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Data Rate (data + rate)
Selected AbstractsExperiments on space diversity effect in MIMO channel transmission with maximum data rate of 1,Gbps in downlink OFDM radio accessEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2006Hidekazu Taoka This paper presents experimental results on the space diversity effect in MIMO multiplexing/diversity with the target data rate up to 1,Gbps using OFDM radio access based on laboratory and field experiments including realistic impairments using the implemented MIMO transceivers with the maximum of four transmitter/receiver branches. The experimental results using multipath fading simulators show that at the frequency efficiency of less than approximately 2,bits/second/Hz, MIMO diversity using the space-time block code (STBC) increases the measured throughput compared to MIMO multiplexing owing to the high transmission space diversity effect. At a higher frequency efficiency than approximately 2--3,bits/second/Hz, however, MIMO multiplexing exhibits performance superior to that of MIMO diversity since the impairments using higher data modulation and a higher channel coding rate in MIMO diversity overcomes the space diversity effect. The results also show that the receiver space diversity effect is very effective in MIMO multiplexing for maximum likelihood detection employing QR-decomposition and the M-algorithm (QRM-MLD) signal detection. Finally, we show that the real-time throughput of 500,Mbps and 1,Gbps in a 100-MHz transmission bandwidth is achieved at the average received Eb/N0 per receiver antenna of approximately 8.0 and 14.0,dB using 16QAM modulation and Turbo coding with the coding rate of 1/2 and 8/9 respectively in 4-by-4 MIMO multiplexing in a real propagation environment. Copyright © 2006 AEIT. [source] Performance analysis of the IEEE 802.11 MAC protocol for wireless LANsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2005P. Chatzimisios Abstract Wireless local area networks (WLANs) are extremely popular being almost everywhere including business, office and home deployments. The IEEE 802.11 protocol is the dominating standard for WLANs. The essential medium access control (MAC) mechanism of 802.11 is called distributed co-ordination function (DCF). This paper provides a simple and accurate analysis using Markov chain modelling to compute IEEE 802.11 DCF performance, in the absence of hidden stations and transmission errors. This mathematical analysis calculates in addition to the throughput efficiency, the average packet delay, the packet drop probability and the average time to drop a packet for both basic access and RTS/CTS medium access schemes. The derived analysis, which takes into account packet retry limits, is validated by comparison with OPNET simulation results. We demonstrate that a Markov chain model presented in the literature, which also calculates throughput and packet delay by introducing an additional transition state to the Markov chain model, does not appear to model IEEE 802.11 correctly, leading to ambiguous conclusions for its performance. We also carry out an extensive and detailed study on the influence on performance of the initial contention window size (CW), maximum CW size and data rate. Performance results are presented to identify the dependence on the backoff procedure parameters and to give insights on the issues affecting IEEE 802.11 DCF performance. Copyright © 2005 John Wiley & Sons, Ltd. [source] Minimal data rate stabilization of nonlinear systems over networks with large delaysINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10 2010C. De Persis Abstract Control systems over networks with a finite data rate can be conveniently modeled as hybrid (impulsive) systems. For the class of nonlinear systems in feedfoward form, we design a hybrid controller, which guarantees stability, in spite of the measurement noise due to the quantization, and of an arbitrarily large delay, which affects the communication channel. The rate at which feedback packets are transmitted from the sensors to the actuators is shown to be arbitrarily close to the infimal one. Copyright © 2009 John Wiley & Sons, Ltd. [source] Robust and efficient quantization and coding for control of multidimensional linear systems under data rate constraintsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 10-11 2007K. Li Abstract Recently, we reported results on coding strategies for scalar feedback systems with data-rate-limited feedback channels in which the data-rate constraints are time varying. Such rate-varying channels are typically encountered in communication networks in which links between nodes are subject to noise, congestion, and intermittent disruption. The present paper describes results of extending this research into the multidimensional domain. An important consideration is that for systems of dimension greater than one, many classical feedback designs cannot be realized for operation near the theoretical minimum possible data rate. A novel control coding scheme will be presented, and in terms of this, it will be shown that the advantages of coarse signal quantization that had been reported earlier for scalar systems remain in the multidimensional case. The key is to allocate the communication bandwidth efficiently among faster and slower modes. We discuss various strategies that allocate bandwidth by scheduling the time slots assigned to each mode. In particular, we propose a ,robust attention varying' technique, whose merit will be discussed in terms of its robustness with respect to time-varying communication channel capacity and also in terms of how well it operates when the feedback channel capacity is near the theoretical minimum data rate. Copyright © 2006 John Wiley & Sons, Ltd. [source] On stabilization of nonlinear systems under data rate constraints using output measurementsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2006C. De Persis Abstract We present a contribution to the problem of semi-global asymptotic stabilization of nonlinear continuous-time systems under data rate constraints when only output measurements are available. We consider systems which are uniformly observable and we point out that the design of an ,embedded-observer' decoder and a controller which semi-globally stabilize this class of systems under data-rate constraints requires an appropriate choice of the observer gain and the data rate. