The Experts below are selected from a list of 5253 Experts worldwide ranked by ideXlab platform
G L Stuber - One of the best experts on this subject based on the ideXlab platform.
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channel estimation for amplify and forward relay based cooperation diversity systems
IEEE Transactions on Wireless Communications, 2007Co-Authors: C S Patel, G L StuberAbstract:Cooperation diversity schemes have been proposed for cellular networks that permit a base station (or a mobile station) to relay signals to a Destination Receiver, thereby increasing the network coverage and reliability. The mobile relays either decode and forward (DF) or amplify and forward (AF) the received signal. Most existing analyses of cooperation diversity assumes perfect channel information at the Receiver. A realistic assessment should consider the effects of practical channel estimation schemes. This paper considers pilot symbol aided channel estimation for cooperation diversity systems. Since the overall channel in AF systems is different from conventional cellular channels, the channel estimation problem is interesting and challenging and therefore our focus is on AF systems. The paper addresses issues such as the estimator design, pilot symbol spacing based upon realistic channel models, and an approximate bit error rate (BER) analysis that accounts for imperfect channel estimation.
Are Hjorungnes - One of the best experts on this subject based on the ideXlab platform.
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decoding and performance bound of demodulate and forward based distributed alamouti stbc
IEEE Transactions on Wireless Communications, 2013Co-Authors: Ankur Bansal, Manav R Bhatnagar, Are HjorungnesAbstract:In a demodulate-and-forward (DF) based cooperative communication system, erroneous relaying of the data leads to degradation in the performance of the Destination Receiver. However, a maximum likelihood (ML) decoder in the Destination can improve the Receiver performance. For achieving a diversity gain, the Alamouti space-time block code (STBC) can be used in the DF based cooperative system in a distributed manner. In this paper, we derive an ML decoder of the distributed Alamouti STBC for the DF based cooperative system with two imperfect relaying nodes. We also consider a DF cooperative communication system in which one out of two relays is in outage. A piece-wise linear (PL) decoder for the DF cooperative system with the distributed Alamouti code and one relay in outage is proposed. The PL decoder provides approximately the same performance as that of the ML decoder with reduced decoding complexity. We derive the pairwise error probability (PEP) of the proposed ML decoder with binary phase-shift keying constellation. An optimized transmit power allocation for the relays is performed by minimizing an upper bound of the PEP. It is shown by simulations that the proposed ML decoder enables the DF protocol based cooperative system to outperform the same rate amplify-and-forward protocol based cooperative system when both systems utilize the distributed Alamouti STBC.
Erik Perrins - One of the best experts on this subject based on the ideXlab platform.
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performance characteristics and metrics for intra pulse radar embedded communication
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Shannon D Blunt, Justin G Metcalf, C R Biggs, Erik PerrinsAbstract:Low probability of intercept (LPI) communication generally relies on the presence of noise to obfuscate a covert signal through the use of spectral spreading or hopping. In contrast, this paper addresses the use of ambient interference from other man-made emissions as a means to mask the presence of covert communication. Specifically, the high power, wide bandwidth, and repeating structure of pulsed radar systems provide an advantageous framework within which to embed a communication signal. The operating paradigm considered here is that of an RF tag/transponder that is illuminated by the radar and intends to covertly communicate with the radar or some other desired Receiver while being masked by the ambient radar backscatter to avoid detection by an intercept Receiver. Communication takes place on an intra-pulse (or individual pulse) basis to maximize the data rate. The impact of multipath, and its exploitation using time reversal to achieve spatio-temporal focusing, is considered. The processing gain for the Destination Receiver and intercept Receiver are derived analytically and subsequently used to optimize the parameterization of communication symbol design.
C S Patel - One of the best experts on this subject based on the ideXlab platform.
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channel estimation for amplify and forward relay based cooperation diversity systems
IEEE Transactions on Wireless Communications, 2007Co-Authors: C S Patel, G L StuberAbstract:Cooperation diversity schemes have been proposed for cellular networks that permit a base station (or a mobile station) to relay signals to a Destination Receiver, thereby increasing the network coverage and reliability. The mobile relays either decode and forward (DF) or amplify and forward (AF) the received signal. Most existing analyses of cooperation diversity assumes perfect channel information at the Receiver. A realistic assessment should consider the effects of practical channel estimation schemes. This paper considers pilot symbol aided channel estimation for cooperation diversity systems. Since the overall channel in AF systems is different from conventional cellular channels, the channel estimation problem is interesting and challenging and therefore our focus is on AF systems. The paper addresses issues such as the estimator design, pilot symbol spacing based upon realistic channel models, and an approximate bit error rate (BER) analysis that accounts for imperfect channel estimation.
Ankur Bansal - One of the best experts on this subject based on the ideXlab platform.
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decoding and performance bound of demodulate and forward based distributed alamouti stbc
IEEE Transactions on Wireless Communications, 2013Co-Authors: Ankur Bansal, Manav R Bhatnagar, Are HjorungnesAbstract:In a demodulate-and-forward (DF) based cooperative communication system, erroneous relaying of the data leads to degradation in the performance of the Destination Receiver. However, a maximum likelihood (ML) decoder in the Destination can improve the Receiver performance. For achieving a diversity gain, the Alamouti space-time block code (STBC) can be used in the DF based cooperative system in a distributed manner. In this paper, we derive an ML decoder of the distributed Alamouti STBC for the DF based cooperative system with two imperfect relaying nodes. We also consider a DF cooperative communication system in which one out of two relays is in outage. A piece-wise linear (PL) decoder for the DF cooperative system with the distributed Alamouti code and one relay in outage is proposed. The PL decoder provides approximately the same performance as that of the ML decoder with reduced decoding complexity. We derive the pairwise error probability (PEP) of the proposed ML decoder with binary phase-shift keying constellation. An optimized transmit power allocation for the relays is performed by minimizing an upper bound of the PEP. It is shown by simulations that the proposed ML decoder enables the DF protocol based cooperative system to outperform the same rate amplify-and-forward protocol based cooperative system when both systems utilize the distributed Alamouti STBC.