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260
Fading Channels: Information-Theoretic And Communications Aspects
- IEEE TRANSACTIONS ON INFORMATION THEORY
, 1998
"... In this paper we review the most peculiar and interesting information-theoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information ..."
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Cited by 426 (3 self)
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In this paper we review the most peculiar and interesting information-theoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information theory of fading channels, by emphasizing capacity as the most important performance measure. Both single-user and multiuser transmission are examined. Further, we describe how the structure of fading channels impacts code design, and finally overview equalization of fading multipath channels.
Joint multipath-Doppler diversity in mobile wireless communications
- IEEE Trans. Commun
, 1999
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Modeling of Indoor Positioning Systems Based on Location Fingerprinting
, 2004
"... In recent years, positioning systems for indoor areas using the existing wireless local area network infrastructure have been suggested. Such systems make use of location fingerprinting rather than time or direction of arrival techniques for determining the location of mobile stations. While experim ..."
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Cited by 105 (2 self)
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In recent years, positioning systems for indoor areas using the existing wireless local area network infrastructure have been suggested. Such systems make use of location fingerprinting rather than time or direction of arrival techniques for determining the location of mobile stations. While experimental results related to such positioning systems have been presented, there is a lack of analytical models that can be used as a framework for designing and deploying the positioning systems. In this paper, we present an analytical model for analyzing such positioning systems. We develop the framework for analyzing a simple positioning system that employs the Euclidean distance between a sample signal vector and the location fingerprints of an area stored in a database. We analyze the effect of the number of access points that are visible and radio propagation parameters on the performance of the positioning system and provide some preliminary guidelines on its design.
Scalable Video Coding and Transport over Broadband Wireless Networks
- Proc. of the IEEE
, 2001
"... Abstract Video application is becoming an important application under the next-generation wireless networks. However, supporting video communication over wireless networks poses many c hallenges due to uctuations of wireless channel conditions. Scalable video coding and adaptive services have been ..."
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Cited by 73 (4 self)
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Abstract Video application is becoming an important application under the next-generation wireless networks. However, supporting video communication over wireless networks poses many c hallenges due to uctuations of wireless channel conditions. Scalable video coding and adaptive services have been shown to be capable of coping e ectively under time-varying wireless environment. We present an adaptive framework to support quality video communication over wireless networks. The adaptive framework include: (1) scalable video representations, (2) network-aware video application, and (3) adaptive service. Under this framework, as wireless channel conditions change, the mobile terminal and network elements can scale the video streams and transport the scaled video streams to receivers with acceptable perceptual quality. The key advantages the adaptive framework are: (1) perceptual quality is degraded gracefully under severe channel conditions (2) network resources are e ciently utilized and (3) the resources are shared in a fair manner.
A score-based opportunistic scheduler for fading radio channels
- in Proc. European Wireless
, 2003
"... Abstract: While fading effects have long been combatted in 2G wireless networks, primarly devoted to voice calls, they are now seen as an opportunity to increase the capacity of 3G networks that incorporate data traffic. The packet delay tolerance of data applications, such as file transfers and Web ..."
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Cited by 58 (1 self)
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Abstract: While fading effects have long been combatted in 2G wireless networks, primarly devoted to voice calls, they are now seen as an opportunity to increase the capacity of 3G networks that incorporate data traffic. The packet delay tolerance of data applications, such as file transfers and Web browsing for instance, allows the system flexibility in scheduling a user’s packets. Opportunistic scheduling ensures transmission occurs when radio conditions are most favorable. This paper discusses different resource sharing strategies and presents some shortcomings of the classical Proportional Fair opportunistic scheduler. A new algorithm, called the Score-Based scheduler, is presented and shown to overcome these drawbacks.
Properties of indoor received signal strength for WLAN location fingerprinting
- Mobile and Ubiquitous Systems - Networking and Services. MOBIQUITOUS. The First Annual International Conference
, 2004
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Error-Resilient Video Transmission Using Long-Term Memory Motion-Compensated Prediction
, 2000
"... Long-term memory prediction extends the spatial displacement vector utilized in hybrid video coding by a variable time delay permitting the use of more than one reference frame for motion compensation. This extension leads to improved rate-distortion performance. However, motion compensation in comb ..."
