Results 1 - 10
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26
Spatio-Temporal Coding for Wireless Communication.
- IEEE Transactions on Communications,
, 1998
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Characterization of ultra-wide bandwidth wireless indoor channels: a communication-theoretic view
- IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
, 2002
"... An ultra-wide bandwidth (UWB) signal propagation experiment is performed in a typical modern laboratory/office building. The bandwidth of the signal used in this experiment is in excess of 1 GHz, which results in a differential path delay resolution of less than a nanosecond, without special proces ..."
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Cited by 125 (12 self)
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An ultra-wide bandwidth (UWB) signal propagation experiment is performed in a typical modern laboratory/office building. The bandwidth of the signal used in this experiment is in excess of 1 GHz, which results in a differential path delay resolution of less than a nanosecond, without special processing. Based on the experimental results, a characterization of the propagation channel from a communications theoretic view point is described, and its implications for the design of a UWB radio receiver are presented. Robustness of the UWB signal to multipath fading is quantified through histograms and cumulative distributions. The all Rake (ARake) receiver and maximum-energy-capture selective Rake (SRake) receiver are introduced. The ARake receiver serves as the best case (bench mark) for Rake receiver design and lower bounds the performance degradation caused by multipath. Multipath components of measured waveforms are detected using a maximum-likelihood detector. Energy capture as a function of the number of single-path signal correlators used in UWB SRake receiver provides a complexity versus performance tradeoff. Bit-error-probability performance of a UWB SRake receiver, based on measured channels, is given as a function of signal-to-noise ratio and the number of correlators implemented in the receiver.
Coded orthogonal frequency division multiplex
- Proc. IEEE
, 1995
"... Technological evolution and the ever-increasing demand for higher-quality services give broadcasters a strong incentive to completely digitize their broadcasting networks. This digitization, which is already well advanced in many program production areas and transmission links, now has to be extende ..."
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Cited by 124 (0 self)
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Technological evolution and the ever-increasing demand for higher-quality services give broadcasters a strong incentive to completely digitize their broadcasting networks. This digitization, which is already well advanced in many program production areas and transmission links, now has to be extended to complete the last link in the broadcast chain; i.e., from broadcast transmitter to consumer receivers. It is therefore necessary to develop wholly new techniques for the broadcasting of digitally coded TV programmes. Thus an efficient baseband digital coding must be combined with a robust digital modulation and channel coding scheme that can meet the requirements of every mode of broadcast reception. This article presents the research work related to the coded orthogonal frequency division multiplex (COFDM) technology, which has now been completed in the field of digital radio (DAB) [I], and which is under progress in the field of digital terrestrial TV. I.
A TRACE-BASED APPROACH FOR MODELING WIRELESS CHANNEL BEHAVIOR
, 1996
"... The loss behavior of wireless networks has become the focus of many recent research efforts. Although it is generally agreed that wireless communications experience higher error rates than wireline, the nature of these lossy links is not fully understood. This paper describes an effort to characteri ..."
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Cited by 119 (3 self)
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The loss behavior of wireless networks has become the focus of many recent research efforts. Although it is generally agreed that wireless communications experience higher error rates than wireline, the nature of these lossy links is not fully understood. This paper describes an effort to characterize the loss behavior of the AT&T WaveLAN, a popular in-building wireless interface. Using a trace-based approach, packet loss information is recorded, analyzed, and validated. Our results indicate that WaveLAN experiences an average packet error rate of 2 to 3 percent. Further analysis reveals that these errors are not independent, making it hard to model them with a simple two-state Markov chain. We derive another model based on the distributions of the error and error-free length of the packet streams. For validation, we modulate both the error models and the traces in a simulator. Simulations based on traces yield an average TCP throughput of about 5 percent less than simulations based our best error model.
Performance of Rake reception in dense multipath channels: Implications of spreading bandwidth and selection diversity order
- IEEE J. Sel. Areas Commun
, 2000
"... Abstract—In this paper, we develop an analytical framework to quantify the effects of the spreading bandwidth (BW) on spread spectrum systems operating in dense multipath environments in terms of the receiver performance, the receiver complexity, and the multipath channel parameters. The focus of th ..."
