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1

Secure End-to-End Communication over GSM and PSTN Networks  

Microsoft Academic Search

GSM (Global System for Mobiles) is the most widely spread mobile communication system in the world. An important objective in mobile communication systems is secure speech communication. GSM suffers from various security weaknesses. The GSM voice traffic is secure outside the core network but it has no security over the core network. This system can be made thoroughly secure by

Saad Islam; Fatima Ajmal; Salman Ali; Jawad Zahid; Adnan Rashdi

2009-01-01

2

Military GSM.  

National Technical Information Service (NTIS)

Military GSM (MGSM) is a term defined here to mean the redesigned and adapted use of civil Global System for Mobile communications (GSM) technology within military scenarios and isolated deployments. MGSM is a first step towards bringing the future benefi...

V. P. Scaffidi

1994-01-01

3

REAL-TIME END-TO-END SECURE VOICE COMMUNICATIONS OVER GSM VOICE CHANNEL  

Microsoft Academic Search

GSM is the most wide spread mobile communications sys- tem in the world. However the security of the GSM voice traffic is not guaranteed especially over the core network. It is highly desirable to have end-to-end secure communica- tions over the GSM voice channel. In order to achieve end- to-end security, speech must be encrypted before it enters the GSM

N. N. Katugampala; K. T. Al-Naimi; S. Villette; A. M. Kondoz

4

Long-term exposure to mobile communication radiation: an analysis of time-variability of electric field level in GSM900 downlink channels.  

PubMed

Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication downlink band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment. PMID:22908352

Miclaus, Simona; Bechet, Paul; Gheorghevici, Marius

2013-04-01

5

Experimental and numerical assessment of low-frequency current distributions from UMTS and GSM mobile phones.  

PubMed

The evaluation of the exposure from mobile communication devices requires consideration of electromagnetic fields (EMFs) over a broad frequency range from dc to GHz. Mobile phones in operation have prominent spectral components in the low-frequency (LF) and radio-frequency (RF) ranges. While the exposure to RF fields from mobile phones has been comprehensively assessed in the past, the LF fields have received much less attention. In this study, LF fields from mobile phones are assessed experimentally and numerically for the global system for mobile (GSM) and universal mobile telecommunications system (UMTS) communication systems and conclusions about the global (LF and RF) EMF exposure from both systems are drawn. From the measurements of the time-domain magnetic fields, it was found that the contribution from the audio signal at a normal speech level, i.e., -16 dBm0, is the same order of magnitude as the fields induced by the current bursts generated from the implementation of the GSM communication system at maximum RF output level. The B-field induced by currents in phones using the UMTS is two orders of magnitude lower than that induced by GSM. Knowing that the RF exposure from the UMTS is also two orders of magnitude lower than from GSM, it is now possible to state that there is an overall reduction of the exposure from this communication system. PMID:24216774

Gosselin, Marie-Christine; Kühn, Sven; Kuster, Niels

2013-12-01

6

Experimental and numerical assessment of low-frequency current distributions from UMTS and GSM mobile phones  

NASA Astrophysics Data System (ADS)

The evaluation of the exposure from mobile communication devices requires consideration of electromagnetic fields (EMFs) over a broad frequency range from dc to GHz. Mobile phones in operation have prominent spectral components in the low-frequency (LF) and radio-frequency (RF) ranges. While the exposure to RF fields from mobile phones has been comprehensively assessed in the past, the LF fields have received much less attention. In this study, LF fields from mobile phones are assessed experimentally and numerically for the global system for mobile (GSM) and universal mobile telecommunications system (UMTS) communication systems and conclusions about the global (LF and RF) EMF exposure from both systems are drawn. From the measurements of the time-domain magnetic fields, it was found that the contribution from the audio signal at a normal speech level, i.e., -16 dBm0, is the same order of magnitude as the fields induced by the current bursts generated from the implementation of the GSM communication system at maximum RF output level. The B-field induced by currents in phones using the UMTS is two orders of magnitude lower than that induced by GSM. Knowing that the RF exposure from the UMTS is also two orders of magnitude lower than from GSM, it is now possible to state that there is an overall reduction of the exposure from this communication system.

Gosselin, Marie-Christine; Kühn, Sven; Kuster, Niels

2013-12-01

7

Dual-band miniaturized microstrip fractal antenna for a small GSM 1800 + UMTS mobile handset  

Microsoft Academic Search

A novel microstrip GSM1800 + UMTS dual-band antenna based on a Koch fractal shaped patch element is presented. The antenna has been developed to be used in small handsets of future multi-standard mobile communication systems. The fractal miniaturization technique has been combined with a patch inverted F antenna (PIFA) structure. The effect of a small ground plane has been taken

J. Guterman; A. A. Moreira; C. Peixerio

2004-01-01

8

Histopathological examinations of rat brains after long-term exposure to GSM900 mobile phone radiation  

Microsoft Academic Search

In order to mimic the real life situation, with often life-long exposure to the electromagnetic fields emitted by mobile phones, we have investigated in a rat model the effects of repeated exposures under a long period to Global System for Mobile Communication-900MHz (GSM-900) radiation. Out of a total of 56 rats, 32 were exposed once weekly in a 2-h period,

Gustav Grafström; Henrietta Nittby; Arne Brun; Lars Malmgren; Bertil R. R. Persson; Leif G. Salford; Jacob Eberhardt

2008-01-01

9

Positioning GSM telephones  

Microsoft Academic Search

Due to the FCC requirement that operators of mobile communications networks be able to accurately locate mobile callers requesting emergency assistance via 911 by the year 2001, there has been a lot of activity among cellular and PCS providers to examine cellular positioning options. This article examines positioning solutions for the GSM group of standards. Worldwide deployment of GSM systems

Christopher Drane; Malcolm Macnaughtan; Craig Scott

1998-01-01

10

The use of SS7 and GSM to support high density personal communications  

Microsoft Academic Search

The authors present an organized method for quantifying the Signaling System 7 (SS7) traffic load associated with terminal mobility when the pan-European standard GSM is used for personal communication networks (PCNs). They use CCIR parameters for an extremely dense, outdoor center-city pedestrian environment to illustrate the possible heavy signaling load. Using the example parameters, the additional SS7 network burden is

KATHLEEN S. MEIER-HELLSTERN; EDUARDO ALONSO; DOUGLAS R. O'NEIL

1992-01-01

11

Electromagnetic interference of GSM mobile phones with the implantable deep brain stimulator, ITREL-III  

PubMed Central

Background The purpose was to investigate mobile phone interference with implantable deep brain stimulators by means of 10 different 900 Mega Hertz (MHz) and 10 different 1800 MHz GSM (Global System for Mobile Communications) mobile phones. Methods All tests were performed in vitro using a phantom especially developed for testing with deep brain stimulators. The phantom was filled with liquid phantom materials simulating brain and muscle tissue. All examinations were carried out inside an anechoic chamber on two implants of the same type of deep brain stimulator: ITREL-III from Medtronic Inc., USA. Results Despite a maximum transmitted peak power of mobile phones of 1 Watt (W) at 1800 MHz and 2 W at 900 MHz respectively, no influence on the ITREL-III was found. Neither the shape of the pulse form changed nor did single pulses fail. Tests with increased transmitted power using CW signals and broadband dipoles have shown that inhibition of the ITREL-III occurs at frequency dependent power levels which are below the emissions of GSM mobile phones. The ITREL-III is essentially more sensitive at 1800 MHz than at 900 MHz. Particularly the frequency range around 1500 MHz shows a very low interference threshold. Conclusion These investigations do not indicate a direct risk for ITREL-III patients using the tested GSM phones. Based on the interference levels found with CW signals, which are below the mobile phone emissions, we recommend similar precautions as for patients with cardiac pacemakers: 1. The phone should be used at the ear at the opposite side of the implant and 2. The patient should avoid carrying the phone close to the implant.

Kainz, Wolfgang; Alesch, Francois; Chan, Dulciana Dias

2003-01-01

12

Nerve cell damage in mammalian brain after exposure to microwaves from GSM mobile phones.  

PubMed Central

The possible risks of radio-frequency electromagnetic fields for the human body is a growing concern for our society. We have previously shown that weak pulsed microwaves give rise to a significant leakage of albumin through the blood-brain barrier. In this study we investigated whether a pathologic leakage across the blood-brain barrier might be combined with damage to the neurons. Three groups each of eight rats were exposed for 2 hr to Global System for Mobile Communications (GSM) mobile phone electromagnetic fields of different strengths. We found highly significant (p< 0.002) evidence for neuronal damage in the cortex, hippocampus, and basal ganglia in the brains of exposed rats.

Salford, Leif G; Brun, Arne E; Eberhardt, Jacob L; Malmgren, Lars; Persson, Bertil R R

2003-01-01

13

The Global System for Mobile Communications Short Message Service  

Microsoft Academic Search

This tutorial presents an overview of the Global System for Mobile Communications Short Message Service from the viewpoint of implementing new telematic services. The SMS offers the users of GSM networks the ability to exchange alphanumeric messages up to the limit of 160 characters. The tutorial is motivated by an acute absence of research publications in this field. The information

C. Peersman; S. Cvetkovic; P. Griffiths; H. Spear

2000-01-01

14

Effects of electromagnetic fields emitted by mobile phones (GSM 900 and WCDMA/UMTS) on the macrostructure of sleep.  

PubMed

In the present double-blind, randomized, sham-controlled cross-over study, possible effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) 900 and Wideband Code-Division Multiple Access (WCDMA)/Universal Mobile Telecommunications System (UMTS) cell-phones on the macrostructure of sleep were investigated in a laboratory environment. An adaptation night, which served as screening night for sleep disorders and as an adjustment night to the laboratory environment, was followed by 9 study nights (separated by a 2-week interval) in which subjects were exposed to three exposure conditions (sham, GSM 900 and WCDMA/UMTS). The sample comprised 30 healthy male subjects within the age range 18-30 years (mean ± standard deviation: 25.3 ± 2.6 years). A cell-phone usage at maximum radio frequency (RF) output power was simulated and the transmitted power was adjusted in order to approach, but not to exceed, the specific absorption rate (SAR) limits of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines for general public exposure (SAR(10g) = 2.0 W kg(-1)). In this study, possible effects of long-term (8 h) continuous RF exposure on the central nervous system were analysed during sleep, because sleep is a state in which many confounding intrinsic and extrinsic factors (e.g. motivation, personality, attitude) are eliminated or controlled. Thirteen of 177 variables characterizing the initiation and maintenance of sleep in the GSM 900 and three in the WCDMA exposure condition differed from the sham condition. The few significant results are not indicative of a negative impact on sleep architecture. From the present results there is no evidence for a sleep-disturbing effect of GSM 900 and WCDMA exposure. PMID:20561179

Danker-Hopfe, Heidi; Dorn, Hans; Bahr, Achim; Anderer, Peter; Sauter, Cornelia

2011-03-01

15

GSM mobile phone radiation suppresses brain glucose metabolism  

PubMed Central

We investigated the effects of mobile phone radiation on cerebral glucose metabolism using high-resolution positron emission tomography (PET) with the 18F-deoxyglucose (FDG) tracer. A long half-life (109?minutes) of the 18F isotope allowed a long, natural exposure condition outside the PET scanner. Thirteen young right-handed male subjects were exposed to a pulse-modulated 902.4?MHz Global System for Mobile Communications signal for 33?minutes, while performing a simple visual vigilance task. Temperature was also measured in the head region (forehead, eyes, cheeks, ear canals) during exposure. 18F-deoxyglucose PET images acquired after the exposure showed that relative cerebral metabolic rate of glucose was significantly reduced in the temporoparietal junction and anterior temporal lobe of the right hemisphere ipsilateral to the exposure. Temperature rise was also observed on the exposed side of the head, but the magnitude was very small. The exposure did not affect task performance (reaction time, error rate). Our results show that short-term mobile phone exposure can locally suppress brain energy metabolism in humans.

Kwon, Myoung Soo; Vorobyev, Victor; Kannala, Sami; Laine, Matti; Rinne, Juha O; Toivonen, Tommi; Johansson, Jarkko; Teras, Mika; Lindholm, Harri; Alanko, Tommi; Hamalainen, Heikki

2011-01-01

16

How to Turn a GSM SIM into a Web Server Projecting Mobile Trust onto the World Wide Web  

Microsoft Academic Search

We describe the WebSIM, an approach that integrates GSM SIMs into the Internet. The underlying idea is to implement a Web Server inside a SIM, and to allow for transparent access to it from the Internet. The contribution of our approach is that a SIM, which is currently a security module (smart card) fitted in a GSM mobile phone, becomes

Scott Guthery; Roger Kehr; Joachim Posegga

2000-01-01

17

Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice.  

PubMed

The purpose of this study using a total of 1170 B6C3F1 mice was to detect and evaluate possible carcinogenic effects in mice exposed to radio-frequency-radiation (RFR) from Global System for Mobile Communication (GSM) and Digital Personal Communications System (DCS) handsets as emitted by handsets operating in the center of the communication band, that is, at 902 MHz (GSM) and 1747 MHz (DCS). Restrained mice were exposed for 2 h per day, 5 days per week over a period of 2 years to three different whole-body averaged specific absorption rate (SAR) levels of 0.4, 1.3, 4.0 mW/g bw (SAR), or were sham exposed. Regarding the organ-related tumor incidence, pairwise Fisher's test did not show any significant increase in the incidence of any particular tumor type in the RF exposed groups as compared to the sham exposed group. Interestingly, while the incidences of hepatocellular carcinomas were similar in EMF and sham exposed groups, in both studies the incidences of liver adenomas in males decreased with increasing dose levels; the incidences in the high dose groups were statistically significantly different from those in the sham exposed groups. Comparison to published tumor rates in untreated mice revealed that the observed tumor rates were within the range of historical control data. In conclusion, the present study produced no evidence that the exposure of male and female B6C3F1 mice to wireless GSM and DCS radio frequency signals at a whole body absorption rate of up to 4.0 W/kg resulted in any adverse health effect or had any cumulative influence on the incidence or severity of neoplastic and non-neoplastic background lesions, and thus the study did not provide any evidence of RF possessing a carcinogenic potential. PMID:17019729

Tillmann, Thomas; Ernst, Heinrich; Ebert, Sven; Kuster, Niels; Behnke, Wolfgang; Rittinghausen, Susanne; Dasenbrock, Clemens

2007-04-01

18

Advanced Communications Technology: Mobile Communications Requirements Report.  

National Technical Information Service (NTIS)

The Coast Guard's mobile communications requirements will outstrip existing system capabilities, available capacity, and affordability by the late 1990s. This will require changes in the mix of mobile communications equipment and services used by operatio...

1998-01-01

19

Autonomous mobile communication relays  

NASA Astrophysics Data System (ADS)

Maintaining a solid radio communication link between a mobile robot entering a building and an external base station is a well-recognized problem. Modern digital radios, while affording high bandwidth and Internet-protocol-based automatic routing capabilities, tend to operate on line-of-sight links. The communication link degrades quickly as a robot penetrates deeper into the interior of a building. This project investigates the use of mobile autonomous communication relay nodes to extend the effective range of a mobile robot exploring a complex interior environment. Each relay node is a small mobile slave robot equipped with sonar, ladar, and 802.11b radio repeater. For demonstration purposes, four Pioneer 2-DX robots are used as autonomous mobile relays, with SSC-San Diego's ROBART III acting as the lead robot. The relay robots follow the lead robot into a building and are automatically deployed at various locations to maintain a networked communication link back to the remote operator. With their on-board external sensors, they also act as rearguards to secure areas already explored by the lead robot. As the lead robot advances and RF shortcuts are detected, relay nodes that become unnecessary will be reclaimed and reused, all transparent to the operator. This project takes advantage of recent research results from several DARPA-funded tasks at various institutions in the areas of robotic simulation, ad hoc wireless networking, route planning, and navigation. This paper describes the progress of the first six months of the project.

Nguyen, Hoa G.; Everett, Hobart R.; Manouk, Narek; Verma, Ambrish

2002-07-01

20

Simulation of pulsed ELF magnetic fields generated by GSM mobile phone handsets for human electromagnetic bioeffects research.  

PubMed

Human provocation studies that investigate the effects of Global System for Mobiles (GSM) communication systems on the brain have focused on Radio Frequency (RF) exposure. We wish to further extend such study by investigating the effect of both RF and Extremely Low Frequency (ELF) field exposure, the latter generated by the GSM handset's battery switching. The use of a commercial handset as an exposure source for such investigations is problematic for a number of reasons and therefore a simulated exposure source, capable of producing both RF and ELF components of exposure, is desirable. As a first step in developing such a source, we have quantified and characterized the ELF field from several commercial handsets (the RF characteristics being already well understood). Through experimental measurement we deduce that these fields can be sufficiently simulated by a 9 mm radius loop residing 10 mm beneath the front surface of the handset device and carrying enough current to generate peak fields of 25 microT at the surface of the handset. PMID:18946983

Perentos, N; Iskra, S; McKenzie, R J; Cosi, I

2008-09-01

21

Assessment of RF radiation levels in the vicinity of 60 GSM mobile phone base stations in Iran.  

PubMed

Increasing development of mobile communication infrastructure while enhancing availability of the technology raises concerns among the public, who see more cell towers erected each day, about possible health effects of electromagnetic radiations. Thereon, a survey of radio-frequency radiation from 60 GSM base stations was carried out in Tehran, Iran at several places mostly located in major medical and educational centres. Measurements were performed at 15 locations near each base station site, i.e. 900 locations in total. Since there are other RF radiation sources such as broadcasting services whose carrier frequencies are <3 GHz, the whole band of 27 MHz to 3 GHz has been assessed for hazardous exposures as well. The results were compared with the relevant guideline of International Commission on Non-Ionising Radiation Protection and that of Iran, confirming radiation exposure levels being satisfactorily below defined limits and non-detrimental. PMID:23222504

Nayyeri, Vahid; Hashemi, Seyed Mohammad; Borna, Maryam; Jalilian, Hamid-Reza; Soleimani, Mohammad

2013-07-01

22

Fade-Free Mobile Communication  

NASA Technical Reports Server (NTRS)

Scheme for mobile communication reduces multipath fading and interference between adjacent channels. Proposed communication system lends itself to almost completely digital implementation, eliminating costly and bulky crystal filters. Scheme suitable for satellite-aided or terrestrial mobile communication, including cellular mobile telephony, at frequencies in 150-to-900-MHz range.

Stevenson, C. R.

1986-01-01

23

Life Cycle Assessment of the Mobile Communication System UMTS: Towards Eco-efficient Systems (12 pp)  

Microsoft Academic Search

Goal, Scope and Background   Goal of this study is an evaluation of the environmental sustainability of the UMTS mobile communication system in Switzerland\\u000a by means of a Life Cycle Assessment (LCA). A baseline environmental impact profile across the full life cycle of the UMTS\\u000a (Universal Mobile Telecommunication System) and its predecessor, the GSM (Global System for Mobile Communication) is presented.

Mireille Faist Emmenegger; Rolf Frischknecht; Markus Stutz; Michael Guggisberg; Res Witschi; Tim Otto

2006-01-01

24

Dosimetric assessment of an exposure system for simulating GSM and WCDMA mobile phone usage.  

PubMed

An exposure system for investigation of volunteers during simulated GSM and WCDMA mobile phone usage has been designed. The apparatus consists of a dual band antenna with enhanced carrying properties that enables exposure for at least 8 h a day. For GSM a 900 MHz pulse modulated carrier was used. The QPSK modulated WCDMA signal at 1966 MHz comprises a power control scheme, which was designed for investigations of biological effects. The dosimetry of the exposure system by measurements and calculations is described in detail within this paper. It is shown that the SAR distribution of the antenna shows similar characteristics to mobile phones with an integrated antenna. The 10 g averaged localized SAR, normalized to an antenna input power of 1 W and measured in the flat phantom area of the SAM phantom, amounts to 7.82 mW/g (900 MHz) and 10.98 mW/g (1966 MHz). The simulated SAR(10 g) in the Visible Human head model agrees with measured values to within 20%. A variation of the antenna rotation angle results in an SAR(10 g) change below 17%. The increase of the antenna distance by 2 mm with respect to the human head leads to an SAR(10 g) change of 9%. PMID:16557502

Bahr, Achim; Dorn, Hans; Bolz, Thomas

2006-05-01

25

Effects of exposure to electromagnetic fields emitted by GSM 900 and WCDMA mobile phones on cognitive function in young male subjects.  

PubMed

Results of studies on the possible effects of electromagnetic fields emitted by mobile phones on cognitive functions are contradictory, therefore, possible effects of long-term (7?h?15?min) electromagnetic field (EMF) exposure to handset-like signals of Global System for Mobile Communications (GSM) 900 and Wideband Code-Division Multiple Access (WCDMA) on attention and working memory were studied. The sample comprised 30 healthy male subjects (mean?±?SD: 25.3?±?2.6?years), who were tested on nine study days in which they were exposed to three exposure conditions (sham, GSM 900 and WCDMA) in a randomly assigned and balanced order. All tests were presented twice (morning and afternoon) on each study day within a fixed timeframe. Univariate comparisons revealed significant changes when subjects were exposed to GSM 900 compared to sham, only in the vigilance test. In the WCDMA exposure condition, one parameter in the vigilance and one in the test on divided attention were altered compared to sham. Performance in the selective attention test and the n-back task was not affected by GSM 900 or WCDMA exposure. Time-of-day effects were evident for the tests on divided and selective attention, as well as for working memory. After correction for multiple testing, only time-of-day effects remained significant in two tests, resulting in faster reactions in the afternoon trials. The results of the present study do not provide any evidence of an EMF effect on human cognition, but they underline the necessity to control for time of day. PMID:21365662

Sauter, Cornelia; Dorn, Hans; Bahr, Achim; Hansen, Marie-Luise; Peter, Anita; Bajbouj, Malek; Danker-Hopfe, Heidi

2011-04-01

26

Advanced Communications Technology: Mobile Communications Requirements Report  

NASA Astrophysics Data System (ADS)

The Coast Guard's mobile communications requirements will outstrip existing system capabilities, available capacity, and affordability by the late 1990s. This will require changes in the mix of mobile communications equipment and services used by operational units. New commercial mobile satellite services are available now, with many others arriving on the market between 1998 and 2003. These new services present unique opportunities to satisfy mission requirements, reduce investment in communications infrastructure, and realize more costeffective communications services. The Coast Guard Research and Development Center (R&DC) has undertaken an effort to identify and evaluate current and emerging satellite services that may be used to satisfy Coast Guard mobile communications requirements. As part of this effort, Anteon Corporation has been tasked by R&DC to collect the mobile communications functional requirements that have been identified by program managers. Anteon analysts have reviewed the Government Furnished Information (GFI) and researched other related documentation to identify and collect the requirements that may be used to describe the needed operating environment. Anteon analysts assessed the functional requirements to develop system requirements that describe the features that a communications system must provide to support the functional requirements. This report presents the current and projected Coast Guard mobile communications system requirements.

1998-05-01

27

Microwaves from GSM Mobile Telephones Affect 53BP1 and ?-H2AX Foci in Human Lymphocytes from Hypersensitive and Healthy Persons  

PubMed Central

The data on biologic effects of nonthermal microwaves (MWs) from mobile telephones are diverse, and these effects are presently ignored by safety standards of the International Commission for Non-Ionizing Radiation Protection (ICNIRP). In the present study, we investigated effects of MWs of Global System for Mobile Communication (GSM) at different carrier frequencies on human lymphocytes from healthy persons and from persons reporting hypersensitivity to electromagnetic fields (EMFs). We measured the changes in chromatin conformation, which are indicative of stress response and genotoxic effects, by the method of anomalous viscosity time dependence, and we analyzed tumor suppressor p53-binding protein 1 (53BP1) and phosphorylated histone H2AX (?-H2AX), which have been shown to colocalize in distinct foci with DNA double-strand breaks (DSBs), using immunofluorescence confocal laser microscopy. We found that MWs from GSM mobile telephones affect chromatin conformation and 53BP1/?-H2AX foci similar to heat shock. For the first time, we report here that effects of MWs from mobile telephones on human lymphocytes are dependent on carrier frequency. On average, the same response was observed in lymphocytes from hypersensitive and healthy subjects.

Markova, Eva; Hillert, Lena; Malmgren, Lars; Persson, Bertil R. R.; Belyaev, Igor Y.

2005-01-01

28

Mobile and wireless communications networks  

Microsoft Academic Search

The purpose of this tutorial is to highlight several aspects of mobile and wireless communications networks. A first part presents a brief overview of the market and technology evolution. The second part is devoted to the radio propagation channel characteristics. In the third section, we present an overview of the transmission techniques related to the definition of new mobile communications

Ghais El Zein

2004-01-01

29

End-to-end security for GSM users [speech coding method  

Microsoft Academic Search

Mobile telecommunications such as GSM are now well established globally and users rely heavily on the convenient communications it provides. The level of security provided by GSM is superior to its predecessors and is more than adequate for the majority of users. However, some users in the areas of government, defence or business require additional security over and above that

A. B. Rekha; B. Urnadevi; Y. Solanke; S. R. Kolli

2005-01-01

30

A large-scale measurement of electromagnetic fields near GSM base stations in Guangxi, China for risk communication.  

PubMed

Radiofrequency (RF) electromagnetic field (EMF) exposure from wireless telecommunication base station antennae can lead to debates, conflicts or litigations among the adjacent residents if inappropriately managed. This paper presents a measurement campaign for the GSM band EMF exposure in the vicinity of 827 base station sites (totally 6207 measurement points) in Guangxi, China. Measurement specifications are designed for risk communication with the residents who previously complained of over-exposure. The EMF power densities with the global positioning system coordinate at each measured point were recorded. Compliance with the International Commission on Non-Ionizing Radiation Protection guidelines and Chinese environmental EMF safety standards was studied. The results show that the GSM band EMF level near the base stations is very low. The measurement results and the EMF risk communication procedures positively influence public perception of the RF EMF exposure from the base stations and promote the exchange of EMF exposure-related knowledge. PMID:23179188

Wu, Tongning; Shao, Qing; Yang, Lei; Qi, Dianyuan; Lin, Jun; Lin, Xiaojun; Yu, Zongying

2013-06-01

31

Mobile Communication Via Satellite  

NASA Technical Reports Server (NTRS)

System mixes real-time and delayed-transmission channels. Combination of L-band and SHF links connect fixed and mobile equipment on ground to satellite relay. Software and hardware architecture conforms structure of open-system-interconnection model suggested by International Standards Organization.

Yan, Tsun-Yee; Naderi, Firouz M.

1988-01-01

32

Improving the efficiency of measurement procedures for assessing human exposure in the vicinity of mobile phone (GSM/DCS/UMTS) base stations.  

PubMed

Standards stipulate 6-min time interval of averaging for measurements of radio-frequency electromagnetic fields to assess human exposure to non-ionising radiation. Having in mind the base stations of public land mobile systems, the time interval defined in such a way noticeably limits the number of measuring points in practical applications. In this paper, based on the results of measurements in the vicinity of a multisystem base station (Global System for Mobile Communications [GSM], Digital Communication System [DCS] and Universal Mobile Telecommunications System [UMTS]), it was shown that the measurement process can be significantly accelerated by using shorter time intervals of averaging--15 s, 30 s and 1 min. It was found that measurement results differed from the 6-min root-mean-square mean by 10.5 %, 15.9 and 19 %, respectively, while the uncertainty of the measurements was increased by 3.0 %, 3.8 and 4.4 %, respectively. Shorter time-averaging intervals would reduce the total duration of the exposure assessment survey, while not compromising too much on measurement quality. PMID:21778156

Neskovic, N; Koprivica, M; Neskovic, A; Paunovic, G

2012-04-01

33

Trends in mobile satellite communication  

NASA Technical Reports Server (NTRS)

Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

1993-01-01

34

Medical reliable network using concatenated channel codes through GSM network.  

PubMed

Although the 4(th) generation (4G) of global mobile communication network, i.e. Long Term Evolution (LTE) coexisting with the 3(rd) generation (3G) has successfully started; the 2(nd) generation (2G), i.e. Global System for Mobile communication (GSM) still playing an important role in many developing countries. Without any other reliable network infrastructure, GSM can be applied for tele-monitoring applications, where high mobility and low cost are necessary. A core objective of this paper is to introduce the design of a more reliable and dependable Medical Network Channel Code system (MNCC) through GSM Network. MNCC design based on simple concatenated channel code, which is cascade of an inner code (GSM) and an extra outer code (Convolution Code) in order to protect medical data more robust against channel errors than other data using the existing GSM network. In this paper, the MNCC system will provide Bit Error Rate (BER) equivalent to the BER for medical tele monitoring of physiological signals, which is 10(-5) or less [1]. The performance of the MNCC has been proven and investigated using computer simulations under different channels condition such as, Additive White Gaussian Noise (AWGN), Rayleigh noise and burst noise. Generally the MNCC system has been providing better performance as compared to GSM. PMID:24110797

Ahmed, Emtithal; Kohno, Ryuji

2013-01-01

35

Comparison of biological effects between continuous and intermittent exposure to GSM900MHz mobile phone radiation: Detection of apoptotic cell-death features  

Microsoft Academic Search

In the present study we used a 6-min daily exposure of dipteran flies, Drosophila melanogaster, to GSM-900MHz (Global System for Mobile Telecommunications) mobile phone electromagnetic radiation (EMR), to compare the effects between the continuous and four different intermittent exposures of 6min total duration, and also to test whether intermittent exposure provides any cumulative effects on the insect's reproductive capacity as

Evangelia D. Chavdoula; Dimitris J. Panagopoulos; Lukas H. Margaritis

2010-01-01

36

Communications Systems for Mobile Robotics  

SciTech Connect

Performance Confirmation is the activity by which the Yucca Mountain Project confirms that the engineered and natural containment barriers of this national nuclear waste repository are performing as predicted, so that an eventual decision to close the repository can be made. This activity involves systems that must be inspected and, in some cases, serviced by mobile robots. This paper discusses systems for underground mobile robot communications, including requirements, environments, options, issues, and down-select criteria. We reviewed a variety of systems, including Slotted Waveguide, Powerline Carrier, Leaky Feeder, Photonic Bandgap Fiber, Free-Space Optics, Millimeter Waves, Terahertz Systems, and RF Systems (including IEEE 802.11 a,b, and g, and Ultra-Wideband radio).

Futterman, J A; Pao, H

2003-12-08

37

Application of Mobile Router to Military Communications.  

National Technical Information Service (NTIS)

Cisco Systems and NASA Glenn Research Center under a NASA Space Act Agreement have been performing joint networking research to apply Internet technologies and protocols to space-based communications. During this time, Cisco Systems developed the mobile-r...

D. H. Stewart W. D. Ivancic T. L. Bell B. A. Kachmar D. Shell K. Leung

2002-01-01

38

Antennas for mobile satellite communications  

NASA Astrophysics Data System (ADS)

A NASA sponsored program, called the Mobile Satellite (MSAT) system, has prompted the development of several innovative antennas at L-band frequencies. In the space segment of the MSAT system, an efficient, light weight, circularly polarized microstrip array that uses linearly polarized elements was developed as a multiple beam reflector feed system. In the ground segment, a low-cost, low-profile, and very efficient microstrip Yagi array was developed as a medium-gain mechanically steered vehicle antenna. Circularly shaped microstrip patches excited at higher-order modes were also developed as low-gain vehicle antennas. A more recent effort called for the development of a 20/30 GHz mobile terminal antenna for future-generation mobile satellite communications. To combat the high insertion loss encountered at 20/30 GHz, series-fed Monolithic Microwave Integrated Circuit (MMIC) microstrip array antennas are currently being developed. These MMIC arrays may lead to the development of several small but high-gain Ka-band antennas for the Personal Access Satellite Service planned for the 2000s.

Huang, John

1991-12-01

39

Satellite communication and navigation for mobile users  

NASA Technical Reports Server (NTRS)

Efforts made to utilize space technology for solving communication and navigation problems faced by mobile users in earth orientated situations are outlined. Applications include transoceanic airline communications, reliable long range ship-shore communications, emergency communications in regions with rough terrain, and military operations.

Bernstein, S. L.

1972-01-01

40

Mobile IP LAN for ARL Mobile Communications/Networking Testbed.  

National Technical Information Service (NTIS)

This report describes the protocol and implementation of a Mobile IP (Internet protocol) LAN (local area network) for the LAN of the U.S. Army Research Laboratory (ARL) Mobile Communications/Networking Testbed. Mobile IP LAN protocol is developed to allow...

B. B. Luu

2001-01-01

41

Spread spectrum mobile radio communications  

NASA Astrophysics Data System (ADS)

This report is made up of two parts. In the first part we present additional results on the performance of random access protocols for mobile packet radio networks. The effect of three different types of diversity reception in Nakagami fading environment on the channel throughput and the average packet delay of nonpersistent carrier sense multiple access (NPCSMA) protocol is considered. Expressions for the probability of packet error with diversity receptions are newly obtained for both independent and correlated diversity branches. A noncoherent frequency shift keying modulation scheme is assumed. In the second part a comprehensive study of the problem of synchronization over fading dispersive channels is presented. Synchronization is a fundamental problem in digital communications as used in mobile radio. In the first chapter, we consider a simple binary detection problem. The effect of receiver mismatch is investigated. A closed form expression for the probability of false alarm and probability of detection are given, also a set of curves are provided to demonstrate the amount of degradation for under-spread channels with some special scattering.

Gupta, S. C.; Soliman, S. S.

1987-02-01

42

Mobile communication security controllers an evaluation paper  

Microsoft Academic Search

Cellular communication via a traditional mobile handset is a ubiquitous part of modern life and as device technology and network performance continues to advance, it becomes possible for laptop computers, Personal Digital Assistants [PDAs; Note abbreviations will be shown in square brackets to avoid confusion with references.] and even electrical meters to better exploit mobile networks for wireless communication. As

Keith E. Mayes; Konstantinos Markantonakis

2008-01-01

43

Effective Protocols for Mobile Communications and Networking  

SciTech Connect

This report examines methods of mobile communications with an emphasis on mobile computing and wireless communications. Many of the advances in communications involve the use of Internet Protocol (IP), Asynchronous Transfer Mode (ATM), and ad hoc network protocols. However, many of the advances in these protocols have been focused on wired communications. Recently much focus has been directed at advancing communication technology in the area of mobile wireless networks. This report discusses various protocols used in mobile communications and proposes a number of extensions to existing protocols. A detailed discussion is also included on desirable protocol characteristics and evaluation criteria. In addition, the report includes a discussion on several network simulation tools that maybe used to evaluate network protocols.

Espinoza, J.; Sholander, P.; Van Leeuwen, B,

1998-12-01

44

Throughput and buffer analysis for GSM General Packet Radio Service (GPRS)  

Microsoft Academic Search

The Global System for Mobile Communications (GSM) Phase 2+ standard specifies a new type of packet data service called General Packet Radio Service (GPRS). GPRS allows the dynamic allocation of bandwidth resources. Wireless channels are allocated to a mobile terminal based on its traffic demands. This results in better resource utilization compared to the circuit-based data services. In general, packet-based

Joseph Ho; Yixin Zhu; S. Madhavapeddy

1999-01-01

45

A GSM, internet and speech controlled wireless interactive home automation system  

Microsoft Academic Search

The home automation today needs to make use of the latest technological components available. In this paper, we present the design and implementation of a home automation system where communication technologies GSM (Global System for Mobile Communication), Internet, and speech recognition have been used. All these techniques are successfully merged in a single wireless home automation system. This system offers

B. Yuksekkaya; A. A. Kayalar; M. B. Tosun; M. K. Ozcan; A. Z. Alkar

2006-01-01

46

Method for Evaluation of Outage Probability on Random Access Channel in Mobile Communication Systems  

NASA Astrophysics Data System (ADS)

In order to access the cell in all mobile communication technologies a so called random-access procedure is used. For example in GSM this is represented by sending the CHANNEL REQUEST message from Mobile Station (MS) to Base Transceiver Station (BTS) which is consequently forwarded as an CHANNEL REQUIRED message to the Base Station Controller (BSC). If the BTS decodes some noise on the Random Access Channel (RACH) as random access by mistake (so- called ‘phantom RACH') then it is a question of pure coincidence which èstablishment cause’ the BTS thinks to have recognized. A typical invalid channel access request or phantom RACH is characterized by an IMMEDIATE ASSIGNMENT procedure (assignment of an SDCCH or TCH) which is not followed by sending an ESTABLISH INDICATION from MS to BTS. In this paper a mathematical model for evaluation of the Power RACH Busy Threshold (RACHBT) in order to guaranty in advance determined outage probability on RACH is described and discussed as well. It focuses on Global System for Mobile Communications (GSM) however the obtained results can be generalized on remaining mobile technologies (ie WCDMA and LTE).

Kollár, Martin

2012-05-01

47

Setup and dosimetry for exposing anaesthetised pigs in vivo to 900 MHz GSM mobile phone fields.  

PubMed

The aim of this study was a dosimetrical analysis of the setup used in the exposure of the heads of domestic pigs to GSM-modulated radio frequency electromagnetic fields (RF-EMF) at 900 MHz. The heads of pigs were irradiated with a half wave dipole using three different exposure routines; short bursts of 1-3 s at two different exposure levels and a continuous 10-min exposure. The electroencephalogram (EEG) was registered continuously during the exposures to search for RF-EMF originated changes. The dosimetry was based on simulations with the anatomical heterogeneous numerical model of the pig head. The simulation results were validated by experimental measurements with the exposure dipole and a homogeneous liquid phantom resembling the pig head. The specific absorption rate (SAR), defined as a maximum average over 10 g tissue mass (SAR(10g)), was 7.3 W/kg for the first set of short bursts and 31 W/kg for the second set of short bursts. The SAR(10g) in the continuous 10-min exposure was 31 W/kg. The estimated uncertainty for the dosimetry was +/-25% (K = 2). PMID:18247366

Toivonen, Tommi; Toivo, Tim; Pitkäaho, Risto; Puranen, Lauri; Silfverhuth, Minna; Mennander, Ari; Hannula, Markus; Hyttinen, Jari; Jokela, Kari

2008-07-01

48

Proceedings of the Workshop on Advanced Network and Technology Concepts for Mobile, Micro, and Personal Communications  

NASA Technical Reports Server (NTRS)

The Workshop on Advanced Network and Technology Concepts for Mobile, Micro, and Personal Communications was held at NASA's JPL Laboratory on 30-31 May 1991. It provided a forum for reviewing the development of advanced network and technology concepts for turn-of-the-century telecommunications. The workshop was organized into three main categories: (1) Satellite-Based Networks (L-band, C-band, Ku-band, and Ka-band); (2) Terrestrial-Based Networks (cellular, CT2, PCN, GSM, and other networks); and (3) Hybrid Satellite/Terrestrial Networks. The proceedings contain presentation papers from each of the above categories.

Paul, Lori (editor)

1991-01-01

49

EFFECT OF GSM MOBILE PHONE RADIATION ON BLOOD-BRAIN BARRIER  

Microsoft Academic Search

Some animal studies have suggested that mobile phone radiation may cause increase in blood-brain barrier permeability. We have hypothesized (Leszczynski et al. Differentiation, 70, 2002, in press) that the mobile phone radiation-induced increased expression and phosphorylation (activity) of stress protein hsp27 might be the molecular mechanism regulating blood-brain barrier permeability and, possibly, cell apoptosis. Here we present evidence suggesting that

Dariusz Leszczynski

50

Reliable Communication for Highly Mobile Agents  

Microsoft Academic Search

The provision of a reliable communication infrastructure for mobile agents is still an open research issue. The challenge to reliability we address in this work does not come from the possibility of faults, but rather from the mere presence of mobility, which complicates the problem of ensuring the delivery of information even in a fault-free network. For instance, the asynchronous

Amy L. Murphy; Gian Pietro Picco

1999-01-01

51

Reduced-Bandwidth Coding for Mobile Communication  

NASA Technical Reports Server (NTRS)

Fade-resistant mobile systems use power and spectrum efficiently. Transmission system employs tone-calibrated technique (TCT). Residual carrier used in technique to reduce fading-induced effects and coherently demodulate received signal. TCT potentially efficient in use of power and of frequency spectrum. Coding technique, intended for residual-carrier transmission system, alleviates fading and spectrum crowding that hamper mobile communications.

Davarian, F.

1986-01-01

52

Increased blood-brain barrier permeability in mammalian brain 7 days after exposure to the radiation from a GSM-900 mobile phone.  

PubMed

Microwaves were for the first time produced by humans in 1886 when radio waves were broadcasted and received. Until then microwaves had only existed as a part of the cosmic background radiation since the birth of universe. By the following utilization of microwaves in telegraph communication, radars, television and above all, in the modern mobile phone technology, mankind is today exposed to microwaves at a level up to 10(20) times the original background radiation since the birth of universe. Our group has earlier shown that the electromagnetic radiation emitted by mobile phones alters the permeability of the blood-brain barrier (BBB), resulting in albumin extravasation immediately and 14 days after 2h of exposure. In the background section of this report, we present a thorough review of the literature on the demonstrated effects (or lack of effects) of microwave exposure upon the BBB. Furthermore, we have continued our own studies by investigating the effects of GSM mobile phone radiation upon the blood-brain barrier permeability of rats 7 days after one occasion of 2h of exposure. Forty-eight rats were exposed in TEM-cells for 2h at non-thermal specific absorption rates (SARs) of 0mW/kg, 0.12mW/kg, 1.2mW/kg, 12mW/kg and 120mW/kg. Albumin extravasation over the BBB, neuronal albumin uptake and neuronal damage were assessed. Albumin extravasation was enhanced in the mobile phone exposed rats as compared to sham controls after this 7-day recovery period (Fisher's exact probability test, p=0.04 and Kruskal-Wallis, p=0.012), at the SAR-value of 12mW/kg (Mann-Whitney, p=0.007) and with a trend of increased albumin extravasation also at the SAR-values of 0.12mW/kg and 120mW/kg. There was a low, but significant correlation between the exposure level (SAR-value) and occurrence of focal albumin extravasation (r(s)=0.33; p=0.04). The present findings are in agreement with our earlier studies where we have seen increased BBB permeability immediately and 14 days after exposure. We here discuss the present findings as well as the previous results of altered BBB permeability from our and other laboratories. PMID:19345073

Nittby, Henrietta; Brun, Arne; Eberhardt, Jacob; Malmgren, Lars; Persson, Bertil R R; Salford, Leif G

2009-08-01

53

USDA Forest Service mobile satellite communications applications  

NASA Technical Reports Server (NTRS)

The airborne IR signal processing system being developed will require the use of mobile satellite communications to achieve its full capability and improvement in delivery timeliness of processed IR data to the Fire Staff. There are numerous other beneficial uses, both during wildland fire management operations or in daily routine tasks, which will also benefit from the availability of reliable communications from remote areas.

