections. Other technologies such as 1553 or serial data links can be used for the network backbone. The Wireless Avionics packet is divided into three parts: a header, a data payload, and a checksum. The header has the following components: magic number, version, quality of service, time to live, sending transceiver, function code, payload length, source Application Data Interface (ADI) address, destination ADI address, sending node address, target node address, and a sequence number. The magic number is used to identify WAV packets, and allows the packet format to be updated in the future. The quality of service field allows routing decisions to be made based on this value and can be used to route critical management data over a dedicated channel. The time to live value is used to discard misrouted packets while the source transceiver is updated at each hop. This information is used to monitor the health of each transceiver in the network. To identify the packet type, the function code is used. Besides having a regular data packet, the system supports diagnostic packets for fault detection and isolation. The payload length specifies the number of data bytes in the payload, and this supports variable-length packets in the network. The source ADI is the address of the originating interface. This can be used by the destination application to identify the originating source of the packet where the address consists of a subnet, subsystem class within the subnet, a subsystem unit, and the local ADI number. The destination ADI is used to route the packet to its ultimate destination. At each hop, the sending interface uses the destination address to determine the next node for the data. The sending node is the node address of the interface that is broadcasting the packet. This field is used to determine the health of the subsystem that is sending the packet. In the case of a packet that traverses several intermediate nodes, it may be the node address of the intermediate node. The target node is the node address of the next hop for the packet. It may be an intermediate node, or the final destination for the packet. The sequence number is used to identify duplicate packets. Because each interface has multiple transceivers, the same packet will appear at both receivers. The sequence number allows the interface to correlate the reception and forward a single, unique packet for additional processing. The subnet field allows data traffic to be partitioned into segregated local networks to support large networks while keeping each subnet at a manageable size. This also keeps the routing table small enough so routing can be done by a simple table lookup in an FPGA device. The subsystem class identifies members of a set of redundant subsystems, and, in a hot standby configuration, all members of the subsystem class will receive the data packets. Only the active subsystem will generate data traffic. Specific units in a class of redundant units can be identified and, if the hot standby configuration is not used, packets will be directed to a specific subsystem unit.

Jump state estimation with multiple sensors with packet dropping and delaying channels

NASA Astrophysics Data System (ADS)

Dolz, Daniel; Peñarrocha, Ignacio; Sanchis, Roberto

2016-03-01

This work addresses the design of a state observer for systems whose outputs are measured through a communication network. The measurements from each sensor node are assumed to arrive randomly, scarcely and with a time-varying delay. The proposed model of the plant and the network measurement scenarios cover the cases of multiple sensors, out-of-sequence measurements, buffered measurements on a single packet and multirate sensor measurements. A jump observer is proposed that selects a different gain depending on the number of periods elapsed between successfully received measurements and on the available data. A finite set of gains is pre-calculated offline with a tractable optimisation problem, where the complexity of the observer implementation is a design parameter. The computational cost of the observer implementation is much lower than in the Kalman filter, whilst the performance is similar. Several examples illustrate the observer design for different measurement scenarios and observer complexity and show the achievable performance.