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Cited by 37 (14 self)
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Abstract—In this paper, we develop an analytical framework to quantify the effects of the spreading bandwidth (BW) on spread spectrum systems operating in dense multipath environments in terms of the receiver performance, the receiver complexity, and the multipath channel parameters. The focus of the paper is to characterize the symbol error probability (SEP) performance of a Rake receiver tracking the strongest multipath components in wide-sense stationary uncorrelated scattering (WSSUS) Gaussian channels with frequency-selective fading. Analytical SEP expres-sions of the Rake receiver are derived in terms of the number of combined paths, the spreading BW, and the multipath spread of the channel. The proposed problem is made analytically tractable by transforming the physical Rake paths, which are correlated and ordered, into the domain of a “virtual Rake ” receiver with indepen-dent virtual paths. This results in a simple derivation of the SEP for a given spreading BW and an arbitrary number of combined paths. Index Terms—Dispersive channels, diversity methods, fading channels, maximal ratio combining, Rake receiver, selection diversity, spreading bandwidth, spread spectrum techniques, virtual path technique. I.
Multipath aided rapid acquisition: Optimal search strategies
- IEEE Transactions on Information Theory
, 2007
"... Abstract—In this paper, we propose a search technique that takes advantage of multipath, which has long been considered deleterious for efficient communication, to aid the sequence acquisition in dense multipath channels. We consider a class of serial-search strategies and use optimization and conve ..."
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Cited by 28 (9 self)
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Abstract—In this paper, we propose a search technique that takes advantage of multipath, which has long been considered deleterious for efficient communication, to aid the sequence acquisition in dense multipath channels. We consider a class of serial-search strategies and use optimization and convexity theories to determine fundamental limits of achievable mean acquisition times (MATs). In particular, we derive closed-form expressions for both the minimum and maximum MATs and the conditions for achieving these limits. We prove that a fixed-step serial search, a form of nonconsecutive serial search, achieves a near-optimal MAT. We also prove that the conventional serial search, in which consecutive cells are tested serially, should be avoided as it results in the maximum MAT. Our results are valid for all signal-to-noise ratio (SNR) values, regardless of the specifics of the detection layer and the fading distributions. Index Terms—Acquisition, dense multipath channels, nonconsecutive serial search, spread spectrum. I.
Vehicle to vehicle RF propagation measurements,"
- Asilomar Conference on Signals, Systems, and Computers,
, 1994
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Design and implementation of a sampling swept time delay short pulse (sstdsp) wireless channel sounder for lmds
- In Short Pulse (SSTDSP) Wireless Channel Sounder for LMDS, Masters Thesis, Virginia Tech. Citeseer
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Propagation and radio system design issues in mobile radio systems for the GloMo project
, 1997
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Dynamic characteristics of a narrowband land mobile communication channel
- IEEE Trans. Vehic. Technol
, 1998
"... Abstract — Land mobile communication signals are subject to propagation effects that result in variation of received sig-nal amplitude and phase. The most rapid signal variations are the result of multipath propagation and occur with sufficient severity to make reception difficult. At microwave freq ..."
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Cited by 2 (0 self)
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Abstract — Land mobile communication signals are subject to propagation effects that result in variation of received sig-nal amplitude and phase. The most rapid signal variations are the result of multipath propagation and occur with sufficient severity to make reception difficult. At microwave frequencies, the narrowband (30-kHz) channel is considered nondispersive. It will experience flat amplitude fading and band-limited fre-quency distortion. An understanding of the dynamic nature of the communication channel is required to design land mobile systems that are tolerant of rapid multipath conditions. In this paper, a model is presented to characterize the dynamic nature of multipath channels, and a new dynamic measure, fractional power change rate, is introduced. Distribution of the fractional power change rate, power change rate, and phase change rate are predicted by the model and validated by comparison to measured data. The research in this paper is part of an ongoing effort to develop multipath-tolerant demodulation techniques for higher order modulation types. The measures developed herein are of primary importance for specifying the dynamic requirements for such demodulators. Index Terms—Channel model, multipath, multipath propaga-tion, narrowband channels, narrowband communication channel. I.