Warren, John R.

1990-01-01

54

Development of a Low-Cost GSM SMS-Based Humidity Remote Monitoring and Control system for Industrial Applications  

Microsoft Academic Search

The paper proposes a wireless solution, based on GSM (Global System for Mobile Communication) networks [1] for the monitoring and control of humidity in industries. This system provides ideal solution for monitoring critical plant on unmanned sites. The system is Wireless [2] therefore more adaptable and cost-effective. Utilizing Humidity sensor HSM-20G, ARM Controller LPC2148 and GSM technology this system offers

2010-01-01

55

Assessment of real exposure to GSM mobile telephones using the SYRPOM.  

PubMed

A mobile telephone user's exposure to the radio-frequency electromagnetic field depends heavily on the power their telephone radiates, which can vary widely according to requests from the base station. This study presents the design and development of a system called SYstem for Radiated POwer Measurement (SYRPOM), which measures the power radiated by a mobile telephone. This study also describes the tests carried out on the system itself and gives the results of two measuring campaigns it has been possible to perform in this way. The first such campaign consisted of assessing the mean power received by a typical mobile telephone user carrying out various activities. The second campaign was aimed at (1) comparing the mean radiated power when stationary and when moving and (2) assessing and contrasting different models of handsets in terms of the mean radiated power. The SYRPOM has proved to be a flexible, easy-to-use high-performance and innovative tool for carrying out this kind of studies. PMID:23685535

Picard, Dominique; Fouquet, Luce; Chauvin, Sébastien

2013-11-01

56

Multi-Layer Realistic Voice Capacity Evaluation in LTE Rel. 9 and Performance Comparison with PMR and GSM  

Microsoft Academic Search

This paper proposes a multi-layer realistic voice capacity evaluation method for long term evolution (LTE) Release 9 downlink transmission, from a private mobile radio (PMR) perspective. The obtained voice spectral efficiency is also compared with existent PMR networks and global system for mobile communications (GSM). The realistic system model considers both transmission protocols overhead, including internet protocol (IP) and robust

Alina Alexandra Florea; Laurent Martinod; Philippe Mege; Hang Nguyen

2012-01-01

57

Impacts of mobile agent technology on mobile communication system evolution  

Microsoft Academic Search

The development of third-generation mobile communication systems, such as UMTS, should be based on state-of-the-art middleware technologies. Today distributed object technology (DOT), such as OMG's CORBA, has gained considerable acceptance in the telecommunications environment, within the evolution of IN, TMN systems, and also in the context of UMTS design. Another new software technology, mobile agent technology (MAT), is gaining momentum

LARS HAGEN; MARKUS BREUGST

1998-01-01

58

Mobile satellite communications in the Forest Service  

NASA Astrophysics Data System (ADS)

There are usually some places within a forest that do not have adequate communication coverage due to line-of-sight or other reasons. These areas are generally known by the foresters and radio technicians and allowances are made for that when working or traveling in those areas. However, when wildfire or other emergencies occur, communications are vital because wildfires can require hundreds of firefighters and cover thousands of acres. During these emergency operations, the existing communications are not adequate and complete radio systems are moved into the area for the conduct of fire communications. Incident command posts (ICPs) and fire camps are set up in remote locations and there is constant need for communications in the fire area and to agency headquarters and dispatch offices. Mobile satellite communications would be an ideal supplement to the Forest Service's current communications system in aiding forest fire control activities.

Warren, John R.

1988-05-01

59

Mobile satellite communications in the Forest Service  

NASA Technical Reports Server (NTRS)

There are usually some places within a forest that do not have adequate communication coverage due to line-of-sight or other reasons. These areas are generally known by the foresters and radio technicians and allowances are made for that when working or traveling in those areas. However, when wildfire or other emergencies occur, communications are vital because wildfires can require hundreds of firefighters and cover thousands of acres. During these emergency operations, the existing communications are not adequate and complete radio systems are moved into the area for the conduct of fire communications. Incident command posts (ICPs) and fire camps are set up in remote locations and there is constant need for communications in the fire area and to agency headquarters and dispatch offices. Mobile satellite communications would be an ideal supplement to the Forest Service's current communications system in aiding forest fire control activities.

Warren, John R.

1988-01-01

60

Dosimetry in the human head for two types of mobile phone antennas at GSM frequencies  

NASA Astrophysics Data System (ADS)

In this paper, a comparative study of dipole and patch antennas commonly used in portable telephones is investigated. The two models antennas are considered working at 900, 1800 and 2450 MHz bands. Thus, we have included different distances between the mobile phone and the human head model. This study shows the effects of electromagnetic waves on the human head model. The objective is to evaluate the SAR in simulation anatomic based model of the human head for different antenna-head distances and in many frequencies. All numerical simulations results are performed using Ansoft HFSS software.

Karli, Radouane; Ammor, Hassan; Terhzaz, Jaouad

2014-03-01

61

Personal Mobile Communications by Satellite.  

National Technical Information Service (NTIS)

The engineering feasibility of satellite systems for paging and message services to mobile users with small terminals is demonstrated. The satellite itself would provide cover mainly in rural and semi-urban areas, but the coverage could be extended into u...

R. J. Cocks P. S. Hansell R. Krawec D. Lewin

1984-01-01

62

Short communication GSM cell phones can interfere with ionizing radiation dose monitoring equipment  

Microsoft Academic Search

Cell phone use is growing worldwide. These phones transmit to adjacent base stations using radiofrequency signals in the microwave range (,900-,1800 MHz). Portable electronic dose monitoring equipment is used in hospitals and other institutions to monitor and control levels of exposure to ionizing radiation, and to reassure staff. The objective of this paper is to investigate the effect of mobile

P GILLIGAN; S SOMERVILLE; J T ENNIS

2000-01-01

63

Satellite multiple access systems for mobile communication  

NASA Technical Reports Server (NTRS)

This paper considers multiple access techniques for a mobile radio system which incorporates a geosynchronous orbiting satellite repeater through which mobile terminals communicate. The communication capacities of FDMA, TDMA and CDMA systems are examined for a 4 MHz bandwidth system to serve up to 10,000 users. An FDMA system with multibeam coverage is analyzed in detail. The system includes an order-wire network for demand-access control and reassignment of satellite channels. Satellite and terminal configurations are developed to a block diagram level and system costs and implementation requirements are discussed.

Lewis, J. L.

1979-01-01

64

Automatic central management for decentral mobilemedical devices using GSM and the Internet for Fleet management  

Microsoft Academic Search

Abstract: Equipping medical devices with long range telemetry opens completely new possibilities for emergency response, home care and remote diagnosis. Mobile communications nowadays seem to be a generaly accepted part of our modern world, but bridging the gap between new (consumer-) technologies and medical devices still is a challenge today. Providing a telemetry link (GSM) is just the trivial part-ensuring

Tobias Bachmor; S. Velykokhatko; Wilhelm Stork; Klaus D. Müller

2003-01-01

65

GLOBAL MOBILE SATELLITE COMMUNICATIONS: A REVIEW OF THREE CONTENDERS  

Microsoft Academic Search

The era of satellite-based mobile communications systems started with the first MARISAT satellite which was launched into a geostationary orbit over the Pacific Ocean in 1976 to provide communications between ships and shore stations. The combination of high cost and unacceptably large equipment has kept mobile satellite communications (MSC) systems from appealing to the wider market of personal mobile communications.

Gary M. Comparetto

1994-01-01

66

Anonymous communications in mobile ad hoc networks  

Microsoft Academic Search

Abstract—Due to the broadcast nature of radio transmissions, communications in mobile ad hoc networks (MANETs) are more susceptible to malicious traffi ca nalysis. In this paper we propose a novel anonymous on-demand routing protocol, termed MASK, to enable anonymous,communications thereby thwarting possible traffic analysis attacks. Based on a new cryptographic concept called pairing, we first propose an anonymous neighborhood authentication

Yanchao Zhang; Wei Liu; Wenjing Lout

2005-01-01

67

Modeling and Analysis of Mobility Management in Mobile Communication Networks  

PubMed Central

Many strategies have been proposed to reduce the mobility management cost in mobile communication networks. This paper studies the zone-based registration methods that have been adopted by most mobile communication networks. We focus on two special zone-based registration methods, called two-zone registration (2Z) and two-zone registration with implicit registration by outgoing calls (2Zi). We provide a new mathematical model to analyze the exact performance of 2Z and 2Zi. We also present various numerical results, to compare the performance of 2Zi with those of 2Z and one-zone registration (1Z), and show that 2Zi is superior to 2Z as well as 1Z in most cases.

Yoon, Ji Hyun; Kim, Chesoong

2014-01-01

68

IP Micro-mobility Protocols  

Microsoft Academic Search

Wireless cellular networks are quickly evolving towards broadband wireless access networks, going from 2G, classical telephony networks such as Global System for Mobile communication (GSM), towards 3G and beyond, with, for example, Universal Mobile Telecommunication System (UMTS). At the same time, these networks are also moving towards all-IP networks. In this paper, we first describe the global mobility landscape for

Pierre Reinbold; Olivier Bonaventure

2003-01-01

69

Statistical characterisation of the EM interferences acting on GSM-R antennas fixed above moving trains  

NASA Astrophysics Data System (ADS)

In order to harmonise the communication systems between the train and the railway control centres over the European territory, a GSM-R (Global System for Mobile communications - Railways) communication network is progressively deployed along the European railway network. However, the GSM-R communications on board high speed trains can be disturbed by the transient electromagnetic (EM) disturbances induced by the sliding contact between the catenary and the pantograph. In order to study the immunity of the embedded GSM-R communication system against these transient electromagnetic disturbances, the transient interferences induced on the GSM-R antennas on board trains, were characterised in terms of time and amplitude parameters. Measurement campaigns were carried out in France to collect a large number of induced EM interferences on GSM-R antennas fixed on the train roof. With the ultimate goal of generating transient noise scenarios representative of those detected by the antennas, and performing immunity tests in laboratory, statistical distributions of the characteristics (rise time, time duration, repetition rate, amplitude) of the transients are presented. This paper presents the different steps of the analysis of the transient disturbances and the generation of the transient EM scenarios. in here

Ben Slimen, N.; Deniau, V.; Rioult, J.; Dudoyer, S.; Baranowski, S.

2009-11-01

70

Time reversal communication with a mobile source.  

PubMed

Broadband underwater acoustic communication signals undergo either a compression or dilation in the presence of relative motion between a source and a receiver. Consequently, underwater acoustic communications with a mobile source/receiver require Doppler compensation through resampling. However, resampling may not be necessary when a channel-estimate-based time reversal approach is applied with frequent channel updates. Using experimental data (20-30 kHz), it is demonstrated that the performance of time reversal communication without resampling is similar to the case with resampling, along with the benefit of a modest computational saving. PMID:24116398

Song, H C

2013-10-01

71

Analysis of maritime mobile satellite communication systems  

NASA Astrophysics Data System (ADS)

The communication channel between a satellite and a ship earth station (SES) is described by a model which includes multipath fading, Doppler shift and noise. Multipath fading is caused by reflections from the sea surface. These reflections can affect the system performance, especially at low elevation angles or when SES is using low gain antennas. Doppler shift is a very important effect when using low altitude satellites, because of the high velocities involved. A software simulator is described and a simulator is presented for multipath fading in the maritime communications environment. Analysis of throughput of an unslotted Aloha maritime mobile satellite communication channel is also presented.

Zapata, Augusto J.

1988-12-01

72

Phased array for mobile satellite communications  

NASA Astrophysics Data System (ADS)

An L-band phased array antenna concept for mobile satellite communications is presented. The array is a multilayer structure with integrated 4-bit switched stub phase shifters and aperture coupled right hand circularly polarized antenna elements. The integrated phased array has an interface for direct computer control. Diagrams describing the operation and structure of the antenna are shown.

Ziegler, Volker

1990-11-01

73

Advanced Communications Payload for Mobile Applications.  

National Technical Information Service (NTIS)

An advanced satellite payload is proposed for single hop linking of mobile terminals of all classes as well as Very Small Aperture Terminal's (VSAT's). It relies on an intensive use of communications on-board processing and beam hopping for efficient link...

S. A. Ames R. K. Kwan

1990-01-01

74

Mobile satellite communications - Vehicle antenna technology update  

NASA Astrophysics Data System (ADS)

This paper discusses options for vehicle antennas to be used in mobile satellite communications systems. Two types of antennas are identified. A non-steerable, azimuthally omnidirectional antenna with a modest gain of 3 to 5 dBi is suggested when a low cost is desired. Alternatively, mechanically or electronically steerable antennas with a higher gain of 10 to 12 dBi are suggested to alleviate power and spectrum scarcity associated with mobile satellite communications. For steerable antennas, both open-loop and closed-loop pointing schemes are discussed. Monopulse and sequential lobing are proposed for the mechanically steered and electronically steered antennas, respectively. This paper suggests a hybrid open-loop/closed-loop pointing technique as the best performer in the mobile satellite environment.

Bell, D.; Naderi, F. M.

75

Application of Mobile Router to Military Communications  

NASA Technical Reports Server (NTRS)

Cisco Systems and NASA Glenn Research Center under a NASA Space Act Agreement have been performing joint networking research to apply Internet technologies and protocols to space-based communications. During this time, Cisco Systems developed the mobile-router which NASA and Cisco jointly tested. The early field trials of this technology have been successfully completed. The mobile-router is software code that resides in a network router. A Mobile-Router allows entire networks to roam while maintaining connectivity to the Internet. This router code is pertinent to a myriad of applications for both the government and commercial sectors. This technology will be applied to the wireless battlefield. NASA and the Department of Defense will utilize this technology for near-planetary observation and sensing spacecraft. It is the enabling technology for communication via the Internet or Intranets to aircraft. Information such as weather, air traffic control, voice and video can be easily and inexpensively transmitted to the aircraft using Internet protocols. The mobile router can be incorporated into emergency vehicles particularly ambulances and life-flight aircraft to provide real-time connectivity back to the hospital and healthcare experts. Commercial applications include entertainment services, IP telephone, and Internet connectivity for cruise ships, commercial shipping, tour busses, aircraft, and eventually cars. This paper will briefly describe the mobile router operation. An upcoming wide area network field test with application to US Coast Guard communications will be described. The paper will also highlight military and government networks that will benefit from the deployment of mobile router and the associated applications.

Stewart, David H.; Ivancic, William D.; Bell, Terry L.; Kachmar, Brian A.; Shell, Dan; Leung, Kent

2002-01-01

76

Antenna technology for advanced mobile communication systems  

NASA Technical Reports Server (NTRS)

The onboard antenna front end is the key subsystem conditioning configuration and performance of mobile communication satellites. The objectives of this paper are to demonstrate this key role and to review L-band satellite antenna technology for earth coverage and regional applications. Multibeam arrays are first discussed, then unfurlable and inflatable reflector antennas are described. These technologies are now qualified in Europe for future mobile systems, for which the optimum choice of antenna technology has been found to be the key to efficient use of spectrum and power resources.

Rammos, Emmanuel; Roederer, Antoine; Rogard, Roger

1988-01-01

77

Pilot-Tone System for Mobile Communications  

NASA Technical Reports Server (NTRS)

In mobile communication system called tone-calibrated technique, pilot tone provides phase- and amplitude-calibration reference to enable coherent demodulation of signal at receiver despite fading. Signal received by or from mobile terminal faded due to motion of terminal and propagation of signal along multiple paths. Fading introduces random amplitude modulation and phase modulation with bandwidth of twice Doppler frequency shift. Degrading effects of multipath fading reduced. Tonecalibrated technique for use with phase-modulated data or telephony systems using Manchester digital pulse-code modulation.

Davarian, F.

1986-01-01

78

Antenna technology for advanced mobile communication systems  

NASA Astrophysics Data System (ADS)

The onboard antenna front end is the key subsystem conditioning configuration and performance of mobile communication satellites. The objectives of this paper are to demonstrate this key role and to review L-band satellite antenna technology for earth coverage and regional applications. Multibeam arrays are first discussed, then unfurlable and inflatable reflector antennas are described. These technologies are now qualified in Europe for future mobile systems, for which the optimum choice of antenna technology has been found to be the key to efficient use of spectrum and power resources.

Rammos, Emmanuel; Roederer, Antoine; Rogard, Roger

1988-05-01

79

Analysis of the General Packet Radio Service (GPRS) of GSM as access to the Internet  

Microsoft Academic Search

The General Packet Radio Service (GPRS) of the Global System for Mobile Communications (GSM) is designed for packet switched data transmission and is a means of mobile access to packet data networks, e.g. the Internet. Packet switched transmission is inherently better suited for bursty traffic as it is generated by typical Internet applications-primarily WWW, FTP and e-mail. A simulator is

Simon Hoff; Michael Meyer; Joachim Sachs

1998-01-01

80

Inmarsat second generation satellites for mobile communications  

NASA Astrophysics Data System (ADS)

The second-generation satellites of Inmarsat (the International Maritime Satellite Organization) are in the final stage of integration and testing. The satellites will satisfy the needs originated by the rapid expansion of the system and will allow the introduction of new mobile communications services. The essentials of the spacecraft design and the types of services that will be provided using the new satellites are discussed, with particular consideration given to the characteristics of the communications transponder, its design and technology, the requirements and the design solutions, and the most significant communications parameters. Paralleled linearized traveling-wave amplifiers, L-band shaped global direct radiating array antennas, and surface-acoustic-wave channelization filters are being implemented in the system. Passive intermodulation product generation and multipaction are being recognized as design drivers.

Gambaruto, E.; Banks, D. K.; Krinsky, B.

81

Integration between terrestrial-based and satellite-based land mobile communications systems  

NASA Technical Reports Server (NTRS)

A survey is given of several approaches to improving the performance and marketability of mobile satellite systems (MSS). The provision of voice/data services in the future regional European Land Mobile Satellite System (LMSS), network integration between the Digital Cellular Mobile System (GSM) and LMSS, the identification of critical areas for the implementation of integrated GSM/LMSS areas, space segment scenarios, LMSS for digital trunked private mobile radio (PMR) services, and code division multiple access (CDMA) techniques for a terrestrial/satellite system are covered.

Arcidiancono, Antonio

1990-01-01

82

Hybrid Mobile Communication Networks for Planetary Exploration  

NASA Technical Reports Server (NTRS)

A paper discusses the continuing work of the Mobile Exploration System Project, which has been performing studies toward the design of hybrid communication networks for future exploratory missions to remote planets. A typical network could include stationary radio transceivers on a remote planet, mobile radio transceivers carried by humans and robots on the planet, terrestrial units connected via the Internet to an interplanetary communication system, and radio relay transceivers aboard spacecraft in orbit about the planet. Prior studies have included tests on prototypes of these networks deployed in Arctic and desert regions chosen to approximate environmental conditions on Mars. Starting from the findings of the prior studies, the paper discusses methods of analysis, design, and testing of the hybrid communication networks. It identifies key radio-frequency (RF) and network engineering issues. Notable among these issues is the study of wireless LAN throughput loss due to repeater use, RF signal strength, and network latency variations. Another major issue is that of using RF-link analysis to ensure adequate link margin in the face of statistical variations in signal strengths.

Alena, Richard; Lee, Charles; Walker, Edward; Osenfort, John; Stone, Thom

2007-01-01

83

Lens Antenna For Mobile/Satellite Communication  

NASA Technical Reports Server (NTRS)

Flat, compact antenna made of stripline elements aimed at fixed elevation angle but steered electronically in azimuth. Design simplified by maintaining fixed elevation and relying on width of beam to cover desired elevation range. Need for phase shifter at each radiating element eliminated by arranging elements in circles and feeding through stripline disks called "R-KR lenses". Used in Mobile/Satellite Service, antenna mounted on top of vehicle on Earth and used to keep transmitted and received antenna beams aimed approximately toward communication satellite.

Bodnar, D. G.; Rainer, B. K.

1988-01-01

84

Geographical dispersal of mobile communication networks  

NASA Astrophysics Data System (ADS)

In this paper, we analyze statistical properties of a communication network constructed from the records of a mobile phone company. The network consists of 2.5 million customers that have placed 810 million communications (phone calls and text messages) over a period of 6 months and for whom we have geographical home localization information. It is shown that the degree distribution in this network has a power-law degree distribution k-5 and that the probability that two customers are connected by a link follows a gravity model, i.e. decreases as d-2, where d is the distance between the customers. We also consider the geographical extension of communication triangles and we show that communication triangles are not only composed of geographically adjacent nodes but that they may extend over large distances. This last property is not captured by the existing models of geographical networks and in a last section we propose a new model that reproduces the observed property. Our model, which is based on the migration and on the local adaptation of agents, is then studied analytically and the resulting predictions are confirmed by computer simulations.

Lambiotte, Renaud; Blondel, Vincent D.; de Kerchove, Cristobald; Huens, Etienne; Prieur, Christophe; Smoreda, Zbigniew; Van Dooren, Paul

2008-09-01

85

Route Optimization for Intra Communication of a Nested Mobile Network  

Microsoft Academic Search

Network mobility, i.e. Internet access services for a moving network as a single unit brings about new challenging issues. A nested mobile network is a hierarchical form of multiple mobile networks. Nested mobile networks sufier from a pin- ball routing problem. This problem becomes more serious in the case of a communication between any two nodes in the same nested

Sungmin Baek; Jinkyu Yoo; Hosik Cho

86

Supporting Secure Communication and Data Collection in Mobile Sensor Networks  

Microsoft Academic Search

Abstract, Sensor deployments may be static, but researchers have recently been making a case for mobile collector nodes to enhance data acquisition. Since mobile nodes are often more privileged, their compromise can give the adversary a significant advantage. Hence, security mechanisms for such networks must tolerate mobile node compromises. Unlike static sensors, which communicate mostly with their neighbors, mobile nodes

Li Zhou; Jinfeng Ni; Chinya V. Ravishankar

2006-01-01

87

Understanding GPRS: the GSM packet radio service  

Microsoft Academic Search

The General Packet Radio Service (GPRS), a data extension of the mobile telephony standard GSM, is emerging as the first true packet-switched architecture to allow mobile subscribers to benefit from high-speed transmission rates and run data applications from their mobile terminals. A high-level description of the GPRS system is given with emphasis on services and architectural aspects.

Brahim Ghribi; Luigi Logrippo

2000-01-01

88

Consensus in networks of mobile communicating agents  

NASA Astrophysics Data System (ADS)

Populations of mobile and communicating agents describe a vast array of technological and natural systems, ranging from sensor networks to animal groups. Here, we investigate how a group-level agreement may emerge in the continuously evolving network defined by the local interactions of the moving individuals. We adopt a general scheme of motion in two dimensions and we let the individuals interact through the minimal naming game, a prototypical scheme to investigate social consensus. We distinguish different regimes of convergence determined by the emission range of the agents and by their mobility, and we identify the corresponding scaling behaviors of the consensus time. In the same way, we rationalize also the behavior of the maximum memory used during the convergence process, which determines the minimum cognitive/storage capacity needed by the individuals. Overall, we believe that the simple and general model presented in this paper can represent a helpful reference for a better understanding of the behavior of populations of mobile agents.

Baronchelli, Andrea; Díaz-Guilera, Albert

2012-01-01

89

Communication-Related Abilities and Upward Mobility: A Longitudinal Investigation.  

ERIC Educational Resources Information Center

Studies relationships among four measures of communication abilities, and between these abilities and job level and upward mobility in a selected insurance company. Concludes that communication abilities are important to the success of individuals in organizations. (MS)

Sypher, Beverly Davenport; Zorn, Theodore E., Jr.

1986-01-01

90

SAW based systems for mobile communications satellites  

NASA Technical Reports Server (NTRS)

Modern mobile communications satellites, such as INMARSAT 3, EMS, and ARTEMIS, use advanced onboard processing to make efficient use of the available L-band spectrum. In all of these cases, high performance surface acoustic wave (SAW) devices are used. SAW filters can provide high selectivity (100-200 kHz transition widths), combined with flat amplitude and linear phase characteristics; their simple construction and radiation hardness also makes them especially suitable for space applications. An overview of the architectures used in the above systems, describing the technologies employed, and the use of bandwidth switchable SAW filtering (BSSF) is given. The tradeoffs to be considered when specifying a SAW based system are analyzed, using both theoretical and experimental data. Empirical rules for estimating SAW filter performance are given. Achievable performance is illustrated using data from the INMARSAT 3 engineering model (EM) processors.

Peach, R. C.; Miller, N.; Lee, M.

1993-01-01

91

Research on Switching Behavior of Mobile Communication Services  

Microsoft Academic Search

In the mobile communications market, the homogeneity phenomenon of product's service appears. The paper combines the Technology Acceptance Model (TAM) and Switching Cost Theory to construct the Convert Selection Model about the mobile communication services for users, which mainly analyzed from five dimensions: perceived switching costs, differences in perceived usefulness, differences in perceived ease of use, perceived difference between the

Qianfan Zhang; Shuiping Mao; Zhangshu Jia

2010-01-01

92

Optical Fiber Feeder for Microcellular Mobile Communication Systems (H-015)  

Microsoft Academic Search

The authors investigate the feasibility of using an optical fiber feeder for microcellular mobile communication systems. The optical feeder enables compact and low-cost base stations, easy radio channel control, and flexible mobile communication systems. Basic transmission characteristics were investigated through optical transmission experiments. Using these results, it is estimated that the optical feeder can transmit 880 telephone channels for digital

Makoto Shibutani; Toshihito Kanai; Watani Domom; Katsumi Emura; Junji Namiki

1993-01-01

93

Key Issues in Expansion of Mobile Data Communications in China  

Microsoft Academic Search

China's mobile communications market presents unique market challenges. Market is experiencing a high subscriber growth rate and its implications for business and end-users and investigation into the current status of this market will improve our understanding on how adoption of mobile communications is evolving at the end-user level. In this paper we use a descriptive method to analyze key issues

Sunanda Sangwan; Chong Guan; Louis-Francois Pau

2008-01-01

94

Development of Mobile Communications in Slovenia: Looking to the Future Global Information (Mobile/Internet) Society.  

ERIC Educational Resources Information Center

Discusses the planning and provision of mobile communications in Slovenia and suggests areas that will be developed in the future. Topics include the global mobile market; digital mobile networks; evolution from voice to multimedia services; wireless application protocol; the Internet; general packet radio service; and universal mobile

Simonic, Tomaz; Mlinar, Tomi

2000-01-01

95

Supporting the WWW in Wireless Communications Through Mobile Agents  

Microsoft Academic Search

Mobile computing is considered of major importance to the computing industry for the forthcoming years due to the progress in wireless mobile communications. We present a proxy-based architecture that manages to accelerate Web browsing in wireless Customer Premises Networks (CPN). We discuss how such an architecture is implemented using the IBM Aglets framework for mobile agents. The suggested architecture relies

Stathes Hadjiefthymiades; Vicky Matthaiou; Lazaros F. Merakos

2002-01-01

96

A generalized transmultiplexer and its application to mobile satellite communications  

NASA Technical Reports Server (NTRS)

A generalization of digital transmultiplexer technology is presented. The proposed method can realize transmultiplexer (TMUX) and transdemultiplexer (TDUX) filter banks whose element filters have bandwidths greater than the channel spacing frequency. This feature is useful in many communications applications. As an example, a satellite switched (SS) Frequency Division Multiple Access (FDMA) system is proposed for spot beam satellite communications, particularly for mobile satellite communications.

Ichiyoshi, Osamu

1990-01-01

97

Mobile communications satellite antenna flight experiment definition  

NASA Astrophysics Data System (ADS)

There are classes of application that collectively require a variety of different types of large-aperture space antennas. Fortunately, there are a number of different deployable antenna concepts that have tremendous potential for such applications. However, these concepts vary in maturity from flight-proven designs to extremely innovative configuration definitions. But these promising concepts lack sufficient demonstrations of maturity to be seriously considered in the large size range for immediate application. The reason for this situation is an extremely limited space flight data base in addition to the technical limitations and great costs associated with meaningful ground testing of large, flexible, precision space structures. The user community of such structures, especially the commercial organizations interested in providing a Mobile Communications Satellite (MSAT) on a profit-making basis, will require significant demonstrations of technology readiness prior to application commitment. Such demonstrations will probably be based on a combination of extensive ground testing and subsequent space flight experiments. The Communications Division of the National Aeronautics and Space Administration (NASA) Office of Space Science and Applications sponsored a study at the Jet Propulsion Laboratory (JPL) to determine the technical feasibility and cost of a Shuttle-based flight experiment specifically intended for the MSAT commercial user community. The experiment will include demonstrations of technology in the areas of radio frequency (RF), sensing and control, and structures. This paper summarizes the results of the structural subsystem study. These results include experiment objective and technical approach, experiment structural description, structure/environment interactions, structural characterization, thermal characterization, structural measurement system, and experiment functional description.

Freeland, Robert E.

98

Communication Concepts for Mobile Agent Systems  

Microsoft Academic Search

Driven by the question how to identify potential communication partners and the need for well-suited communication schemes in agent-based systems, we discuss two communication concepts: sessions and global event management.

Joachim Baumann; Fritz Hohl; Nikolaos Radouniklis; Kurt Rothermel; Markus Straßer

1997-01-01

99

Efficient spectrum utilization in mobile radio communication systems  

NASA Astrophysics Data System (ADS)

The problem of efficient spectrum utilization in mobile radio communication systems is addressed. A frequency channel assignment algorithm is proposed and studied by computer simulations for applications to mobile telephone systems and combined mobile telephone and dispatch systems. Spectrum efficient modulation techniques, namely, Duobinary Coded MSK and TFM are studied for the application of data transmission via mobile radio. The performance of coherent and noncoherent detections is studied under the mobile radio environments. The probability of error is calculated for both discriminator detection and differential detection. The steady state phase error probability of a digital phase locked loop with a phase step input is calculated under the fast fading mobile radio environments.

Elnoubi, S. M.

1980-03-01

100

Mobile communications via satellite in the 1990s  

NASA Astrophysics Data System (ADS)

The International Maritime Satellite Organization (Inmarsat) began operations in February 1982. It has the objective to provide satellite communications capacity which can best serve the mobile user in the international environment. It is pointed out that Inmarsat is the world's only organization providing commercial mobile communications via satellite. Inmarsat is concerned with the improvement of maritime communications. Attention is given to structure and financing, the Inmarsat satellites in geostationary orbit, the coast earth stations, the ship earth stations, applications and users, a future global maritime distress and safety system, polar-orbiting satellites, aeronautical communications, and the second-generation system.

Lundberg, O.

1984-07-01

101

A modified two-ring reference model for MIMO Mobile-to-Mobile communication channels  

Microsoft Academic Search

Analysis and design of multi-element antenna systems in mobile fading channels require a model for the space-time cross-correlation among the links of the underlying multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) communication channel. In this paper, we propose a MIMO channel reference model for M-to-M communication systems that we call it as the modified geometrical two-ring model. This model is based on

Gholamreza Bakhshi; Reza Saadat; Kamal Shahtalebi

2008-01-01

102

How to Turn a GSM SIM into a Web Server  

Microsoft Academic Search

We describe the WebSIM, an approach that integrates GSM SIMs into the Internet. The underlying idea is to implement a Web Server inside a SIM, and to allow for transparent access to it from the Internet. The contribution of our approach is that a SIM, which is currently a security module (smart card) fitted in a GSM mobile phone, becomes

Scott B. Guthery; Roger Kehr; Joachim Posegga

2000-01-01

103

Isolated and Coupled Superquadric Loop Antennas for Mobile Communications Applications.  

National Technical Information Service (NTIS)

This work provides an investigation of the performance of loop antennas for use in mobile communications applications. The analysis tools developed allow for high flexibility by representing the loop antenna as a superquadric curve, which includes the cas...

M. A. Jensen Y. Rahmat-samii

1993-01-01

104

Mobile Router Testing with Diverse RF Communications Links  

NASA Technical Reports Server (NTRS)

This is a short report on demonstrations using Mobile IP and several diverse physical communications links to connect a mobile network to a fixed IPv4 internet. The first section is a description of the equipment used, followed by descriptions of the tests, the theoretical results, and finally conclusions and the actual data.

Brooks, David; Hoder, Doug; Wilkins, Ryan

2004-01-01

105

A survey of various propagation models for mobile communication  

Microsoft Academic Search

In order to estimate the signal parameters accurately for mobile systems, it is necessary to estimate a system's propagation characteristics through a medium. Propagation analysis provides a good initial estimate of the signal characteristics. The ability to accurately predict radio-propagation behavior for wireless personal communication systems, such as cellular mobile radio, is becoming crucial to system design. Since site measurements

Tapan K. Sarkar; Zhong Ji; Kyungiung Kim; A. Medouri; Magdalena Salazar-Palma

2003-01-01

106

The flexibility of ATM: supporting future multimedia and mobile communications  

Microsoft Academic Search

ATM is no longer considered a vision for the more distant future, but as a technology that will be deployed worldwide within the very near future, in both the private and public sectors. ATM will progressively support fixed and mobile communications in several steps, beginning with data communications and possibly leading to general purpose ATM switches for narrow- and broadband,

H. Armbruster

1995-01-01

107

Tracking Mobile Users in Wireless Communication Networks  

Microsoft Academic Search

Tracking strategies for mobile wireless networks are studied. We assume a cellulararchitecture where base stations that are interconnected by a wired network communicatewith mobile units via wireless links. Previous works focused on the cost of utilizing thewired links for management of directories. In this paper, the issue considered is thecost of utilizing the wireless links for the actual tracking of

Amotz Bar-noy; Ilan Kessler

1993-01-01

108

Intelligent network concepts in mobile communications  

Microsoft Academic Search

A mobile cellular network architecture that is based on intelligent network concepts is presented. Subscriber service mobility and call management attributes of the network, including location information retrieval and updating, authentication, call routing, handover, charging, and operations and maintenance, are discussed

Bijan Jabbari

1992-01-01

109

Presence Aware Location-Based Service For Managing Mobile Communications  

Microsoft Academic Search

Presence technology based on Session Initiation Protocol can be used as an enabling platform for delivering communication and providing event-based services. We present a mobile workforce management solution which integrates fleet management with presence-based communication to show how presence technology can be used to realize location-based communication services. In particular, our solution integrates a user's presence information with their vehicle's

Vishal Kumar Singh; Henning Schulzrinne; Piotr Boni; Boris Elman; David Kenneson

2007-01-01

110

Measurement and analysis of electromagnetic pollution generated by GSM-900 mobile phone networks in Erciyes University, Turkey.  

PubMed

Mobile phones are becoming increasingly important in our everyday lives. The rising number of mobile phones reflects a similar increase in the number of base stations. Because of this rapid evolution, the establishment and planning of new base stations has become mandatory. However, the rise in the number of base stations, in terms of human health, is potentially very harmful. It is important to analyze the radiation levels of base stations until we can confirm that they are definitely not harmful in the long term. Mapping of electromagnetic field (EMF) is also important from a medical point of view because it provides useful information, for example, on the detection of diseases caused by EMF. With the help of this information the distribution of diseases over different regions can be obtained. In this article, the electromagnetic radiation levels of base stations were measured at 80 different points in Erciyes University (ERU), Turkey and detailed information about the measurement tools and measurement method were given. It was observed that no area in ERU exceeded the national and international limits. It is also observed that the effects of base stations vary according to duration and degree of exposure. Therefore, if people are exposed to a very low-intensity electromagnetic field for a very long time, serious health problems can occur. PMID:22676177

Sorgucu, Ugur; Develi, Ibrahim

2012-12-01

111

Development of a mobile satellite communication unit  

NASA Technical Reports Server (NTRS)

A compact 210(W) x 280(H) x 330(D) mm mobile terminal capable of transmitting voice and data through L-band mobile satellites is described. The Voice Codec can convert an analog voice to or from digital codes at rates of 9.6, 8 and 4.8 kb/s by an MPC algorithm. The terminal functions with a single 12 V power supplied vehicle battery. The equipment can operate at any L-band frequency allocated for mobile uses in a full duplex mode and will soon be put into a field test via Japans's ETS-V satellite.

Suzuki, Ryutaro; Ikegami, Tetsushi; Hamamoto, Naokazu; Taguchi, Tetsu; Endo, Nobuhiro; Yamamoto, Osamu; Ichiyoshi, Osamu

1988-01-01

112

Development of a mobile satellite communication unit  

Microsoft Academic Search

A compact 210(W) x 280(H) x 330(D) mm mobile terminal capable of transmitting voice and data through L-band mobile satellites is described. The Voice Codec can convert an analog voice to or from digital codes at rates of 9.6, 8 and 4.8 kb\\/s by an MPC algorithm. The terminal functions with a single 12 V power supplied vehicle battery. The

Ryutaro Suzuki; Tetsushi Ikegami; Naokazu Hamamoto; Tetsu Taguchi; Nobuhiro Endo; Osamu Yamamoto; Osamu Ichiyoshi

1988-01-01

113

Multichannel receivers performance comparison in the presence of ISI and CCI-application to a GSM link  

Microsoft Academic Search

In a few years, multichannel receivers have been developed particularly for mobile radiocommunications, such as the GSM system, to improve the reception performance in the presence of both inter-symbol interference (ISI) and co-channel interference (CCI). Two powerful training sequence-based multichannel receivers have been proposed and patented by Thomson-CSF-Communications for radiocommunications applications. This paper presents a performance comparison of these two

FranGois Pipon; Pascal Chevalier

1997-01-01

114

Increasing clinical presence of mobile communication technology: avoiding the pitfalls.  

PubMed

Mobile communication technologies are employed in many diverse areas of healthcare delivery to provide improved quality and efficiency of communication and facilitate increased rapidity of data or information transfer. Mobile phones enable healthcare professionals to possess a portable platform from which to provide many healthcare-related applications and are a popular means to directly communicate with colleagues and patients. As involvement of mobile communication technology in healthcare delivery continues to rapidly expand, there are also important considerations of relevance to patient safety and security as a result. Here, we review the previous evidence of reported clinical risks associated with mobile communication technology, such as electromagnetic interference, confidentiality and data security, distraction/noise, infection control, and cross contamination. In conclusion, although mobile phones provide much putative potential improvement to healthcare delivery, further evaluation and research are required to both inform and protect health professionals and users of such technology in the healthcare environment and provide the evidence base to support the provision of clear and comprehensive guidelines. PMID:21780941

Visvanathan, Akila; Gibb, Alan P; Brady, Richard R W

2011-10-01

115

Analysis of Maritime Mobile Satellite Communication Systems.  

National Technical Information Service (NTIS)

The communication channel between a satellite and a ship earth station (SES) is described by a model which includes multipath fading, doppler shift and noise. Multipath fading is caused by reflections from the sea surface. These reflections can affect the...

A. J. Zapata

1988-01-01

116

Satellite systems requirements for land mobile communications  

NASA Technical Reports Server (NTRS)

The system design objective is to provide a satellite link through a gateway station, connecting mobile users in areas not served by a terrestrial cellular system to the switched telephone network (STN). The proposed frequency allocation comprises a pair of 10-MHz bands in the 806-890 MHz range specified by the 1979 World Administrative Radio Conference (WARC) for land-mobile satellite service (LMSS). The satellite design is constrained by projected STS capability with an upper stage of the wide-body Centaur or Integral Propulsion System (IPS) type. For the latter (a TRW design), the payload is limited to approximately 10,400 lb. The design is to be based on 1990's technology, with initial operating capability scheduled for 1995. The satellite should be designed for a 7-year life. Mobile-unit compatibility with cellular system specifications is desirable, if consistent with other system requirements.

Horstein, M.

1983-01-01

117

The Turbo Principle in Mobile Communications  

Microsoft Academic Search

This overview talk shows that the so-called turbo codes(decoders) entail a much broader principle. It dis- cusses how the feedback of extrinsic information which we call the turbo principle can be used in many mobile com- munications receivers to improve performance through iter- ative processing. As an analysis and design tool the EXIT charts of mutual information transfer are used.

Joachim Hagenauer

118

Mobile Communication and Innovation: More than Convenience  

Microsoft Academic Search

Systems of mobile tools and practices support innovation through access to people and information, the reduction of barriers to the innovation process, and increased engagement. These positive effects can be understood by overlaying the needs for motivation, opportunity, and ability in all forms of performance. We offer illustrations of these relationships, a resulting pair of design recommendations, and ultimately, an

Terri L. Griffith; Lynne P. Cooper; T. Milbrourn

2010-01-01

119

Wireless\\/mobile communication Aegis taciturn  

Microsoft Academic Search

“Technology does not drive change, it enables change.” The primary purpose of Technology is its implementation in day-to-day life wherein it could enhance the lifestyle as well as provide better safety and performance to its end users. The government has enforced stringent laws against usage of mobile phones while driving a vehicle. Yet, there seems to be a sense of

S. Aparajith; M. L. Naarayan

2010-01-01

120

Mobile satellite communications - Applications for developing countries  

NASA Astrophysics Data System (ADS)

The paper considers the institutional commitments and development of new service applications of the International Maritime Satellite Organization. It illustrates how a mobile-satellite system can offer a range of applications and reach user communities that cannot be served by fixed systems.

von Noorden, Wolf D.