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ka-band link optimization with rate adaptation for Mars and lunar communicationsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2007Jun Sun Abstract On-going development of Ka-band capability for the Deep Space Networks (DSN) will radically increase the bandwidth available to support advanced mission concepts envisioned for future robotic as well as human exploration of Mars and beyond. While Ka-band links can operate at much higher data rate than X-band, they are much more susceptible to fluctuating weather conditions and manifest a significant trade-off between throughput and availability. If the operating point is fixed, the maximum average throughput for deep space Ka-band link is achieved at about 80% availability, i.e. weather-related outages will occur about 20% of the time. Low availability increases the complexity of space mission operation, while higher availability would require additional link margins that lowers the overall throughput. To improve this fundamental throughput-availability trade-off, data rate adaptation based on real-time observation of the channel condition is necessary. In this paper, we model the Ka-band channel using a Markov process to capture the impact of the temporal correlation in weather conditions. We then develop a rate adaptation algorithm to optimize the data rate based on real time feedback on the measured channel conditions. Our algorithm achieves both higher throughput and link availability as compared to the constant rate scheme presently in use. Copyright © 2007 John Wiley & Sons, Ltd. [source] Multimedia satellite communications experiments to the international space stationINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2002Carlo Matarasso Abstract In the present concept of the International Space Station ISS, it is planned to provide the communication services between the European Columbus module of the ISS and the ground equipment via the TDRS (tracking and data relay satellite) network provided by the American NASA (National Aeronautics and Space Agency). Especially because of its low uplink data rate, an unacceptable limitation of the communication services with Columbus is to be expected. In order to investigate possible improvements to this situation, the MEDIS proposal studies the feasibility of a 150 Mbps full duplex communication system to the Columbus Module on via two MEO satellites. A mixed topology with optical inter satellite links and Ka-band up/down-links shall be employed. Also possible liaisons with the Artemis mission will be considered. The MEDIS project is a collaboration of Astrium GmbH, which is project manager, Bosch SatCom, GMD-Fokus and the German Aerospace Center (DLR). The preparation phase of the project will investigate the concept of the communications infrastructure and the experiments that could be realized when the MEOs are launched. This stage has been completed in February 2001. An additional study phase followed, which will be completed with a presentation in July 2002. Briefly the following aspects have been studied by DLR in the preparation phase: the overall concept of experimental communication services for Columbus, the system requirements and network topology, the relevant protocol and hardware architectures, useful satellite constellations and link scenarios. Two phases could follow the preparation phase, in phase one the satellite will be launched and the link will be tested. In phase two the satellites will be connected to the ISS. Copyright © 2002 John Wiley & Sons, Ltd. [source] X-ray beam-position monitoring in the sub-micrometre and sub-second regimeJOURNAL OF SYNCHROTRON RADIATION, Issue 6 2005Oliver Bunk It is demonstrated that X-ray beam positions can be extracted from two-dimensional profiles with sub-pixel resolution. Beam-position measurements utilizing a self-designed low-cost two-dimensional detector have been performed at two synchrotron radiation beamlines of the Swiss Light Source. The effective detector pixel size was 4.8,µm and the resolution achieved for the beam position was about 5,nm. At a data rate of 25 frames per second, periodic variations of the beam position could be detected with a frequency resolution below 0.1,Hz. This allowed, for example, the influence of a turbo-pump in the X-ray optics hutch on the beam position to be quantified, and even minute variations related to the electron beam in the storage ring could be detected. [source] 60 GHz SoC/SoP radio system for high data-rate transmissionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2010K. C. Eun Abstract We present the 60 GHz CMOS and system-on-package (SoP) research activities in Korea Advanced Institute of Science and Technology for high data-rate and short-range wireless communication. A low-power single-chip resonant frequency CMOS receiver for 60 GHz mobile terminals consists of four-stage current reuse LNA, resistive mixer, Ka-band