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Cited by 56 (17 self)
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Long-term memory prediction extends the spatial displacement vector utilized in hybrid video coding by a variable time delay permitting the use of more than one reference frame for motion compensation. This extension leads to improved rate-distortion performance. However, motion compensation in combination with transmission errors leads to temporal error propagation that occurs when the reference frames at coder and decoder differ. In this paper, we present a framework that incorporates an estimated error into rate-constrained motion estimation and mode decision. Experimental results with a Rayleigh fading channel show that long-term memory prediction significantly outperforms the single-frame prediction H.263-based anchor. When a feedback channel is available, the decoder can inform the encoder about successful or unsuccessful transmission events by sending positive (ACK) or negative (NACK) acknowledgments. This information is utilized for updating the error estimates at the encoder. Similar concepts such as the ACK and NACK mode known from the H.263 standard are unified into a general framework providing superior transmission performance.
Analysis and Optimization of the Performance of OFDM on Frequency Selective Time-Selective Fading Channels
- IEEE Transaction On Communications
, 1999
"... Abstract—In mobile radio communication, the fading channels generally exhibit both time-selectivity and frequency-selectivity. Orthogonal frequency-division multiplexing has been proposed to combat the frequency-selectivity, but its performance is also affected by the time-selectivity. In this paper ..."
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Cited by 41 (5 self)
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Abstract—In mobile radio communication, the fading channels generally exhibit both time-selectivity and frequency-selectivity. Orthogonal frequency-division multiplexing has been proposed to combat the frequency-selectivity, but its performance is also affected by the time-selectivity. In this paper, we investigate how various parameters, such as the number of carriers, the guard time length, and the sampling offset between receiver and transmitter, affect the system performance. Further, we determine the optimum values of the above parameters, which minimize the degradation of the signal-to-noise ratio at the input of the decision device. Index Terms—Fading channel, OFDM, performance optimization. I.
Long Range Prediction of Fading Signals: Enabling Adaptive Transmission for Mobile Radio Channels
- IEEE SIGNAL PROCESSING MAGAZINE
, 2000
"... Recently it was proposed to adapt several transmission methods, including modulation, power control, channel coding and antenna diversity to rapidly time variant fading channel conditions. Prediction of the channel coefficients several tens-to-hundreds of symbols ahead is essential to realize these ..."
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Cited by 41 (3 self)
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Recently it was proposed to adapt several transmission methods, including modulation, power control, channel coding and antenna diversity to rapidly time variant fading channel conditions. Prediction of the channel coefficients several tens-to-hundreds of symbols ahead is essential to realize these methods in practice. We describe a novel adaptive long range fading channel prediction algorithm (LRP) and its utilization with adaptive transmission methods. This channel prediction algorithm computes the linear Minimum Mean Squared Error (MMSE) estimates of future fading coefficients based on past observations. This algorithm can forecast fading signals far into the future due to its significant memory span, achieved by using a sufficiently low sampling rate for a given fixed filter size. The LRP is validated for standard stationary fading models, and tested with measured data and with data produced by our novel realistic physical channel model. This model accounts for the variation of the amplitude, frequency and phase of each reflected component of the fading signal. Both numerical and simulation results show that long range prediction makes adaptive transmission techniques feasible for mobile radio channels.
Cellular performance bounds via shotgun cellular systems
- IEEE Journal on Selected Areas in Communications
, 2000
"... This paper considers two-dimensional interference-limited cellular radio systems. It introduces the shotgun cellular system that places base stations randomly and assigns channels randomly. Such systems are shown to provide lower bounds to cellular performance that are easy to compute, independent o ..."
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Cited by 40 (2 self)
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This paper considers two-dimensional interference-limited cellular radio systems. It introduces the shotgun cellular system that places base stations randomly and assigns channels randomly. Such systems are shown to provide lower bounds to cellular performance that are easy to compute, independent of shadow fading, and apply to a number of design scenarios. Traditional hexagonal systems provide an upper performance bound. The difference between upper and lower bounds is small under operating conditions typical in modern TDMA and CDMA cellular systems. Furthermore, in the strong shadow fading limit the bounds converge. To give insights into the design of practical systems, several variations are explored including mobile access methods, sectorizing, channel assignments, and placement with deviations. Together these results indicate cellular performance is very robust and little is lost in making rapid minimally-planned deployments.