121

Mobile message services and communications policy  

Microsoft Academic Search

Something of a design after-thought, mobile phone SMS (Short-Message Services) have been enthusiastically adopted by consumers worldwide, who have created a new text culture. SMS is now being deployed to provide a range of services and transactions, as well as playing a critical role in offering an interactive path for television broadcasting. In this paper we offer a case study

Gerard Goggin; Christina Spurgeon

2005-01-01

122

Land-mobile satellite communication system  

NASA Technical Reports Server (NTRS)

A satellite communications system includes an orbiting communications satellite for relaying communications to and from a plurality of ground stations, and a network management center for making connections via the satellite between the ground stations in response to connection requests received via the satellite from the ground stations, the network management center being configured to provide both open-end service and closed-end service. The network management center of one embodiment is configured to provides both types of service according to a predefined channel access protocol that enables the ground stations to request the type of service desired. The channel access protocol may be configured to adaptively allocate channels to open-end service and closed-end service according to changes in the traffic pattern and include a free-access tree algorithm that coordinates collision resolution among the ground stations.

Yan, Tsun-Yee (Inventor); Rafferty, William (Inventor); Dessouky, Khaled I. (Inventor); Wang, Charles C. (Inventor); Cheng, Unjeng (Inventor)

1993-01-01

123

High Spectral Efficient and Flexible Next Generation Mobile Communications  

Microsoft Academic Search

In this paper we identify and describe the requirements and challenges of next generation mobile communications systems. The so-called fourth genera- tion (4G) aims at throughput rates of more than 100 MBit=s outdoors with high mobility and 1 GBit=s indoors. This requires new advanced techniques in the air interface of such a system. We outline new possible techniques and introduce

Simon Plass; Stephan Sand; Mikael Sternad; Arne Svensson

2007-01-01

124

High Spectral Efficient and Flexible Next Generation Mobile Communications  

Microsoft Academic Search

In this article we identify and describe the requirements and challenges of next generation mobile communications systems.\\u000a The so-called fourth generation (4G) aims at throughput rates of more than 100 MBit\\/s outdoors with high mobility and 1GBit\\/s\\u000a indoors. This requires new advanced techniques in the air interface of such a system. We outline new possible techniques and\\u000a introduce a future

Simon Plass; Stephan Sand; Mikael Sternad; Arne Svensson

2008-01-01

125

Mobility of a Disaster Recover Communication System  

Microsoft Academic Search

What is the best platform to build a Disaster Management Communication System (DMCS)? There is a need to investigate how to best use a DMCS. The two most important uses of a DMCS for any size disaster, is the need for information and getting relief to those that need it. The DMCS needs to collect information from the people affected

Edward Sobanski; Barbara Nicolai

2011-01-01

126

Mobile satellite service communications tests using a NASA satellite  

NASA Technical Reports Server (NTRS)

Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

Chambers, Katherine H.; Koschmeder, Louis A.; Hollansworth, James E.; ONeill, Jack; Jones, Robert E.; Gibbons, Richard C.

1995-01-01

127

Voice intelligibility in satellite mobile communications  

NASA Technical Reports Server (NTRS)

An amplitude control technique is reported that equalizes low level phonemes in a satellite narrow band FM voice communication system over channels having low carrier to noise ratios. This method presents at the transmitter equal amplitude phonemes so that the low level phonemes, when they are transmitted over the noisey channel, are above the noise and contribute to output intelligibility. The amplitude control technique provides also for squelching of noise when speech is not being transmitted.

Wishna, S.

1973-01-01

128

Satellite-aided mobile communications, experiments, applications and prospects  

NASA Technical Reports Server (NTRS)

NASA's ATS-series of satellites were used in a series of communications and position fixing experiments with automotive vehicles, ships and aircraft. Applications of the communications were demonstrated and evaluated for public services including law enforcement, search and rescue, and medical emergency, and for commercial uses in the land and maritime transportation industries. The technical success of the experiments and the demonstrated potential value of the communications prompted a study that concluded an operational satellite-aided system would be a valuable augmentation of planned trunking or cellular type terrestrial mobile radio telephone systems.

Anderson, R. E.; Frey, R. L.; Lewis, J. R.; Milton, R. T.

1980-01-01

129

A Mobile Communication Solution Based on Accessing Identifier  

Microsoft Academic Search

Internets has severe problem in security and mobility because it use the only unique source IP address and destination IP address during the process of communication all the time, IP address is overloaded in semantics because it is used to represent both the location and the identity of a user, so a new mechanism should be proposed. Although there are

Li Xiuqin; Lan Julong

2009-01-01

130

Anonymous and untraceable communications: Location privacy in mobile internetworking  

Microsoft Academic Search

Data protection and privacy is rapidly becoming one of the most important is- sues on the Internet today. Larger number of Internet sites are collecting personal information from users through forms, cookies, online registrations, or surveys than ever before. New commercial services are springing up that can exploit the ability of mobile communication service providers to determine the geographic location

Alberto Escudero Pascual

2001-01-01

131

An Interference Cancellation Scheme for Mobile Communication Radio Repeaters  

Microsoft Academic Search

An interference cancellation (ICAN) scheme for mobile communication radio repeaters is presented. When a radio repeater has a gain that is larger than the isolation between its transmit and receive antennas, it oscillates due to feedback interference signals. To prevent feedback oscillation of a radio repeater, we first formulate a feedback oscillation model of the radio repeater and then derive

Moohong Lee; Byungjik Keum; Young Serk Shim; Hwang Soo Lee

2009-01-01

132

A Model and Measure of Mobile Communication Competence  

ERIC Educational Resources Information Center

This article deals with two studies that develop a measure and model of mobile communication competence (MCC). The first study examines the dimensionality of the measure by conducting an exploratory factor analysis on 350 students at a large university in the midwestern United States. Results identified six constructs across 24 items: willingness…

Bakke, Emil

2010-01-01

133

Application of radio-over-fiber (ROF) in mobile communication  

Microsoft Academic Search

Future generation of mobile communication system must be capable of serving high quality and broadband services even in highly dense populated area. The radio-over-fibre is one of the promising systems which can be used along the emerging wireless technologies such as smart antenna or multiple input multiple output (MIMO) systems to meet these requirements. In this paper, the role of

Reza Abdolee; Razali Ngah; Vida Vakilian; Tharek A. Rahman

2007-01-01

134

Joint source-channel (de-)coding for mobile communications  

Microsoft Academic Search

Real world source coding algorithms usually leave a certain amount of redundancy within the coded bit stream. Shannon (1948) already mentioned that this redundancy can be exploited at the receiver side to achieve a higher robustness against channel errors. We show how joint source-channel decoding can be performed in a way that is applicable to any mobile communication system standard.

Tim Fingscheidt; Thomas Hindelang; Richard V. Cox; Nambi Seshadri

2002-01-01

135

Remotely controlled communication and control system for limited mobility individuals  

Microsoft Academic Search

Design improvements to a remotely controlled system for patients with limited mobility are described. This system provides communication and control of the room environment with mouse control that can be adapted to the functional need of the user. Analysis is provided on the selection and integration of components within the system as well as an overview of the simulated access

Matthew Goldman; Ettore Cervo; Alexander Melle; Bryan Wilson; Seyitriza Tigrek; Frank Agyei-Ntim; Kimberly E. Newman; Frank Barnes; Michael Blei

2011-01-01

136

Nationwide mobile communication systems, volume 1, chapters 1 thru 4  

Microsoft Academic Search

This thesis provides a basic understanding of nationwide terrestrial and satellite mobile communications and tracking technologies. Covered are systems currently available and in development. An analysis of user costs is performed for comparison. A more detailed satellite cost\\/benefit analysis for use by the trucking industry is also presented. Follow-on chapters contain discussions of the basic economic issues faces by satellite

William Joseph Schworer III

1990-01-01

137

The triple helix model in Korean mobile communication technology innovation  

Microsoft Academic Search

The aim of this research is to analyse the determining factors for the success of the Korean mobile communications industry based on the CDMA technology. We argue that the determining factors of the success lie in the close co-operative working relationship between the government, the research institutes and the industries, the unprecedented establishment of the service commercialisation and the expansion

Sang-Young Han; Yun-Bong Auh; YeongWha Sawng

2001-01-01

138

Processing voice and data in mobile satellite communications  

Microsoft Academic Search

An on-line self adaptive scheme is required to overcome delays in voice transmission to mobile terminals in satellite communications systems. A method to combat specular multipath and increase signal processing capability for voice and data transmission is described, and system performance evaluated. A signal model is developed to account for transmission parameters, with attention to Gaussian variables. Finally, an optimum

T. P. McGarty; K. S. Schneider

1977-01-01

139

4-element printed array antenna for land mobile satellite communications  

Microsoft Academic Search

A high-efficiency four-element printed array antenna composed of one-point feed crossed-dipole printed elements with a reflector has been developed. The authors describe the design techniques of the antenna for INMARSAT mobile satellite communication system use and present experimental results

Y. Kazama; Sigeru MATSUMOTO; Hajime SHIROTORI; Tamotsu SUDA; Kenzo KASAMAKI

1992-01-01

140

Coherent versus noncoherent signaling for satellite-aided mobile communications  

NASA Technical Reports Server (NTRS)

The use of coherent versus noncoherent communications is an unresolved issue for the mobile satellite community. Should one select the more robust but less efficient noncoherent strategy for communications over satellite-aided mobile channels, or does the introduction of a space platform in the mobile link improve signal stability (both amplitude and phase) such that conventional coherent schemes become attractive? This publication tries to answer some of the questions by discussing the results from experiments using a coherent QPSK receiver. The issues discussed include items such as the measured performance in Rician fading, the link error floor in a fading environment, etc. The results are compared and contrasted with that of a noncoherent limiter/discriminator FM receiver.

Davarian, F.; Sumida, J.

1986-01-01

141

The application of mobile satellite services to emergency response communications  

NASA Technical Reports Server (NTRS)

The application of an integrated satellite/terrestrial emergency response communications system in disaster relief operations is discussed. Large area coverage communications capability, full-time availability, a high degree of mobility, plus reliability, are pointed out as criteria for an effective emergency communications system. Response time is seen as a major factor determining the possible survival and/or protection of property. These criteria, can not be met by existing communications systems and complete blackouts were experienced during the past decades caused by either interruption or destruction of existing power lines, and overload or inadequacy of remaining lines. Several emergency cases, caused by either hurricanes, tornados, or floods, during which communication via satellite was instrumental to inform rescue and relief teams, are described in detail. Seismic Risk Maps and charts of Major Tectonic Plates Earthquake Epicenters are given, and it is noted that, 35 percent of the U.S. population is living in critical areas. National and international agreements for the implementation of a satellite-aided global Search and Rescue Program is mentioned. Technological and economic breakthroughs are still needed in large multibeam antennas, switching circuits, and low cost mobile ground terminals. A pending plan of NASA to initiate a multiservice program in 1982/83, with a Land Mobile Satellite capability operating in the 806 - 890 MHz band as a major element, may help to accelerate the needed breakthroughs.

Freibaum, J.

1980-01-01

142

Frequency diversity for OFDM mobile communication via underwater acoustic channels  

NASA Astrophysics Data System (ADS)

The major constraint on the performance of orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication (UWAC) based on OFDM were carried out with 0.17 bit/(s·Hz) spectral efficiency. The validity and the dependability of the scheme were also analyzed.

Qiao, Gang; Wang, Wei; Guo, Ran; Khan, Rehan; Wang, Yue

2012-03-01

143

76 FR 80402 - Certain Personal Data and Mobile Communications Devices and Related Software; Final Determination...  

Federal Register 2010, 2011, 2012, 2013

...Mobile Communications Devices and Related Software; Final Determination Finding Violation...mobile communications devices and related software. The Commission has determined that...Apple Inc., and its subsidiary NeXT Software, Inc., both of Cupertino,...

2011-12-23

144

Consideration on minimizing the mass of communications equipments for the mobile communications satellite  

NASA Astrophysics Data System (ADS)

In mobile satellite communication, small and economical earth terminals can be employed if large satellite EIRP can be realized. In order to satisfy this requirement, a large antenna and high-power transponders are necessary; simultaneously reducing the mass of communication equipments in the satellite is required. In this paper, the relations between the total mass of communication equipment and the characteristics of the transponder and antenna in the satellite are derived. As a result, the optimum transponder output power, antenna diameter, and beam number which give large satellite EIRP with minimum mass of communication equipment, are obtained.

Dooi, Yoshikazu; Iso, Akio; Okubo, Naofumi; Sekine, Kenji; Baba, Yuichirou

145

The Globalstar mobile satellite system for worldwide personal communications  

NASA Technical Reports Server (NTRS)

Loral Aerospace Corporation along with Qualcomm Inc. have developed a satellite system which offers global mobile voice and data services to and from handheld and mobile user terminals with omni-directional antennas. By combining the use of low-earth orbit (LEO) satellites with existing terrestrial communications systems and innovative, highly efficient spread spectrum techniques, the Globalstar system provides users with low-cost, reliable communications throughout the world. The Globalstar space segment consists of a constellation of 48 LEO satellites in circular orbits with 750 NM (1389 km) altitude. Each satellite communicates with the mobile users via the satellite-user links and with gateway stations. The gateway stations handle the interface between the Globalstar network and the OSTN/PLMN systems. Globalstar transceivers are similar to currently proposed digital cellular telephones in size and have a serial number that will allow the end user to make and receive calls from or to that device anywhere in the world. The Globalstar system is designed to operate as a complement to existing local, long-distance, public, private and specialized telecommunications networks. Service is primarily designed to serve the rural and thin route communications needs of consumers, government users, and private networks.

Wiedeman, Robert A.; Viterbi, Andrew J.

1993-01-01

146

Cockpit weather graphics using mobile satellite communications  

NASA Astrophysics Data System (ADS)

Many new companies are pushing state-of-the-art technology to bring a revolution in the cockpits of General Aviation (GA) aircraft. The vision, according to Dr. Bruce Holmes - the Assistant Director for Aeronautics at National Aeronautics and Space Administration's (NASA) Langley Research Center, is to provide such an advanced flight control system that the motor and cognitive skills you use to drive a car would be very similar to the ones you would use to fly an airplane. We at ViGYAN, Inc., are currently developing a system called the Pilot Weather Advisor (PWxA), which would be a part of such an advanced technology flight management system. The PWxA provides graphical depictions of weather information in the cockpit of aircraft in near real-time, through the use of broadcast satellite communications. The purpose of this system is to improve the safety and utility of GA aircraft operations. Considerable effort is being extended for research in the design of graphical weather systems, notably the works of Scanlon and Dash. The concept of providing pilots with graphical depictions of weather conditions, overlaid on geographical and navigational maps, is extremely powerful.

Seth, Shashi

147

Cockpit weather graphics using mobile satellite communications  

NASA Technical Reports Server (NTRS)

Many new companies are pushing state-of-the-art technology to bring a revolution in the cockpits of General Aviation (GA) aircraft. The vision, according to Dr. Bruce Holmes - the Assistant Director for Aeronautics at National Aeronautics and Space Administration's (NASA) Langley Research Center, is to provide such an advanced flight control system that the motor and cognitive skills you use to drive a car would be very similar to the ones you would use to fly an airplane. We at ViGYAN, Inc., are currently developing a system called the Pilot Weather Advisor (PWxA), which would be a part of such an advanced technology flight management system. The PWxA provides graphical depictions of weather information in the cockpit of aircraft in near real-time, through the use of broadcast satellite communications. The purpose of this system is to improve the safety and utility of GA aircraft operations. Considerable effort is being extended for research in the design of graphical weather systems, notably the works of Scanlon and Dash. The concept of providing pilots with graphical depictions of weather conditions, overlaid on geographical and navigational maps, is extremely powerful.

Seth, Shashi

1993-01-01

148

A wideband propagation simulator for high speed mobile radio communications  

NASA Astrophysics Data System (ADS)

Multipath, jamming, listening and detection are the main limitations for mobile radio communications. Spread spectrum techniques, especially frequency hopping, can be used to avoid these problems. Therefore, a wideband simulation for multipath mobile channels appeared the most appropriate evaluation technique. It also gives useful indications for system characteristic improvements. This paper presents the design and realization of a new UHF-VHF propagation simulator, which can be considered as an extended version of Bussgang's one. This frequency hopping simulator (up to 100,000 hops per second) is wideband thus capable to deal with spread spectrum signals. As it generates up to 16 paths, it can be used in almost all mobile radio propagation situations. Moreover, it is also able to simulate high mobile relative speeds up to 2000km/h such as air-air communication systems. This simulator can reproduce, in laboratory, 16 rays Rician or Rayleigh fading channels with a maximum time delay of about 15 ms. At the highest frequency of 1200 MHz, Doppler rates up to 2 kHz can be generated corresponding to vehicle speeds up to 2000 km/h. Let note that the Bussgang simulator was defined for narrowband and fixed radio communications. In both equipments, in-phase and quadrature signals are obtained using two numerical transversal filters. Simulation results were derived in various situations especially in terrestrial urban and suburban environments, where they could be compared with measurements. The main advantage of the simulator lies in its capacity to simulate the high speed and wideband mobile radio communication channels.

Busson, P.; Lejannic, J. C.; Elzein, G.; Citerne, J.

1994-07-01

149

Close Relationships: A Study of Mobile Communication Records  

NASA Astrophysics Data System (ADS)

Mobile phone communication as digital service generates ever-increasing datasets of human communication actions, which in turn allow us to investigate the structure and evolution of social interactions and their networks. These datasets can be used to study the structuring of such egocentric networks with respect to the strength of the relationships by assuming direct dependence of the communication intensity on the strength of the social tie. Recently we have discovered that there are significant differences between the first and further "best friends" from the point of view of age and gender preferences. Here we introduce a control parameter p max based on the statistics of communication with the first and second "best friend" and use it to filter the data. We find that when p max is decreased the identification of the "best friend" becomes less ambiguous and the earlier observed effects get stronger, thus corroborating them.

Palchykov, Vasyl; Kertész, János; Dunbar, Robin; Kaski, Kimmo

2013-05-01

150

Why is CDMA the solution for mobile satellite communication  

NASA Technical Reports Server (NTRS)

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

151

Monitoring Heart Disease and Diabetes with Mobile Internet Communications  

PubMed Central

A telemedicine system is described for monitoring vital signs and general health indicators of patients with cardiac and diabetic conditions. Telemetry from wireless sensors and readings from other instruments are combined into a comprehensive set of measured patient parameters. Using a combination of mobile device applications and web browser, the data can be stored, accessed, and displayed using mobile internet communications to the central server. As an extra layer of security in the data transmission, information embedded in the data is used in its verification. The paper highlights features that could be enhanced from previous systems by using alternative components or methods.

Mulvaney, David; Woodward, Bryan; Datta, Sekharjit; Harvey, Paul; Vyas, Anoop; Thakker, Bhaskar; Farooq, Omar; Istepanian, Robert

2012-01-01

152

Near field communication: getting in touch with mobile users.  

PubMed

Near field communication is a method for sending and receiving small amounts of data across very short distances wirelessly. This technology is already available in a number of mobile devices and has many possible uses, including electronic payment, access control, and information exchange. This article will explain the basic principles of near field communication, discuss some of the ways it can be used in libraries, and explore some possible concerns with the technology. A list of resources for additional information is also included. PMID:23869639

Hoy, Matthew B

2013-01-01

153

FEC decoder design optimization for mobile satellite communications  

NASA Technical Reports Server (NTRS)

A new telecommunications service for location determination via satellite is being proposed for the continental USA and Europe, which provides users with the capability to find the location of, and communicate from, a moving vehicle to a central hub and vice versa. This communications system is expected to operate in an extremely noisy channel in the presence of fading. In order to achieve high levels of data integrity, it is essential to employ forward error correcting (FEC) encoding and decoding techniques in such mobile satellite systems. A constraint length k = 7 FEC decoder has been implemented in a single chip for such systems. The single chip implementation of the maximum likelihood decoder helps to minimize the cost, size, and power consumption, and improves the bit error rate (BER) performance of the mobile earth terminal (MET).

Roy, Ashim; Lewi, Leng

1990-01-01

154

NASA's mobile satellite communications program; ground and space segment technologies  

NASA Technical Reports Server (NTRS)

This paper describes the Mobile Satellite Communications Program of the United States National Aeronautics and Space Administration (NASA). The program's objectives are to facilitate the deployment of the first generation commercial mobile satellite by the private sector, and to technologically enable future generations by developing advanced and high risk ground and space segment technologies. These technologies are aimed at mitigating severe shortages of spectrum, orbital slot, and spacecraft EIRP which are expected to plague the high capacity mobile satellite systems of the future. After a brief introduction of the concept of mobile satellite systems and their expected evolution, this paper outlines the critical ground and space segment technologies. Next, the Mobile Satellite Experiment (MSAT-X) is described. MSAT-X is the framework through which NASA will develop advanced ground segment technologies. An approach is outlined for the development of conformal vehicle antennas, spectrum and power-efficient speech codecs, and modulation techniques for use in the non-linear faded channels and efficient multiple access schemes. Finally, the paper concludes with a description of the current and planned NASA activities aimed at developing complex large multibeam spacecraft antennas needed for future generation mobile satellite systems.

Naderi, F.; Weber, W. J.; Knouse, G. H.

1984-01-01

155

Looking at the other side of the coin: the search for possible biopositive cognitive effects of the exposure to 900 MHz GSM mobile phone radiofrequency radiation  

PubMed Central

Although exposure to electromagnetic radiation in radiofrequency range has caused a great deal of concern globally, radiofrequency radiation has many critical applications in both telecommunication and non-communication fields. The induction of adaptive response phenomena by exposure to radiofrequency radiation as either increased resistance to a subsequent dose of ionizing radiation or resistance to a bacterial infection has been reported recently. Interestingly, the potential beneficial effects of mobile phone radiofrequency radiation are not only limited to the induction of adaptive phenomena. It has previously been indicated that the visual reaction time of university students significantly decreased after a 10 min exposure to radiofrequency radiation emitted by a mobile phone. Furthermore, it has been revealed that occupational exposures to radar radiations decreased the reaction time in radar workers. Based on these findings, it can be hypothesized that in special circumstances, these exposures might lead to a better response of humans to different hazards. Other investigators have also provided evidence that confirms the induction of RF-induced cognitive benefits. Furthermore, some recent reports have indicated that RF radiation may play a role in protecting against cognitive impairment in Alzheimer’s disease. In this light, a challenging issue will arise if there are other RF-induced stimulating effects. It is also challenging to explore the potential applications of these effects. Further research may shed light on dark areas of the health effects of short and long-term human exposure to radiofrequency radiation.

2014-01-01

156

Trellis-coded CPM for satellite-based mobile communications  

NASA Technical Reports Server (NTRS)

Digital transmission for satellite-based land mobile communications is discussed. To satisfy the power and bandwidth limitations imposed on such systems, a combination of trellis coding and continuous-phase modulated signals are considered. Some schemes based on this idea are presented, and their performance is analyzed by computer simulation. The results obtained show that a scheme based on directional detection and Viterbi decoding appears promising for practical applications.

Abrishamkar, Farrokh; Biglieri, Ezio

1988-01-01

157

Rayleigh fading compensation for QAM in land mobile radio communications  

Microsoft Academic Search

A pilot symbol-aided Rayleigh fading compensation is investigated for M-ary quadrature amplitude modulation (QAM) to achieve highly spectrally efficient land mobile communication systems. The optimum parameters for fading compensation, bit error rate (BER) performance against Eb\\/N0 (energy per bit to the noise power spectrum density), adjacent channel interference, and cochannel interference for 16-QAM, 64-QAM, and 256-QAM, and the spectral efficiencies

Seiichi Sampei; Terumi Sunaga

1993-01-01

158

First satellite mobile communication trials using BLQS-CDMA  

NASA Technical Reports Server (NTRS)

In this paper, technical results obtained in the first MSBN Land mobile technical trial are reported. MSBN (Mobile Satellite Business Network) is a new program undertaken by the European Space Agency (ESA) to promote mobile satellite communication in Europe, in particular voice capability. The first phase of the MSBN system implementation plan is an experimental phase. Its purpose is to evaluate through field experiments the performance of the MSBN system prior to finalization of its specifications. Particularly, the objective is to verify in the field and possibly improve the performance of the novel satellite access technique BLQS-CDMA (Band Limited Quasi-Synchronous-Code Division Multiple Access), which is proposed as baseline for the MSBN.

Luzdemateo, Maria; Johns, Simon; Dothey, Michel; Vanhimbeeck, Carl; Deman, Ivan; Wery, Bruno

1993-01-01

159

Mobile satellite digital communications - Prodat and Standard C  

NASA Astrophysics Data System (ADS)

The ESA Prodat system aimed at demonstrating the usefulness of satellite communications for mobile users is outlined, and emphasis is placed on mobile terminals. The specifics of the land-mobile environment are discussed including open areas with no obstructions and partial and complete obstructions. A Prodat terminal connected to a handheld personal computer is described, along with its modes of operation: tracking and synchronization, standby mode when the link is interrupted, and acquisition mode. The second part of the paper is devoted to the development of an Inmarsat Standard C Ship Earth Station. A Standard C terminal is described, and attention is focused on microwave performance, a fading simulator, and Standard C demodulator. Error probability and performance characteristics are assessed.

Meuleman, F.; Glavieux, A.

160

An improved procedure to accurately assess the variability of the exposure to electromagnetic radiation emitted by GSM base station antennas  

NASA Astrophysics Data System (ADS)

Long-term human exposure around Global System for Mobile Communications (GSM) base station antennas has not yet been precisely established; this is of interest from human health and epidemiological perspectives. Actual exposure is difficult to assess accurately, mainly because there is a lack of technical information directly from the GSM operators. The in situ measurement standards available at present provide only a worst-case prediction method; the present work goes beyond this and proposes a methodology that, without the need for data from operators, allows a reliable way to express real exposure with a greater accuracy than all other methods proposed to date. The method is based on dual measurements of the signal strengths in the frequency domain and the time domain and takes into consideration the instantaneous traffic in GSM channels. In addition, it allows a channel-individualized exposure assessement, by making possible the separate analysis of the electric field level in the two types of channel of the GSM standard—the traffic channels and the control channels.

Bechet, Paul; Miclaus, Simona

2013-01-01

161

Aeronautical Mobile Airport Communications System (AeroMACS)  

NASA Technical Reports Server (NTRS)

To help increase the capacity and efficiency of the nation s airports, a secure wideband wireless communications system is proposed for use on the airport surface. This paper provides an overview of the research and development process for the Aeronautical Mobile Airport Communications System (AeroMACS). AeroMACS is based on a specific commercial profile of the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard known as Wireless Worldwide Interoperability for Microwave Access or WiMAX (WiMax Forum). The paper includes background on the need for global interoperability in air/ground data communications, describes potential AeroMACS applications, addresses allocated frequency spectrum constraints, summarizes the international standardization process, and provides findings and recommendations from the world s first AeroMACS prototype implemented in Cleveland, Ohio, USA.

Budinger, James M.; Hall, Edward

2011-01-01

162

Mobile Computing, Programming, Games and Online Communities: Changes to the Communicative Ecology of Design Students Through Mobile Computing: Part 2  

Microsoft Academic Search

In this paper, we discuss the influence the increased mobility afforded by Tablet PCs has had on the way multimedia students learn programming concepts and practice skills and techniques through their communicative ecology. Following on from our previous ethnographic action research study, on mobile computing, visual diaries, learning and communication, (Berry & Hamilton, 2006) we allocated Tablet PCs to a

Margaret Hamilton; Marsha Berry

163

Interference Analysis for an Aeronautical Mobile Airport Communications System  

NASA Technical Reports Server (NTRS)

The next generation of aeronautical communications for airport surface applications has been identified through a NASA research program and an international collaborative future communications study. The result, endorsed by both the United States and European regulatory agencies is called AeroMACS (Aeronautical Mobile Airport Communications System) and is based upon the IEEE 802.16e mobile wireless standard. Coordinated efforts to develop appropriate aviation standards for the AeroMACS system are now underway within RTCA (United States) and Eurocae (Europe). AeroMACS will be implemented in a recently allocated frequency band, 5091- 5150 MHz. As this band is also occupied by fixed satellite service uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference to the fixed satellite service are under analysis in order to enable the definition of standards that assure that such interference will be avoided. The NASA Glenn Research Center has been involved in this analysis, and the first results of modeling and simulation efforts directed at this analysis are the subject of this paper.12

Wilson, Jeffrey D.; Kercewski, Robert J.

2010-01-01

164

PERCEPTIONS OF SECURITY AND PRIVACY WHEN USING MOBILE COMMUNICATION SYSTEMS An Analysis of Administrative and Line Staff Congruence  

Microsoft Academic Search

Mobile communication systems have revolutionized business communication and become common communication tools within business organizations. The dramatic increase in the use of mobile communication systems would not have been possible without the assumption of information security and privacy. However, in many workplaces, this assumption is wrong, and, in fact, mobile communications are vulnerable in many ways. The purpose of this

Cheon-Pyo Lee; Xin Luo; Merrill Warkentin

165

More About Lens Antenna For Mobile/Satellite Communication  

NASA Technical Reports Server (NTRS)

Report presents additional details of design of proposed phased-array antenna described in "Lens Antenna for Mobile/Satellite Communication" (NPO-16948). Intended to be compact and to lie flat on top of vehicle on ground. Transmits and receives circularly polarized radiation in frequency ranges of 821 to 825 MHz and 860 to 870 MHz. Transmitting and receiving beams electronically steerable to any of 48 evenly spaced directions to provide complete azimuth coverage, and would be fixed, but wide, in elevation, to provide coverage at elevation angles from 20 degrees to 60 degrees.

Rahmat-Samii, Y.; Bodnar, D. G.; Rainer, B. K.

1990-01-01

166

User requirements for interruption management in mobile communications in hospitals.  

PubMed

In hospitals, mobile communication devices increase the occurrence of inappropriate interruptions during clinical task performance. These interruptions have been related to decreased quality of clinical care. User requirements were elicited using a scenario based approach. The results present insights into user requirements for an interruption management system for hospitals. Hospital workflow protocols were identified as a major source of interruptions. Many suggestions for managing these interruptions related to improving workflow using IT. We have shown that even though the hospital is an exceptionally demanding environment, the user requirements for interruption management concur with earlier findings in the broader fields of context aware interruption management and computer supported cooperative work. PMID:23920869

Talsma, Bernd G; Solvoll, Terje; Hartvigsen, Gunnar

2013-01-01

167

Omni-directional L-band antenna for mobile communications  

NASA Technical Reports Server (NTRS)

The principle and design of an L-band omni-directional mobile communication antenna are discussed. The antenna is a circular wave guide aperture with hybrid circuits attached to higher order mode excitation. It produces polarized and symmetric two split beams in elevation. The circular waveguide is fed by eight probes with a 90 degree phase shift between their inputs. Radiation pattern characteristics are controlled by adjusting the aperture diameter and mode excitation. This antenna satisfies gain requirements as well as withstanding the harsh environment.

Kim, C. S.; Moldovan, N.; Kijesky, J.

1988-01-01

168

Channel Modelling and Characterization of Mobile Satellite Communication Systems  

NASA Astrophysics Data System (ADS)

Reliable characterization of the propagation environment and channel modelling of mobile satellite communication systems is necessary in order to provide better quality of service and efficient design of these systems. In this paper, the channel impairments affecting the performance and an overview of the satellite channel models are presented. The statistical distributions of the received signal that can be used to characterize the dynamic nature of these propagation channels are also presented. The main modelling parameters are investigated and simulation results show that the bit error rate (BER) performance is predominantly affected by the shadowing factor. Finally, in order to further test the channel models and the effect of the propagation environment, we investigate a novel application of using satellite diversity in conjunction with compact MIMO (multiple-input multiple-output) antenna array configurations in order to enhance the capacity of satellite communication links.

Mohammed, Abbas; Seun, Ajayi; Yang, Zhe; Erman, Maria; Hult, Tommy

2009-03-01

169

Design for Social Presence and Exploring Its Mediating Effect in Mobile Data Communication Services  

ERIC Educational Resources Information Center

The mobility, flexibility, convenience, and ubiquity of mobile data services (MDS) have contributed to their enormous growth and popularity with users. MDS allow users to communicate through mobile texting (mTexting), mobile Instant Messaging (mIM), multimedia messaging services (MMS), and email. A unique feature of MDS that enhances its…

Ogara, Solomon Omondi

2011-01-01

170

Radial microstrip slotline feed network for circular mobile communications array  

NASA Astrophysics Data System (ADS)

In mobile and satellite communications there is a need for low cost and low profile antennas which have a toroidal pattern. Antennas that have been developed for mobile communications include a L-Band electronically steered stripline phased array, a Ka-Band mechanically steered elliptical reflector antenna and a Ka-Band printed dipole. In addition, a L-Band mechanically steered microstrip array, a L-Band microstrip phased array tracking antenna for mounting on a car roof and an X-Band radial line slotted waveguide antenna have been demonstrated. In the above electronically scanned printed arrays, the individual element radiates normally to the plane of the array and hence require a phase shifter to scan the beam towards the horizon. Scanning in the azimuth is by mechanical or electronic steering. An alternate approach is to mount microstrip patch radiators on the surface of a cone to achieve the required elevation angle. The array then scans in the azimuth by beam switching.

Simons, Rainee N.; Kelly, Eron S.; Lee, Richard Q.; Taub, Susan R.

1994-04-01

171

The System of Wireless Smart House Based on GSM and ZigBee  

Microsoft Academic Search

GSM is combined with the new generation wireless network communication technology ZigBee, which established a wireless smart house system based on the GSM and ZigBee. The system refer to DSP chips to achieve controlling and monitoring the home applications, achieving to remote control and monitoring. This designment has reflected the characteristic of low cost, low power dissipation, great practical and

Gao Mingming; Shaoliangshan; Huixiaowei; Sunqingwei

2010-01-01

172

Robust Timing Synchronization in Aeronautical Mobile Communication Systems  

NASA Technical Reports Server (NTRS)

This work details a study of robust synchronization schemes suitable for satellite to mobile aeronautical applications. A new scheme, the Modified Sliding Window Synchronizer (MSWS), is devised and compared with existing schemes, including the traditional Early-Late Gate Synchronizer (ELGS), the Gardner Zero-Crossing Detector (GZCD), and the Sliding Window Synchronizer (SWS). Performance of the synchronization schemes is evaluated by a set of metrics that indicate performance in digital communications systems. The metrics are convergence time, mean square phase error (or root mean-square phase error), lowest SNR for locking, initial frequency offset performance, midstream frequency offset performance, and system complexity. The performance of the synchronizers is evaluated by means of Matlab simulation models. A simulation platform is devised to model the satellite to mobile aeronautical channel, consisting of a Quadrature Phase Shift Keying modulator, an additive white Gaussian noise channel, and a demodulator front end. Simulation results show that the MSWS provides the most robust performance at the cost of system complexity. The GZCD provides a good tradeoff between robustness and system complexity for communication systems that require high symbol rates or low overall system costs. The ELGS has a high system complexity despite its average performance. Overall, the SWS, originally designed for multi-carrier systems, performs very poorly in single-carrier communications systems. Table 5.1 in Section 5 provides a ranking of each of the synchronization schemes in terms of the metrics set forth in Section 4.1. Details of comparison are given in Section 5. Based on the results presented in Table 5, it is safe to say that the most robust synchronization scheme examined in this work is the high-sample-rate Modified Sliding Window Synchronizer. A close second is its low-sample-rate cousin. The tradeoff between complexity and lowest mean-square phase error determines the rankings of the Gardner Zero-Crossing Detector and both versions of the Early-Late Gate Synchronizer. The least robust models are the high and low-sample-rate Sliding Window Synchronizers. Consequently, the recommended replacement synchronizer for NASA's Advanced Air Transportation Technologies mobile aeronautical communications system is the high-sample-rate Modified Sliding Window Synchronizer. By incorporating this synchronizer into their system, NASA can be assured that their system will be operational in extremely adverse conditions. The quick convergence time of the MSWS should allow the use of high-level protocols. However, if NASA feels that reduced system complexity is the most important aspect of their replacement synchronizer, the Gardner Zero-Crossing Detector would be the best choice.

Xiong, Fu-Qin; Pinchak, Stanley

2004-01-01

173

A review of earth observation using mobile personal communication devices  

NASA Astrophysics Data System (ADS)

Earth observation using mobile personal communication devices (MPCDs) is a recent advance with considerable promise for acquiring important and timely measurements. Globally, over 5 billion people have access to mobile phones, with an increasing proportion having access to smartphones with capabilities such as a camera, microphone, global positioning system (GPS), data storage, and networked data transfer. Scientists can view these devices as embedded sensors with the potential to take measurements of the Earth's surface and processes. To advance the state of Earth observation using MPCDs, scientists need to consider terms and concepts, from a broad range of disciplines including citizen science, image analysis, and computer vision. In this paper, as a result of our literature review, we identify a number of considerations for Earth observation using MPCDs such as methods of field collection, collecting measurements over broad areas, errors and biases, data processing, and accessibility of data. Developing effective frameworks for mobile data collection with public participation and strategies for minimizing bias, in combination with advancements in image processing techniques, will offer opportunities to collect Earth sensing data across a range of scales and perspectives, complimenting airborne and spaceborne remote sensing measurements.

Ferster, Colin J.; Coops, Nicholas C.

2013-02-01

174

Advanced mobile satellite communications using COMETS satellite in MM-wave and Ka-band  

NASA Technical Reports Server (NTRS)

Early in the 21st century, the demand for personal communications using mobile, hand-held, and VSAT terminals will rapidly increase. In a future system, many different types of services should be provided with one-hop connection. The Communications Research Laboratory (CRL) has studied a future advanced mobile satellite communications system using millimeter wave and Ka band. In 1990, CRL started the Communications and Broadcasting Engineering Test Satellite (COMETS) project. The satellite has been developed in conjunction with NASDA and will be launched in 1997. This paper describes the COMETS payload configuration and the experimental system for the advanced mobile communications mission.

Ohmori, Shingo; Isobe, Shunkichi; Takeuchi, Makoto; Naito, Hideyuki

1993-01-01

175

Influence of Mobile Phones on the Quality of ECG Signal Acquired by Medical Devices  

NASA Astrophysics Data System (ADS)

Health aspects of the use of radiating devices, like mobile phones, are still a public concern. Stand-alone electrocardiographic systems and those built-in, more sophisticated, medical devices have become a standard tool used in everyday medical practice. GSM mobile phones might be a potential source of electromagnetic interference (EMI) which may affect reliability of medical appliances. Risk of such event is particularly high in places remote from GSM base stations in which the signal received by GSM mobile phone is weak. In such locations an increase in power of transmitted radio signal is necessary to enhance quality of the communication. In consequence, the risk of interference of electronic devices increases because of the high level of EMI. In the present paper the spatial, temporal, and spectral characteristics of the interference have been examined. The influence of GSM mobile phone on multilead ECG recordings was studied. It was observed that the electrocardiographic system was vulnerable to the interference generated by the GSM mobile phone working with maximum transmit power and in DTX mode when the device was placed in a distance shorter than 7.5 cm from the ECG electrode located on the surface of the chest. Negligible EMI was encountered at any longer distance.

Buczkowski, T.; Janusek, D.; Zavala-Fernandez, H.; Skrok, M.; Kania, M.; Liebert, A.

2013-10-01

176

Multi-purpose HealthCare Telemedicine Systems with mobile communication link support.  

PubMed

The provision of effective emergency telemedicine and home monitoring solutions are the major fields of interest discussed in this study. Ambulances, Rural Health Centers (RHC) or other remote health location such as Ships navigating in wide seas are common examples of possible emergency sites, while critical care telemetry and telemedicine home follow-ups are important issues of telemonitoring. In order to support the above different growing application fields we created a combined real-time and store and forward facility that consists of a base unit and a telemedicine (mobile) unit. This integrated system: can be used when handling emergency cases in ambulances, RHC or ships by using a mobile telemedicine unit at the emergency site and a base unit at the hospital-expert's site, enhances intensive health care provision by giving a mobile base unit to the ICU doctor while the telemedicine unit remains at the ICU patient site and enables home telemonitoring, by installing the telemedicine unit at the patient's home while the base unit remains at the physician's office or hospital. The system allows the transmission of vital biosignals (3-12 lead ECG, SPO2, NIBP, IBP, Temp) and still images of the patient. The transmission is performed through GSM mobile telecommunication network, through satellite links (where GSM is not available) or through Plain Old Telephony Systems (POTS) where available. Using this device a specialist doctor can telematically "move" to the patient's site and instruct unspecialized personnel when handling an emergency or telemonitoring case. Due to the need of storing and archiving of all data interchanged during the telemedicine sessions, we have equipped the consultation site with a multimedia database able to store and manage the data collected by the system. The performance of the system has been technically tested over several telecommunication means; in addition the system has been clinically validated in three different countries using a standardized medical protocol. PMID:12694629

Kyriacou, E; Pavlopoulos, S; Berler, A; Neophytou, M; Bourka, A; Georgoulas, A; Anagnostaki, A; Karayiannis, D; Schizas, C; Pattichis, C; Andreou, A; Koutsouris, D

2003-03-24

177

Isolated and coupled superquadric loop antennas for mobile communications applications  

NASA Astrophysics Data System (ADS)

This work provides an investigation of the performance of loop antennas for use in mobile communications applications. The analysis tools developed allow for high flexibility by representing the loop antenna as a superquadric curve, which includes the case of circular, elliptical, and rectangular loops. The antenna may be in an isolated environment, located above an infinite ground plane, or placed near a finite conducting plate or box. In cases where coupled loops are used, the two loops may have arbitrary relative positions and orientations. Several design examples are included to illustrate the versatility of the analysis capabilities. The performance of coupled loops arranged in a diversity scheme is also evaluated, and it is found that high diversity gain can be achieved even when the antennas are closely spaced.