low-phase noise VCO, high-suppression frequency doubler, and two-stage current reuse drive amplifiers. The receiver conversion gain and input P1dB are ,9.5 dB and ,12.5 dBm, respectively, with a size of 2.67 × 0.75 mm2 and power consumption of 21.9 mW. The integration and communication tests of a transmitter/receiver (Tx/Rx) radio have been demonstrated at a data rate of 3 Gbps for short-range transmission and with a communication distance of over 3.5 m at 650 Mbps data rate. The design and fabrication of mmW subcircuits, such as low-loss transmission lines and transitions with noble air cavity structures, a high-Q resonator using zigzagged dual-row via posts and a ,/4 short stub, and the monolithic integration of band-pass filter and antennas, have been performed for low-temperature cofired ceramic SoP integration with a size of 37 × 11 mm2 for the whole Tx or Rx radio. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 667,673, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25024 [source] A 2.4/5.7-GHz dual-band low-power CMOS RF receiver with embedded band-select switchesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009D.-R. Huang Abstract This article presents a 2.4-/5.7-GHz dual-band low-power direct-conversion CMOS RF receiver for the 802.11a/b/g WLAN applications. The RF receiver includes a low noise amplifier (LNA) with dual input stages and dual switches for each of 2.4/5.7-GHz applications. This design can substitute the use of two LNAs in conventional structure and eliminate the use of the costly external band-select switches. It also alleviates the difficulty of single matching for multiple frequency bands. The RF receiver also includes a Gilbert-cell-based broadband mixer which is designed to be both low power consumption and relatively high conversion gain. Fabricated in 0.18-,m CMOS technology, the RF receiver exhibits a conversion gain of 25.8/20.6 dB, DSB noise figure of 4.4/5.6 dB, and input IP3 of ,18/,12.5 dBm at 2.4/5.7 GHz frequency band, respectively. The measured EVM for IEEE 802.11a/b/g is 1.2/1.6/1.1% at data rate of 11/54/54 Mbps. The power consumption under 1.8 V supply is 10.6 mW for the 2.4 GHz mode, and 17.2 mW for the 5.7 mode. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 593,597, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24120 [source] Design and signal-integrity analysis of a backplane for high-speed digital systemsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2005Hua Zhang Abstract The design of a backplane in high-speed digital systems is presented, with an emphasis on systematic analysis of the signal integrity using full-wave electromagnetic methods when the system carries high-speed digital signals. The simulation and measurement results in both the frequency and time domains are presented for a high-speed digital-circuit demo system at the data rate of 500 M/bs, and are in good agreement. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 194,199, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20768 [source] 60 GHz fiber-radio communication system for indoor ATM networkMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2001S. Dupont Abstract This paper presents a 60 GHz radio over fiber communication system for high-data-rate ATM indoor transmission. The radio interface is fully MMIC integrated (OMMIC ED 0.2 AH foundry). The system has been successfully tested in an indoor environment for a data rate up to 100 Mbits/s. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 307,310, 2001. [source] Signal-to-interference-plus-noise ratio estimation for wireless communication systems: Methods and analysisNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 5 2004Daniel R. Jeske Abstract The Signal-to-Interference-plus-Noise Ratio (SINR) is an important metric of wireless communication link quality. SINR estimates have several important applications. These include optimizing the transmit power level for a target quality of service, assisting with handoff decisions and dynamically adapting the data rate for wireless Internet applications. Accurate SINR estimation provides for both a more efficient system and a higher user-perceived quality of service. In this paper, we develop new SINR estimators and compare their mean squared error (MSE) performance. We show that our new estimators dominate estimators that have previously appeared in the literature with respect to MSE. The sequence of transmitted bits in wireless communication systems consists of both pilot bits (which are known both to the transmitter and receiver) and user bits (which are known only by the transmitter). The SINR estimators we consider alternatively depend exclusively on pilot bits, exclusively on user bits, or simultaneously use both pilot and user bits. In addition, we consider estimators that utilize smoothing and feedback mechanisms. Smoothed estimators are motivated by the fact that the interference component of the SINR changes relatively slowly with time, typically with the addition or departure of a user to the system. Feedback estimators are motivated by the fact that receivers typically decode bits correctly with a very high probability, and therefore user bits can be thought of as quasipilot bits. For each estimator discussed, we derive an exact or approximate formula for its MSE. Satterthwaite approximations, noncentral F distributions (singly and doubly) and distribution theory of quadratic forms are the key statistical tools used in developing the MSE formulas. In the case of approximate MSE formulas, we validate their accuracy using simulation techniques. The approximate MSE formulas, of interest in their own right for comparing the quality of the estimators, are also used for optimally combining estimators. In particular, we derive optimal weights for linearly combining an estimator based on pilot bits with an estimator based on user bits. The optimal weights depend on the MSE of the two estimators being combined, and thus the accurate approximate MSE formulas can conveniently be used. The optimal weights also depend on the unknown SINR, and therefore need to be estimated in order to construct a useable combined estimator. The impact on the MSE of the combined estimator due to estimating the weights is examined. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 [source] Optical CDMA codes for use in a lightwave communication network with multiple data rates,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2002Jian-Guo Zhang This paper presents a new kind of optical code-division multiple-access (CDMA) codes, called unequal-length optical orthogonal codes (UL-OOC's), for multirate data communications. The autocorrelation and cross-correlation functions of UL-OOC's are dependent only on each individual codeword, in spite of either an aperiodic or a periodic pulse-sequence pattern at the input of optical CDMA decoders. This property can be thus used to support multirate data communications in a lightwave network, without any violation of the minimum correlation constraint (i.e., "1") for incoherent optical processing. Theory and simple design of UL-OOC's are presented. Applications of the proposed codes to multirate optical CDMA is also explained in detail. [source] Space-time ring-TCM codes with CPM based on the decomposed model for transmission over Rayleigh fading channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2006A. Pereira Abstract Space,time (ST) coding is a proved technique for achieving high data rates in 3G mobile systems that combines coding, modulation and multiple transmitters and receivers. A novel algorithm is proposed for ST ring trellis-coded modulation (ST-RTCM) systems with continuous-phase modulation (CPM) when the channel coefficients are known to the receiver. This algorithm is based on the CPM decomposed model, which exploits the memory properties of this modulation method, resulting in a straightforward implementation of joint ST coding and CPM, which is particularly suitable for ring codes. This new scheme is used to investigate the performance of the delay diversity code with CPM over slow Rayleigh fading channels, in particular with MSK which is one of the most widely used modulation methods of continuous phase. Furthermore, a feedback version of delay diversity allowed by the decomposition is tested in 1REC and 1RC systems. This feedback configuration is seen to provide good results for low signal-to-noise ratios. Simulations results are also provided for multilevel ST-RTCM codes that achieve a higher throughput than MSK-coded systems. Additionally the serial concatenation of an outer Reed,Solomon code with an ST-RTCM code is shown, this combination further reduces the error probability and achieves even more reliable communications. Copyright © 2005 John Wiley & Sons, Ltd. [source] On optimal cell planning: Case study for a DCS 1800 systemINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 9 2001Stavroula Bouzouki Abstract Micro and pico cell planning strategies are adopted in personal communication systems (PCS) in order to increase their capacity. The usage of the upper UHF band in combination with greater bandwidth is already proposed by telecom engineers in order to achieve the promised service quality and data rates. These strategies are characterized by an increased number of cells in specific geographical areas with the corresponding operating base transceiving stations (BTS) located at relatively low heights above the street level. In this case, the cell planning procedure in linear streets under line-of-sight (LOS) conditions needs further study concerning the technical characteristics of the PCS. In this paper, the propagation characteristics of a DCS 1800 system are investigated on a theoretical and experimental basis in a specific geographical area (center of Patras City in Northern Pelloponesse). An improved RF propagation model is proposed in order to determine the propagation path losses occurring under certain multipath fading conditions. Hence an optimum determination of a system's cellular area can be achieved. Copyright © 2001 John Wiley & Sons, Ltd. [source] Evolution of UMTS toward high-speed downlink packet accessBELL LABS TECHNICAL JOURNAL, Issue 3 2002Arnab Das An expanded effort is under way to support the evolution of the Universal Mobile Telecommunications System (UMTS) standard to meet the rapidly developing needs associated with wireless data applications. A new, shared channel,the high-speed downlink shared channel (HS-DSCH),provides support to packet-switched high-speed data users. A number of performance-enhancing technologies are included in the high-speed downlink packet access (HSDPA) system to ensure high peak and average packet data rates while supporting circuit-switched voice and packet data on the same carrier. Lucent Technologies took a pivotal role in specifying many of these techniques, including adaptive modulation and coding (AMC), hybrid automatic repeat request (HARQ), and fat-pipe scheduling. In this paper, we provide system-level simulations results to indicate the achievable performance and capacity with these advanced technologies. We also discuss HSDPA protocol architecture along with the uplink and downlink control channel design and performance. We conclude with a discussion of potential enhancements for the future. © 2003 Lucent Technologies Inc. [source] | |||||||||||||