Jensen, Michael A.; Rahmat-Samii, Yahya

178

Considerations of digital phase modulation for narrowband satellite mobile communication  

NASA Technical Reports Server (NTRS)

The Inmarsat-M system for mobile satellite communication is specified as a frequency division multiple access (FDMA) system, applying Offset Quadrature Phase Shift Keying (QPSK) for transmitting 8 kbit/sec in 10 kHz user channel bandwidth. We consider Digital Phase Modulation (DPM) as an alternative modulation format for INMARSAT-M. DPM is similar to Continuous Phase Modulation (CPM) except that DPM has a finite memory in the premodular filter with a continuous varying modulation index. It is shown that DPM with 64 states in the VA obtains a lower bit error rate (BER). Results for a 5 kHz system, with the same 8 kbit/sec transmitted bitstream, is also presented.

Grythe, Knut

1990-01-01

179

Speech coding at 4800 bps for mobile satellite communications  

NASA Technical Reports Server (NTRS)

A speech compression project has recently been completed to develop a speech coding algorithm suitable for operation in a mobile satellite environment aimed at providing telephone quality natural speech at 4.8 kbps. The work has resulted in two alternative techniques which achieve reasonably good communications quality at 4.8 kbps while tolerating vehicle noise and rather severe channel impairments. The algorithms are embodied in a compact self-contained prototype consisting of two AT and T 32-bit floating-point DSP32 digital signal processors (DSP). A Motorola 68HC11 microcomputer chip serves as the board controller and interface handler. On a wirewrapped card, the prototype's circuit footprint amounts to only 200 sq cm, and consumes about 9 watts of power.

Gersho, Allen; Chan, Wai-Yip; Davidson, Grant; Chen, Juin-Hwey; Yong, Mei

1988-01-01

180

Isolated and coupled superquadric loop antennas for mobile communications applications  

NASA Technical Reports Server (NTRS)

This work provides an investigation of the performance of loop antennas for use in mobile communications applications. The analysis tools developed allow for high flexibility by representing the loop antenna as a superquadric curve, which includes the case of circular, elliptical, and rectangular loops. The antenna may be in an isolated environment, located above an infinite ground plane, or placed near a finite conducting plate or box. In cases where coupled loops are used, the two loops may have arbitrary relative positions and orientations. Several design examples are included to illustrate the versatility of the analysis capabilities. The performance of coupled loops arranged in a diversity scheme is also evaluated, and it is found that high diversity gain can be achieved even when the antennas are closely spaced.

Jensen, Michael A.; Rahmat-Samii, Yahya

1993-01-01

181

Adaptive beamforming in a CDMA mobile satellite communications system  

NASA Technical Reports Server (NTRS)

Code-Division Multiple-Access (CDMA) stands out as a strong contender for the choice of multiple access scheme in these future mobile communication systems. This is due to a variety of reasons such as the excellent performance in multipath environments, high scope for frequency reuse and graceful degradation near saturation. However, the capacity of CDMA is limited by the self-interference between the transmissions of the different users in the network. Moreover, the disparity between the received power levels gives rise to the near-far problem, this is, weak signals are severely degraded by the transmissions from other users. In this paper, the use of time-reference adaptive digital beamforming on board the satellite is proposed as a means to overcome the problems associated with CDMA. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference sources. Since CDMA is interference limited, the interference protection provided by the antenna converts directly and linearly into an increase in capacity. Furthermore, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of power control. A payload architecture will be presented that illustrates the practical implementation of this concept. This digital payload architecture shows that with the advent of high performance CMOS digital processing, the on-board implementation of complex DSP techniques -in particular digital beamforming- has become possible, being most attractive for Mobile Satellite Communications.

Munoz-Garcia, Samuel G.

1993-01-01

182

Parametric Models for Speech Quality Estimation in GSM Networks  

Microsoft Academic Search

Speech quality assessment is an emergent QoS aspect in cellular network monitoring. This contribution deals with the estimation of perceived speech quality in GSM networks, by means of parametric models. Our goal is to provide a model for MOS estimation, based on parameters available in the operation and maintenance centre (OMC) and in the measurement reports from mobile stations. Specifically,

M. Barile; P. Camarda; R. Dell'Aquila; N. Vitti

2006-01-01

183

Efficient simulation of TCP\\/IP for mobile wireless communications using importance sampling  

Microsoft Academic Search

Future military communications systems are expected to exchange information in a seamless and reliable manner across heterogeneous networks composed of both fixed, wired nodes and mobile, wireless nodes. While commercial protocols such as TCP\\/IP have improved the seamlessness of military communications systems, the use of TCP\\/IP in the mobile, wireless environment for which it was not designed can have a

Zsolt Haraszti; J. Keith Townsend; James A. Freebersyser

1998-01-01

184

A study and experiment plan for digital mobile communication via satellite  

Microsoft Academic Search

The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll

J. J. Jones; E. J. Craighill; R. G. Evans; A. D. Vincze; N. N. Tom

1978-01-01

185

Technological Developments and Socio-Economic Issues of Wireless Mobile Communications.  

ERIC Educational Resources Information Center

Examines technological developments and the worldwide social-economic impacts of wireless mobile communications. Provides an overview of the technological developments of wireless mobile communications. Describes the evolution towards next-generation systems. Analyzes reasons for the growth rate of subscribers and the related social development.…

Beaubrun, Ronald; Pierre, Samuel

2001-01-01

186

Mobile forms of communication and the transformation of relations between the public and private spheres  

Microsoft Academic Search

Mobile communications have transformed the way people interact in those countries where technology, economics and policy have intersected to foster its profusion. That much would appear self-evident. Anecdotally we can call up a host of archetypal instances of mobile communications impacting upon our everyday lives in ways which less than two decades ago (in an age of fixed-line telephony) would

Bob Jeffery

187

Low and Medium-Gain antennas for Mobile Satellite Communications (MSC) and Navigation  

Microsoft Academic Search

In this paper are introduced Low-Gain Omnidirectional Antennas for Mobile Satellite Communications (MSC) and Navigation. In many respects the Mobile Satellite Antenna (MSA) infrastructures currently available for MSC and Navigation. Medium and high gain MSA need to track the satellite, following both movements of mobiles and satellite orbital motions. Sometimes this is difficult and expensive to synchronize and have to

Stojce Dimov Ilcev

2011-01-01

188

A Analysis of Noise and Interference in a Satellite Based Mobile Communications System  

Microsoft Academic Search

In any satellite-to-mobile or mobile-to-mobile communications system, the effects of fading, propagation path loss, noise, interference, and non-linearities on the signal have to be considered. The basic problem is to evaluate the performance of such a communications link for various signaling schemes. However, the multitude of the noise, attenuation and interference effects described above would introduce so many variables that

Shalom Solomon Bergstein

1983-01-01

189

An analysis of noise and interference in a satellite based mobile communications system  

Microsoft Academic Search

In any satellite-to-mobile or mobile-to-mobile communications system, the effects of fading, propagation path loss, noise, interference, and non-linearities on the signal have to be considered. The basic problem is to evaluate the performance of such a communications link for various signaling schemes. However, the multitude of the noise, attenuation and interference effects described above would introduce so many variables that

S. S. Bergstein

1983-01-01

190

How can we use mobile apps for disaster communications in Taiwan: Problems and possible practice  

Microsoft Academic Search

The growth rate of global smart phone in 2010 is as high as 78.1%, showing that smart phone gradually becomes the mainstream in the mobile phone market. Smart phone has the function of installing applications, provides users with more diversified mobile value-added services and will change users' communication habits in the future. Mobile communication follows the development trend of 3G

Sz Jie Sung

2011-01-01

191

77 FR 40399 - Qiao Xing Universal Resources, Inc., and Qiao Xing Mobile Communication Co., Ltd.; Order of...  

Federal Register 2010, 2011, 2012, 2013

...Xing Universal Resources, Inc., and Qiao Xing Mobile Communication Co., Ltd.; Order of Suspension of Trading July...information concerning the securities of Qiao Xing Mobile Communication Co., Ltd. (``QXM''), a British...

2012-07-09

192

Study on Communication between Home and School System Based on Mobile Education Platform  

Microsoft Academic Search

As the two significant sides of the education, it is all-important to communicate and intercourse between the home and school. With the development of the information and the internet, Notebook computers, mobile phones and other modern communications equipments continues to increase, they are constructing the timely exchange of information and the emotion platform. So this article firstly introduces the communication

Weifeng Jiao; Jialing Zhao

2007-01-01

193

Placement of UAVs as Communication Relays Aiding Mobile Ad Hoc Wireless Networks  

Microsoft Academic Search

Unmanned aerial vehicles (UAVs) have been used for surveillance and reconnaaissance operations. Such communications enabled platforms can also be effectively utilized to enhance the communications transport capabilitites of a mobile ad hoc wireless network. When properly embedded into the architecture of a communications network, the resultirng UAV aided terrestrial network architecture is expended into a multi-layered hierarchical network structure. The

Izhak Rubin; Runhe Zhang

2007-01-01

194

Technical design and service aspects of digital mobile satellite communication systems  

Microsoft Academic Search

The key technical elements in designing digital mobile satellite communication systems are identified, and tradeoff studies on the transmission parameters of the satellite link, which were based on experience with an experimental system and the results of field trials, on digital maritime and aeronautical satellite communication systems, are described. The future evolution of the various new communication services to be

Yutaka YASUDA; Masayoshi OHASHI; Fumiaki SUGAYA; Yasuo HIRATA

1988-01-01

195

Adaptive digital beamforming for a CDMA mobile communications payload  

NASA Technical Reports Server (NTRS)

In recent years, Spread-Spectrum Code Division Multiple Access (CDMA) has become a very popular access scheme for mobile communications due to a variety of reasons: excellent performance in multipath environments, high scope for frequency reuse, graceful degradation near saturation, etc. In this way, a CDMA system can support simultaneous digital communication among a large community of relatively uncoordinated users sharing a given frequency band. Nevertheless, there are also important problems associated with the use of CDMA. First, in a conventional CDMA scheme, the signature sequences of asynchronous users are not orthogonal and, as the number of active users increases, the self-noise generated by the mutual interference between users considerably degrades the performance, particularly in the return link. Furthermore, when there is a large disparity in received powers - due to differences in slant range or atmospheric attenuation - the non-zero cross-correlation between the signals gives rise to the so-called near-far problem. This leads to an inefficient utilization of the satellite resources and, consequently, to a drastic reduction in capacity. Several techniques were proposed to overcome this problem, such as Synchronized CDMA - in which the signature sequences of the different users are quasi-orthogonal - and power control. At the expense of increased network complexity and user coordination, these techniques enable the system capacity to be restored by equitably sharing the satellite resources among the users. An alternative solution is presented based upon the use of time-reference adaptive digital beamforming on board the satellite. This technique enables a high number of independently steered beams to be generated from a single phased array antenna, which automatically track the desired user signal and null the unwanted interference source. In order to use a time-reference adaptive antenna in a communications system, the main challenge is to obtain a reference signal highly correlated with the desired user signal and uncorrelated with the interferences. CDMA lends itself very easily to the generation of such a reference signal, thanks to the a priori knowledge of the user's signature sequence. First, the integration of an adaptive antenna in an asynchronous CDMA system is analyzed. The adaptive antenna system can provide increased interference rejection - much higher than that afforded by the code alone - and, since CDMA is mainly interference limited, any reduction in interference converts directly and linearly into an increase in capacity. Analyses and computer simulations are presented that show how an asynchronous CDMA system incorporating adaptive beamforming can provide at least as much capacity as a synchronous system. More importantly, the proposed concept allows the near-far effect to be mitigated without requiring a tight coordination of the users in terms of transmitted power control or network synchronization. The system is extremely robust to the near-far effect because the signals reaching the satellite from directions other than that of the desired user - which are likely to have different power levels - are adaptively canceled by the antenna. Finally, a payload architecture is presented that illustrates the practical implementation of this concept. This digital payload architecture demonstrates that with the advent of high performance CMOS digital processing, the on-board implementation of complex DSP techniques - in particular Digital Beamforming - has become possible, being most attractive for Mobile Satellite Communications.

Munoz-Garcia, Samuel G.; Ruiz, Javier Benedicto

1993-01-01

196

GSM SIMs as Web Servers  

Microsoft Academic Search

This paper outlines a prototype that integrates the GSMsecurity infrastructure into the Internet: The idea is to extend a GSM SIM to a securityserver for a GSM subscriber in the Internet. Such a WebSIM, like any other server inthe Internet, speaks TCP\\/IP and is transparently accessible from Internet hosts viaHTTP. Specific services offered by SIMs, e.g. authentication, can be accessed

Scott Guthery; Roger Kehr; Joachim Posegga; Harald Vogt

2000-01-01

197

An Interference Cancellation Scheme for Mobile Communication Radio Repeaters  

NASA Astrophysics Data System (ADS)

An interference cancellation (ICAN) scheme for mobile communication radio repeaters is presented. When a radio repeater has a gain that is larger than the isolation between its transmit and receive antennas, it oscillates due to feedback interference signals. To prevent feedback oscillation of a radio repeater, we first formulate a feedback oscillation model of the radio repeater and then derive an ICAN model from that model. From the derived ICAN model, we show that the stability and the signal quality of the repeater depend on the repeater's gain and delay, the propagation delay on feedback paths, feedback channel characteristics, and the capability of the feedback channel estimation algorithm. It is also shown that the stability condition of the repeater does not guarantee the quality of the repeater's output signal. To guarantee repeater's stability and signal quality, an ICAN scheme based on an iterative algorithm is subsequently proposed. The simulation results confirm the relationship between the stability and signal quality of the repeater and the impact of the aforementioned factors. Using the proposed ICAN scheme, a mean error vector magnitude (quality indicator) of about 6.3% for the repeater's output signal was achieved.

Lee, Moohong; Keum, Byungjik; Shim, Young Serk; Lee, Hwang Soo

198

L-band antennas for regional mobile communication satellites  

NASA Astrophysics Data System (ADS)

Satellite L-band antennas ranging for state of the art small reflector systems to multibeam arrays, to large array-fed reflectors, with frequency reuse, flexible channel to beam allocation and/or steerable beam capabilities over an extended European coverage are reviewed. Both 2.5 to 5 m multifeed reflectors and foldable multibeam arrays are valid candidates for regional mobile communication satellites in the next decade. The foldable multibeam arrays have the major advantage over the multifeed reflectors of quasi-total traffic to beam allocation flexibility. In the longer term, when increase in traffic is such that on board minimum gains greater than 35 dBi are required, unfurlable reflectors with diameters greater than 10 m are preferable, since direct radiating arrays with equivalent aperture area cannot easily be deployed. Technologies for foldable arrays and reflectors up to 5 m diameter should be available for flight in the early nineties from present hardware developments. The same technology is applicable up to greater than 10 m, but with a serious additional effort required, particularly in testing.

Roederer, A.

1986-09-01

199

David Florida Laboratory: Support for mobile satellite communications  

NASA Technical Reports Server (NTRS)

The comprehensive integration and environmental (including RF) test facilities of the Canadian Space Agency's David Florida Laboratory (CSA)(DFL) were used extensively for the MSAT Program. Following a description of the facilities, the paper outlines their application to the qualification of the two MSAT satellites following an overview of the test plan. Particular emphasis is given to passive intermodulation measurement (PIM) demands, which for the MSAT satellites, contributed to the need to extend the anechoic chamber. The extended chamber was also used for an EMC test and SAR signature test of the RADARSAT satellite. The DFL's facilities are being used for additional aspects of mobile satellite communications. One shielded anechoic Extra High Frequency (EHF) chamber and associated test equipment are employed predominantly for measuring the performance of the IRIDIUM satellites' Engineering Model Gateway Moveable Antennas (EM)(GMA). Other chambers are used for testing aeronautical antennas on behalf of Inmarsat. Still others combine thermal and PIM testing. The paper concludes with a review of the test requirements of evolving satcom missions such as Inmarsat Aero-1.

Dumoulin, Jean-Guy; Mamen, Rolf

1995-01-01

200

Experimental mobile satellite system for communications using engineering test satellite-V(ETS-V/EMSS-C)  

NASA Astrophysics Data System (ADS)

For establishing key technology of the maritime satellite communication system for small vessels and the aeronautical satellite communications and for research on general mobile satellite communications, Experimental Mobile Satellite System for Communications using Engineering Test Satellite-V(ETS-V/EMSS-C) is developed in Japan. Phase C development of the satellite and transponders will start this year and development of an aircraft earth station and a coast/aeronautical earth station have started. Ship earth stations and small mobile stations will be developed in 1985. C-band and L-band frequencies are used for communications experiments. A multibeam antenna and solid state transponders are used on the satellite and digital communication technics play an important role. The satellite will be launched in 1987.

Miura, S.; Ishide, A.; Kondo, K.

1984-10-01

201

A Survey of Routing Techniques for Mobile Communications Networks  

Microsoft Academic Search

. Mobile wireless networks pose interesting challenges for routing system design. To producefeasible routes in a mobile wireless network, a routing system must be able to accommodate roving users,changing network topology, and fluctuating link quality. We discuss the impact of node mobility and wirelesscommunication on routing system design, and we survey the set of techniques employed in or proposed forrouting

S. Ramanathan; Martha Steenstrup

1996-01-01

202

A Study on the Role of Mobile Phone Communication in Tuberculosis DOTS Treatment  

PubMed Central

Background: Every year, a lot of Tuberculosis (TB) patients undergo Directly Observed Treatment Short-course (DOTS) in Salem city, one of the high TB districts in South India. Mobile phone usage among these patients and health workers is common. Mobile phone communication has a great potential in TB treatment. Objectives: To analyze the mobile phone usage and its effectiveness in TB DOTS treatment. Materials and Methods: A cross-sectional survey with 150 TB patients was followed by a focus group discussion with treatment supervisors, DOTS providers, and health workers. Results: Majority of patients use mobile phones to make calls to health workers to clarify their doubts on side effects, food, and symptoms of the disease. TB treatment supervisors effectively use mobile phones to counsel patients to adhere to the treatment regimen. Patients see mobile phones as a useful communication tool in TB treatment though they prefer direct interpersonal communication with health workers. Though the mobile ownership is 68% among the TB patients, many of them are not able to send text messages or read messages in English. Conclusion: Mobile phone possession and usage is high among the patients. Patients need to be trained to use mobile phone features such as alarm, voice mail, and interactive voice response. Incentives like free talk time and short message service (SMS) will encourage patients to communicate frequently with health workers, thereby, increasing the chances of better adherence to DOTS. SMS could be made available in the regional languages.

Elangovan, R; Arulchelvan, S

2013-01-01

203

Application of smart antennas in CDMA mobile communication system  

NASA Astrophysics Data System (ADS)

Full coverage in mobile service region will elate mobile telephone customers. Limited frequency resources make mobile system capacity poor. High capacity and full coverage are two main key problems for system design. CDMA system has advantage of customer capacity, and Antenna array brings its coverage ability and intelligence into full play. Smart antenna combined with code division multiple access will improve mobile telecom system performance. Increasing system performance and capacity appear through enhancing desired signal and suppressing interference signals. Several kinds of antenna array techniques including beam forming, diversity, switched-beam antenna array and sectorization were discussed here in detail. The small antenna applications in TDMA mobile telecommunication systems are also discussed.

Guo, Congliang; Zhou, Yingui; Liu, Tonghui; Wang, Rongsheng; Liu, Shijian

2001-10-01

204

Trellis-Coded CPM (Continuous-Phase Modulated Signals) for Satellite-Based Mobile Communications.  

National Technical Information Service (NTIS)

Digital transmission for satellite-based land mobile communications is discussed. To satisfy the power and bandwidth limitations imposed on such systems, a combination of trellis coding and continuous-phase modulated signals are considered. Some schemes b...

F. Abrishamkar E. Biglieri

1988-01-01

205

Interference Analysis for an Aeronautical Mobile Airport Communications System.  

National Technical Information Service (NTIS)

The next generation of aeronautical communications for airport surface applications has been identified through a NASA research program and an international collaborative future communications study. The result, endorsed by both the United States and Euro...

J. D. Wilson R. J. Kerczewski

2011-01-01

206

Evolution of Implicit and Explicit Communication in Mobile Robots  

NASA Astrophysics Data System (ADS)

This work investigates the conditions in which a population of embodied agents evolved for the ability to display coordinated/cooperative skills can develop an ability to communicate, whether and to what extent the evolved communication system can complexify during the course of the evolutionary process, and how the characteristics of such communication system varies evolutionarily. The analysis of the obtained results indicates that evolving robots develop a capacity to access/generate information which has a communicative value, an ability to produce different signals encoding useful regularities, and an ability to react appropriately to explicit and implicit signals. The analysis of the obtained results allows us to formulate detailed hypothesis on the evolution of communication for what concern aspects such us: (i) how communication can emerge from a population of initially non-communicating agents, (ii) how communication systems can complexify, (iii) how signals/meanings can originate and how they can be grounded in agents' sensory-motor states.

de Greeff, Joachim; Nolfi, Stefano

207

Free Space Optics Communication for Mobile Military Platforms.  

National Technical Information Service (NTIS)

Free Space Optics (FSO) is widely regarded as the next-generation high-speed wireless communication technology. FSO has demonstrated its capability to deliver data faster than any other state-of-the-art wireless communication technology. Today, terrestria...

S. S. Neo

2003-01-01

208

The design of a linear L-band high power amplifier for mobile communication satellites  

NASA Technical Reports Server (NTRS)

A linear L-band solid state high power amplifier designed for the space segment of the Mobile Satellite (MSAT) mobile communication system is described. The amplifier is capable of producing 35 watts of RF power with multitone signal at an efficiency of 25 percent and with intermodulation products better than 16 dB below carrier.

Whittaker, N.; Brassard, G.; Li, E.; Goux, P.

1990-01-01

209

Design of a Communications Network to Support Mobile Health Systems (Telemedicine) in Arkansas.  

National Technical Information Service (NTIS)

This research study analyzed the design of a communications network to support a mobile health system. The need was defined in a previous study where the concept of the integration of a mobile health care system to deliver primary medical care to the rura...

E. W. Fant J. C. Winburn

1995-01-01

210

Improving the Communication of Spatial Information in Crisis Response by Combining Paper Maps and Mobile Devices  

Microsoft Academic Search

Ecient and eective communication between mobile units and the central emergency operation center is a key factor to respond successfully to the challenges of emergency management. Nowadays, the only ubiquitously available modality is a voice channel through mobile phones or radio transceivers. This makes it often very dicult to convey exact geographic locations and can lead to misconceptions with severe

Johannes Schoning; Michael Rohs; Antonio Kruger; Christoph Stasch

211

Error control for Ka-band land mobile satellite communications systems  

Microsoft Academic Search

Error control for Ka-band land mobile satellite communications systems is examined. The dominant propagation effect at Ka-band is signal shadowing caused by obstructions in the propagation path. Depending on the mobile speed, shadow events may last for many seconds and will typically result in attenuations at the receiver too severe to be addressed by raw link margin. The performance of

Jeffrey B. Schodorf

2000-01-01

212

Design of the mobile satellite communications constellations with common ground track  

Microsoft Academic Search

This paper, from the viewpoint characteristics of the mobile satellite ground track, discusses a method of designing of mobile satellite constellations with a common ground track., and also uses the method for China's area coverage design by way of computer simulation and a specialized satellite communication tool. By choosing the satellite orbit period as one fourth of the sidereal day,

He Jiafu; Wu Jiuyin; Ma Yifei; Gan Zhongmin

1999-01-01

213

Mobile Communications, Social Networks, and Urban Travel: Hypertext as a New Metaphor for Conceptualizing Spatial Interaction  

Microsoft Academic Search

The widespread use of mobile communications is leading to new practices in family life and social life, and these changes have significant implications for the study of urban travel. Because of the adoption of new modes of space-time coordination, changing time use and increasing mobility, changing use of existing urban nodes, the blurring of boundaries between home and work, the

Mei-Po Kwan

2007-01-01

214

Application of antenna arrays to mobile communications. II. Beamforming and direction-of-arrival considerations  

Microsoft Academic Search

Array processing involves manipulation of signals induced on various antenna elements. Its capabilities of steering nulls to reduce cochannel interferences and pointing independent beams toward various mobiles, as well as its ability to provide estimates of directions of radiating sources, make it attractive to a mobile communications system designer. Array processing is expected to play an important role in fulfilling

LAL C. GODARA

1997-01-01

215

Using Mobile Communication Technology in High School Education: Motivation, Pressure, and Learning Performance  

ERIC Educational Resources Information Center

Motivation and pressure are considered two factors impacting vocational senior high school student learning. New communication technology, especially mobile communication technology, is supposed to be effective in encouraging interaction between the student and the instructor and improving learning efficiency. Social presence and information…

Rau, Pei-Luen Patrick; Gao, Qin; Wu, Li-Mei

2008-01-01

216

Dedicated short-range communication mobile device for intelligent transport systems  

US Patent & Trademark Office Database

A dedicated short-range communication mobile device for Intelligent transport systems, including: an antenna; a data transmission/reception circuit for transmitting and receiving data to and from a ground device through the antenna; a first power supply circuit for supplying power to the data transmission/reception circuit; a received electric field strength detecting unit for measuring a power level of a radio wave transmitted from the ground device; a communication area detecting unit for recognizing a communication area based on an output of the received electric field strength detecting unit; a power supply starting unit for starting the first power supply circuit based on an output of the communication area detecting unit; and a second power supply circuit for supplying power to the received electric field strength detecting unit, the communication area detecting unit and the power supply starting unit. As a result of the above configuration, the mobile device can reduce dissipation and does not complicate communication control.

2002-01-08

217

An efficient communication strategy for ad-hoc mobile networks  

Microsoft Academic Search

We investigate here the problem of establishing communica- tion in an ad-hoc mobile network, that is, we assume the extreme case of a total absense of any flxed network infrastructure (for example a case of rapid deployment of a set of mobile hosts in an unknown terrain). We propose, in such a case, that a small subset of the deployed

Ioannis Chatzigiannakis; Sotiris E. Nikoletseas; Paul G. Spirakis

2001-01-01

218

Minimizing the mass of a communications system for a multi-beam mobile communications satellite with elliptical beams  

NASA Astrophysics Data System (ADS)

The mass-minimizing configuration was studied for a multi-beam mobile communications satellite by using an elliptical-beam with a greater number of beams for receiving than for transmitting. Optimum transponder output power, major and minor axes size of the elliptical antenna, and the number of transmitting and receiving beams are obtained along with the lowest possible effective mass for the communications equipment. The minimum effective mass achieved is about 10 % smaller than the effective mass of communications system which use conventional multi-circular beams.

Kobayashi, Akihiko; Ishii, Kyoichi; Okamoto, Teruki; Masuda, Nobuo; Iso, Akio; Sato, Shin-Ichi

219

Mobile communication, public participation and e-governance in China: a case study of Xiamen anti-PX demonstration  

Microsoft Academic Search

China has become the biggest mobile communication carrier in the world since 2001. Advanced technologies create a communication revolution, and the individual, through the advent of mobile media, has become an active participant in this process. This study investigates the mobile phone's impact upon the developments of public participation, social inclusion and citizenship through the case study of Xiamen PX

Liu Jun; Zhao Hui

2010-01-01

220

A Mobile Robots Experimental Environment with Event-Based Wireless Communication  

PubMed Central

An experimental platform to communicate between a set of mobile robots through a wireless network has been developed. The mobile robots get their position through a camera which performs as sensor. The video images are processed in a PC and a Waspmote card sends the corresponding position to each robot using the ZigBee standard. A distributed control algorithm based on event-triggered communications has been designed and implemented to bring the robots into the desired formation. Each robot communicates to its neighbors only at event times. Furthermore, a simulation tool has been developed to design and perform experiments with the system. An example of usage is presented.

Guinaldo, Maria; Fabregas, Ernesto; Farias, Gonzalo; Dormido-Canto, Sebastian; Chaos, Dictino; Sanchez, Jose; Dormido, Sebastian

2013-01-01

221

A mobile robots experimental environment with event-based wireless communication.  

PubMed

An experimental platform to communicate between a set of mobile robots through a wireless network has been developed. The mobile robots get their position through a camera which performs as sensor. The video images are processed in a PC and a Waspmote card sends the corresponding position to each robot using the ZigBee standard. A distributed control algorithm based on event-triggered communications has been designed and implemented to bring the robots into the desired formation. Each robot communicates to its neighbors only at event times. Furthermore, a simulation tool has been developed to design and perform experiments with the system. An example of usage is presented. PMID:23881139

Guinaldo, María; Fábregas, Ernesto; Farias, Gonzalo; Dormido-Canto, Sebastián; Chaos, Dictino; Sánchez, José; Dormido, Sebastián

2013-01-01

222

[Mobile communication and health of population: estimation of danger, social and ethical problems].  

PubMed

Population lives under new electromagnetic conditions: constant round-the-clock compulsory chronic exposure of all groups of population to modulated wide spectrum of EMF RF during the work of base stations of mobile communication; daily and lifelong (from childhood) exposure of the brain to EMF RF of the mobile phone. Effects of exposure to EMF RF of low levels are presented. Results of research into chronic EMF RF exposure are absent. International recommendations and domestic guidelines do not take into account the changing conditions of EMF RF influence on the population: the brain has become a critical body, and children have been included in the risk group. Population actively continues to use mobile communication. In this situation estimation of the risks from mobile communication has become a social and ethical problem. PMID:21866836

Grigor'ev, Iu G; Grigor'ev, O A

2011-01-01

223

TDMA-Based Dual-Mode Communication for Mobile Wireless Sensor Networks  

PubMed Central

Small highly mobile robots, and in particular micro air vehicles (MAVs), are well suited to the task of exploring unknown indoor environments such as buildings and caves. Such a task imposes a number of requirements on the underlying communication infrastructure, with differing goals during various stages of the mission. This work addresses those requirements with a hybrid communications infrastructure consisting of a stationary mesh network along with the mobile nodes. The combined network operates in two independent modes, coupling a highly efficient, low duty cycle, low throughput mode for routing and persistent sensing with a burst mode for high data rate communication. By strategically distributing available frequency channels between the mobile agents and the stationary nodes, the overall network provides reliable long-term communication paths while maximizing data throughput when needed.

Mehta, Ankur; Kerkez, Branko; Glaser, Steven D.; Pister, Kristofer S. J.

2012-01-01

224

Satellite-aided land mobile communications system implementation considerations  

NASA Technical Reports Server (NTRS)

It was proposed that a satellite-based land mobile radio system could effectively extend the terrestrial cellular mobile system into rural and remote areas. The market, technical and economic feasibility for such a system is studied. Some of the aspects of implementing an operational mobile-satellite system are discussed. In particular, two key factors in implementation are examined: (1) bandwidth requirements; and (2) frequency sharing. Bandwidth requirements are derived based on the satellite antenna requirements, modulation characteristics and numbers of subscribers. Design trade-offs for the satellite system and potential implementation scenarios are identified. Frequency sharing is examined from a power flux density and modulation viewpoint.

Leroy, B. E.

1982-01-01

225

Need for, and financial feasibility of, satellite-aided land mobile communications  

NASA Technical Reports Server (NTRS)

Questions regarding the role of a mobile-satellite system in augmenting the terrestrial communications system are considered, and a market assessment study is discussed. Aspects of an investment analysis are examined, taking into account a three phase financial study of four postulated land Mobile Satellite Service (LMSS) systems, project profitability evaluation methods, risk analysis methods, financial projections, potential investor acceptance standards, and a risk analysis. It is concluded that a satellite augmented terrestrial mobile service appears to be economically and technically superior to a service depending exclusively on terrestrial systems. The interest in the Mobile Satellite Service is found to be worldwide, and the ground equipment market is potentially large.

Castruccio, P. A.; Marantz, C. S.; Freibaum, J.

1982-01-01

226

The application of the diversity in mobile free-space optical communication  

NASA Astrophysics Data System (ADS)

Traditional free-space optical (FSO) communications use a single transmitting antenna (laser/VCSEL/LED) and a receiving antenna (a photo-detector) for single channel communication between two nodes. In this paper we study two transmitting antenna one receiving antenna M-FSO (mobile FSO) communication system. In the process of single transmitting antenna moving, the optical beam broadens to make receive power smaller with the divergence angle larger and the power is difficult to be detected when long-distance communication. When short-distance communication, the divergence angle is so small that it makes a narrow beam which is hard to be aimed at receive aperture, even more serious when the beam is out of target caused by vibration. We take advantage of space diversity technology to reduce BER caused by atmospheric turbulence and mobile vibration. Through the multi-transmitter, the best choice of multi-divergence angle reduces BER, thus the receiver accurately recovers information.

Li, Yingchun; Zhang, Rui

2008-03-01

227

Propagation measurements using a digital channel sounder matched to the GSM-system bandwidth  

Microsoft Academic Search

Area coverage in the Pan-European Group Special Mobile (GSM) system requires both a specified minimum field strength and a high local probability that the length of the impulse response (IR) does not exceed a duration of about 16 ?s. Because of the lack of commercial equipment to measure and record complex IRs in mobile radio, an entirely digital channel sounder

Rudolf Werner Lorenz; Gerhard Kadel

1991-01-01

228

Application of Space Communications to the Maritime Mobile Service.  

National Technical Information Service (NTIS)

There is growing interest in the use of satellites for maritime communications and position determination. Presentation is made of operational requirements, joint use by ships and aircraft, areas to be covered, conditions of system's operations, frequency...

C. Dorian

1971-01-01

229

Satellite-aided land mobile communications system implementation considerations  

NASA Technical Reports Server (NTRS)

It was proposed that a satellite-based land mobile radio system could effectively extend the terrestrial cellular mobile system into rural and remote areas. The market, technical and economic feasibility for such a system is studied. Some of the aspects of implementing an operational mobile-satellite system are discussed. In particular, two key factors in implementation are examined: (1) bandwidth requirements; and (2) frequency sharing. Bandwidth requirements are derived based on the satellite antenna requirements, modulation characteristics and numbers of subscribers. Design trade-offs for the satellite system and potential implementation scenarios are identified. Frequency sharing is examined from a power flux density and modulation viewpoint. Previously announced in STAR as N82-25290

Leroy, B. E.

1982-01-01

230

LOOPUS Mob-D: System concept for a public mobile satellite system providing integrated digital services for the Northern Hemisphere from an elliptical orbit  

NASA Technical Reports Server (NTRS)

A new concept for a satellite based public mobile communications system, LOOPUS Mob-D, is introduced, whereby most of the classical problems in mobile satellite systems are approached in a different way. The LOOPUS system will offer a total capacity of 6000 high rate channels in three service areas (Europe, Asia, and North America), covering the entire Northern Hemisphere with a set of group special mobile (GSM) compatible mobile services, eventually providing the 'office in the car'. Special characteristics of the LOOPUS orbit and the communications network architecture are highlighted.

Kuhlen, H.; Horn, P.

1990-01-01

231

Wireless Communications  

NSDL National Science Digital Library

Wireless communications is an industry that is growing at an incredible rate. Cellular phones are the most obvious example of this trend; it is hard to go anywhere without seeing someone using one. Rapidly advancing technologies and lower prices are making this all possible. At the current pace, there seems to be no limit to what is possible in the wireless industry.To learn about the events that led up to present day wireless communications, this site offers a very informative history of telecommunications (1) that goes all the way back to the time of carrier pigeons. A good introduction to wireless networking can be found in this mini-tutorial (2). The best parts of this tutorial are the discussions of many recent wireless developments and technologies. There are a few interactive games and activities that are supposed to be instructive and entertaining, but some of them can be annoying. For the more technically savvy user, the third site (3) starts by describing many of the principles that drive current wireless systems. The second part examines the technologies that will be used in future generations of services. To build on this material, the third generation mobile communications systems (3G) is the central topic at 3G Newsroom (4), providing breaking news about the development of 3G technology. Additionally, the site has an excellent introduction to 3G, including its applications and specifications. One of the advancements that is paving the way toward 3G is Bluetooth, which is explained in great detail here (5). This technology is capable of very high data transfer rates, but there are some limitations, which are all discussed in the articles on the site. Although Bluetooth is raising plenty of interest, this recent news story (6) is creating more than its share of debate. It outlines a very controversial move by the FCC to allow the use of ultrawideband technology in commercial wireless applications. The author explains in simple terms why there are so many concerns about something that could revolutionize wireless systems. The evolution of the global system for mobile communications (GSM) is traced at GSM World (7). Here users can learn about the roots of the wireless industry as well as what is in store for the future. A special section addresses health concerns associated with mobile phone use. Radio was one of the earliest form of wireless communication, and the Invention of Radio (8) documents the people and events that made it what it is today. The stories of such famous scientists and inventors as Marconi, DeForest, and Armstrong are told in brief accounts, and there is even a link to the well known War of the Worlds radio broadcast.

Leske, Cavin.

2002-01-01

232

Low delay, error resilient error control for mobile video communication  

Microsoft Academic Search

This paper proposes a low delay, error resilient video transmission scheme for mobile radio channels. Compressed video data is sensitive to channel error. Channel error can fatally degraded the reconstructed video sequence by causing intra-frame and inter-frame error propagation. Using ARQ to prevent all forms of error propagation, significantly increases the transmission delay of the video frame. We propose a

Naoto Matoba; Yasushi Kondo; Toshiaki Tanaka

1997-01-01

233

Power Control and MIMO Beamforming in CDMA Mobile Communications Systems.  

National Technical Information Service (NTIS)

This thesis concerns two interference management methods, the power control and the smart antenna. Power control balances received powers of all users so that a measure of the co-channel interference achieves a minimum. Using the beamforming in the mobile...

M. S. Elmusrati

2002-01-01

234

Improving the Communication of Spatial Information in Crisis Response by Combining Paper Maps and Mobile Devices  

Microsoft Academic Search

Efficient and effective communication between mobile units and the central emergency operation center is a key factor to respond\\u000a successfully to the challenges of emergency management. Nowadays, the only ubiquitously available modality is a voice channel\\u000a through mobile phones or radio transceivers. This makes it often very difficult to convey exact geographic locations and can\\u000a lead to misconceptions with severe

Johannes Schöning; Michael Rohs; Antonio Krüger; Christoph Stasch

2008-01-01

235

A model for local\\/mobile radio communications with correct packet capture  

Microsoft Academic Search

The performance of a local\\/mobile radio communications system utilizing the slotted ALOHA multiple random access protocol is analyzed. The probability of correct packet capture is evaluated for a local\\/mobile packet radio system using ideal coherent binary phase-shift keying (BPSK) modulation. Both the near\\/far effect and the effect of Rayleigh fading on the probability of correct packet capture are taken into

R. Clark Robertson; Tri T. Ha

1992-01-01

236

[Psychophysiological indicators for children using mobile phones. Communication 2. Results of four-year monitoring].  

PubMed

This study submits the results of a four-year monitoring of a complex diagnostics of the psychophysiological indicators for 196 children aged 7 to 12 years old: 147 of them are child users of mobile communication (test group) and 49 are in the control group. We have identified the following major trends of the psychophysiological indicators for child users of mobile communication: an increased number of phonemic perception disorders, abatement of efficiency, reduced indicators for the arbitrary and semantic memory, an increased fatigue. A steady decline of the parameters from high values to bottom standards has been found. PMID:22279774

Khorseva, N I; Grigor'ev, Iu G; Gorbunova, N V

2011-01-01

237

Advanced mobile satellite communications experiment in MM-wave and Ka-band using Japans's COMETS  

NASA Astrophysics Data System (ADS)

Early in the 21st century, the demand for personal communications using mobile, hand-held and very small aperture terminals (VSAT) will rapidly increase. In a future system, many different types of services should be provided with one-hop connection. The Communications Research Laboratory (CRL) has studied a future advanced mobile satellite communications system using millimeter-wave and Ka-band. In 1990, CRL started the Communications and Broadcasting Engineering Test Satellite (COMETS) project. The satellite has been developed in conjunction with the National Space Development Agency of Japan (NASDA) and will be launched in 1997. This paper describes the COMETS payload configuration and the experimental system for the advanced mobile communications mission. The 2-m-diameter on-board antenna has three beams, two adjacent Ka-band beams and one millimeter-wave beam. The two Ka-band transponders have high output power SSPAs of 20 W and 10 W. The millimeter-wave transponder consists of a 20 W traveling wave tube amplifier (TWTA) and a high electron mobility transistor/low noise amplifier (HEMT/LNA) with a low noise figure of 3 dB.

Isobe, Shunkichi; Hamamoto, Naokazu; Takeuchi, Makoto; Ohmori, Shingo; Yamamoto, Minoru

238

Efficient Use of Narrowband Radio Channels for Mobile Digital Communications.  

National Technical Information Service (NTIS)

The project developed a wireless modem architecture that provides bandwidth efficient data communications in the 220 MHz ITS spectral allocations. The goal was to provide greater than 12 kbps transmission capacity on the 4 kHz channels (3 bps/Hz spectral ...

M. P. Fitz

1996-01-01

239

Information and Communication Technology and International Business Travel: Mobility Allies?  

Microsoft Academic Search

Like forecasts about the paperless office, technological solutions to the problem of international business travel continue to be deferred. As with the increased use of office paper, international business travel is defying predictions of its decline. There is growing evidence to suggest that business sectors which seem ideally placed to substitute information and communication technology (ICT) for travel, are actually

Paul Haynes

2010-01-01

240

Joint multipath-Doppler diversity in mobile wireless communications  

Microsoft Academic Search

We introduce a new approach for achieving diversity in spread-spectrum communications over fast-fading multipath channels. The RAKE receiver used in existing systems suffers from significant performance degradation due to the rapid channel variations encountered under fast fading. We show that the Doppler spread induced by temporal channel variations in fact provides another means for diversity that can be further exploited

Akbar M. Sayeed; Behnaam Aazhang

1999-01-01

241

[Problems of harmonization of sanitary regulations of the electromagnetic fields of mobile radio communication equipment].  

PubMed

In the article there are presented data on the probable adverse effects of electromagnetic fields generated by means of mobile cellulary radio communication equipment, a comparative analysis of hygienic rating and methods of measurement of their parameters in Russia and abroad has been performed, and the ways of harmonizing hygienic rules have been outlined, the necessity of further research to risk assessment of the use of cellular radio communication devices by population and preventive measures have been substantiated. PMID:24340578

Pal'tsev, Iu P; Pokhodze?, L V; Rubtsova, N B; Bogacheva, E V

2013-01-01

242

Increased Capacity Using CDMA for Mobile Satellite Communication  

Microsoft Academic Search

The performance of a spread-spectrum CDMA (code-division multiple access) system in a mobile satellite environment is analyzed. Comparisons to single-channel-per-carrier FDMA systems are presented which show that the CDMA approach provides greater capacity. Results from computer simulations, laboratory tests, and field tests of a prototype modem are also presented. The tests results show excellent performance of the modem in the

Klein S. Gilhousen; Irwin M. Jacobs; Roberto Padovani; Lindsay A. Weaver Jr.

1990-01-01

243

Carrier aggregation for LTE-advanced mobile communication systems  

Microsoft Academic Search

In order to achieve up to 1 Gb\\/s peak data rate in future IMT-Advanced mobile systems, carrier aggregation technology is introduced by the 3GPP to support very-high-data-rate transmissions over wide frequency bandwidths (e.g., up to 100 MHz) in its new LTE-Advanced standards. This article first gives a brief review of continuous and non-continuous CA techniques, followed by two data aggregation

Guangxiang Yuan; Xiang Zhang; Wenbo Wang; Yang Yang

2010-01-01

244

Control based mobile ad-hoc networks for video communications  

Microsoft Academic Search

This paper presents a feedback control scheme for transmission of video signals over mobile ad-hoc channels. The scheme is a combination of cross-layer (local) feedback and receiver feedback. The receiver feedback is based on the real time transport control protocol (RTCP), which is designed to provide an end-to-end feedback assessment of multihop transmission channels by tracking packet receptions in synchronization

Hamid Gharavi

2006-01-01

245

Tracking Vehicle in GSM Network to Support Intelligent Transportation Systems  

NASA Astrophysics Data System (ADS)

The penetration of GSM capable devices is very high, especially in Europe. To exploit the potential of turning these mobile devices into dynamic data acquisition nodes that provides valuable data for Intelligent Transportation Systems (ITS), position information is needed. The paper describes the basic operation principles of the GSM system and provides an overview on the existing methods for deriving location data in the network. A novel positioning solution is presented that rely on handover (HO) zone measurements; the zone geometry properties are also discussed. A new concept of HO zone sequence recognition is introduced that involves application of Probabilistic Deterministic Finite State Automata (PDFA). Both the potential commercial applications and the use of the derived position data in ITS is discussed for tracking vehicles and monitoring traffic flow. As a practical cutting edge example, the integration possibility of the technology in the SafeTRIP platform (developed in an EC FP7 project) is presented.

Koppanyi, Z.; Lovas, T.; Barsi, A.; Demeter, H.; Beeharee, A.; Berenyi, A.

2012-07-01

246

Toll free mobile communication: overcoming barriers in maternal and neonatal emergencies in Rural Bangladesh  

PubMed Central

Background Toll free mobile telephone intervention to support mothers in pregnancy and delivery period was tested in one sub district of Bangladesh. Qualitative research was conducted to measure the changes of mobile phone use in increasing communication for maternal and neonatal complications. Methods In-depth interviews were conducted among twelve Community Skilled Birth Attendants and fourteen mothers along with their husbands prior to intervention. At intervention end, six Community Skilled Birth Attendants were purposively selected for in-depth interview. Semi structured interviews were conducted among all 27 Community Skilled Birth Attendants engaged in the intervention. One Focus Group Discussion was conducted with 10 recently delivered mothers. Thematic analysis and triangulation of different responses were conducted. Results Prior to intervention, Community Skilled Birth Attendants reported that mobile communication was not a norm. It was also revealed that poor mothers had poor accessibility to mobile services. Mothers, who communicated through mobile phone with providers noted irritability from Community Skilled Birth Attendants and sometimes found phones switched off. At the end of the project, 85% of mothers who had attended orientation sessions of the intervention communicated with Community Skilled Birth Attendants through mobile phones during maternal health complications. Once a complication is reported or anticipated over phone, Community Skilled Birth Attendants either made a prompt visit to mothers or advised for direct referral. More than 80% Community Skilled Birth Attendants communicated with Solution Linked Group for guidance on maternal health management. Prior to intervention, Solution Linked Group was not used to receive phone call from Community Skilled Birth Attendants. Community Skilled Birth Attendants were valued by the mothers. Mothers viewed that Community Skilled Birth Attendants are becoming confident in managing complication due to communication with Solution Linked Group. Conclusions The use of mobile technology in this intervention took a leap from simply rendering information to providing more rapid services. Active participation of service providers along with mothers’ accessibility motivated both the service providers and mothers to communicate through mobile phone for maternal health issues. These altogether made the shift towards adoption of an innovation.

2014-01-01

247

An adaptive array antenna for mobile satellite communications  

NASA Technical Reports Server (NTRS)

The design of an adaptive array antenna for land vehicle operation and its performance in an operational satellite system is described. Linear and circularly polarized antenna designs are presented. The acquisition and tracking operation of a satellite is described and the effect on the communications signal is discussed. A number of system requirements are examined that have a major impact on the antenna design. The results of environmental, power handling, and RFI testing are presented and potential problems are identified.

Milne, Robert

1990-01-01

248

Intercepting mobile communications: the insecurity of 802.11  

Microsoft Academic Search

The 802.11 standard for wireless networks includes a Wired Equivalent Privacy (WEP) protocol, used to protect link-layer communications from eavesdropping and other attacks. We have discovered several serious security flaws in the protocol, stemming from mis-application of cryptographic primitives. The flaws lead to a number of practical attacks that demonstrate that WEP fails to achieve its security goals. In this

Nikita Borisov; Ian Goldberg; David Wagner

2001-01-01

249

Design of a Mobile Agent-Based Adaptive Communication Middleware for Federations of Critical Infrastructure Simulations  

NASA Astrophysics Data System (ADS)

The simulation of critical infrastructures (CI) can involve the use of diverse domain specific simulators that run on geographically distant sites. These diverse simulators must then be coordinated to run concurrently in order to evaluate the performance of critical infrastructures which influence each other, especially in emergency or resource-critical situations. We therefore describe the design of an adaptive communication middleware that provides reliable and real-time one-to-one and group communications for federations of CI simulators over a wide-area network (WAN). The proposed middleware is composed of mobile agent-based peer-to-peer (P2P) overlays, called virtual networks (VNets), to enable resilient, adaptive and real-time communications over unreliable and dynamic physical networks (PNets). The autonomous software agents comprising the communication middleware monitor their performance and the underlying PNet, and dynamically adapt the P2P overlay and migrate over the PNet in order to optimize communications according to the requirements of the federation and the current conditions of the PNet. Reliable communications is provided via redundancy within the communication middleware and intelligent migration of agents over the PNet. The proposed middleware integrates security methods in order to protect the communication infrastructure against attacks and provide privacy and anonymity to the participants of the federation. Experiments with an initial version of the communication middleware over a real-life networking testbed show that promising improvements can be obtained for unicast and group communications via the agent migration capability of our middleware.

Görbil, Gökçe; Gelenbe, Erol

250

Study of LEO-SAT microwave link for broad-band mobile satellite communication system  

NASA Astrophysics Data System (ADS)

In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

251

75 FR 17434 - In the Matter of Certain Personal Data and Mobile Communications Devices and Related Software...  

Federal Register 2010, 2011, 2012, 2013

...Mobile Communications Devices and Related Software; Notice of Investigation AGENCY: U...of Cupertino, California and NeXT Software, Inc. f/k/a NeXT Computer, Inc...mobile communications devices and related software by reason of infringement of...

2010-04-06

252

AI Based Approach of Predicting the Credit Limits of Users to Middle Customer based Mobile Communication Services  

Microsoft Academic Search

Most of the developing countries even, mobile communication has become a matter of course for many people. As markets saturate, the care and retention of existing customers becomes a key element for revenue stabilization for mobile communication network operators. We present a predictive data mining model to reduce the rate of forced churn as a consequence of non-payment: estimations of

A. Pallegedara; V. S. Amaratunga; R. A. R. C. Gopura; P. D. Jayathileka

2006-01-01

253

Secure communication of medical information using mobile agents.  

PubMed

Recently several efficient schemes are proposed to provide security of e-medicine systems. Almost all of these schemes have tried to achieve the highest security level in transmission of patients' medical information to medical institutions through a heterogeneous network like Internet. In this paper, we explain the insecurity of these schemes against "man-in-the-middle" attack. Furthermore, a dynamic mobile agent system based on hybrid cryptosystem is proposed that is both secure and also efficient in computation cost. Analyzing the security criteria confirms suitability of the proposed scheme for e-medicine systems. PMID:22569875

Nikooghadam, Morteza; Zakerolhosseini, Ali

2012-12-01

254

An efficient communication strategy for mobile agent based distributed spatial data mining application  

NASA Astrophysics Data System (ADS)

An efficient communication strategy is proposed in this paper, which aims to improve the response time and availability of mobile agent based distributed spatial data mining applications. When dealing with decomposed complex data mining tasks or On-Line Analytical Processing (OLAP), mobile agents authorized by the specified user need to coordinate and cooperate with each other by employing given communication method to fulfill the subtasks delegated to them. Agent interactive behavior, e.g. messages passing, intermediate results exchanging and final results merging, must happen after the specified path is determined by executing given routing selection algorithm. Most of algorithms exploited currently run in time that grows approximately quadratic with the size of the input nodes where mobile agents migrate between. In order to gain enhanced communication performance by reducing the execution time of the decision algorithm, we propose an approach to reduce the number of nodes involved in the computation. In practice, hosts in the system are reorganized into groups in terms of the bandwidth between adjacent nodes. Then, we find an optimal node for each group with high bandwidth and powerful computing resources, which is managed by an agent dispatched by agent home node. With that, the communication pattern can be implemented at a higher level of abstraction and contribute to improving the overall performance of mobile agent based distributed spatial data mining applications.

Han, Guodong; Wang, Jiazhen

2005-11-01

255

A frame synchronization method for adaptive array antennas in digital mobile communications  

Microsoft Academic Search

This paper proposes a frame synchronization method for an adaptive array antenna (AAA) used in digital mobile communications. The proposed scheme, which is based on the maximum likelihood estimation (MLE), calculates error signals by subtracting a training sequence convolved with an estimated channel impulse response from the AAA outputs and searches for the timing that minimizes the mean squared errors.

Kazuhiko Fukawa; Hiroshi Suzuki

2005-01-01

256

TCP\\/IP Performance Evaluations Based on Elevation Angles for Mobile Communications Employing Stratospheric Platform  

Microsoft Academic Search

This paper describes a proposed propagation estimation method and TCP\\/IP-based evaluations for mobile communications employing a stratospheric platform. To estimate a wireless channel, a realistic and detailed description of its physical environment must be accurately defined. Therefore, a building distribution model characterizing the physical environment in areas in Japan is presented. The analyses of the propagation estimation method are based

Marry Kong; Otabek Yorkinov; Shigeru Shimamoto

2009-01-01

257

The land mobile satellite communication channel-recording, statistics, and channel model  

Microsoft Academic Search

The communication channel between the MARECS satellite at 26 deg W and a cruising van was measured and recorded in European areas exhibiting satellite elevations from 13 to 43 deg. Different environments and mobile antennas were tested. Results of an extensive statistical evaluation include spectra of the fading amplitude, probability density, and distribution of the received signal power as well

Erich Lutz; Daniel Cygan; Michael Dippold; Frank Dolainsky; Wolfgang Papke

1991-01-01

258

Channel aware HARQ scheme based on LDPC codes for land mobile satellite communication system  

Microsoft Academic Search

In this paper, a channel aware HARQ (CA-HARQ) scheme based on data punctured rate compatible LDPC (DP-LDPC) codes, which might satisfy the demand for bandwidth and rate in land mobile communication system, is proposed. The scheme is based on type II HARQ technique cooperated with a DP- LDPC code. In the proposed scheme, the effective rate of the LDPC code

Yongli Yang; Guangxi Zhu; Desheng Wang; Lifen Wu

2007-01-01

259

User and Concept Studies as Tools in Developing Mobile Communication Services for the Elderly  

Microsoft Academic Search

The basis of this study was the ageing of the population all over the world. The study concentrated on finding out the key service needs of elderly people. The service needs from the end users’ as well as the experts’ perspective were gathered by means of various group methods such ideation sessions. Four mobile communication service concepts were created using

M. Mikkonen; S. Väyrynen

2002-01-01

260

How Can Mobile SMS Communication Support and Enhance a First Year Undergraduate Learning Environment?  

ERIC Educational Resources Information Center

In this paper we discuss a case study investigating how the academic and personal development of first year students on an undergraduate sports education degree can be supported and enhanced with mobile SMS (Short Message Service) communication. SMS-based technologies were introduced in response to students' particular needs (in transition to…

Jones, Geraldine; Edwards, Gabriele; Reid, Alan

2009-01-01

261

Enhancing Motivation in Online Courses with Mobile Communication Tool Support: A Comparative Study  

ERIC Educational Resources Information Center

Mobile technologies have helped establish new channels of communication among learners and instructors, potentially providing greater access to course information, and promoting easier access to course activities and learner motivation in online learning environments. The paper compares motivation between groups of learners being taught through an…

Chaiprasurt, Chantorn; Esichaikul, Vatcharaporn

2013-01-01

262

Communication and processing consideration for alerting systems implemented through mobile sensor networks  

Microsoft Academic Search

At the beginning of the paper it is presented an alerting system architecture based on mobile sensor network. Then it is analyzed the current available radio communication infrastructure which can be used for implementation of alerting systems in conjunction with the alerting systems requirements. Further we shown how the digital signal processor (DSPs) are the best fit for the processing

DAN POPESCU; RADU DOBRESCU; MAXIMILIAN NICOLAE; ALEXANDRU IORDAN

2009-01-01

263

Switching Costs, Consumers' Heterogeneity and Price Discrimination in the Mobile Communications Industry  

Microsoft Academic Search

In this paper we develop a formal model that captures some basic features of competition in the mobile communications service industry. In a model of oligopolistic competition with price discrimination and switching costs, we study the role of firms’ installed base of consumers in providing the incentives to offer contracts for a new class of consumers with a lower willingness

Nicoletta Corrocher; Lorenzo Zirulia

2005-01-01

264

Fusion of digital television, broadband Internet and mobile communications - Part I: Enabling technologies  

Microsoft Academic Search

SUMMARY The introduction of digital video broadcasting (DVB) satellite systems has become an important tool for future mobile communication and is currently a focus in several research areas such as the integration of DVB satellite systems with different wireless technologies. This tutorial consists of two parts, Enabling technologies and Future service scenarios, which aims to provide an introduction to the

F. L. C. Ong; X. Liang; Prashant Pillai; P. M. L. Chan; Georgios Koltsidas; Fotini-Niovi Pavlidou; Erina Ferro; Alberto Gotta; Haitham S. Cruickshank; S. Iyengar; Gorry Fairhurst; V. Mancuso

2007-01-01

265

Twin-object platform: a generic proxy-based system for communication customization in mobile computing  

Microsoft Academic Search

Communication customization has been widely used and proved having benefits in mobile computing. However, most systems are designed for specific purposes. They may have weaknesses in compatibility and portability, and incur unnecessary overheads in certain situations. Besides, they may be not flexible as a generic system because of requiring particular software facilities or hardware devices. In the paper, we propose

Tzu-Chi Huang; Ce-Kuen Shieh; Yu-Ben Miao

2005-01-01

266

An Implanted Spherical Head Model Exposed to Electromagnetic Fields at a Mobile Communication Frequency  

Microsoft Academic Search

Can cellular phones and personal communication systems base station antennas affect the active or passive implantable medical devices adversely? Concerns over the possible harmful effects of nonionizing irradiation upon implanted medical devices have been present for many years. Key issues to address are the questions of whether mobile phones have a detrimental effect on implants, and how the interaction of

S. M. S. Reyhani; Simone A. Ludwig

2006-01-01

267

Laypeople's Health Concerns and Health Beliefs in Regard to Risk Perception of Mobile Communication  

Microsoft Academic Search

The consensus scientific view is that there is an absence of convincing scientific evidence for health risks of exposures to electromagnetic fields (EMF) at levels below those recommended in international guidelines. Nevertheless, some citizens are worried about EMF emitted by mobile communication and its consequences for health. The present study explored, by means of a mail survey, health concerns and

Marie-Eve Cousin; Michael Siegrist

2008-01-01

268

Advanced mobile satellite communications system using Ka and MM-wave bands in Japan's R and D satellite project  

NASA Technical Reports Server (NTRS)

Communications Research Laboratory (CRL) studied an advanced mobile satellite communications system using Ka and millimeter-wave bands in the R&D Satellite project. The project started in 1990 and the satellite will be launched in 1997. On-board multi-beam interconnecting is one of basic functions to realize one-hop connection among Very Small Aperture Terminals (VSATs), mobile, and hand-held terminals in future mobile satellite communications system. An Intermediate Frequency (IF) filter bank and regenerative transponder are suitable for this function. The transponder configuration of an advanced mobile communications mission of the R&D Satellite for experiment is shown. High power transmitters of Ka and millimeter-wave bands, a 3x3 IF filter band and Single Channel Per Carrier/Time Division Multiplexing (SCPC/TDM) regenerative MODEMS, which will be boarded on the R&D Satellite, are being developed for the purpose of studying the feasibility of advanced mobile communications system.

Isobe, Shunkichi; Ohmori, Shingo; Hamamoto, Naokazu; Yamamoto, Minoru

1991-01-01

269

A study and experiment plan for digital mobile communication via satellite  

NASA Technical Reports Server (NTRS)

The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll quality speech. A traffic model is derived on which to base the determination of the required maximum number of satellite channels to provide the anticipated level of service. Various voice digitalization and digital modulation schemes are reviewed along with a general link analysis of the mobile system. Demand assignment multiple access considerations and analysis tradeoffs are presented. Finally, a completed configuration is described.

Jones, J. J.; Craighill, E. J.; Evans, R. G.; Vincze, A. D.; Tom, N. N.

1978-01-01

270

Design of an anti-Rician-fading modem for mobile satellite communication systems  

NASA Technical Reports Server (NTRS)

To design a demodulator applicable to mobile satellite communication systems using differential phase shift keying modulation, we have developed key technologies including an anti-Rician-fading demodulation scheme, an initial acquisition scheme, automatic gain control (AGC), automatic frequency control (AFC), and bit timing recovery (BTR). Using these technologies, we have developed one-chip digital signal processor (DSP) modem for mobile terminal, which is compact, of light weight, and of low power consumption. Results of performance test show that the developed DSP modem achieves good performance in terms of bit error ratio in mobile satellite communication environment, i.e., Rician fading channel. It is also shown that the initial acquisition scheme acquires received signal rapidly even if the carrier-to-noise power ratio (CNR) of the received signal is considerably low.

Kojima, Toshiharu; Ishizu, Fumio; Miyake, Makoto; Murakami, Keishi; Fujino, Tadashi

1995-01-01

271

Steerable L-band antenna for land mobile voice communication terminal  

NASA Astrophysics Data System (ADS)

The ESA is developing an EMS (European Mobile System) land mobile voice communication system. Two steerable prototype antennas were developed for an EMS mobile voice communication terminal. The first one is a rotating antenna consisting of two OTA (One Turn Antenna) elements. The feed network generates two separate beams slightly shifted from the boresight. The tracking is based on level difference measurements from these two beams. The mechanical rotation is accomplished by the aid of a step motor. The acquisition and tracking are controlled by a microprocessor. The second antenna is a fully electronic array consisting of 12 OTA elements locating on a circle. The compact feed network gives rise to 24 separate beams in the azimuth plane. The tracking is based on the use of these multiple beams and the performance is enhanced by direction information from a digital compass. The design and performance of both these antennas are described.

Aurinsalo, J.; Hujanen, A.; Jongejans, A.; Marttila, I.; Mutanen, R.; Pitkaenen, I.; Tallqvist, S.

1991-10-01

272

[Perspectives of mobile communication in the management of diabetics].  

PubMed

Sufficient control of blood glucose levels has been demonstrated to be associated with improved long-term outcome in patients with diabetes. Recent advances in interface technology allow transfer of measurement data to mobile devices, which enables control, multiple access, and storage of these data and virtually links patients and care-giving physicians. The possibility of alerting predefined addressee in case of measurements below or above certain limits offers some sort of security that cannot be obtained by simply penning a single value to a scratchpad. Therefore, treating physicians are able to follow the therapeutic course in an easy and finally time-independent manner. Furthermore, physical contact is not necessary, which may be favorable especially for elderly, sometimes immobile patients. PMID:21858635

Mlekusch, Wolfgang

2011-07-01

273

Future mobile satellite communication concepts at 20/30 GHz  

NASA Technical Reports Server (NTRS)

The outline of a design of a system using ultra small earth stations (picoterminals) for data traffic at 20/30 GHz is discussed. The picoterminals would be battery powered, have an RF transmitter power of 0.5 W, use a 10 cm square patch antenna, and have a receiver G/T of about -8 dB/K. Spread spectrum modulation would be required (due to interference consideration) to allow a telex type data link (less than 200 bit/s data rate) from the picoterminal to the hub station of the network and about 40 kbit/s on the outbound patch. An Olympus type transponder at 20/30 GHz could maintain several thousand simultaneous picoterminal circuits. The possibility of demonstrating a picoterminal network with voice traffic using Olympus is discussed together with fully mobile systems based on this concept.

Barton, S. K.; Norbury, J. R.

1990-01-01

274

Design and evaluation of speech coders for mobile satellite communications  

NASA Astrophysics Data System (ADS)

The authors deal with the design and performance analysis of two real-time speech coder algorithms implemented on an array processor, i.e., a linear predictive coder (LPC) operating at 2.4 kb/s, and a baseband residual coder (BBC) operating at 7.2/9.6 kb/s. The effects of channel impairments typical of mobile satellite systems, such as multipath fading and shadowing, on the subjective quality is evaluated by means of the diagnostic rhyme test (DRT) and the diagnostic acceptability measure (DAM). The subjective scores have been examined to pinpoint the fidelity with which distinctive phonetic features are transmitted, and important quality attributes are preserved. Results show that a BBC at 9.6 kb/s, incorporating a suitable error correcting scheme, provides a moderately good quality, while the LPC at 2.4 kb/s yields a quality that is not felt to be commercially acceptable.

Copperi, M.; Perosino, F.; Biglieri, E.; Albertengo, G.

275

Should we bother with the speed of light in everyday life? A closer look at GSM technology  

NASA Astrophysics Data System (ADS)

The speed of light, or more generally, the speed of electromagnetic waves, seems to be incredibly high. 300?000 km s-1 is far greater than the typical speed of a car, a plane or even a rocket, which is just several kilometres per second. It is thus natural that we treat the speed of light as infinite in everyday life. It appears, however, that even such a high but finite speed causes problems that have to be solved in one of the most popular electronic devices—cellular phones. Here we look more closely how the global system for mobile communications (GSM) phone works and how it deals with the speed of electromagnetic waves.

Kawalec, Tomasz

2012-09-01

276

Controlled mobility of unmanned aircraft chains to optimize network capacity in realistic communication environments  

NASA Astrophysics Data System (ADS)

This dissertation presents a decentralized gradient-based mobility control algorithm for the formation and maintenance of an optimal end-to-end communication chain using a team of unmanned aircraft acting as communication relays. With the use of unmanned aircraft (UA) as communication relays, a common mode of operation is to form a communication relay chain between a lead exploring node (which may be ground based or another UA) and a control station. In this type of operation the lead node is typically deployed to explore (sense) a remote region of interest that is beyond direct radio frequency (RF) communication range, or out of line-of-sight, to the control station. To provide non-line-of-sight service, and extend the communication range of the lead node, unmanned aircraft acting as communication relays are deployed in a convoy fashion behind the lead vehicle to form a cascaded relay chain. The focus of this work is the use of the mobility of a fixed number of relay aircraft to maximize the capacity of a directed communication chain from a source node to a destination node. Local objective functions are presented that use the signal-to-noise-and-interference ratio (SNIR) of neighbor communication links as inputs to maximize the end-to-end capacity of packet-based and repeater-type network chains. An adaptive gradient-based SNIR controller using the local objective function can show significant improvement in the capacity of the communication chain that is not possible with range-based controllers, or static deployment strategies, in RF environments containing unknown localized noise sources and terrain effects. Since the SNIR field is unknown, an online estimate of the SNIR field gradient is formed using methods of Stochastic Approximation from the orbital motion of the aircraft tracking a control point. Flight demonstrations using the Networked Unmanned Aircraft System Command, Control and Communications testbed were conducted to validate the controller presented herein. Results from flight experiments show that mobility of unmanned aircraft, following locally estimated SNIR gradients, can be used to form a locally optimized communication chain by driving the aircraft to locations that improve the end-to-end capacity of the chain over that of a range-based controller or a static deployment algorithm.

Dixon, Cory

277

Requirements for a mobile communications satellite system. Volume 2: Technical report  

NASA Technical Reports Server (NTRS)

Three types of satellite aided mobile communications are considered for users in areas not served by (terrestrial) cellular radio systems. In system 1, mobile units are provided a direct satellite link to a gateway station, which serves as the interface to the terrestrial toll network. In system 2, a terrestrial radio link similar to those in cellular systems connects the mobile unit to a translator station; each translator relays the traffic from mobile units in its vicinity, via satellite, to the regional gateway. It is not feasible for system 2 to provide obiquitous coverage. Therefore, system 3 is introduced, in which the small percentage of users not within range of a translator are provided a direct satellite link as in system 1.

Horstein, M.

1983-01-01

278

Worldwide Seamless Cellular Satellite Communications: The Global Mobile Communication by Globalstar System.  

National Technical Information Service (NTIS)

Presentation viewgraphs are presented that describe the need and technology requirements for a worldwide cellular satellite communication system. Specific services provided by such a system are outlined and the role of the service provider is described.

A. J. Navarra

1992-01-01

279

Traditional and Mobile Public Health Alert Communications with Health Care Providers  

PubMed Central

Objective To systematically compare mobile (SMS) and traditional (email, FAX) communication strategies to identify which modality is most effective for communication of health alerts and advisories between public health agencies and health care providers in order to improve emergency preparedness and response. Introduction The effectiveness of emergency preparedness and response systems depends, in part, on the effectiveness of communication between agencies and individuals involved in emergency response, including health care providers who play a significant role in planning, event detection, response and communication with the public. Although much attention has been paid to the importance of communicating clinical data from health care providers to public health agencies for purposes of early event detection and situational awareness (e.g., BioSense) and to the need for alerting health care providers of public health events (e.g., Health Alert Networks), no studies to date have systematically identified the most effective methods of communication between public health agencies and community health care providers for purposes of public health emergency preparedness and response. The REACH (Rapid Emergency Alert Communication in Health) study is a 4-year randomized controlled trial to evaluate and compare the effectiveness of mobile (SMS) and traditional (email, FAX) communication strategies for sending public health messages to health care providers—physicians, pharmacists, nurse practitioners, physician’s assistants and veterinarians. Methods Providers were recruited from three sites (King County, WA; Spokane County, WA; and across the state of Montana; N=845) and randomized to receive time-sensitive public health messages via email, Fax, short message service (SMS) or to a control group that did not receive messages. For one year, alerts based on real events of public health interest were sent quarterly with follow-up telephone interviews conducted 5–10 days after the delivery date. Interviews consisted of approximately six questions that elicited information about message receipt, recall of its content and perceived credibility and trustworthiness of the message and source. In addition, provider access to online alert information and delivery success or failure was collected. Results Frequency of receipt, timeliness, content awareness, perceived credibility and perceived trustworthiness were measured and compared across communication delivery systems. On average 84.0% of participants were contacted in each follow-up survey following all alerts and across all three sites. Primary data analysis was designed to measure differences between the three communication groups using intent-to-treat methods. A set of secondary analyses examined the outcomes excluding providers who could not have received messages (due to incorrect contact information, known technical failures, or because providers could not receive messages by the assigned delivery message—for example, a provider without a Fax number randomized to the Fax group). We will discuss preliminary results of intent-to-treat analyses regarding rate of recall of study alert message content between traditional and mobile communications and perceived trustworthiness and credibility of message and message source by providers. In addition, we will report on frequency of accessing online alert information between traditional and mobile delivery groups. Conclusions There is currently no evidence-based research to guide or improve the practice of public health communication between public health agencies and health care providers before, during and after a public health emergency. Improving this communication via the use of effective media can enhance disease surveillance, which will aid in early detection and enhance case finding and situational awareness for public health emergencies. By systematically evaluating the relative effectiveness of mobile and traditional message delivery systems for emergency preparedness and response communications, th

Revere, Debra; Painter, Ian; Baseman, Janet

2013-01-01

280

A device for concurrent, local\\/remote control of RS232-based devices by GSM\\/GPRS  

Microsoft Academic Search

Industrial appliances do usually have RS232 ports to enable computer control and monitoring. In this paper we present a system to allow remote control by GSM\\/GPRS messaging not disturbing local link. To do so, the module must include a port arbiter to handle bi-directional communications between a RS232 and the two other ports (RS232 and GSM\\/GPRS).

Eloi Ramon; Lluís Ribas

281

Preliminary study on the induction of sperm head abnormalities in mice, Mus musculus, exposed to radiofrequency radiations from global system for mobile communication base stations.  

PubMed

The exposure of male mice to radiofrequency radiations from mobile phone (GSM) base stations at a workplace complex and residential quarters caused 39.78 and 46.03%, respectively, in sperm head abnormalities compared to 2.13% in control group. Statistical analysis of sperm head abnormality score showed that there was a significant (p < 0.05) difference in occurrence of sperm head abnormalities in test animals. The major abnormalities observed were knobbed hook, pin-head and banana-shaped sperm head. The occurrence of the sperm head abnormalities was also found to be dose dependent. The implications of the observed increase occurrence of sperm head abnormalities on the reproductive health of humans living in close proximity to GSM base stations were discussed. PMID:19816647

Otitoloju, A A; Obe, I A; Adewale, O A; Otubanjo, O A; Osunkalu, V O

2010-01-01

282

A frequency-reconfigurable multi-port antenna operating over LTE, GSM, DCS, and PCS bands  

Microsoft Academic Search

A small frequency reconfigurable antenna consisting of a PIFA and a monopole have been presented for mobile phone applications. The PIFA, with the use of a switch, can cover LTE, GPS, GSM900, and DCS 1800, and the monopole can cover PCS 1900. The switch will be included in the future work.

Jeongsam Cho; Kangwook Kim

2009-01-01

283

Diversity Interference Cancellation for GSM\\/ EDGE using Reduced-Complexity Joint Detection  

Microsoft Academic Search

In cellular mobile radio systems, multiple ac- cess is causing interference that limits capacity of the net- works. The GSM system with multiple users can be inter- preted as MIMO system with a desired user and (cochan- nel and adjacent channel) interferers. Using a multiple- input multiple-output (MIMO) multiuser joint detection approach for desired signal and one or more (strongest)

Patrick Nickel; Wolfgang Gerstacker

2005-01-01

284

GSM Phase 2+ General Packet Radio Service GPRS: Architecture, Protocols, and Air Interface  

Microsoft Academic Search

The General Packet Radio Service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks, e.g., to the Internet. It applies a packet radio principle to transfer user data packets in an efficient way between mobile stations and external packet data networks. This tutorial gives an introduction to GPRS. The article

Christian Bettstetter; Hans-jörg Vögel; Jörg Eberspäche

1999-01-01

285

GSM phase 2+ general packet radio service GPRS: Architecture, protocols, and air interface  

Microsoft Academic Search

The general packet radio service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks, e.g., to the Internet. It applies a packet radio principle to transfer user data packets in an efficient way between mobile stations and external packet data networks. This tutorial gives an introduction to GPRS. The article

Christian Bettstetter; Hans-Jorg Vogel; Jorg Eberspacher

1999-01-01

286

A Mobile Communications Space Link Between the Space Shuttle Orbiter and the Advanced Communications Technology Satellite  

NASA Technical Reports Server (NTRS)

A communications experiment is described as a link between the Space Shuttle Orbiter (SSO) and the Advanced Communications Technology Satellite (ACTS). Breadboarding for this experiment has led to two items with potential for commercial application: a 1-Watt Ka-band amplifier and a Ka-band, circularly polarized microstrip antenna. Results of the hybrid Ka-band amplifier show gain at 30 dB and a saturated output power of 28.5 dBm. A second version comprised of MMIC amplifiers is discussed. Test results of the microstrip antenna subarray show a gain of approximately 13 dB and excellent circular polarization.

Fink, Patrick; Arndt, G. D.; Bondyopadhyay, P.; Shaw, Roland

1994-01-01

287

Maintaining communication link based on AODV routing protocol in mobile robot networks  

NASA Astrophysics Data System (ADS)

Wired computer networks are vital in modern life. However, these networks are extremely vulnerable to disaster or attack in emergency situations. Therefore, how to maintain communication link under emergency situations is very important. In this paper, we utilize a series of autonomous mobile slave robots which follow behind the lead robot and automatically stop where needed to maintain an ad hoc network for guaranteeing a link between the lead robot and its remote monitor/control station. To accomplish this target, an efficient communication protocol limitation mobile robots broadcast based on AODV (LMRB-AODV) is proposed for deployment in multi-robot system. After then the lead robot could carry service traffics to the monitor station under emergency situations through the communication link. At any instance, the lead robot has the ability to reclaim the relay robot(s) which are unneeded in the network to rejoin the convoy behind the lead robot and use it to extend the range of wireless communication when the radio frequency (RF) shortcuts are detected by the lead robot. All relay deployment and reclaiming strategy functions occur without the operator's involvement. Finally, we provide a comparative study of their performance in a number of different simulation environments. The results show that the proposed scheme is very efficient in maintaining communication link in wireless network.

Hu, Hui; Jiang, Hong

2007-12-01

288

Trellis coding with Continuous Phase Modulation (CPM) for satellite-based land-mobile communications  

NASA Technical Reports Server (NTRS)

This volume of the final report summarizes the results of our studies on the satellite-based mobile communications project. It includes: a detailed analysis, design, and simulations of trellis coded, full/partial response CPM signals with/without interleaving over various Rician fading channels; analysis and simulation of computational cutoff rates for coherent, noncoherent, and differential detection of CPM signals; optimization of the complete transmission system; analysis and simulation of power spectrum of the CPM signals; design and development of a class of Doppler frequency shift estimators; design and development of a symbol timing recovery circuit; and breadboard implementation of the transmission system. Studies prove the suitability of the CPM system for mobile communications.

1989-01-01

289

An Energy Efficient Communication Protocol Based on Data Equilibrium in Mobile Wireless Sensor Network  

Microsoft Academic Search

This paper considers large-scale dense wireless sensor networks with path-constrained mobile sink. From the viewpoints of\\u000a improving data equilibrium and energy-saving, we propose an enhanced energy efficient communication protocol in which a partition\\u000a algorithm of overlapping time based on data equilibrium is designed to minimize the data variance and disequilibrium from\\u000a each node. We present a data equilibrium information diffusion

Shuai Gao; Yanchao Niu; Hongwei Huo; Hongke Zhang

2007-01-01

290

Cascaded CCI cancellation and error-correcting codes for DS-SS CDMA mobile communication system  

Microsoft Academic Search

This paper investigates the robustness of the conventional cascaded combination of co-channel interference cancellation (CCI) and the decoding of error-correcting techniques for a DS-SS CDMA mobile communication system. The system is evaluated under extreme interference conditions where the receiver is subjected to intersymbol interference (ISI), multi-access interference (MAI), and co-code CCI (CCCCI) generated within the mother cell and from the

K. M. Shaheen; Someshwar C. Gupta

1995-01-01

291

Reduced complexity comb-filters for decimation and interpolation in mobile communications terminals  

Microsoft Academic Search

In mobile communications systems complexity and efficiency are issues of paramount importance. Therefore when implementing integer factor sample-rate conversion, comb-filters-especially cascaded-integrator-comb (CIC) filters-are a good choice of realizing linear-phase filters with low complexity. However, neither the direct implementation of comb-filters as transversal filters nor their implementation as CIC-filters are minimal realizations. Since both, decimators and interpolators are time-variant systems, the

Tim Hentschel; Gerhard Fettweis

1999-01-01

292

A 60 GHz Radio-Over-Fiber Network Architecture for Seamless Communication With High Mobility  

Microsoft Academic Search

We demonstrate a 60 GHz broadband picocellular Radio-over-Fiber network architecture that enables seamless connectivity for highly mobile end-users. Its seamless communication capabilities arise by the supported handover scheme that relies on a novel Moving Extended Cell (MEC) concept. MEC exploits user-centric virtual groups of adjacent cells that transmit the same data content to the user and utilizes a switch mechanism

Nikos Pleros; Konstantinos Vyrsokinos; Kostas Tsagkaris; Nikolaos D. Tselikas

2009-01-01

293

DSD (Double Soft Decision) Concatenated FEC Scheme in Mobile Satellite Communication Systems  

Microsoft Academic Search

In order to realize a higher-code-gain forward error correction scheme in mobile satellite communication systems, a novel concatenated coding scheme employing soft decision decoding for not only inner codes but also outer codes (double soft decision, or DSD, concatenated forward error correction scheme) is proposed. Soft-decision outer decoding can improve the bit error probability of inner decoded data. In this

Shunji Honda; Shuji Kubota; Shuzo Kato

1992-01-01

294

Performance of shorted microstrip patch antennas for mobile communications handsets at 1800 MHz  

Microsoft Academic Search

We have investigated the application of two different types of novel shorted-patch antennas for mobile communications handsets at 1800 MHz. A single shorted-patch and a stacked shorted-patch antenna offering improved bandwidth are compared with data for a ?\\/4 monopole. The finite-difference time-domain (FDTD) technique was used to calculate antenna characteristics such as impedance and radiation patterns for two cases: on

Jack T. Rowley; Rod B. Waterhouse

1999-01-01

295

Novel array antenna for mobile and satellite communications with an omnidirectional radiation pattern  

NASA Astrophysics Data System (ADS)

A novel array antenna is proposed for obtaining omnidirectional radiation pattern and is suitable for satellite and mobile communication applications. The method is based on application of the Bessel function to derive a new family of array current distribution to achieve omnidirectional pattern. The array provides a microstrip implementation of an omnidirectional antenna that is simple to design and inexpensive to fabricate. Simulated results for the rectangular microstrip patch array validate the present design technique.

Singh, Ranjit

1998-07-01

296

Mobile Networked Text Communication: The case of SMS and its Influence on Social Interaction  

Microsoft Academic Search

Abstract This chapter introduces a qualitative study of the use of mobile text messaging (SMS) and reflects on how,SMS influences social interaction. It describes how,this new communication,technology is used to maintain,social relations and how,it generally assists users in their everyday activities. Three issues are highlighted: how,users use SMS to overcome shyness, how they use it for micro-grooming and how users

Louise Barkhuus

297

Research on the cancellation of Doppler Offset by information aid for aviation Mobile Broadband Communication  

Microsoft Academic Search

A new method, IAADO (Information-Aided Anti-Doppler-Offset), aiming at eliminating ICI (Inter-Channel-Interference) caused by DFO (Doppler Frequency Offset) and improving the performance of AMBC (Aviation Mobile Broadband Communication), is presented with a view to the characteristics of the high DFO of aviation channel and the aircraft as a platform of AMBC. The strong ICI caused by large DFO, degrades the performance

Wu Xian; Zhang Jun; Liu Zhongkan

2008-01-01

298

An integrated Ka/Ku-band payload for personal, mobile and private business communications  

NASA Astrophysics Data System (ADS)

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.

Hayes, Edward J.; Keelty, J. Malcolm

1991-09-01

299

Satellite-aided mobile communications limited operational test in the trucking industry  

NASA Technical Reports Server (NTRS)

An experiment with NASA's ATS-6 satellite, that demonstrates the practicality of satellite-aided land mobile communications is described. Satellite communications equipment for the experiment was designed so that it would be no more expensive, when mass produced, than conventional two-way mobile radio equipment. It embodied the operational features and convenience of present day mobile radios. Vehicle antennas 75 cm tall and 2 cm in diameter provided good commercial quality signals to and from trucks and jeeps. Operational applicability and usage data were gathered by installing the radio equipment in five long-haul tractor-trailer trucks and two Air Force search and rescue jeeps. Channel occupancy rates are reported. Air Force personnel found the satellite radio system extremely valuable in their search and rescue mission during maneuvers and actual rescue operations. Propagation data is subjectively analyzed and over 4 hours of random data is categorized and graded as to signal quality on a second by second basis. Trends in different topographic regions are reported. An overall communications reliability of 93% was observed despite low satellite elevation angles ranging from 9 to 24 degrees.

Anderson, R. E.; Frey, R. L.; Lewis, J. R.

1980-01-01

300

An integrated Ka/Ku-band payload for personal, mobile and private business communications  

NASA Technical Reports Server (NTRS)

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.

Hayes, Edward J.; Keelty, J. Malcolm

1991-01-01

301

Broadband and scalable mobile satellite communication system for future access networks  

NASA Astrophysics Data System (ADS)

Due to the recent market trends, NTT has begun research into next generation satellite communication systems, such as broadband and scalable mobile communication systems. One service application objective is to provide broadband Internet access for transportation systems, temporal broadband access networks and telemetries to remote areas. While these are niche markets the total amount of capacity should be significant. We set a 1-Gb/s total transmission capacity as our goal. Our key concern is the system cost, which means that the system should be unified system with diversified services and not tailored for each application. As satellites account for a large portion of the total system cost, we set the target satellite size as a small, one-ton class dry mass with a 2-kW class payload power. In addition to the payload power and weight, the mobile satellite's frequency band is extremely limited. Therefore, we need to develop innovative technologies that will reduce the weight and maximize spectrum and power efficiency. Another challenge is the need for the system to handle up to 50 dB and a wide data rate range of other applications. This paper describes the key communication system technologies; the frequency reuse strategy, multiplexing scheme, resource allocation scheme, and QoS management algorithm to ensure excellent spectrum efficiency and support a variety of services and quality requirements in the mobile environment.

Ohata, Kohei; Kobayashi, Kiyoshi; Nakahira, Katsuya; Ueba, Masazumi

2005-07-01

302

Acute exposure to low-level CW and GSM-modulated 900 MHz radiofrequency does not affect Ba 2+ currents through voltage-gated calcium channels in rat cortical neurons.  

PubMed

We have studied the non-thermal effects of radiofrequency (RF) electromagnetic fields (EMFs) on Ba(2+) currents (I Ba 2+) through voltage-gated calcium channels (VGCC), recorded in primary cultures of rat cortical neurons using the patch-clamp technique. To assess whether low-level acute RF field exposure could modify the amplitude and/or the voltage-dependence of I Ba 2+, Petri dishes containing cultured neurons were exposed for 1-3 periods of 90 s to 900 MHz RF-EMF continuous wave (CW) or amplitude-modulated according to global system mobile communication standard (GSM) during whole-cell recording. The specific absorption rates (SARs) were 2 W/kg for CW and 2 W/kg (time average value) for GSM-modulated signals, respectively. The results obtained indicate that single or multiple acute exposures to either CW or GSM-modulated 900 MHz RF-EMFs do not significantly alter the current amplitude or the current-voltage relationship of I Ba 2+, through VGCC. PMID:17620299

Platano, Daniela; Mesirca, Pietro; Paffi, Alessandra; Pellegrino, Monica; Liberti, Micaela; Apollonio, Francesca; Bersani, Ferdinando; Aicardi, Giorgio

2007-12-01

303

SIMspeak - Towards an Open and Secure Application Platform for GSM SIMs  

Microsoft Academic Search

Today mobile operators are in the possession of the SIM application toolkit technology available in their GSM SIM smartcards\\u000a plugged into the mobile handsets of their subscribers. Although there are roughly 500 mio. SIMs deployed all over the world,\\u000a they are not integrated into the Internet yet. With the WebSIM approach [6] we have demonstrated how SIMs can be integrated

Roger Kehr; Hendrik Mieves

2001-01-01

304

Modems for emerging digital cellular-mobile radio system  

NASA Technical Reports Server (NTRS)

Digital modem techniques for emerging digital cellular telecommunications-mobile radio system applications are described and analyzed. In particular, theoretical performance, experimental results, principles of operation, and various architectures of pi/4-QPSK (pi/4-shifted coherent or differential QPSK) modems for second-generation US digital cellular radio system applications are presented. The spectral/power efficiency and performance of the pi/4-QPSK modems (American and Japanese digital cellular emerging standards) are studied and briefly compared to GMSK (Gaussian minimum-shift keying) modems (proposed for European DECT and GSM cellular standards). Improved filtering strategies and digital pilot-aided (digital channel sounding) techniques are also considered for pi/4-QPSK and other digital modems. These techniques could significantly improve the performance of digital cellular and other digital land mobile and satellite mobile radio systems. More spectrally efficient modem trends for future cellular/mobile (land mobile) and satellite communication systems applications are also highlighted.

Feher, Kamilo

1991-01-01

305

[Changes in the parameters of the simple auditory-motor response in children users of mobile communication: longitudinal study].  

PubMed

The study presents the findings of longitudinal observations of the changes in the parameters of simple auditory-motor response in children-users of mobile communication. The obtained results indicate the multivariability of possible effects of radiation from mobile phones on the auditory system of children. PMID:22891552

Khorseva, N I; Grigor'ev, Iu G; Gorbunova, N V

2012-01-01

306

Mobile Communication and Civil Society: Linking Patterns and Places of Use to Engagement with Others in Public  

ERIC Educational Resources Information Center

This study examined whether and how mobile communication influences the extent to which one engages with new people in public settings. Contrary to our expectation, general use of the technology in public did not detract from conversing with strangers. Shifting focus from "where" one uses the mobile phone to "how" it is used, we found that uses…

Campbell, Scott W.; Kwak, Nojin

2011-01-01

307

Communication and Political Mobilization: Digital Media and the Organization of Anti-Iraq War Demonstrations in the U.S  

Microsoft Academic Search

The speed and scale of mobilization in many contemporary protest events may reflect a transformation of movement organizations toward looser ties with members, enabling broader mobilization through the mechanism of dense individual-level political networks. This analysis explores the dynamics of this communication process in the case of U.S. protests against the Iraq war in 2003. We hypothesize that individual activists

W. Lance Bennett; Christian Breunig; Terri Givens

2008-01-01

308

Handoff with DSP Support: Enabling Seamless Voice Communications across Heterogeneous Telephony Systems on Dual-Mode Mobile Devices  

Microsoft Academic Search

Many mobile handsets manufactured today are equipped with wireless data modules that can provide users with the alternative to access Internet telephony service for voice communications. Due to the limited coverage area of wireless data service, however, a call established through VoIP service may need to be transferred transparently to mobile telephony service, and vice versa, for maintaining voice call

Hung-yun Hsieh; Chung-wei Li; Hsiao-pu Lin

2009-01-01

309

ICSW 2 AN : An Inter-vehicle Communication System Using Mobile Access Point over Wireless Wide Area Networks  

Microsoft Academic Search

\\u000a This paper presents a prototype of inter-vehicle communication system using mobile access point that internetworks wired or\\u000a wireless LAN and wireless WAN anywhere. Implemented mobile access point can be equipped with various wireless WAN interfaces\\u000a such as WCDMA and HSDPA. Mobile access point in the IP mechanism has to process connection setup procedure to one wireless\\u000a WAN. To show the

Tae-Young Byun

2010-01-01

310

GSM-Railway as part of the European Rail Traffic Management System  

NASA Astrophysics Data System (ADS)

GSM-R is a vital component inside the ERTMS which is also an essential element of European Community rail projects; investment in equipping and the rolling stock with ERTMS could reach 5 billion eurodollars in the period 2007-2016. GSM-R is the result of over ten years of collaboration between the various European railway companies, the railway communication industry and the different standardization bodies. GSM-R provides a secure platform for voice and data communication between the operational staff of the railway companies including drivers, dispatchers, shunting team members, train engineers, and station controllers. It delivers advanced features such as group calls, voice broadcast, location based connections, and call pre-emption in case of an emergency, which significantly improves communication, collaboration, and security management across operational staff members. Taking into account the above mentioned, the paper will permit to audience to discover the GSM-R network architecture, services and applications proposed by this technology together with the future development and market situation due to the market liberalization.

Bibac, Ionut

2007-06-01

311

Feasibility study on radio communications using high altitude radio platform in the stratosphere - Applicability to mobile radio and coverage performance  

Microsoft Academic Search

It is possible that a platform, powered by microwaves beamed from the earth, carrying radio equipment and flying in the stratosphere, could be used for radio relay such as satellite communications, terrestrial microwave radio relay, land mobile base stations. In the Communication Research Laboratory, feasibility studies were started in 1989 on application of the high altitude radio platform (HARP) to

Taiji Saruwatari

1991-01-01

312

Performance of a low data rate speech codec for land-mobile satellite communications  

NASA Technical Reports Server (NTRS)

In an effort to foster the development of new technologies for the emerging land mobile satellite communications services, JPL funded two development contracts in 1984: one to the Univ. of Calif., Santa Barbara and the other to the Georgia Inst. of Technology, to develop algorithms and real time hardware for near toll quality speech compression at 4800 bits per second. Both universities have developed and delivered speech codecs to JPL, and the UCSB codec was extensively tested by JPL in a variety of experimental setups. The basic UCSB speech codec algorithms and the test results of the various experiments performed with this codec are presented.

Gersho, Allen; Jedrey, Thomas C.

1990-01-01

313

Unsupervised User Similarity Mining in GSM Sensor Networks  

PubMed Central

Mobility data has attracted the researchers for the past few years because of its rich context and spatiotemporal nature, where this information can be used for potential applications like early warning system, route prediction, traffic management, advertisement, social networking, and community finding. All the mentioned applications are based on mobility profile building and user trend analysis, where mobility profile building is done through significant places extraction, user's actual movement prediction, and context awareness. However, significant places extraction and user's actual movement prediction for mobility profile building are a trivial task. In this paper, we present the user similarity mining-based methodology through user mobility profile building by using the semantic tagging information provided by user and basic GSM network architecture properties based on unsupervised clustering approach. As the mobility information is in low-level raw form, our proposed methodology successfully converts it to a high-level meaningful information by using the cell-Id location information rather than previously used location capturing methods like GPS, Infrared, and Wifi for profile mining and user similarity mining.

Shad, Shafqat Ali; Chen, Enhong

2013-01-01

314

Mobile phone emission modulates interhemispheric functional coupling of EEG alpha rhythms.  

PubMed

We tested the working hypothesis that electromagnetic fields from mobile phones (EMFs) affect interhemispheric synchronization of cerebral rhythms, an important physiological feature of information transfer into the brain. Ten subjects underwent two electroencephalographic (EEG) recordings, separated by 1 week, following a crossover double-blind paradigm in which they were exposed to a mobile phone signal (global system for mobile communications; GSM). The mobile phone was held on the left side of the subject head by a modified helmet, and orientated in the normal position for use over the ear. The microphone was orientated towards the corner of the mouth, and the antenna was near the head in the parietotemporal area. In addition, we positioned another similar phone (but without battery) on the right side of the helmet, to balance the weight and to prevent the subject localizing the side of GSM stimulation (and consequently lateralizing attention). In one session the exposure was real (GSM) while in the other it was Sham; both sessions lasted 45 min. Functional interhemispheric connectivity was modelled using the analysis of EEG spectral coherence between frontal, central and parietal electrode pairs. Individual EEG rhythms of interest were delta (about 2-4 Hz), theta (about 4-6 Hz), alpha 1 (about 6-8 Hz), alpha 2 (about 8-10 Hz) and alpha 3 (about 10-12 Hz). Results showed that, compared to Sham stimulation, GSM stimulation modulated the interhemispheric frontal and temporal coherence at alpha 2 and alpha 3 bands. The present results suggest that prolonged mobile phone emission affects not only the cortical activity but also the spread of neural synchronization conveyed by interhemispherical functional coupling of EEG rhythms. PMID:17432975

Vecchio, Fabrizio; Babiloni, Claudio; Ferreri, Florinda; Curcio, Giuseppe; Fini, Rita; Del Percio, Claudio; Rossini, Paolo Maria

2007-03-01

315

Effects of GSM 900 MHz on middle cerebral artery blood flow assessed by transcranial Doppler sonography.  

PubMed

Mobile phone use has increased worldwide but its possible effects on the brain remain unclear. The aim of the present study was to investigate the effect of acute exposure to a radio frequency electromagnetic field (RF EMF) generated by a mobile phone operating in the Global System for Mobile Communication (GSM) 900 MHz on cerebral blood flow. Twenty-nine volunteers attended two experimental sessions: a sham exposure session and a real exposure session in a cross-over double-blind study in which a mobile phone was positioned on the left side of the head. In one session, the mobile phone was operated without RF radiation (sham phone) and in the other study it was operated with RF radiation (real phone) for 20 min. Thus, each subject served as its own control. Middle cerebral artery blood flow was monitored noninvasively by transcranial Doppler sonography to measure middle cerebral artery blood flow velocity. Pulsatility index and resistance index were also evaluated. A voluntary breath holding physiological test was carried out as a positive control for testing cerebral vasoreactivity. Hemodynamic variables were recorded and analyzed before, during and after mobile phone exposure. No significant changes were detected in studied variables in middle cerebral arteries during sham or real exposure. In the exposed side the cerebral blood flow velocity, the pulsatility index and the resistance index during sham and real exposure were respectively: [61.9 ± 1.3, 61.7 ± 1.3 cm/s (P = 0.89)]; [0.93 ± 0.03, 0.90 ± 0.02 (P = 0.84)] and [0.58 ± 0.01, 0.58 ± 0.01 (P = 0.96)] at baseline; and [60.6 ± 1.3, 62 ± 1.6 cm/s (P = 0.40)]; [0.91 ± 0.03, 0.87 ± 0.03 (P = 0.97)]; [0.57 ± 0.01, 0.56 ± 0.01 (P = 0.82)] after 20 min of exposure. Twenty minutes of RF exposure to a mobile phone does not seem to affect the cerebral circulation. PMID:23106209

Ghosn, Rania; Thuróczy, György; Loos, Nathalie; Brenet-Dufour, Valérie; Liabeuf, Sophie; de Seze, René; Selmaoui, Brahim

2012-12-01

316

Efficient QoS provisioning for adaptive multimedia in mobile communication networks by reinforcement learning  

NASA Astrophysics Data System (ADS)

The scarcity and large fluctuations of link bandwidth in wireless networks have motivated the development of adaptive multimedia services in mobile communication networks, where it is possible to increase or decrease the bandwidth of individual ongoing flows. This paper studies the issues of quality of service (QoS) provisioning in such systems. In particular, call admission control and bandwidth adaptation are formulated as a constrained Markov decision problem. The rapid growth in the number of states and the difficulty in estimating state transition probabilities in practical systems make it very difficult to employ classical methods to find the optimal policy. We present a novel approach that uses a form of reinforcement learning known as Q-learning to solve QoS provisioning for wireless adaptive multimedia. Q-learning does not require the explicit state transition model to solve the Markov decision problem; therefore more general and realistic assumptions can be applied to the underlying system model for this approach than in previous schemes. Moreover, the proposed scheme can efficiently handle the large state space and action set of the wireless adaptive multimedia QoS provisioning problem. Handoff dropping probability and average allocated bandwidth are considered as QoS constraints in our model and can be guaranteed simultaneously. Simulation results demonstrate the effectiveness of the proposed scheme in adaptive multimedia mobile communication networks.

Yu, Fei; Wong, Vincent W. S.; Leung, Victor C.

2003-12-01

317

Channel aware HARQ scheme based on LDPC codes for land mobile satellite communication system  

NASA Astrophysics Data System (ADS)

In this paper, a channel aware HARQ (CA-HARQ) scheme based on data punctured rate compatible LDPC (DP-LDPC) codes, which might satisfy the demand for bandwidth and rate in land mobile communication system, is proposed. The scheme is based on type II HARQ technique cooperated with a DP- LDPC code. In the proposed scheme, the effective rate of the LDPC code is adapted according to the channel quality information (CQI) estimated at the receiver, so as to decrease the redundancy when the channel is good and vice versa, the retransmitted blocks are combined with the previous information transmitted to achieve high probability of successful decoding. In this paper, we use a 2-bit CQI feedback scheme. Simulation results, which based on a land mobile satellite channel, show that the proposed channel aware H-ARQ scheme based on DP-LDPC codes improved the throughput by 0.4dB at low SNR compared to a pure DP-LDPC type II HARQ, and it can also be an effective solution to compensate rain attenuation and multipath fading in land mobile satellite systems.

Yang, Yongli; Zhu, Guangxi; Wang, Desheng; Wu, Lifen

2007-11-01

318

Proactive TCP Mechanism to Improve Handover Performance in Mobile Satellite and Terrestrial Networks  

NASA Astrophysics Data System (ADS)

Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is having strong resemblance to terrestrial GSM (Global System for Mobile communications) at the upper protocol layers and TCP (Transmission Control Protocol) is one of them. This space segment technology as well as terrestrial technology, is characterized by periodic variations in communication properties and coverage causing the termination of ongoing call as connections of Mobile Nodes (MN) alter stochastically. Although provisions are made to provide efficient communication infrastructure this hybrid space and terrestrial networks must ensure the end-to-end network performance so that MN can move seamlessly among these networks. However from connectivity point of view current TCP performance has not been engineered for mobility events in multi-radio MN. Traditionally, TCP has applied a set of congestion control algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery) to probe the currently available bandwidth on the connection path. These algorithms need several round-trip times to find the correct transmission rate (i.e. congestion window), and adapt to sudden changes connectivity due to handover. While there are protocols to maintain the connection continuity on mobility events, such as Mobile IP (MIP) and Host Identity Protocol (HIP), TCP performance engineering has had less attention. TCP is implemented as a separate component in an operating system, and is therefore often unaware of the mobility events or the nature of multi-radios' communication. This paper aims to improve TCP communication performance in Mobile satellite and terrestrial networks.

Vinayakray-Jani, Preetida; Sanyal, Sugata

2012-06-01

319

Combined Effect of Random Transmit Power Control and Inter-Path Interference Cancellation on DS-CDMA Packet Mobile Communications  

NASA Astrophysics Data System (ADS)

In mobile communication systems, high speed packet data services are demanded. In the high speed data transmission, throughput degrades severely due to severe inter-path interference (IPI). Recently, we proposed a random transmit power control (TPC) to increase the uplink throughput of DS-CDMA packet mobile communications. In this paper, we apply IPI cancellation in addition to the random TPC. We derive the numerical expression of the received signal-to-interference plus noise power ratio (SINR) and introduce IPI cancellation factor. We also derive the numerical expression of system throughput when IPI is cancelled ideally to compare with the Monte Carlo numerically evaluated system throughput. Then we evaluate, by Monte-Carlo numerical computation method, the combined effect of random TPC and IPI cancellation on the uplink throughput of DS-CDMA packet mobile communications.

Kudoh, Eisuke; Ito, Haruki; Wang, Zhisen; Adachi, Fumiyuki

320

Requirements for a mobile communications satellite system. Volume 1: Executive summary  

NASA Technical Reports Server (NTRS)

Three types of satellite-aided mobile communications are considered for users in areas not served by (terrestrial) cellular radio systems. In System 1, mobile units are provided a direct satellite link to a gateway station, which serves as the interface to the terrestrial toll network. In System 2, a terrestrial radio link similar to those in cellular systems connects the mobile unit to a translator station; each translator relays the traffic from mobile units in its vicinity, via satellite, to the regional gateway. It is not feasible for System 2 to provide ubiquitous coverage. Therefore, System 3 is introduced, in which the small percentage of users not within range of a translator are provided a direct satellite link as in System 1. While System 2 can operate with leased satellite capacity, Systems 1 and 3 require a dedicated satellite. A major portion of this study is concerned with the design of a satellite for System 1. A weight limit of 10,000 lbs, corresponding to the projected 1990 STS capability, is imposed on the design. Frequency re-use of the allocated spectrum, through multiple satellite beams, is employed to generate the specified system capacity. Both offset-fed and center-fed reflectors are considered. For an assumed 10-MHz allocation and a population of 350,000 subscribers, a two-satellite system is required. The reflector diameters corresponding to offset-fed and center-fed geometries are 46 m and 62 m, respectively. Thus, large-space-structure technology is inherent to the implementation of System 1. In addition to establishing the technical requirements for the three types of satellite systems, the monthly service charge needed to provide a specified return on invested capital is computed. A net present value analysis is used for this purpose.

1983-01-01

321

Technical characteristics of the OmniTRACS: The first operation mobile Ku-band satellite communications system  

NASA Technical Reports Server (NTRS)

The techinical characteristics of the OmniTRACS system are described. The system is the first operational mobile Ku-band satellite communications system and provides two-way message and position determination service to mobile terminals using existing Ku-band satellites. Interference to and from the system is minimized by the use of special spread-spectrum techniques, together with low power and low data rate transmissions.

Antonio, Franklin P.; Gilhousen, Klein S.; Jacobs, Irwin M.; Weaver, Linday A., Jr.

1988-01-01

322

Mobile telecommunication: Current knowledge on risk perception and risk communication: Results gained within the German Mobile Telecommunication Research Programme  

Microsoft Academic Search

Factors influencing the public' risk perception have already been investigated since the 70s of the last century. With the increased use of mobile telecommunication and the increased public attention to potential health risks from electromagnetic fields, the risk perception and society's dealing with the topic “mobile telecommunication” came into focus. From 2002 to 2008, the German Mobile Telecommunication Research Programme

Poelzl Christiane

2011-01-01

323

Studies on tumor incidence in mice exposed to GSM cell-phone radiation [Health Effects  

Microsoft Academic Search

This paper studies on tumor incidence in mice exposed to GSM cell-phone radiation. The first study of lymphomas in female Emu_Pim1 transgenic mice using frequencies and modulations specific to cellular mobile phones was conducted in Australia in which the incidence was shown to be significantly higher (odds ratio, OR = 2.4) in the exposed mice (43%) than in the sham

James C. Lin

2008-01-01

324

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

PubMed

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. PMID:24741363

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

2014-01-01

325

Control over social interactions: an important reason for young people's use of the Internet and mobile phones for communication?  

PubMed

This paper reports some research that was undertaken to determine why young people choose to use certain communication media, especially the Internet and mobile phones for social purposes. Focus group methodology was employed in achieving this aim. Specifically, two focus groups containing young people aged 18-20 years were asked to discuss the question "why do you use different communication media, such as the Internet and mobile phones, in your social lives?" Discussions from the sessions were recorded on audiotapes, and then transcribed, and analyzed according to the principles of Grounded Theory. A number of categories emerged from the data. The most significant category indicated that young people often liked to use communication media such as the Internet and mobile phones to communicate because these afforded them control over their interactions. In particular, the data seemed to suggest that participants felt that because some communication media such as email, text messaging and instant messaging can be used asynchronously as well as synchronously, they allow one time to stop and think before giving a response if this is desired, or, alternatively, allowed one to retain the conversational nature of interactions if this is preferred. This gave participants greater control over interactions than they would have if, say, communicating via voice calls using the telephone or face-to-face, which are necessarily synchronous. PMID:17305461

Madell, Dominic E; Muncer, Steven J

2007-02-01

326

Enhanced spectral efficiency using bandwidth switchable SAW filtering for mobile satellite communications systems  

NASA Technical Reports Server (NTRS)

Currently proposed mobile satellite communications systems require a high degree of flexibility in assignment of spectral capacity to different geographic locations. Conventionally this results in poor spectral efficiency which may be overcome by the use of bandwidth switchable filtering. Surface acoustic wave (SAW) technology makes it possible to provide banks of filters whose responses may be contiguously combined to form variable bandwidth filters with constant amplitude and phase responses across the entire band. The high selectivity possible with SAW filters, combined with the variable bandwidth capability, makes it possible to achieve spectral efficiencies over the allocated bandwidths of greater than 90 percent, while retaining full system flexibility. Bandwidth switchable SAW filtering (BSSF) achieves these gains with a negligible increase in hardware complexity.

Peach, Robert; Malarky, Alastair

1990-01-01

327

Concepts and cost trade-offs for land vehicle antennas in satellite mobile communications  

NASA Technical Reports Server (NTRS)

Several antenna design concepts, operating at UHF (821 to 825 MHz transmit and 866 to 870 MHz receive bands), with gain ranging between 6 and 12 dBic, that are suitable for land mobile vehicles are presented. The antennas may be used within CONUS and ALASKA to communicate to and from a geosynchronous satellite. Depending on the type of steering mechanism, the antennas are broken down into three categories; (1) electronically scanned arrays with phase shifters, (2) electronically switched arrays with switchable power dividers/combiners, and (3) mechanically steered arrays. The operating characteristics of two of these design concepts, one a conformal antenna with electronic beam steering and the other a nonconformal design with mechanical steering, were evaluated with regard to two and three satellite system. Cost estimates of various antenna concepts were made and plotted against their overall gain performance.

Haddad, H. A.

1948-01-01

328

The design and networking of dynamic satellite constellations for global mobile communication systems  

NASA Technical Reports Server (NTRS)

Various design factors for mobile satellite systems, whose aim is to provide worldwide voice and data communications to users with hand-held terminals, are examined. Two network segments are identified - the ground segment (GS) and the space segment (SS) - and are seen to be highly dependent on each other. The overall architecture must therefore be adapted to both of these segments, rather than each being optimized according to its own criteria. Terrestrial networks are grouped and called the terrestrial segment (TS). In the SS, of fundamental importance is the constellation altitude. The effect of the altitude on decisions such as constellation design choice and on network aspects like call handover statistics are fundamental. Orbit resonance is introduced and referred to throughout. It is specifically examined for its useful properties relating to GS/SS connectivities.

Cullen, Cionaith J.; Benedicto, Xavier; Tafazolli, Rahim; Evans, Barry

1993-01-01

329

Impact of GPRS on Existing GSM Services.  

National Technical Information Service (NTIS)

The main taks of this Thesis is to find out how much resources can be assigned to GPRS traffic and how this assignment affects the existing GSM services, mainly focusing on the impacts on the capacity of handover traffic. The main objective is to improve ...

J. V. Agustina

2001-01-01

330

Measured performance of GSM, HSCSD and GPRS  

Microsoft Academic Search

In this paper we present results of measurements on the performance of GSM HSCSD and GPRS data transmission. We used a measurement tool that we have developed to study the performance of various wireless links as perceived by nomadic applications using TCP. The results show that in stationary connections the throughput and response time are stable and, in general, close

Jouni Korhonen; Olli Aalto; Andrei Gurtov; Heimo Laamanen

2001-01-01

331

Power attenuation characteristics as switch-over criterion in personal satellite mobile communications  

NASA Technical Reports Server (NTRS)

A third generation mobile system intends to support communications in all environments (i.e., outdoors, indoors at home or office and when moving). This system will integrate services that are now available in architectures such as cellular, cordless, mobile data networks, paging, including satellite services to rural areas. One way through which service integration will be made possible is by supporting a hierarchical cellular structure based on umbrella cells, macro cells, micro and pico cells. In this type of structure, satellites are part of the giant umbrella cells allowing continuous global coverage, the other cells belong to cities, neighborhoods, and buildings respectively. This does not necessarily imply that network operation of terrestrial and satellite segments interconnect to enable roaming and spectrum sharing. However, the cell concept does imply hand-off between different cell types, which may involve change of frequency. Within this propsective, the present work uses power attenuation characteristics to determine a dynamic criterion that allows smooth transition from space to terrestrial networks. The analysis includes a hybrid channel that combines Rician, Raleigh and Log Normal fading characteristics.

Castro, Jonathan P.

1993-01-01

332

Hysteresis in consumer markets with focus on the mobile communications market  

NASA Astrophysics Data System (ADS)

Our aim here is to try to identify hysteresis in the switching patterns of consumers in the Irish mobile phone industry. It was not until the introduction by the Communication Regulator of full-number portability that consumers began to take advantage of the savings that switching mobile phone operator could produce. As with most relatively new industries, the awareness of savings is clouded by a lack of understanding of whats on offer and an underlying fear of change from something they have only just started to comprehend. With people changing company loyalties more frequently than ever at the prospect of better, more cost-efficient services, it is now the million euro question for the phone companies on how close they should match each others' offers to maximize their profits, and what their best pricing strategy should be to obtain an even larger share of the market. Through the use of experimental economics and by modelling switching behaviour using the Preisach model, along with observed and market data, we hope to both pose this problem and start the journey to answering this question.

Twomey, C.

2008-11-01

333

Power attenuation characteristics as switch-over criterion in personal satellite mobile communications  

NASA Astrophysics Data System (ADS)

A third generation mobile system intends to support communications in all environments (i.e., outdoors, indoors at home or office and when moving). This system will integrate services that are now available in architectures such as cellular, cordless, mobile data networks, paging, including satellite services to rural areas. One way through which service integration will be made possible is by supporting a hierarchical cellular structure based on umbrella cells, macro cells, micro and pico cells. In this type of structure, satellites are part of the giant umbrella cells allowing continuous global coverage, the other cells belong to cities, neighborhoods, and buildings respectively. This does not necessarily imply that network operation of terrestrial and satellite segments interconnect to enable roaming and spectrum sharing. However, the cell concept does imply hand-off between different cell types, which may involve change of frequency. Within this propsective, the present work uses power attenuation characteristics to determine a dynamic criterion that allows smooth transition from space to terrestrial networks. The analysis includes a hybrid channel that combines Rician, Raleigh and Log Normal fading characteristics.

Castro, Jonathan P.

334

Adaptive data rate SSMA system for personal and mobile satellite communications  

NASA Technical Reports Server (NTRS)

An adaptive data rate SSMA (spread spectrum multiple access) system is proposed for mobile and personal multimedia satellite communications without the aid of system control earth stations. This system has a constant occupied bandwidth and has variable data rates and processing gains to mitigate communication link impairments such as fading, rain attenuation and interference as well as to handle variable data rate on demand. Proof of concept hardware for 6MHz bandwidth transponder is developed, that uses offset-QPSK (quadrature phase shift keying) and MSK (minimum shift keying) for direct sequence spread spectrum modulation and handle data rates of 4k to 64kbps. The RS422 data interface, low rate voice and H.261 video codecs are installed. The receiver is designed with coherent matched filter technique to achieve fast code acquisition, AFC (automatic frequency control) and coherent detection with minimum hardware losses in a single matched filter circuit. This receiver structure facilitates variable data rate on demand during a call. This paper shows the outline of the proposed system and the performance of the prototype equipment.

Ikegami, Tetsushi; Takahashi, Takashi; Arakaki, Yoshiya; Wakana, Hiromitsu

1995-01-01

335

Satellite applications to electric-utility communications needs. [land mobile satellite service  

NASA Technical Reports Server (NTRS)

Significant changes in the Nation's electric power systems are expected to result from the integration of new technology, possible during the next decade. Digital communications for monitor and control, exclusive of protective relaying, are expected to double or triple current traffic. A nationwide estimate of 13 Mb/s traffic is projected. Of this total, 8 Mb/s is attributed to the bulk-power system as it is now being operated (4 Mb/s). This traffic could be accommodated by current communications satellites using 3- to 4.5-m-diameter ground terminals costing $35,000 to $70,000 each. The remaining 5-Mb/s traffic is attributed to new technology concepts integrated into the distribution system. Such traffic is not compatible with current satellite technology because it requires small, low-cost ground terminals. Therefore, a high effective isotropic radiated power satellite, such as the one being planned by NASA for the Land Mobile Satellite Service, is required.

Horstein, M.; Barnett, R.

1981-01-01

336

A high capacity mobile communications satellite system for the first generation MSS  

NASA Astrophysics Data System (ADS)

A low-cost high-capacity dual-band mobile communications satellite system using existing equipment is proposed for the first generation MSS. Cost effectiveness and the requirements of beam optimization and passive intermodulation avoidance dictated the choice of two single band satellites for separate UHF and L-band coverage of North America. Similar designs for the two satellites, based on the Intelsat V and Insat/Arabsat configurations, will achieve over 6000 5-kHz SCPC, communications channels for the system. The 12 beam UHF and 17 beam L-band satellites achieve up to a three-fold frequency reuse of the FCC allocated MSS frequency spectrum. Spacecraft design features include separate 9.1 m antennas for sending and receiving, SAW filters for channel noise attenuation, an integrated bipropellant propulsion system, and a 3.8 kW 10-year electrical power subsystem with a solar array. The satellites are compatible with the STS, Ariane, and other expendable boosters.

Wiedeman, R. A.

337

A VHE architecture for advanced value-added service provision in 3rd generation mobile communication networks  

Microsoft Academic Search

In the emerging era of 3rd generation mobile communication networks, it is expected that operator differentiation in the market will highly depend on the advanced provision of value-added services, including the successful implementation of the virtual home environment (VHE) concept. In this paper, after discussing some issues critical to VHE realization, we introduce a distributed application platform architecture, capable of

Nikos Houssos; Maria Koutsopoulou; Sibylle Schaller

2000-01-01

338

Performance Analysis of Maximal Ratio Combining and Comparison with Optimum Combining for Mobile Radio Communications with Cochannel Interference  

Microsoft Academic Search

The performance of maximal ratio combining for space diversity reception in digital cellular mobile radio systems is studied for communications in the presence of multiple cochannel interference (CCI) sources and is compared to optimum com- bining. The main contribution of the paper is that the analysis accounts for fading of the signal of interest (SOI) as well as the cochannel

A. Shah; A. M. Haimovich

2000-01-01

339

Performance analysis of maximal ratio combining and comparison with optimum combining for mobile radio communications with cochannel interference  

Microsoft Academic Search

The performance of maximal ratio combining for space diversity reception in digital cellular mobile radio systems is studied for communications in the presence of multiple cochannel interference (CCI) sources and is compared to optimum combining. The main contribution of the paper is that the analysis accounts for fading of the signal of interest (SOI) as well as the cochannel interference

A. Shah; A. M. Haimovich

2000-01-01

340

Performance of multi-level QAM with maximal ratio combining space diversity for land mobile radio communications  

Microsoft Academic Search

A novel type of space diversity with maximal ratio combining for multilevel quadrature amplitude modulation (QAM) in land mobile communications to improve transmission performance is proposed. In order to realize maximal ratio combining space diversity for QAM, a novel type of diversity combining method using a pilot symbol insertion type fading estimator is applied. The proposed diversity combining is carried

S. Sampei; T. Sunaga

1990-01-01

341

A novel channel estimation method for OFDM mobile communication systems based on pilot signals and transform-domain processing  

Microsoft Academic Search

A method of estimating the channel transfer function is presented for orthogonal frequency division multiplexing (OFDM) mobile communication systems working under time-variant radio channel conditions. The proposed method employs lowpass filtering in a transform domain so that intercarrier interference and additive white Gaussian noise components in the received pilot signals are significantly reduced. The cutoff frequency of the transform-domain filter

Yuping Zhao; Aiping Huang

1997-01-01

342

Market and committee-based mechanisms in the creation and diffusion of global industry standards: the case of mobile communication  

Microsoft Academic Search

The existing literature on industrial standards almost exclusively focuses on pure market competition; this paper shows how and why both governments and firms have had a strong effect on the creation of global standards in the mobile communication industry through a hybrid system of committees and markets. According to our model, governments can and did influence forecasted and actual installed

Jeffrey L. Funk; David T. Methe

2001-01-01

343

The Investigation of Cloud-Computing-based Image Mining Mechanism in Mobile Communication WEB on Android  

Microsoft Academic Search

With the development of 3G network technology, the rapid upgrading of mobile phone hardware, and the refined requirements for mobile phones by mobile phone users, it is essential for mobile phones to be able to promptly and accurately process images. A mobile phone terminal sends the service requests to cloud computer system which then processes the requests and sends the

Cai-Dong Gu; Kan Lu; Jian-Ping Wu; Ying-li Fu; Jing-xiang Li; Chang-shui Xiao; Mao-xin Si; Zhao-bin Liu

2010-01-01

344

Security, Privacy, Trust, and Resource Management in Mobile and Wireless Communications  

Microsoft Academic Search

Mobile cloud computing has grown out of two hot technology trends, mobility and cloud. The emergence of cloud computing and its extension into the mobile domain creates the potential for a global, interconnected mobile cloud computing environment that will allow the entire mobile ecosystem to enrich their services across multiple networks. We can utilize significant optimization and increased operating power

Hassan Takabi; James B. D. Joshi

2013-01-01

345

The role of interpersonal communication in the process of knowledge mobilization within a community-based organization: a network analysis  

PubMed Central

Background Diffusion of innovations theory has been widely used to explain knowledge mobilization of research findings. This theory posits that individuals who are more interpersonally connected within an organization may be more likely to adopt an innovation (e.g., research evidence) than individuals who are less interconnected. Research examining this tenet of diffusion of innovations theory in the knowledge mobilization literature is limited. The purpose of the present study was to use network analysis to examine the role of interpersonal communication in the adoption and mobilization of the physical activity guidelines for people with spinal cord injury (SCI) among staff in a community-based organization (CBO). Methods The study used a cross-sectional, whole-network design. In total, 56 staff completed the network survey. Adoption of the guidelines was assessed using Rogers’ innovation-decision process and interpersonal communication was assessed using an online network instrument. Results The patterns of densities observed within the network were indicative of a core-periphery structure revealing that interpersonal communication was greater within the core than between the core and periphery and within the periphery. Membership in the core, as opposed to membership in the periphery, was associated with greater knowledge of the evidence-based physical activity resources available and engagement in physical activity promotion behaviours (ps?communication is associated with knowledge mobilization and highlight how the network structure could be improved for further dissemination efforts. Keywords: diffusion of innovations; network analysis; community-based organization; knowledge mobilization; knowledge translation, interpersonal communication.

2014-01-01

346

Exposure assessment of mobile phone base station radiation in an outdoor environment using sequential surrogate modeling.  

PubMed

Human exposure to background radiofrequency electromagnetic fields (RF-EMF) has been increasing with the introduction of new technologies. There is a definite need for the quantification of RF-EMF exposure but a robust exposure assessment is not yet possible, mainly due to the lack of a fast and efficient measurement procedure. In this article, a new procedure is proposed for accurately mapping the exposure to base station radiation in an outdoor environment based on surrogate modeling and sequential design, an entirely new approach in the domain of dosimetry for human RF exposure. We tested our procedure in an urban area of about 0.04?km(2) for Global System for Mobile Communications (GSM) technology at 900?MHz (GSM900) using a personal exposimeter. Fifty measurement locations were sufficient to obtain a coarse street exposure map, locating regions of high and low exposure; 70 measurement locations were sufficient to characterize the electric field distribution in the area and build an accurate predictive interpolation model. Hence, accurate GSM900 downlink outdoor exposure maps (for use in, e.g., governmental risk communication and epidemiological studies) are developed by combining the proven efficiency of sequential design with the speed of exposimeter measurements and their ease of handling. PMID:23315952

Aerts, Sam; Deschrijver, Dirk; Joseph, Wout; Verloock, Leen; Goeminne, Francis; Martens, Luc; Dhaene, Tom

2013-05-01

347

R&D of a Next Generation LEO System for Global Multimedia Mobile Satellite Communications  

NASA Astrophysics Data System (ADS)

Next-generation LEO System Research Center (NeLS) was formed in the end of 1997 as a research group under the Telecommunications Advancement Organization of Japan, in cooperation with the telecommunications operators, manufacturers, universities and governmental research organization. The aim of this project is to develop new technology for global multimedia mobile satellite communications services with a user data rate around 2Mbps for handy terminals. component of the IMT-2000, and the second generation of the big-LEO systems. In prosecuting this project, two-phase approach, phase 1 and phase 2, is considered. Phase 1 is the system definition and development of key technologies. In Phase 2, we plan to verify the developed technology in Phase 1 on space. From this year we shifted the stage to Phase 2, and are now developing the prototype of on-board communication systems for flight tests, which will be planed at around 2006. The satellite altitude is assumed to be 1200 km in order to reduce the number of satellites, to avoid the Van Allen radiation belts and to increase the minimum elevation angle. Ten of the circular orbits with 55 degree of inclination are selected to cover the earth surface from -70 to 70 degree in latitude. 12 satellites are positioned at regular intervals in each orbit. In this case, the minimum elevation angle from the user terminal can be keep more than 20 degree for the visibility of the satellite, and 15 degree for simultaneous visibility of two satellites. Then, NeLS Research Center was focusing on the development of key technologies as the phase 1 project. Four kinds of key technologies; DBF satellite antenna, optical inter-satellite link system, satellite network technology with on-board ATM switch and variable rate modulation were selected. Satellite Antenna Technology: Development of on-board direct radiating active phased array antenna with digital beam forming technology would be one of the most important breakthroughs for the satellite communication systems. Therefore, the experimental DBF network with 16 radiating elements was developed for confirming a basic signal processing performance. A/D sampled data are processed by using FPGA circuit for beam forming by real-time basis. Optical Inter-Satellite Link Technology: The inter-satellite link (ISL) technology is also important, because the inter-satellite network is essential to realize the low delay network connection for multimedia services. The optical ISL simulator was developed for the study of optical modem and optical tracking mechanism. And the sensitivity of 56 photons/bit at 10-9 of error rate has been achieved by employing the Erbium doped fiber amplifier, polarizing filter and narrow band optical filter. Coude path type, the active universal joint (AUJ) type and two flat mirror type of optical antenna mechanism were developed. Satellite Network Technology: For constructing this optical ISL ring, the utilization of wavelength division multiplexing (WDM) technology is envisaged. By applying WDM technology to the optical intra-orbital ISL, logical mesh connections can be achieved by assigning the appropriate wavelength for the links among satellites. By using inclined orbit, inter-orbital ISL connection can be keep continuously. Therefore, WDM technology is also applicable to the inter-orbital ISL network. The satellite ATM network simulator was developed in order to investigate the effect of delay fluctuation caused by the satellite constellations. This simulator works as real-time basis by using commercial ATM switches and personal computers. This simulator was installed Dijkstra's algorithm to determine satellite routing path in order to minimize the end-to-end delay time from the source terminal to the destination terminal. The satellite IP network simulator has been developed in order to evaluate the congestion of the multimedia traffic. Variable Rate Modulation Technology: Considering the propagation impairments in the mobile conditions, we employ the variable rate transmission, which maintains the communication service

Morikawa, E.; Motoyoshi, S.; Koyama, Y.; Suzuki, R.; Yasuda, Y.

2002-01-01

348

OSI-compatible protocols for mobile-satellite communications: The AMSS experience  

NASA Technical Reports Server (NTRS)

The protocol structure of the international aeronautical mobile satellite service (AMSS) is reviewed with emphasis on those aspects of protocol performance, validation, and conformance which are peculiar to mobile services. This is in part an analysis of what can be learned from the AMSS experience with protocols which is relevant to the design of other mobile satellite data networks, e.g., land mobile.

Moher, Michael

1990-01-01

349

A comparison of metropolitan and non-metropolitan employment characteristics: Indications of the size of non-metropolitan mobile communication services user classes  

NASA Technical Reports Server (NTRS)

The similarities and differences between areas inside and outside U.S. metropolitan areas were evaluated in terms of their commercial/industrial and government employment characteristics. The comparison focuses on the levels, shares, and composition of employment in the commercial/industrial and government sectors that represent potential classes of land mobile communications users. The major findings of the analysis are as follows: (1) non-metropolitan commercial/industrial user classes of land mobile communication services exist in significant numbers; (2) the compositions of non-metropolitan and metropolitan commercial/industrial user classes of land mobile communication services closely resemble each other; (3) non-metropolitan areas have significant levels of the government user classes that represent potential markets for land mobile communication services; and (4) non-metropolitan local governments have a significantly larger proportion of their employment in the primary user classes of private land mobile radio service than do metropolitan local governments.

Wilcox, R. E.

1985-01-01

350

7 CFR 1493.6 - Additional required determinations for GSM-103.  

Code of Federal Regulations, 2010 CFR

... Additional required determinations for GSM-103. 1493.6 Section 1493.6 ...Additional required determinations for GSM-103. Notwithstanding any other provision...part, CCC shall not guarantee under the GSM-103 program the repayment of...

2009-01-01

351

7 CFR 1493.6 - Additional required determinations for GSM-103.  

Code of Federal Regulations, 2010 CFR

... Additional required determinations for GSM-103. 1493.6 Section 1493.6 ...Additional required determinations for GSM-103. Notwithstanding any other provision...part, CCC shall not guarantee under the GSM-103 program the repayment of...

2010-01-01

352

78 FR 79253 - CCC Export Credit Guarantee (GSM-102) Program and Facility Guarantee Program (FGP)  

Federal Register 2010, 2011, 2012, 2013

...7 CFR Part 1493 CCC Export Credit Guarantee [lpar]GSM-102...Corporation 7 CFR Part 1493 RIN 0551-AA74 CCC Export Credit Guarantee (GSM-102) Program...amend the regulations that administer the Export Credit Guarantee (GSM-102)...

2013-12-27

353

Performance of the unique-word-reverse-modulation type demodulator for mobile satellite communications  

NASA Technical Reports Server (NTRS)

This paper proposes a new type of coherent demodulator, the unique-word (UW)-reverse-modulation type demodulator, for burst signal controlled by voice operated transmitter (VOX) in mobile satellite communication channels. The demodulator has three individual circuits: a pre-detection signal combiner, a pre-detection UW detector, and a UW-reverse-modulation type demodulator. The pre-detection signal combiner combines signal sequences received by two antennas and improves bit energy-to-noise power density ratio (E(sub b)/N(sub 0)) 2.5 dB to yield 10(exp -3) average bit error rate (BER) when carrier power-to-multipath power ratio (CMR) is 15 dB. The pre-detection UW detector improves UW detection probability when the frequency offset is large. The UW-reverse-modulation type demodulator realizes a maximum pull-in frequency of 3.9 kHz, the pull-in time is 2.4 seconds and frequency error is less than 20 Hz. The performances of this demodulator are confirmed through computer simulations and its effect is clarified in real-time experiments at a bit rate of 16.8 kbps using a digital signal processor (DSP).

Dohi, Tomohiro; Nitta, Kazumasa; Ueda, Takashi

1993-01-01

354

A new coherent demodulation technique for land-mobile satellite communications  

NASA Astrophysics Data System (ADS)

An advanced coherent demodulation technique is described for land mobile satellite (LMS) communications. The proposed technique features a combined narrow/wind band dual open loop carrier phase estimator, which is effectively able to compensate the fast carrier phase fluctuation by fading with sacrificing a phase slip rate. Also included is the realization of quick carrier and clock reacquisition after shadowing by taking open loop structure. Its bit error rate (BER) performance is superior to that of existing detection schemes, showing a BER of 1 x 10(exp -2) at 6.3 dB E sub b/N sub o over the Rician channel with 10 dB C/M and 200 Hz (1/16 modulation rate) fading pitch f sub d for QPSK. The proposed scheme consists of a fast response carrier recovery and a quick bit timing recovery with an interpolation. An experimental terminal model was developed to evaluate its performance at fading conditions. The results are quite satisfactory, giving prospects for future LMS applications.

Yoshida, Shousei; Tomita, Hideho

355

[Metabolic changes in cells under electromagnetic radiation of mobile communication systems].  

PubMed

Review is devoted to the analysis of biological effects of microwaves. The results of last years' researches indicated the potential risks of long-term low-level microwaves exposure for human health. The analysis of metabolic changes in living cells under the exposure of microwaves from mobile communication systems indicates that this factor is stressful for cells. Among the reproducible effects of low-level microwave radiation are overexpression of heat shock proteins, an increase of reactive oxygen species level, an increase of intracellular Ca2+, damage of DNA, inhibition of DNA reparation, and induction of apoptosis. Extracellular-signal-regulated kinases ERK and stress-related kinases p38MAPK are involved in metabolic changes. Analysis of current data suggests that the concept of exceptionally thermal mechanism of biological effects of microwaves is not correct. In turn, this raises the question of the need to revaluation of modern electromagnetic standards based on thermal effects of non-ionizing radiation on biological systems. PMID:21851043

Iakimenko, I L; Sidorik, E P; Tsybulin, A S

2011-01-01

356

Requirements for a mobile communications satellite system. Volume 3: Large space structures measurements study  

NASA Technical Reports Server (NTRS)

This study report defines a set of tests and measurements required to characterize the performance of a Large Space System (LSS), and to scale this data to other LSS satellites. Requirements from the Mobile Communication Satellite (MSAT) configurations derived in the parent study were used. MSAT utilizes a large, mesh deployable antenna, and encompasses a significant range of LSS technology issues in the areas of structural/dynamics, control, and performance predictability. In this study, performance requirements were developed for the antenna. Special emphasis was placed on antenna surface accuracy, and pointing stability. Instrumentation and measurement systems, applicable to LSS, were selected from existing or on-going technology developments. Laser ranging and angulation systems, presently in breadboard status, form the backbone of the measurements. Following this, a set of ground, STS, and GEO-operational were investigated. A third scale (15 meter) antenna system as selected for ground characterization followed by STS flight technology development. This selection ensures analytical scaling from ground-to-orbit, and size scaling. Other benefits are cost and ability to perform reasonable ground tests. Detail costing of the various tests and measurement systems were derived and are included in the report.

Akle, W.

1983-01-01

357

A new coherent demodulation technique for land-mobile satellite communications  

NASA Technical Reports Server (NTRS)

An advanced coherent demodulation technique is described for land mobile satellite (LMS) communications. The proposed technique features a combined narrow/wind band dual open loop carrier phase estimator, which is effectively able to compensate the fast carrier phase fluctuation by fading with sacrificing a phase slip rate. Also included is the realization of quick carrier and clock reacquisition after shadowing by taking open loop structure. Its bit error rate (BER) performance is superior to that of existing detection schemes, showing a BER of 1 x 10(exp -2) at 6.3 dB E sub b/N sub o over the Rician channel with 10 dB C/M and 200 Hz (1/16 modulation rate) fading pitch f sub d for QPSK. The proposed scheme consists of a fast response carrier recovery and a quick bit timing recovery with an interpolation. An experimental terminal model was developed to evaluate its performance at fading conditions. The results are quite satisfactory, giving prospects for future LMS applications.

Yoshida, Shousei; Tomita, Hideho

1990-01-01

358

A 24-pole high Tc superconducting filter for mobile communication applications  

NASA Astrophysics Data System (ADS)

This paper presents a highly selective 24-pole Chebyshev HTS bandpass filter. The filter was designed at 1748 MHz centre frequency with 75 MHz bandwidth, which was suitable for the GSM base station. The filter was fabricated using double-sided YBCO films on a 3 in diameter, 0.43 mm thick sapphire substrate. The simulation of the filter performance was carried out using Sonnet software. A novel resonator structure was proposed. The resonator exhibited a very high Q value of about 30 000 at 77 K. The filter showed an excellent selectivity. At the band edge of the filter, the slope was about 17 dB MHz-1. Out of the band, the rejection level is better than -90 dB.

Zhang, Xueqiang; Meng, Qingduan; Li, Fei; Li, Chunguang; Li, Shunzhou; He, Aisheng; Li, Hong; He, Yusheng

2006-05-01

359

Performance of a Joint CDMA\\/PRMA Protocol for Mixed Voice\\/Data Transmission for Third Generation Mobile Communication  

Microsoft Academic Search

A joint code-division multiple-access\\/packet-reservation multiple-access (CDMA\\/PRMA) technique is proposed and investigated as a candidate for an uplink protocol for third generation mobile communication systems. Access to the radio channel is controlled such that compared to random access CDMA, interference variance is reduced and throughput increased. Mixed voice\\/data traffic is investigated for an isolated cell only, whereas voice-only traffic is also

Alex E. Brand; Hamid Aghvami

1996-01-01

360

Field Testing of a Remote Controlled Robotic Tele-echo System in an Ambulance Using Broadband Mobile Communication Technology  

Microsoft Academic Search

We report the testing of a mobile Robotic Tele-echo system that was placed in an ambulance and successfully transmitted clear\\u000a real time echo imaging of a patient's abdomen to the destination hospital from where this device was being remotely operated.\\u000a Two-way communication between the paramedics in this vehicle and a doctor standing by at the hospital was undertaken. The\\u000a robot

Ryohei Takeuchi; Hiroshi Harada; Kohji Masuda; Gen-ichiro Ota; Masaki Yokoi; Nobuyasu Teramura; Tomoyuki Saito

2008-01-01

361

MobiCloud: Building Secure Cloud Framework for Mobile Computing and Communication  

Microsoft Academic Search

Cloud services can greatly enhance the computing capability of mobile devices. Mobile users can rely on the cloud to perform computationally intensive operations such as searching, data mining, and multimedia processing. In this paper, we propose a new mobile cloud framework called MobiCloud. In addition to providing traditional computation services, MobiCloud also enhances the operation of the ad hoc network

Dijiang Huang; Xinwen Zhang; Myong Kang; Jim Luo

2010-01-01

362

Practical Metropolitan-Scale Positioning for GSM Phones  

Microsoft Academic Search

This paper examines the positioning accuracy of a GSM beacon- based location system in a metropolitan environment. We explore five factors effecting positioning accuracy: location algorithm choice, scan set size, simultaneous use of cells from different providers, training and testing on different devices, and calibration data density. We collected a 208-hour, 4350Km driving trace of three different GSM networks covering

Mike Y. Chen; Timothy Sohn; Dmitri Chmelev; Dirk Haehnel; Jeffrey Hightower; Jeff Hughes; Anthony Lamarca; Fred Potter; Ian E. Smith; Alex Varshavsky

2006-01-01

363

Transmission of compressed video over GSM data channels  

Microsoft Academic Search

This paper considers the evaluation of transmission of compressed video over GSM data traffic channels. A need for such transmission has been identified in the operation of light rail transport systems in the UK and this paper addresses this application in particular. The results presented are based on a simulator which incorporates a GSM TCH\\/F 9.6 data channel model. The

J. Dunlop; E. Santos

1996-01-01

364

Communicators' Perceptions of Social Presence as a Function of Avatar Realism in Small Display Mobile Communication Devices  

Microsoft Academic Search

This study describes an experiment in which 126 participants engaged via a mobile telephone simulation that included a visual display in a discussion that required self-disclosure and affective evaluation of the other participant. Participants in same gender and mixed gender dyads were represented by avatars that varied in visual realism (unmodified video, modified video, graphic display, or no visual display)

Sin-hwa Kang; James H. Watt; Sasi Kanth Ala

2008-01-01

365

Weather Information Communication Technologies for Increased Safety and Mobility in the National Airspace System.  

National Technical Information Service (NTIS)

The purpose of the NASA Glenn Research Center Weather Information Communications (WINCOMM) project was to develop advanced communications and information technologies to enable the high-quality and timely dissemination of strategic weather information bet...

D. R. Hilderman

2006-01-01

366

Printed Monopole Slot Antenna for Internal Multiband Mobile Phone Antenna  

Microsoft Academic Search

A new internal multiband mobile phone antenna formed by two printed monopole slots of different lengths cut at the edge of the system ground plane of the mobile phone is presented. The antenna can generate two wide bands centered at about 900 and 2100 MHz to cover the GSM850\\/GSM900\\/DCS\\/PCS\\/UMTS bands and the 2.4-GHz WLAN band. Further, the antenna has a

Chun-I. Lin; Kin-Lu Wong

2007-01-01

367

An internal dual-band mobile phone antenna  

Microsoft Academic Search

An internal dual-band mobile phone antenna designed to operate at GSM900 and GSM1800 bands is presented. The antenna is derived from a quarter-wave planar inverted F-type antenna, which has at this state proved to be the most promising candidate for mobile applications due to its compact size and good performance. The FDTD method is used in the study and an

S. Tarvas; A. Isohatala

2000-01-01

368

Manufacturing consent?: Media messages in the mobilization against HIV/AIDS in India and lessons for health communication.  

PubMed

Despite repeated calls for a more critical and "culture-centered" approach to health communication, textual analysis of televised public service advertising (PSA) campaigns has been largely neglected, even by critical communication scholars. In the case of "developing" countries in particular, there is an acute shortage of such literature. On the other hand, following the outbreak of major public health diseases such as AIDS, most countries have adopted PSA campaigns as the most preferred means of communicating messages. Drawing on insights from cultural studies (especially Antonio Gramsci and Stuart Hall), this article engages in textual analysis of the televised PSA campaigns launched by the Indian state to prevent HIV/AIDS between 2002 and 2005. Through such analysis, it argues that although few diseases in Indian history have spurred such massive and creative efforts for mass mobilization as AIDS, these efforts, in terms of their ethical implications, have been far from emancipatory. In fact, they have constructed and perpetuated the logic of domination and control along class, gender, sexuality, and knowledge systems, often contradicting and potentially harming the very goal of HIV prevention and of health promotion and empowerment. This article also holds that assessing public health campaigns through textual analysis, a highly neglected tool in health communication, can shed important light on a far more complex and changing nature of the state and public policy, especially in the developing world, thereby opening up space for alternative theorizing for health communication and social change. PMID:23631645

Khan, Shamshad

2014-01-01

369

Opening communication channels with people living with HIV using mobile phone text messaging: insights from the CAMPS trial  

PubMed Central

Background Using two-way mobile phone text messages to improve adherence to antiretroviral medication enhances communication between patients and health workers. We describe the implications of participants’ responses to text messages in the Cameroon Mobile Phone SMS (CAMPS) trial. Findings This is a cross-sectional analysis of data from the intervention arm of the CAMPS trial. CAMPS was a randomized controlled trial of motivational text messaging versus usual care to improve adherence to antiretroviral medication among people living with HIV in Yaounde, Cameroon (n?=?200) over a 6 month period. Participants in the intervention arm (n?=?101) were given a contact phone number, but were not required to respond to their reminder messages. If they did, their responses were noted and reported as counts and percentages. We received 99 phone calls and 55 text messages (154 responses) from 48 participants during the study period. The median number of responses was 1 (first quartile [Q1]: 1; third quartile [Q3]: 3). Half (n?=?79, 51.1%) of them were expressions of gratitude. The rest included requests for logistical (n?=?21, 13.6%), medical (n?=?20, 12.9%) and financial (n?=?11, 7.1%) support. Conclusion Initiating two-way mobile communication opens more channels for people living with HIV to express unmet needs. Researchers, policy makers and clinicians should be ready to respond to the needs expressed by patients who respond to text messages. Trial registration Pan-African Clinical Trials Registry: PACTR201011000261458; Clinicaltrials.gov: NCT01247181

2013-01-01

370

Architecture for delay-sensitive communications in mobile optical free-space networks  

Microsoft Academic Search

Mobile optical free space networks are an emerging architecture that can provide high speed connectivity between a ground-based backbone network and mobile users in challenging environments. In such a network traffic could be relayed by airborne or ground routers using wireless optical links. The variable nature of the wireless optical channel complicates support for real-time distributed applications demanding bounds on

I. Cardei; A. Pavan; R. Bettati

2005-01-01

371

Application of radio channel modelling to a planning tool in a mobile radio indoor communication system  

Microsoft Academic Search

For mobile radio systems, it is very important to know how the propagation medium performs at the right frequency and within the given geographical environment. When this environment is an indoor one, that is, when a mobile system is being deployed within a building, a number of new issues appear that pose a number of constraints and restrictions to the

Gema Vallejo-Cabrejas; P. Batolome-Pascual

1993-01-01

372

Traffic Capacity of Three Types of Common-User Mobile Radio Communication Systems  

Microsoft Academic Search

The traffic-carrying capability of three types of common-user mobile radio systems are derived and compared; they are also compared with a private-user system. The systems considered make use of multichannel capability for mobile units or a dispersed array of base stations, or both.

L. Schiff

1970-01-01

373

Agent Communication Network - A Mobile Agent Computation Model for Internet Applications  

Microsoft Academic Search

We propose a graph-based model, with a simulation, for the mobile agents to evolve over the Internet. Based on the concepts of Food Web (or Food Chain), one of the natural laws that we may use besides neural networks and genetic algorithms, we define an agent niche overlap graph and agent evolution states for the distributed computation of mobile agent

Timothy K. Shih

1999-01-01

374

Satellite-aided mobile radio concepts study: Concept definition of a satellite-aided mobile and personal radio communication system  

NASA Technical Reports Server (NTRS)

The satellite system requires the use of a large satellite antenna and spacecraft array power of about 12 kW or more depending on the operating frequency. Technology developments needed include large offset reflector multibeam antennas, satellite electrical power sybsystems providing greater than 12 kW of power, signal switching hardware, and linearized efficient solid state amplifiers for the satellite-aided mobile band. Presently there is no frequency assignment for this service, and it is recommended that an allocation be pursued. The satellite system appears to be within reasonable extrapolation of the state of the art. It is further recommended that the satellite-aided system spacecraft definition studies and supporting technology development be initiated.

Anderson, R. E.

1979-01-01

375

A medical application integrating remote 3D visualization tools to access picture archiving and communication system on mobile devices.  

PubMed

With computing capability and display size growing, the mobile device has been used as a tool to help clinicians view patient information and medical images anywhere and anytime. However, for direct interactive 3D visualization, which plays an important role in radiological diagnosis, the mobile device cannot provide a satisfactory quality of experience for radiologists. This paper developed a medical system that can get medical images from the picture archiving and communication system on the mobile device over the wireless network. In the proposed application, the mobile device got patient information and medical images through a proxy server connecting to the PACS server. Meanwhile, the proxy server integrated a range of 3D visualization techniques, including maximum intensity projection, multi-planar reconstruction and direct volume rendering, to providing shape, brightness, depth and location information generated from the original sectional images for radiologists. Furthermore, an algorithm that changes remote render parameters automatically to adapt to the network status was employed to improve the quality of experience. Finally, performance issues regarding the remote 3D visualization of the medical images over the wireless network of the proposed application were also discussed. The results demonstrated that this proposed medical application could provide a smooth interactive experience in the WLAN and 3G networks. PMID:24705800

He, Longjun; Ming, Xing; Liu, Qian

2014-04-01

376

Mobile Phone Location Determination in Urban and Rural Areas Using Enhanced Observed Time Difference Technique  

Microsoft Academic Search

3 Abstract: An extensive research has been carried out to evaluate method for the tracking of mobile equipment using it's base stations in a GSM network. Enhanced Observed Time Difference (E-OTD) method is one of the promising and fairly developed positioning technologies that has been standardized for GSM systems. This Method has been utilized in this research work to locate

S. F. Shaukat; M. I. Ansari; R. Farooq; U. Ibrahim; Muhammad Faisal

2009-01-01

377

Performance comparisons of dynamic resource allocation with\\/without channel de-allocationin GSM\\/GPRS networks  

Microsoft Academic Search

In this letter, we analyzed and compared the performance of dynamic resource allocation with\\/without channel de-allocation in GSM\\/GPRS networks. It is quite known that dynamic resource allocation allows communication systems to utilize their resources more efficiently than the traditional fixed allocation schemes. In GPRS, multiple channels may be allocated to a user to increase the transmission rate. In the case

Wei-Yeh Chen; Jean-Lien C. Wu; Li-Liann Lu

2003-01-01

378

Remote monitoring system research and implementation based on wireless communication  

NASA Astrophysics Data System (ADS)

With rapid development of automatic control and network techniques, network-based remote monitoring is becoming an investigating hotspot in the elevator industry. At the same time as the development of wireless communication technology, remote wireless monitoring technology is applied more and more widely in recent years. A variety of wireless detection equipment is entering various industrial enterprises, and has been widely used. At present, there are many defects of the traditional monitoring system, such as poor real-time, low reliability, low intelligence. Based on the analysis of the difficulties to monitor the mobile terminal, this paper firstly analyzes the GSM/GPRS technology, and then discusses a design of the remote monitoring system based on wireless communication. The architecture of the monitoring center is introduced in detail. It is characterized by user-friendly, easy operate, good real-time and easy to extend.

Fu, Weizhi; Meng, Xiaofeng

2013-03-01

379

Relationships between Emotional States and Emoticons in Mobile Phone Email Communication in Japan  

ERIC Educational Resources Information Center

Three related studies conducted on the role of emotional transfer in email messages were studied in order to better understand Japanese college students' online communications and their broader participation in online communications. The first study investigated users' initiatives in preventing emotional misunderstandings when sending email.…

Kato, Shogo; Kato, Yuuki; Scott, Douglass

2009-01-01

380

Modular, Cost-Effective, Extensible Avionics Architecture for Secure, Mobile Communications.  

National Technical Information Service (NTIS)

Current onboard communication architectures are based upon an all-in-one communications management unit. This unit and associated radio systems has regularly been designed as a one-off, proprietary system. As such, it lacks flexibility and cannot adapt ea...

W. D. Ivancic

2006-01-01

381

Modular, Cost-Effective, Extensible Avionics Architecture for Secure, Mobile Communications.  

National Technical Information Service (NTIS)

Current onboard communication architectures are based upon an all-in-one communications management unit. This unit and associated radio systems has regularly been designed as a one-off, proprietary system. As such, it lacks flexibility and cannot adapt ea...

W. D. Ivancic

2007-01-01

382

Modular, Cost-Effective, Extensible Avionics Architecture for Secure, Mobile Communications  

NASA Technical Reports Server (NTRS)

Current onboard communication architectures are based upon an all-in-one communications management unit. This unit and associated radio systems has regularly been designed as a one-off, proprietary system. As such, it lacks flexibility and cannot adapt easily to new technology, new communication protocols, and new communication links. This paper describes the current avionics communication architecture and provides a historical perspective of the evolution of this system. A new onboard architecture is proposed that allows full use of commercial-off-the-shelf technologies to be integrated in a modular approach thereby enabling a flexible, cost-effective and fully deployable design that can take advantage of ongoing advances in the computer, cryptography, and telecommunications industries.

Ivancic, William D.

2007-01-01

383

Modular, Cost-Effective, Extensible Avionics Architecture for Secure, Mobile Communications  

NASA Technical Reports Server (NTRS)

Current onboard communication architectures are based upon an all-in-one communications management unit. This unit and associated radio systems has regularly been designed as a one-off, proprietary system. As such, it lacks flexibility and cannot adapt easily to new technology, new communication protocols, and new communication links. This paper describes the current avionics communication architecture and provides a historical perspective of the evolution of this system. A new onboard architecture is proposed that allows full use of commercial-off-the-shelf technologies to be integrated in a modular approach thereby enabling a flexible, cost-effective and fully deployable design that can take advantage of ongoing advances in the computer, cryptography, and telecommunications industries.

Ivancic, William D.

2006-01-01

384

77 FR 28797 - Redundancy of Communications Systems: Backup Power Private Land Mobile Radio Services: Selection...  

Federal Register 2010, 2011, 2012, 2013

...Systems: Backup Power Private Land Mobile Radio Services: Selection and Assignment of Frequencies, and Transition of the Upper...collection burden for small business concerns with fewer than 25 employees,'' pursuant to the Small Business Paperwork Relief...

2012-05-16

385

Interworking and Integration of the Inmarsat Standard-M with Pan-European GSM System.  

National Technical Information Service (NTIS)

The market demand on mobile telephone communications has been increasing since the introduction of the cellular mobile telephone systems about twelve years ago. In Europe, projections indicate a demand of about 17 million subscribers for a fully deployed ...

R. Tafazolli B. G. Evans

1993-01-01

386

Implementation and Performance Evaluation of Communications Security in a Mobile E-health Service  

Microsoft Academic Search

\\u000a This paper discusses the implementation and performance evaluation of the security services in a mobile healthcare system.\\u000a The system consists of a number of sensors attached to the patient, which collect data that are sent via 2.5G or 3G mobile\\u000a telephony to a hospital or healthcare centre for monitoring. Security is an essential requirement of the system due to the

Juan C. Sánchez; Xavier Perramon; Ramon Martí; Jaime Delgado

2004-01-01

387

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

PubMed

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. PMID:18333403

Eren, Ali; Subasi, Abdulhamit; Coskun, Osman

2008-02-01

388

Low complexity source controlled channel decoding in a GSM system  

Microsoft Academic Search

In this paper we investigate source controlled channel decoding with a hard output channel decoder. Various methods have been devised in the past for source controlled channel decoding, but most of them assume that a soft output channel decoder is used. Most receivers in mobile wireless communications have a standard Viterbi channel decoder which produces only hard outputs. It is

Paul Strauch; Carlo Luschi; Magnus Sandell; Ran Yan

1999-01-01

389

76 FR 44836 - CCC Export Credit Guarantee (GSM-102) Program  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF AGRICULTURE Commodity Credit Corporation 7 CFR Part 1493 RIN 0551-AA74 CCC Export Credit Guarantee (GSM-102) Program AGENCY: Foreign Agricultural Service and Commodity Credit Corporation, USDA. ACTION:...

2011-07-27

390

76 FR 57940 - CCC Export Credit Guarantee (GSM-102) Program  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF AGRICULTURE Commodity Credit Corporation 7 CFR Part 1493 RIN 0551-AA74 CCC Export Credit Guarantee (GSM-102) Program AGENCY: Foreign Agricultural Service and Commodity Credit Corporation, USDA. ACTION:...

2011-09-19

391

Idotai tsushin system no denryoku tsushinmo eno tekiyo. 1. Idotai tsushin system no genjo to PHS ni yoru juyo kakei network no teian. (Studies of an application of a mobile communication system to the private telecommunication network. Part 1. Present condition of mobile communication system and proposal of the customer information network by PHS).  

National Technical Information Service (NTIS)

An application of various mobile communication systems to the electric power telecommunication network has been investigated. Among these, the customer information network by PHS (personal handy-phone system) has been proposed. Although great numbers of b...

H. Iwasaki

1996-01-01

392

Application of mobile digital communications in law enforcement, an introductory planning guide  

NASA Technical Reports Server (NTRS)

A set of planning guidelines for the application of digital communications techniques to law enforcement use is presented. Some essential characteristics of digital techniques and their applications are outlined, as are some principles of system analysis, evaluation, and planning. Requirements analysis, system concept design, implementation planning, and performance and cost modeling are described and demonstrated with respect to this application problem. Information on law enforcement digital communications systems and equipment and a list of vendor sources are given in appendices.

Sohn, R. L.; Abraham, J. E.; Leflang, W. G.; Kennedy, R. D.; Wilson, J. H.; Gurfield, R. M.

1975-01-01

393

Feeding reconfigurable PIFA for GSM\\/PCS\\/DCS applications  

Microsoft Academic Search

A novel compact planar inverted-F antenna (PIFA) with reconfigurable feedings for GSM\\/PCS\\/DCS applications is proposed in this paper. The U-shaped PIFA with only one branch is folded into 3 planes is designed to reduce the dimensions. The antenna occupies a relatively small volume of 50*7*7 mm3. Two feeds can be switched to achieve two different matching states, and GSM\\/PCS\\/DCS bands

Yue Li; Zhijun Zhang; Wenhua Chen; Zhenghe Feng; Magdy F. Iskander; An-Ping Zhao

2009-01-01

394

Mobility Prediction Progressive Routing (MP2R), a Cross-Layer Design for Inter-Vehicle Communication  

NASA Astrophysics Data System (ADS)

In this paper we analyze the characteristics of vehicle mobility and propose a novel Mobility Prediction Progressive Routing (MP2R) protocol for Inter-Vehicle Communication (IVC) that is based on crosslayer design. MP2R utilizes the additional gain provided by the directional antennas to improve link quality and connectivity; interference is reduced by the directional transmission. Each node learns its own position and speed and that of other nodes, and performs position prediction. (i) With the predicted progress and link quality, the forwarding decision of a packet is locally made, just before the packet is actually transmitted. In addition the load at the forwarder is considered in order to avoid congestion. (ii) The predicted geographic direction is used to control the beam of the directional antenna. The proposed MP2R protocol is especially suitable for forwarding burst traffic in highly mobile environments. Simulation results show that MP2R effectively reduces Packet Error Ratio (PER) compared with both topology-based routing (AODV [1], FSR [2]) and normal progressive routing (NADV [18]) in the IVC scenarios.

Tang, Suhua; Kadowaki, Naoto; Obana, Sadao

395

Dynamic topology optimization and transition schemes for assuring connectivity in multihop mobile optical wireless communications networks  

Microsoft Academic Search

Mobile free space optical (FSO) links suffer from frequent link blockages due to opaque obstructions or link degradations that can result in degraded or failed networks. In this paper, a dynamic layer-1 based topology and routing control methodology is presented for assuring connectivity in networks with fragile links. Core components of this methodology are described with special emphasis on the

Paul Velez; Anurag Dwivedi; P. Harshavardhana; Daniel Tebben; A. Roger Hammons Jr

2009-01-01

396

The electrophoretic mobility of peptides on paper at pH1.9 (Short Communication)  

PubMed Central

The relationship between the electrophoretic mobility, the molecular weight and the charge of peptides at pH1.9 was re-investigated. It was shown that the relationship at pH1.9 is quantitatively similar to that which holds at pH6.5.

Bailey, C. J.; Ramshaw, J. A. M.

1973-01-01

397

Socializing Messages in Blue-Collar Families: Communicative Pathways to Social Mobility and Reproduction  

ERIC Educational Resources Information Center

This study explicitly links processes of anticipatory socialization to social mobility and reproduction. An examination of the socializing messages exchanged between blue-collar parents (n = 41) and their children (n = 25) demonstrate that family-based messages about work and career seldom occur in straightforward, unambiguous ways. Instead,…

Lucas, Kristen

2011-01-01

398

Performance analysis of cellular mobile communication systems with dynamic channel assignment  

Microsoft Academic Search

The traffic analysis of small-cell mobile networks with dynamic channel assignment is investigated to determine their blocking performance, using a hybrid method of analysis and simulation. The authors particularly focus on the performance problems presented by networks with heterogeneous cell traffic loads, the impact of traffic volatility among the cells, and the impact of multichannel traffic on the channel blocking

D. Everitt; D. Manfield

1989-01-01

399

Local Sociality in Young People's Mobile Communications: A Korean Case Study  

ERIC Educational Resources Information Center

Drawing upon ethnographic data, this article explores how young Koreans appropriate mobile phones. By examining the role of local norms of sociality among young people, the study shows that this "individualizing" technology is articulated through "traditionalizing" forces. Despite dominant representations of young people's individualization via…

Yoon, Kyongwon

2006-01-01

400

Capacity of a Mobile Multiple-Antenna Communication Link in Rayleigh Flat Fading  

Microsoft Academic Search

We analyze a mobile wireless link comprising transmitter and receiver antennas operating in a Rayleigh flat-fading environment. The propagation coef ficients between every pair of transmitter and receiver antennas are statistically independent and un known; they remain constant for a coherence interval of symbol periods, after which they change to new independent values which they maintain for another symbol periods,

Thomas L. Marzetta; Bertrand M. Hochwald

1999-01-01

401

Ultra-low Power Sensors with Near Field Communication for Mobile Applications  

Microsoft Academic Search

In this paper, we study the applicability of an emerging RFID-based communication technology, NFC (Near Field Communication),\\u000a to ultra-low power wireless sensors. We present potential application examples of passive and semi-passive NFC-enabled sensors.\\u000a We compare their NFC-based implementations to corresponding implementations based on short-range radios such as Bluetooth\\u000a and Wibree. The comparison addresses both technical properties and usability. We also

Esko Strömmer; Mika Hillukkala; Arto Ylisaukko-oja

402

Communication.  

ERIC Educational Resources Information Center

This theme issue on communication includes annotated listings of Web sites, CD-ROM and computer software, videos, books, and professional resources that deal with various methods of communication. Sidebars discuss mythology, photojournalism, sharing ideas on the Web, and songs of protest. Suggestions for class activities are also included. (LRW)

Online-Offline, 1998

1998-01-01

403

The ELLIPSO (tm) system: Elliptical low orbits for mobile communications and other optimum system elements  

Microsoft Academic Search

On 5 Nov. 1990, Ellipsat filed with the FCC the first application to provide voice communication services via low earth orbiting (LEO) satellites. The proposed system, ELLIPSO, aims at achieving end-user costs comparable to those in the cellular industry. On 3 Jun. 1991 Ellipsat filed for the second complement of its system. Ellipsat was also the first company to propose

David Castiel

1991-01-01

404

Do We Keep Driving? Effectiveness of Rural Augmentative and Alternative Communication Mobile Service Delivery.  

ERIC Educational Resources Information Center

Evaluation of a program that traveled to various sites in rural New Mexico to evaluate special education students for augmentative and alternative communication needs revealed that parents and teachers were positive about the quality of services provided. Additionally, graduate students involved in providing services were positive about their…

Stuart, Sheela; Massey, Anne

1995-01-01

405

Small-Scale Design Experiments as Working Space for Larger Mobile Communication Challenges  

ERIC Educational Resources Information Center

In this paper, a design experiment using Instagram as a cultural probe is submitted as a method for analyzing the challenges that arise when considering the implementation of social media within a distributed communication space. It outlines how small, iterative investigations can reveal deeper research questions relevant to the education of…

Lowe, Sarah; Stuedahl, Dagny

2014-01-01

406

Performance of turbo and trellis coded OFDM for LEO satellite channels in global mobile communications  

Microsoft Academic Search

Orthogonal frequency division multiplexing (OFDM) is a robust transmission technique in a Raleigh fading and Rician fading environments. The growing interest in OFDM research motivated us to propose OFDM for satellite communications. In this paper, trellis coded modulation (TCM) and turbo coding are considered with OFDM for a Rician fading channel according to the specifications given by the Iridium system.

W. A. C. Fernando; R. M. A. P. Rajatheva

1998-01-01

407

System considerations, projected requirements and applications for aeronautical mobile satellite communications for air traffic services  

NASA Technical Reports Server (NTRS)

The projected application and requirements in the near term (to 1995) and far term (to 2010) for aeronautical mobile services supporting air traffic control operations are addressed. The implications of these requirements on spectrum needs, and the resulting effects on the satellite design and operation are discussed. The U.S. is working with international standards and regulatory organizations to develop the necessary aviation standards, signalling protocols, and implementation methods. In the provision of aeronautical safety services, a number of critical issues were identified, including system reliability and availability, access time, channel restoration time, interoperability, pre-emption techniques, and the system network interfaces. Means for accomplishing these critical services in the aeronautical mobile satellite service (AMSS), and the various activities relating to the future provision of aeronautical safety services are addressed.

Mcdonald, K. D.; Miller, C. M.; Scales, W. C.; Dement, D. K.

1990-01-01

408

Communications quality of service for ad-hoc mobile optical free-space networks  

Microsoft Academic Search

Mobile Optical Free Space networks are an emerg- ing technology that will offer low-delay and high speed con- nectivity using air-borne and ground wireless laser terminals. The time-variable link capacity and dynamic topology make Quality of Service provisioning a difficult problem. We present an architecture for end-to-end statistical delay guarantees. We describe a delay model that uses the concept of

Ionut Cardei; Allalaghatta Pavan; Riccardo Bettati

2006-01-01

409

A New Frequency Partitioning and Allocation of Subcarriers for Fractional Frequency Reuse in Mobile Communication Systems  

NASA Astrophysics Data System (ADS)

Some OFDMA-based wireless commuication systems, e. g., Wireless Broadband Internet (WiBro) or Worldwide interoperability for Microwave Access (WiMAX), support frequency reuse of 1 to maximize spectral efficiency. One of the efficient methods to reduce co-channel interference (CCI) caused by frequency reuse is fractional frequency reuse (FFR). In this paper, we propose and validate a novel frequency partitioning method and subcarrier assignment mechanism to improve system and individual capacity of mobile systems using FFR.

Han, Seung Su; Park, Jongho; Lee, Tae-Jin; Ahn, Hyun Gi; Jang, Kyunghun

410

Empirical evaluation of mobile peer-to-peer wellness group communication application for Symbian OS  

Microsoft Academic Search

In this paper, we analyze the results of the end-user evaluation of a wellness-related mobile application for Symbian OS, the Wellness. With the application, users were able to plan their physical exercise beforehand, keep track of their performed exercise, and share that information to a peer group in real-time or after the exercise. The evaluation was carried out with 15

Timo Koskela; Otso Kassinen; Jussi Ala-kurikka; Mika Ylianttila

2007-01-01

411

Study on the spectral efficiency of SFH-GMSK in land mobile telephone communication by direct simulation  

NASA Technical Reports Server (NTRS)

A spread spectrum system, slow frequency hopping with GMSK (Gaussian minimum shift keying) modulation (SFH-GMSK), is proposed for mobile telephone communications. The system performance is evaluated using computer simulation and is compared with an unspread system. Results show that under multipath fading conditions, when the signal-to-noise ratio (SNR) is greater than 15 dB, slow frequency hopping gives some bit error rate improvement over the unspread system. Theoretical predictions indicate that a system efficiency of 20-65 users per cell can be achieved in the cellular configuration. Joint use of SFH-GMSK and FM is also investigated. It is shown that FM interference can cause serious degradation to the SFH-GMSK performance.

Bao, H.; Kwatra, S. C.; Kim, Junghwan; Stevens, G. H.

1990-01-01

412

Maximum likelihood sequence estimation of quadrature pulse-overlapping modulated signals for portable/mobile satellite communications  

NASA Astrophysics Data System (ADS)

A maximum likelihood sequence estimation (MLSE) receiver for constant-envelope hardlimited quadrature pulse-overlapping modulated (QPOM) signals is presented. Its performance is analyzed for both AWGN and Rayleigh fading channels and then verified by computer simulations. The quadrature pulse-overlapping modulation is first decomposed into a linear encoder followed by a memoryless modulator. A trellis diagram that describes this inherent nonredundant coding structure is then used to construct the MLSE receiver. Results of the performance analysis indicate that the scheme outperforms conventional QPSK techniques in fading channels. It is concluded that the constant-envelope compact spectrum superior performance in fading channels and low complexity make the hardlimited QPOM scheme a good choice for portable and mobile satellite communication systems.

Slimane, S. B.; Le-Ngoc, Tho

1992-10-01

413

[Development of mobile monitor for risk factor control on chronic disease].  

PubMed

In order to improve the control rate of risk factors of chronic disease, it is developed a status control method of risk factor and its mobile monitor. The monitor uses 32 bit RISC microprocessor of S3C2410X as a controller based on ARM920T core, and MC35i cellular engine GSM/GPRS supported by SIEMENS as the communication unit. The proving tests show that the physical activity, diet, smoking and alcohol of the controlled people can be controlled using the status control method, and the monitor plays a key role in the method. The conclusion is that status control method and mobile monitor can become an alternation method and technology for the risk factor control of chronic disease. PMID:24617209

Yao, Danhua; Zhu, Chaoyang; Bao, Jiali

2013-11-01

414

Media Affordances of a Mobile Push-To-Talk Communication Service  

Microsoft Academic Search

This paper presents an exploratory study of college-age students using two- way, push-to-talk cellular radios. We describe the observed and reported use of cellular radio by the participants, the activities and purposes for which they adopted it, and their responses. We then examine these empirical results using mediated communication theory. Cellular radios have a unique combination of affordances relative to

Allison Woodruff; Paul M. Aoki

2003-01-01

415

Improving communication and social support for caregivers of high-risk infants through mobile technologies  

Microsoft Academic Search

Upon leaving the hospital, parents of high-risk infants experience a variety of challenges in providing care at home. In this work, we present results from a qualitative study to understand the role of social interaction and information-sharing surrounding high-risk infants among both home caregivers and health professionals. These results demonstrate challenges in communication and social support for caregivers of these

Leslie S. Liu; Sen H. Hirano; Monica Tentori; Karen G. Cheng; Sheba George; Sun Young Park; Gillian R. Hayes

2011-01-01

416

Block based predistortion for amplifier linearization in burst type mobile satellite communications  

Microsoft Academic Search

Predistortion (PD) technique has been proposed to linearize the power amplifier (PA) and improve the power efficiency for non-constant envelope modulation schemes (Cavers, 1990). In this paper a new PD scheme based on block estimation suitable for burst type communications is described. Piecewise linear regression is applied to estimate the AM\\/AM and AM\\/PM distortions. The predistortion is simply the inverse

Nima Safari; Joar Petter Tanem; Terje Roste

2005-01-01

417

Communication  

Microsoft Academic Search

\\u000a Communication impairment is a core deficit associated with autism spectrum disorder (ASD). Therefore, it should not be surprising\\u000a that this topic has become a major thrust of assessment and treatment in applied behavior analysis (ABA). The types of communication\\u000a skills to target for intervention and the behavioral assessment methods that can be used to identify these target behaviors\\u000a are reviewed

Jeff Sigafoos; Mark F. O’Reilly; Giulio E. Lancioni

418

Linkage to HIV, TB and Non-Communicable Disease Care from a Mobile Testing Unit in Cape Town, South Africa  

PubMed Central

Background HIV counseling and testing may serve as an entry point for non-communicable disease screening. Objectives To determine the yield of newly-diagnosed HIV, tuberculosis (TB) symptoms, diabetes and hypertension, and to assess CD4 count testing, linkage to care as well as correlates of linkage and barriers to care from a mobile testing unit. Methods A mobile unit provided screening for HIV, TB symptoms, diabetes and hypertension in Cape Town, South Africa between March 2010 and September 2011. The yield of newly-diagnosed cases of these conditions was measured and clients were followed-up between January and November 2011 to assess linkage. Linkage to care was defined as accessing care within one, three or six months post-HIV diagnosis (dependent on CD4 count) and one month post-diagnosis for other conditions. Clinical and socio-demographic correlates of linkage to care were evaluated using Poisson regression and barriers to care were determined. Results Of 9,806 clients screened, the yield of new diagnoses was: HIV (5.5%), TB suspects (10.1%), diabetes (0.8%) and hypertension (58.1%). Linkage to care for HIV-infected clients, TB suspects, diabetics and hypertensives was: 51.3%, 56.7%, 74.1% and 50.0%. Only disclosure of HIV-positive status to family members or partners (RR=2.6, 95% CI: 1.04-6.3, p=0.04) was independently associated with linkage to HIV care. The main barrier to care reported by all groups was lack of time to access a clinic. Conclusion Screening for HIV, TB symptoms and hypertension at mobile units in South Africa has a high yield but inadequate linkage. After-hours and weekend clinics may overcome a major barrier to accessing care.

Govindasamy, Darshini; Kranzer, Katharina; van Schaik, Nienke; Noubary, Farzad; Wood, Robin; Walensky, Rochelle P.; Freedberg, Kenneth A.; Bassett, Ingrid V.; Bekker, Linda-Gail

2013-01-01

419

Performance of band-limited 16-ary DEQAM transmission over mobile satellite communication links  

NASA Astrophysics Data System (ADS)

The paper presents the results of a computer simulation study on the performance of 16-ary differentially encoded quadrature-amplitude-modulation (16-ary DEQAM) through nonlinear satellite channels, in the presence of additive white Gaussian noise (AWGN) and adjacent-channel-interference (ACI). It is assumed that the satellite transponder is linear, and each of the earth stations uses a newly developed solid-state power amplifier (SSPA) for high power amplification. The results are compared with those of a 16-ary DEQAM system employing a conventional travelling wave tube amplifier (TWTA). Results indicate that 16-ary DEQAM transmission for mobile satellite systems employing SSPA's is promising.

Cheung, S. W.; Aghvami, A. H.

420

A High Speed, Long-Range Mobile Communications Link for use in Polar Regions  

NASA Astrophysics Data System (ADS)

The Polar Radar for Ice Sheet Measurements (PRISM) project has developed a high bandwidth, wireless communications link between an autonomous rover and a manned vehicle deployed on a polar ice sheet to exchange real-time video, timing signals for a bistatic radar, and rover sensory data. The PRISM project is developing advanced intelligent remote sensing technology that involves radar systems, an autonomous rover, and communications systems to measure detailed ice sheet characteristics, and to determine bed conditions (frozen or wet) below active ice sheets in both Greenland and Antarctica. While this wireless communications link is being developed to fill a need within the PRISM Project, the same technology will allow polar researchers separated by moderate distances ( ˜10 km) to exchange data. The communications link is based on a high data rate 802.11b wireless technology, and a prototype system has been tested and evaluated during field experiments conducted at the NorthGRIP ice core drilling camp in Greenland (75° 06\\'\\ N, 42° 20\\'\\ W) from June 23-July 17, 2003. The IEEE 802.11b standard works in the 2.4-2.483 GHz band and has been widely used for high-speed data transfer in a WLAN (Wireless Local Area Network). It typically has a range of a few hundred meters and theoretical data rates on the order of 11 Mbps. It has been used for a number of applications in home and office environments. We modified a 802.11b system to operate up to a maximum distance of about 8 km and investigated the radio propagation environment over the flat terrain of the Greenland ice sheet. We evaluated its performance along three different tracks of 8 km in length, and made throughput measurements at intervals of 0.5 km. We measured the received signal strength and noise level in 2-s intervals along these 8 km tracks. Also we conducted experiments for four different antenna heights (1, 2, 3 and 5 m) for developing a radio propagation model for WLAN communication over the ice sheet. We found that peer-to-peer communication between nodes on the ice had data rates varying from 4.5 Mbps at close range to 2.5 Mbps at a distance of 8 km from the base station. The design, propagation model, throughput and coverage of this peer-to-peer communications system in Greenland are presented in this paper. This WLAN system has numerous applications in polar field camps. We tested the transfer of real-time video segments across this link for our educational outreach efforts in the field. These video segments were subsequently uploaded using an Iridium-based Internet link, and sent back to the University of Kansas. The wireless Internet connectivity was also made available to members of the North Grip camp, who were able to access e-mail and the Internet from their tents and common areas. However, throughput for wireless access to the Internet was limited by the Iridium-based Internet connection that had a maximum bandwidth of 9.6 Kbps.

Chalishazar, N.; Prescott, G.; Braaten, D.

2003-12-01

421

Effects of mobile phone radiation on reproduction and development in Drosophila melanogaster  

Microsoft Academic Search

In this report we examined the effects of a discontinuous radio frequency (RF) signal produced by a GSM multiband mobile phone (900\\/1,900 MHz; SAR ? 1.4 W\\/kg) on Drosophila melanogaster, during the 10-day developmentalperiodfromegglayingthroughpupation. Asfoundearlierwithlowfrequencyexposures,thenon-thermal radiation from the GSM mobile phone increased numbers of offspring, elevated hsp70 levels, increased serum response element (SRE) DNA-binding and induced the phosphorylation of the

David Weisbrot; Hana Lin; Lin Ye; Martin Blank; Reba Goodman

2003-01-01

422

A second anniversary operational review of the OmniTRACS(R): The first two-way mobile Ku-band satellite communications system  

NASA Technical Reports Server (NTRS)

A novel two-way mobile satellite communications and vehicle position reporting system that is currently operational in the United States and Europe is described. The system characteristics and service operations are described in detail. Technical descriptions of the equipment and signal processing techniques are provided.

Jacobs, Irwin M.; Salmasi, Allen; Gilhousen, Klein S.; Weaver, Lindsay A., Jr.; Bernard, Thomas J.

1990-01-01

423

Electromagnetic hypersensitivity (EHS) and subjective health complaints associated with electromagnetic fields of mobile phone communication—a literature review published between 2000 and 2004  

Microsoft Academic Search

Literature published between 2000 to 2004 concerning electromagnetic fields (EMF) of mobile communication and electromagnetic hypersensitivity (EHS) or unspecific symptoms of ill health, respectively, is reviewed. Basically, literature from established databases was systematically searched for. For each study, the design and quality were evaluated by means of a criteria list in order to judge evidence for causality of exposures on

H. Seitz; D. Stinner; Th. Eikmann; C. Herr; M. Röösli

2005-01-01

424

Electromagnetic hypersensitivity (EHS) and subjective health complaints associated with electromagnetic fields of mobile phone communication—a literature review published between 2000 and 2004  

Microsoft Academic Search

Literature published between 2000 to 2004 concerning electromagnetic fields (EMF) of mobile communication and electromagnetic hypersensitivity (EHS) or unspecific symptoms of ill health, respectively, is reviewed. Basically, literature from established databases was systematically searched for. For each study, the design and quality were evaluated by means of a criteria list in order to judge evidence for causality of exposures on

H. Seitz; D. Stinner; C. Herr; M. Roosli

425

The complexity of social mobilization in health communication: top-down and bottom-up experiences in polio eradication.  

PubMed

The Polio Eradication Initiative (PEI) has been one of the most ambitious global health efforts in recent times. Social mobilization (SM) has been a strategic component of the PEI. Yet, a close-up analysis of SM dynamics seems to be lacking in the health communication literature. We examine critical aspects of the PEI experience in an attempt to move from dominant informational perspectives to a focus on emerging challenges in polio eradication efforts and new levels of complexity to SM. We examine available literature on communication and public health, available data on SM experiences that support polio eradication in Africa and Asia, and field work conducted by the authors where polio eradication efforts are ongoing. Our analysis suggests that (1) SM should not be casually approached as a top-down informational strategy to advance pre-established health goals; (2) centralized strategies hardly amount to SM; and (3) hybrid options that combine both activist and pragmatic SM are concrete possibilities for global health initiatives. In the context of renewed global democratization and persistent conflicts rooted in ethnicity, religion, and economics, it cannot be assumed that communities will either diligently espouse global goals or necessarily oppose them. Communication and SM strategies should rely on a clear understanding of the motives and agendas of involved actors. Resistance or opposition are important analytical dimensions as they may uncover new opportunities for effective health interventions. Further studies using these perspectives should be a priority for global health programs, including studies of the trust level, or lack thereof, among social actors. PMID:20455165

Obregón, Rafael; Waisbord, Silvio

2010-01-01

426

A practical DCA implementation for GSM networks: dynamic frequency and channel assignment  

Microsoft Academic Search

A new dynamic channel assignment (DCA) scheme specifically adapted for the GSM system is introduced and evaluated. This functionality is fully compatible with the existing GSM standards and therefore it can be implemented in existing GSM networks with legacy handsets. The channel assignment decisions are based on the downlink measurement and radio resource usage data that are already available in

Matti Salmenkaita; Jose Gimenez; Pablo Tapia

2001-01-01

427

Weather Information Communication Technologies for Increased Safety and Mobility in the National Airspace System  

NASA Technical Reports Server (NTRS)

The purpose of the NASA Glenn Research Center Weather Information Communications (WINCOMM) project was to develop advanced communications and information technologies to enable the high-quality and timely dissemination of strategic weather information between the flight deck and ground users as well as tactical turbulence hazard information between relevant aircraft and to the ground. This report will document and reference accomplishments on the dissemination of weather information during the en route phase of flight from ground-based weather information providers to the flight deck (ground-to-air), from airborne meteorological sensors to ground users (air-to-ground), and weather turbulence and icing hazard information between relevant aircraft (air-to-air). In addition, references in this report will demonstrate the architecture necessary to implement and perform successful transmission and reception of weather information to the cockpit, show that weather information flow does not impact "normal" traffic, demonstrate the feasibility of operational implementation, and lay foundation for future data link development.

Hilderman, Don R.

2006-01-01

428

A Knowledge Navigation Method for the Domain of Customers' Services of Mobile Communication Corporations in China  

NASA Astrophysics Data System (ADS)

Rapidly increasing amount of mobile phone users and types of services leads to a great accumulation of complaining information. How to use this information to enhance the quality of customers' services is a big issue at present. To handle this kind of problem, the paper presents an approach to construct a domain knowledge map for navigating the explicit and tacit knowledge in two ways: building the Topic Map-based explicit knowledge navigation model, which includes domain TM construction, a semantic topic expansion algorithm and VSM-based similarity calculation; building Social Network Analysis-based tacit knowledge navigation model, which includes a multi-relational expert navigation algorithm and the criterions to evaluate the performance of expert networks. In doing so, both the customer managers and operators in call centers can find the appropriate knowledge and experts quickly and exactly. The experimental results show that the above method is very powerful for knowledge navigation.

Wu, Jiangning; Wang, Xiaohuan

429

Performance and operational considerations in the design of vehicle antennas for mobile satellite communications  

NASA Technical Reports Server (NTRS)

This paper examines the vehicle antenna requirements for mobile satellite systems. The antenna parameters are discussed in the light of the requirements and the limitations in performance imposed by the physical constraints of antenna and by vehicle geometries. Measurements of diffraction and antenna noise temperature in an operational environment are examined, as well as their effects on system margins. Mechanical versus electronic designs are compared with regards to performance, cost, reliability, and design complexity. Comparisons between open-loop and close-loop tracking systems are made and the effects of bandwidth, sidelobe levels, operational constraints, vehicle angular velocity, and acceleration are discussed. Some consideration is given to the use of hybrid systems employing both open and closed-loop tracking. Changes to antenna/terminal specifications are recommended which will provide greater design flexibility and increase the likelihood of meeting the performance and operational requirements.

Milne, R.

1995-01-01

430

Communications.  

ERIC Educational Resources Information Center

Five articles discussing communications in vocational education include "The Golden Rule of Administration" by Ben Mortensen; "Vital Link with Parents" by Richard Sullivan; "An Interpersonal Exercise" by John Villiers; "Face to Face with Employers" by Gregg Bosak; and "Recruitment Strategies" by Susan Miller. (SK)

Mortensen, Ben F.; And Others

1981-01-01

431

Output power distributions of terminals in a 3G mobile communication network.  

PubMed

The objective of this study was to examine the distribution of the output power of mobile phones and other terminals connected to a 3G network in Sweden. It is well known that 3G terminals can operate with very low output power, particularly for voice calls. Measurements of terminal output power were conducted in the Swedish TeliaSonera 3G network in November 2008 by recording network statistics. In the analysis, discrimination was made between rural, suburban, urban, and dedicated indoor networks. In addition, information about terminal output power was possible to collect separately for voice and data traffic. Information from six different Radio Network Controllers (RNCs) was collected during at least 1 week. In total, more than 800000?h of voice calls were collected and in addition to that a substantial amount of data traffic. The average terminal output power for 3G voice calls was below 1?mW for any environment including rural, urban, and dedicated indoor networks. This is <1% of the maximum available output power. For data applications the average output power was about 6-8?dB higher than for voice calls. For rural areas the output power was about 2?dB higher, on average, than in urban areas. Bioelectromagnetics. © 2011 Wiley Periodicals, Inc. PMID:22012866

Persson, Tomas; Törnevik, Christer; Larsson, Lars-Eric; Lovén, Jan

2011-10-19

432

Wireless optical transceiver design, link analisys and alignment control for mobile communication  

NASA Astrophysics Data System (ADS)

Pointing, acquisition and tracking of a free-space optical node in a mobile network experiencing misalignment due to adverse factors including vibration, motion and atmospheric turbulence requires a different approach than traditional free-space optical transceivers. A recent fiber-bundle approach for beam steering at the transmitter was investigated to provide continuous beam coverage at the receiver without the application of mechanical devices. Utilizing multiple fibers-lenses sets at the receiver was also proposed to enhance the tolerance of optical link misalignment. In this work, both laboratory experiments and software simulation were implemented to evaluate the optical link performance for different fiber-bundle-based transceiver setups as the link parameters were varied. The performance was evaluated in terms of the coverage area at the receiver, which is a measure of misalignment tolerance and is dependent not only on wavelength but on other key parameters such as link length, transmitted power, the pattern of transmitters, beam divergence, and the receiver construction. The results showed that fiber-bindle-based transceivers reveal significant potential to maximize the up time of the link, and the results also provide guidance on the further development of the overall system. To incorporate the proposed transceiver designs, an alignment control system was developed and evaluated as well. The laboratory results show that the optical control system successfully recovered and maintained the link while the receiver was in motion and the signal coverage at the target area was enhanced significantly.

Zhou, Dayong

433

Comparative international analysis of radiofrequency exposure surveys of mobile communication radio base stations.  

PubMed

This paper presents analyses of data from surveys of radio base stations in 23 countries across five continents from the year 2000 onward and includes over 173,000 individual data points. The research compared the results of the national surveys, investigated chronological trends and compared exposures by technology. The key findings from this data are that irrespective of country, the year and cellular technology, exposures to radio signals at ground level were only a small fraction of the relevant human exposure standards. Importantly, there has been no significant increase in exposure levels since the widespread introduction of 3G mobile services, which should be reassuring for policy makers and negate the need for post-installation measurements at ground level for compliance purposes. There may be areas close to antennas where compliance levels could be exceeded. Future potential work includes extending the study to additional countries, development of cumulative exposure distributions and investigating the possibility of linking exposure measurements to population statistics to assess the distribution of exposure levels relative to population percentiles. PMID:22377680

Rowley, Jack T; Joyner, Ken H

2012-01-01

434

A study of neurotoxic biomarkers, c-fos and GFAP after acute exposure to GSM radiation at 900 MHz in the picrotoxin model of rat brains.  

PubMed

The acute effects of microwave exposure from the Global System for Mobile Communication (GSM) were studied in rats, using 900MHz radiation at an intensity similar to mobile phone emissions. Acute subconvulsive doses of picrotoxin were then administered to the rats and an experimental model of seizure-proneness was created from the data. Seventy-two adult male Sprague-Dawley rats underwent immunochemical testing of relevant anatomical areas to measure induction of the c-fos neuronal marker after 90min and 24h, and of the glial fibrillary acidic protein (GFAP) 72h after acute exposure to a 900MHz electromagnetic field (EMF). The experimental set-up facilitated measurement of absorbed power, from which the average specific absorption rate was calculated using the finite-difference time-domain (FDTD) 2h after exposure to EMF radiation at 1.45W/kg in picrotoxin-treated rats and 1.38W/kg in untreated rats. Ninety minutes after radiation high levels of c-fos expression were recorded in the neocortex and paleocortex along with low hippocampus activation in picrotoxin treated animals. Most brain areas, except the limbic cortical region, showed important increases in neuronal activation 24h after picrotoxin and radiation. Three days after picrotoxin treatment, radiation effects were still apparent in the neocortex, dentate gyrus and CA3, but a significant decrease in activity was noted in the piriform and entorhinal cortex. During this time, glial reactivity increased with every seizure in irradiated, picrotoxin-treated brain regions. Our results reveal that c-fos and glial markers were triggered by the combined stress of non-thermal irradiation and the toxic effect of picrotoxin on cerebral tissues. PMID:21524663

Carballo-Quintás, M; Martínez-Silva, I; Cadarso-Suárez, C; Alvarez-Figueiras, M; Ares-Pena, F J; López-Martín, E

2011-08-01

435

Do GSM 900MHz signals affect cerebral blood circulation? A near-infrared spectrophotometry study  

NASA Astrophysics Data System (ADS)

Effects of GSM 900MHz signals (EMF) typical for a handheld mobile phone on the cerebral blood circulation were investigated using near-infrared spectrophotometry (NIRS) in a three armed (12W/kg, 1.2W/kg, sham), double blind, randomized crossover trial in 16 healthy volunteers. During exposure we observed borderline significant short term responses of oxyhemoglobin and deoxyhemoglobin concentration, which correspond to a decrease of cerebral blood flow and volume and were smaller than regular physiological changes. Due to the relatively high number of statistical tests, these responses may be spurious and require further studies. There was no detectable dose-response relation or long term response within 20min. The detection limit was a fraction of the regular physiological changes elicited by functional activation. Compared to previous studies using PET, NIRS provides a much higher time resolution, which allowed investigating the short term effects efficiently, noninvasively, without the use of radioactive tracers and with high sensitivity.

Wolf, Martin; Haensse, Daniel; Morren, Geert; Froehlich, Juerg

2006-06-01

436

Simple Switched-Beam Array Antenna System for Mobile Satellite Communications  

NASA Astrophysics Data System (ADS)

This paper presents a simple antenna system for land vehicle communication aimed at Engineering Test Satellite-VIII (ETS-VIII) applications. The developed antenna system which designed for mounting in a vehicle is compact, light weight and offers simple satellite-tracking operation. This system uses a microstrip patch array antenna, which includes onboard-power divider and switching circuit for antenna feeding control, due to its low profile. A Global Positioning System (GPS) receiver is constructed to provide accurate information on the vehicle's position and bearing during traveling. The personal computer (PC) interfaces as the control unit and data acquisition, which were specifically designed for this application, allow the switching circuit control as well as the retrieving of the received power levels. In this research, the antenna system was firstly examined in an anechoic chamber for S parameter, axial ratio, and radiation characteristics. Satisfactory characteristics were obtained. As for beam-tracking of antenna, it was examined in the anechoic chamber with the gain above 5dBic and the axial ratio below 3dB. Moreover, good received power levels for tracking the ETS-VIII satellite in outdoor measurement, were confirmed.

Basari; Purnomo, M. Fauzan E.; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi

437

A matrix-form GSM-CFD solver for incompressible fluids and its application to hemodynamics  

NASA Astrophysics Data System (ADS)

A GSM-CFD solver for incompressible flows is developed based on the gradient smoothing method (GSM). A matrix-form algorithm and corresponding data structure for GSM are devised to efficiently approximate the spatial gradients of field variables using the gradient smoothing operation. The calculated gradient values on various test fields show that the proposed GSM is capable of exactly reproducing linear field and of second order accuracy on all kinds of meshes. It is found that the GSM is much more robust to mesh deformation and therefore more suitable for problems with complicated geometries. Integrated with the artificial compressibility approach, the GSM is extended to solve the incompressible flows. As an example, the flow simulation of carotid bifurcation is carried out to show the effectiveness of the proposed GSM-CFD solver. The blood is modeled as incompressible Newtonian fluid and the vessel is treated as rigid wall in this paper.

Yao, Jianyao; Liu, G. R.

2014-02-01

438

LTE-SAE: Evolution of GSM towards «all IP»  

Microsoft Academic Search

LTE and SAE form the basis of 3GPP Release 8 •LTE and SAE are IP-based, bringing reduced latency, better spectrum efficiency & flexibility, larger & more efficient cell size, and access•Provide inter-working with legacy standards (GSM, UMTS, CDMA, TD-SCDMA)

Jean-Gabriel Remy

2010-01-01

439

Bit error rate based link adaptation for GSM  

Microsoft Academic Search

This paper investigates a link adaptation algorithm based on channel quality heuristics, which are extracted from the GSM transmission chain at the output of the equaliser. The aim is to take change of code decisions as the bit error rate crosses a given threshold. A triggering algorithm which takes the heuristics as input is proposed, and its performance is assessed

J. Pons; J. Dunlop

1998-01-01

440

Mobile Display of Information about Aggregated Antibiotic Resistance in the Hospital Setting Supported by Near Field Communication.  

PubMed

Antibiotic resistance is a heterogeneous phenomenon. It does not only differ between countries or states, but also between wards of hospitals, where different resistance patterns have been found. To support clinicians in administering empiric antibiotic therapy, we developed software to present information about antibiotic resistance using a mobile concept. A pre-existing infrastructure was deployed as the server component. The systems analyze and aggregate data from laboratory information systems, generating statistical data on antibiotic resistance. The information is presented to the Android client using a Representational State Transfer (REST) interface. Geographical localization is performed using near field communication (NFC) tags. The prototype provides tabulated data concerning antibiotic resistance patterns in the wards of a hospital. Using Android, NFC, and data caching, the usability of the system is estimated to be high. We hypothesize that antibiotic stewardship in hospitals can be supported by this software, thus improving medical monitoring of antibiotic resistance. Future studies in a productive environment are needed to measure the impact of the system on the outcome of patient care. PMID:24851968

Meng, Philipp; Fehre, Karsten; Rappelsberger, Andrea; Adlassnig, Klaus-Peter

2014-01-01

441

A power line communication stack for metering, SCADA and large-scale domotic applications  

Microsoft Academic Search

This paper describes the communication stack of the REMPLI system: a structure using power-lines and IP-based networks for communication, for data acquisition and control of energy distribution and consumption. It is furthermore prepared to use alternative communication media like GSM or analog modem connections. The REMPLI system provides communication service for existing applications, namely automated meter reading, energy billing and

Filipe Pacheco; Maksim Lobashov; Miguel Pinho; Gerhard Pratl

2005-01-01

442

A comparison of metropolitan and non-metropolitan employment characteristics: Indications of the size of non-metropolitan mobile communication services user classes  

Microsoft Academic Search

The similarities and differences between areas inside and outside U.S. metropolitan areas were evaluated in terms of their commercial\\/industrial and government employment characteristics. The comparison focuses on the levels, shares, and composition of employment in the commercial\\/industrial and government sectors that represent potential classes of land mobile communications users. The major findings of the analysis are as follows: (1) non-metropolitan

R. E. Wilcox

1985-01-01

443

Performance of multi-level QAM with post-detection maximal ratio combining space diversity for digital land-mobile radio communications  

Microsoft Academic Search

A new type of post-detection maximal ratio combining for space diversity receivers in digital land-mobile communications is proposed. The combining scheme is designed for multilevel quadrature amplitude modulation (QAM) and employs a pilot-symbol-aided fading estimator. It is realized at baseband using a digital signal processing (DSP) technique to simplify the receiver hardware. Computer simulation and laboratory experiments confirm that the

Terumi Sunaga; Seiichi Sampei

1993-01-01

444

Mobile Agent Middleware for Mobile Computing  

Microsoft Academic Search

Mobile computing requires an advanced infrastructure that integrates suitable support protocols, mechanisms, and tools. This mobility middleware should dynamically reallocate and trace mobile users and terminals and permit communication and coordination of mobile entities. In addition, open and untrusted environments must overcome system heterogeneity and grant the appropriate security level. Solutions to these issues require compliance with standards to interoperate

Paolo Bellavista; Antonio Corradi; Cesare Stefanelli

2001-01-01

445

The relation between the specific absorption rate and electromagnetic field intensity for heterogeneous exposure conditions at mobile communications frequencies.  

PubMed

The relation between the incident electromagnetic field strength and both the whole-body and the local specific absorption rate (SAR) was investigated for typical heterogeneous exposure scenarios for frequencies relevant for mobile communication. The results were compared to results from plane wave exposure. Heterogeneous exposure arises from multiple path propagation of the electromagnetic waves to the location of interest. It is shown that plane wave exposure does not represent worst-case exposure conditions. When the electric field strength arising at plane wave exposure is compared to the electric field strength averaged over the volume of the human body occurring during multipath exposure, 12% of all heterogeneous cases examined represent worse exposure conditions than plane wave exposure for whole-body exposure at 946 MHz, 15% at 1840 MHz, and 22% at 2140 MHz. The deviation between plane wave and heterogeneous whole-body SAR ranges from -54% to 54%. For partial-body SAR averaged over 10 g of tissue, a range from -93% to 209% was found when comparing multiple wave exposure to single incoming plane waves. The investigations performed using the Visible Human as phantom showed that the basic restrictions are met as long as the reference levels are not exceeded. However, this must not be necessarily the case when different phantoms are used to perform similar investigations because recent studies demonstrated that reference levels might not be conservative when phantoms of children are used. Therefore, the results of this work indicate the need to extend the investigations to numerical simulations with additional human phantoms representing parts of the human population having different anatomy and morphology compared to the phantom used within the frame of this project. This also applies to phantoms of children. PMID:19551765

Neubauer, Georg; Preiner, Patrick; Cecil, Stefan; Mitrevski, Niki; Gonter, Johannes; Garn, Heinrich

2009-12-01

446

Near Field Communication and Health: Turning a Mobile Phone into an Interactive Multipurpose Assistant in Healthcare Scenarios  

NASA Astrophysics Data System (ADS)

In this paper we discuss the introduction of the Near Field Communication (NFC) technology in the management of the assistance operations in the hospitals. NFC is a new short range communication system based on RFID technology.

Benelli, Giuliano; Pozzebon, Alessandro

447

Design of a multiband internal antenna for third generation mobile phone handsets  

Microsoft Academic Search

A multiband internal antenna is introduced. The antenna consists of a driven meander-line element and two parasitic elements. The design is particularly unique since it supports the third generation mobile phone handsets where multiband operation is greatly desired. The proposed antenna operates effectively in the AMPS 800 (824-894 MHz), GSM 900 (880-960 MHz), and GSM 1900 (1850-1990 MHz) bands within

Mohammod Ali; Gerard James Hayes; Huan-Sheng Hwang; Robert A. Sadler

2003-01-01

448

The use of a 'phantom scalp' to assess the possible direct pickup of mobile phone handset emissions by electroencephalogram electrode leads.  

PubMed

A 'Phantom Scalp' was constructed from a conducting foam mat to form a layer under a 62-electrode electroencephalogram cap closely approximating the electrical properties of a human scalp. The mat was placed over a polystyrene manikin head to preserve a correct anatomical arrangement. Electrical signals were recorded with a Global System for Mobile (GSM) communications mobile phone handset in place against the side of the 'head'. Amplitude spectra were compared for three phone conditions: 'off', 'standby' and 'transmit'. At 217 Hz, significant differences were obtained between 'transmit' and the other two conditions, but no significant differences were noted for the physiologically important range 0.5-30 Hz. An anomalous difference was noted for one electrode in the range 30-45 Hz. PMID:12892371

Wood, A W; Hamblin, D L; Croft, R J

2003-07-01

449

Electromagnetic interference assessment of CDMA and GSM wireless phones to aircraft navigation radios  

Microsoft Academic Search

A radiated emission measurement process for CDMA (IS-95) and GSM (ETSI GSM 11.22) wireless handsets was developed. Spurious radiated emissions were efficiently characterized from devices tested in either a semi-anechoic or reverberation chamber, in terms of effective isotropic radiated power. Eight representative handsets (4 GSM, 4 CDMA) were commanded to operate while varying their radio transmitter parameters (power, modulation, etc.).

Jay J. Ely; Truong X. Nguyen; Sandra V. Koppen; M. Theresa Salud

2002-01-01

450

A Low-Cost GPS GSM/GPRS Telemetry System: Performance in Stationary Field Tests and Preliminary Data on Wild Otters (Lutra lutra)  

PubMed Central

Background Despite the increasing worldwide use of global positioning system (GPS) telemetry in wildlife research, it has never been tested on any freshwater diving animal or in the peculiar conditions of the riparian habitat, despite this latter being one of the most important habitat types for many animal taxa. Moreover, in most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects. Methodology/Principal Findings We have developed a low-cost, easily constructed GPS GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service) and examined its performance in stationary tests, by assessing the influence of different habitat types, including the riparian, as well as water submersion and certain climatic and environmental variables on GPS fix-success rate and accuracy. We then tested the GPS on wild diving animals, applying it, for the first time, to an otter species (Lutra lutra). The rate of locations acquired during the stationary tests reached 63.2%, with an average location error of 8.94 m (SD?=?8.55). GPS performance in riparian habitats was principally affected by water submersion and secondarily by GPS inclination and position within the riverbed. Temporal and spatial correlations of location estimates accounted for some variation in the data sets. GPS-tagged otters also provided accurate locations and an even higher GPS fix-success rate (68.2%). Conclusions/Significance Our results suggest that GPS telemetry is reliably applicable to riparian and even diving freshwater animals. They also highlight the need, in GPS wildlife studies, for performing site-specific pilot studies on GPS functioning as well as for taking into account eventual spatial and temporal correlation of location estimates. The limited price, small dimensions, and high performance of the device presented here make it a useful and cost-effective tool for studies on otters and other aquatic or terrestrial medium-to-large-sized animals.

Quaglietta, Lorenzo; Martins, Bruno Herlander; de Jongh, Addy; Mira, Antonio; Boitani, Luigi

2012-01-01

451

Global Interconnectivity Between Mobile Satellite and Terrestrial Users: Call Signalling Issues and Challenges  

NASA Technical Reports Server (NTRS)

This paper will discuss some of the challenges in connecting mobile satellite users and mobile terrestrial users in a cost efficient manner and with a grade of service comparable to that of satellite to fixed user calls. Issues arising from the translation between the mobility management protocols resident at the satellite Earth station and those resident at cellular switches - either GSM (Group Special Mobile) or IS-41 (used by U.S. digital cellular systems) type - will be discussed. The impact of GSM call routing procedures on the call setup of a satellite to roaming GSM user will be described. Challenges facing provision of seamless call handoff between satellite and cellular systems will be given. A summary of the issues explored in the paper are listed and future work outlined.

Estabrook, Polly; Moon, Todd; Spade, Rob

1996-01-01

452

Efficacy of communication amongst staff members at plastic and reconstructive surgery section using smartphone and mobile WhatsApp  

PubMed Central

Objective: The objective of this study is to assess the efficacy of smartphone and its WhatsApp application as a communication method amongst the staff of plastic and reconstructive surgery section at tertiary care health facility. Materials and Methods: From January 2012 onwards, the authors used smartphones and its WhatsApp application as a communication method amongst their team for various aspects of patient management and as a tool for academic endorsements. Results: During the period of this study, there were 116 episodes regarding patient management, which were handled, in a timely fashion by using this application. In addition opinion of rotating residents in the section was sought regarding the efficacy of this method of communication. Overall majority of residents were satisfied with this mode of communication. Conclusions: This new method of communication is an effective method for clinical and academic endorsements. The method is cheap and quick and easy to operate.

Wani, Shabeer Ahmad; Rabah, Sari M.; AlFadil, Sara; Dewanjee, Nancy; Najmi, Yahya

2013-01-01

453

GSM\\/moment-method CAD of waffle-iron-filters with round teeth  

Microsoft Academic Search

A combined generalized scattering matrix (GSM) moment method is presented for the CAD of waveguide components including structures of more universal shape. For appropriate 3D subsections, the GSM is calculated based on the Kirchhoff-Huygens principle and the free space Green's function. The combination of the GSMs of the subsections with those of the homogeneous waveguide sections in between yields the

Rainer Bunger; Fritz Arndt

1999-01-01

454

GSM-R: A Hybrid Scheduling Approach to Dynamic Load Balancing in Hierarchical Cluster of Servers  

Microsoft Academic Search

Assume a hierarchical cluster of servers is composed of logical groups, and each logical group is further made up of physical servers. Based on certain assumptions and the generalized supermarket model (GSM) scheduling, we present a hybrid scheduling based approach to dynamic load balancing in a hierarchical cluster of servers, GSM-R. From the viewpoint of probability, this model is analyzed

Jincai Chen; Gongye Zhou

2007-01-01

455

Highly integrated RF-IC's for GSM and DECT systems-A status review  

Microsoft Academic Search

TDMA based digital systems like GSM for cellular and DECT for cordless application have created an increasing market within Europe and gained widespread acceptance also outside Europe. This paper gives an overview of both systems, The system requirements and their influences on highly integrated RF IC's for GSM and DECT are discussed in detail. The various trends of progresses in

Josef Fenk

1997-01-01

456

Cranial and postcranial skeletal variations induced in mouse embryos by mobile phone radiation  

Microsoft Academic Search

This study focuses on foetal development following mild daily exposure of pregnant mice to near field electromagnetic radiation emitted by a mobile phone. The investigation was motivated by the fact that the potentially hazardous electromagnetic radiation emitted by mobile phones is currently of tremendous public interest. Physically comparable pregnant mice were exposed to radiofrequency radiation GSM 900 MHz emitted by

Adamantia F. Fragopoulou; Stauros L. Koussoulakos; Lukas H. Margaritis

2009-01-01

457

Modeling Mobility  

NASA Astrophysics Data System (ADS)

In wireless networks, communication can take place based on an infrastructure (e.g. WLAN access point or GPRS base station) or it can take place in adhoc mode, where mobile devices are connected directly to each other and care for the routing by themselves (mobile ad-hoc networks). When such wireless networks are investigated and simulations are performed, it is often necessary to consider the movement of entities within the simulated environment.

Berl, Andras

458

Location management methods for third generation mobile systems  

Microsoft Academic Search

This article provides an overview of the means and techniques used for subscriber location management in present cellular mobile networks. The overhead due to location management techniques used in the present cellular systems such as GSM, in particular in high traffic spots, has already been a source of concern and is expected to augment dramatically in future wireless systems. Several

Sami Tabbane

1997-01-01

459

Experiments in Composing Proxy Audio Services for Mobile Users  

Microsoft Academic Search

Abstract: This paper describes an experimental study in the use of acomposable proxy framework to improve the quality of interactive audiostreams delivered to mobile hosts. Two forward error correction (FEC)proxylets are developed, one using block erasure codes, and the otherusing the GSM 06.10 encoding algorithm. Separately, each type of FECimproves the ability of the audio stream to tolerate errors in

Philip K. Mckinley; Udiyan I. Padmanabhan; Nandagopal Ancha

2001-01-01

460

Land Mobile Satellite Service (LMSS) channel simulator: An end-to-end hardware simulation and study of the LMSS communications links  

NASA Technical Reports Server (NTRS)

The design and implementation of the Land Mobile Satellite Service (LMSS) channel simulator as a facility for an end to end hardware simulation of the LMSS communications links, primarily with the mobile terminal is described. A number of studies are reported which show the applications of the channel simulator as a facility for validation and assessment of the LMSS design requirements and capabilities by performing quantitative measurements and qualitative audio evaluations for various link design parameters and channel impairments under simulated LMSS operating conditions. As a first application, the LMSS channel simulator was used in the evaluation of a system based on the voice processing and modulation (e.g., NBFM with 30 kHz of channel spacing and a 2 kHz rms frequency deviation for average talkers) selected for the Bell System's Advanced Mobile Phone Service (AMPS). The various details of the hardware design, qualitative audio evaluation techniques, signal to channel impairment measurement techniques, the justifications for criteria of different parameter selection in regards to the voice processing and modulation methods, and the results of a number of parametric studies are further described.

Salmasi, A. B. (editor); Springett, J. C.; Sumida, J. T.; Richter, P. H.

1984-01-01

461

Mobile health for non-communicable diseases in Sub-Saharan Africa: a systematic review of the literature and strategic framework for research  

PubMed Central

Background Mobile health (mHealth) approaches for non-communicable disease (NCD) care seem particularly applicable to sub-Saharan Africa given the penetration of mobile phones in the region. The evidence to support its implementation has not been critically reviewed. Methods We systematically searched PubMed, Embase, Web of Science, Cochrane Central Register of Clinical Trials, a number of other databases, and grey literature for studies reported between 1992 and 2012 published in English or with an English abstract available. We extracted data using a standard form in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results Our search yielded 475 citations of which eleven were reviewed in full after applying exclusion criteria. Five of those studies met the inclusion criteria of using a mobile phone for non-communicable disease care in sub-Saharan Africa. Most studies lacked comparator arms, clinical endpoints, or were of short duration. mHealth for NCDs in sub-Saharan Africa appears feasible for follow-up and retention of patients, can support peer support networks, and uses a variety of mHealth modalities. Whether mHealth is associated with any adverse effect has not been systematically studied. Only a small number of mHealth strategies for NCDs have been studied in sub-Saharan Africa. Conclusions There is insufficient evidence to support the effectiveness of mHealth for NCD care in sub-Saharan Africa. We present a framework for cataloging evidence on mHealth strategies that incorporates health system challenges and stages of NCD care. This framework can guide approaches to fill evidence gaps in this area. Systematic review registration: PROSPERO CRD42014007527.

2014-01-01

462

Mobility Anchor Controlled Route Optimization for Network Based Mobility Management  

Microsoft Academic Search

Future Internet Protocol mobile communications systems will implement solutions for network-based mobility management to enable mobility for terminals, which do not support Mobile IP. The Internet Engineering Task Force is specifying a base protocol for network-based mobility, which supports registration, deregistration and handover. Support for optimization will be considered in a subsequent standardization step. This paper proposes a solution to

Julien Abeillé; Marco Liebsch; Telemaco Melia

2007-01-01

463

Smartphones Enabling Mobile Collaboration  

Microsoft Academic Search

Mobilization of the work-force is demanding new mobile and wireless technologies to facilitate contact between the growing number of mobile eWorkers and organizations. Smartphones incorporating mobile e-mail functionality enable instant access to e-mail boxes and company resources without complex synchronization. A study amongst sixteen German companies was conducted to elicit the influence of mobile e-mail on work-processes and communication. The

Bettina Beurer-zuellig; Miriam Meckel

2008-01-01

464

Parallelism in Mobile Agent Network  

Microsoft Academic Search

The paper deals with parallel mobile agents and related performance evaluation framework. A model called mobile agent network is proposed. It includes a multi-agent system consisting of co-operating and communicating mobile agents, a set of processing nodes in which the agents perform services and a network that connects processing nodes and allows agent mobility. Parallelism in mobile agent network is

Vjekoslav Sinkovic; Ignac Lovrek; Mario Kusek

465

Short communication The impact of an air quality advisory program on voluntary mobile source air pollution reduction  

Microsoft Academic Search

Air pollution from mobile source emissions is a major cause of air quality degradation in the Denver, Colorado, metropolitan area. The projected increase in both population and vehicle miles driven, coupled with the high altitude, predominantly clear skies, and prevalent wintertime temperature inversions aid in the formation and retention of pollutants. The Colorado Department of Public Health issues an air

Peter D. Blanken; Jennifer Dillon; Genevieve Wismann

466

In-vitro exposure of neuronal networks to the GSM-1800 signal.  

PubMed

The central nervous system is the most likely target of mobile telephony radiofrequency (RF) field exposure in terms of biological effects. Several electroencephalography (EEG) studies have reported variations in the alpha-band power spectrum during and/or after RF exposure, in resting EEG and during sleep. In this context, the observation of the spontaneous electrical activity of neuronal networks under RF exposure can be an efficient tool to detect the occurrence of low-level RF effects on the nervous system. Our research group has developed a dedicated experimental setup in the GHz range for the simultaneous exposure of neuronal networks and monitoring of electrical activity. A transverse electromagnetic (TEM) cell was used to expose the neuronal networks to GSM-1800 signals at a SAR level of 3.2 W/kg. Recording of the neuronal electrical activity and detection of the extracellular spikes and bursts under exposure were performed using microelectrode arrays (MEAs). This work provides the proof of feasibility and preliminary results of the integrated investigation regarding exposure setup, culture of the neuronal network, recording of the electrical activity, and analysis of the signals obtained under RF exposure. In this pilot study on 16 cultures, there was a 30% reversible decrease in firing rate (FR) and bursting rate (BR) during a 3 min exposure to RF. Additional experiments are needed to further characterize this effect. PMID:23913345

Moretti, Daniela; Garenne, André; Haro, Emmanuelle; Poulletier de Gannes, Florence; Lagroye, Isabelle; Lévêque, Philippe; Veyret, Bernard; Lewis, Noëlle

2013-12-01

467

Route optimization solution for nested mobile network in local mobility domain with multiple local mobility anchors  

Microsoft Academic Search

NEMO basic support protocol enables mobile networks preserve communication with other nodes, while changing their point of attachment to the Internet. But in nested mobile network, Pinball routing problem appears. In this paper, a route optimization solution for mobile networks based on local mobility management framework was proposed to improve the performance. By defining the operation on local mobility anchor,

Lu Li-hua; Ma Xiao-lei; Liu Yuan-an