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51
Noncoherent receivers for differential space–time modulation
 IEEE Trans. Commun
, 2002
"... Abstract — In this paper, noncoherent receivers for differential space–time modulation (DSTM) are investigated. It is shown that the performance of the previously proposed conventional differential detection (DD) receiver is satisfactory only for very slow flat fading channels. However, convention ..."
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Cited by 47 (6 self)
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Abstract — In this paper, noncoherent receivers for differential space–time modulation (DSTM) are investigated. It is shown that the performance of the previously proposed conventional differential detection (DD) receiver is satisfactory only for very slow flat fading channels. However, conventional DD suffers from a considerable loss in performance even for moderately fast fading. In order to overcome this problem, multiple–symbol detection (MSD) and low–complexity decision–feedback differential detection (DF–DD) receivers are derived. 1.
Joint Map Equalization And Channel Estimation For FrequencySelective FastFading Channels
, 1998
"... This paper presents a maximum a posteriori (MAP) equalizer for bandlimited signals on frequency selective fading channels. A key contribution is the way in which the statespace of the MAP trellis is expanded for the purpose of joint channel estimation and equalization. The fading channel is estimate ..."
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Cited by 41 (9 self)
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This paper presents a maximum a posteriori (MAP) equalizer for bandlimited signals on frequency selective fading channels. A key contribution is the way in which the statespace of the MAP trellis is expanded for the purpose of joint channel estimation and equalization. The fading channel is estimated by coupling minimum mean square error techniques with the expanded MAP trellis. The symbolbysymbol MAP algorithm is a softinput softoutput technique. The new MAP receiver can also be applied to iterative
Adaptive SoftInput SoftOutput Algorithms for Iterative Detection with Parametric Uncertainty,” submitted to
 IEEE Trans. Communications
, 1998
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Reducedstate BCJRtype algorithms
, 2001
"... In this paper, we propose a technique to reduce the number of trellis states in BCJRtype algorithms, i.e., algorithms with a structure similar to that of the wellknown algorithm by Bahl, Cocke, Jelinek, and Raviv (BCJR). This work is inspired by reducedstate sequence detection (RSSD). The key id ..."
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Cited by 32 (10 self)
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In this paper, we propose a technique to reduce the number of trellis states in BCJRtype algorithms, i.e., algorithms with a structure similar to that of the wellknown algorithm by Bahl, Cocke, Jelinek, and Raviv (BCJR). This work is inspired by reducedstate sequence detection (RSSD). The key idea is the construction, during one of the recursions in the reducedstate trellis, of a “survivor map” to be used in the other recursion. In a more general setting, two distinct survivor maps could be determined in the two recursions and used jointly to approximate the a posteriori probabilities. Three examples of application to iterative decoding are shown: 1) coherent detection for intersymbol interference (ISI) channels; 2) noncoherent detection based on an algorithm recently proposed by the authors; and 3) detection based on linear prediction for Rayleigh fading channels. As in classical RSSD, the proposed algorithm allows significant statecomplexity reduction with limited performance degradation.
DecisionFeedback Differential Detection of MDPSK for Flat Rayleigh Fading Channels
 IEEE TRANS. ON COMMUN
, 1999
"... In this paper, a novel decisionfeedback differential detection (DF{DD) scheme for 16level differentially encoded amplitude phase shift keying (16 DAPSK) is proposed. It is shown that the new technique based on multiplesymbol detection (MSD) [1] may obtain a significant gain in power efficiency un ..."
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Cited by 28 (5 self)
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In this paper, a novel decisionfeedback differential detection (DF{DD) scheme for 16level differentially encoded amplitude phase shift keying (16 DAPSK) is proposed. It is shown that the new technique based on multiplesymbol detection (MSD) [1] may obtain a significant gain in power efficiency under additive white Gaussian noise (AWGN) conditions when compared with a previously proposed DFDD scheme [2]. This gain increases with decreasing number of feedback symbols, which makes the novel scheme attractive for implementation since DFDD schemes are the more robust against frequency offset the less feedback symbols are applied. In addition, a recursive version of the DFDD scheme is derived which allows to find out easily the best tradeoff between power efficiency under AWGN conditions and robustness against frequency offset via adjustment of a forgetting factor.
On LDPC codes over channels with memory
 IEEE Trans. Wireless Commun
, 2006
"... Abstract — The problem of detection and decoding of lowdensity paritycheck (LDPC) codes transmitted over channels with memory is addressed. A new general method to build a factor graph which takes into account both the code constraints and the channel behavior is proposed and the a posteriori proba ..."
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Cited by 18 (12 self)
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Abstract — The problem of detection and decoding of lowdensity paritycheck (LDPC) codes transmitted over channels with memory is addressed. A new general method to build a factor graph which takes into account both the code constraints and the channel behavior is proposed and the a posteriori probabilities of the information symbols, necessary to implement maximum a posteriori (MAP) symbol detection, are derived by using the sumproduct algorithm. With respect to the case of a LDPC code transmitted on a memoryless channel, the derived factor graphs have additional factor nodes taking into account the channel behavior and not the code constraints. It is shown that the function associated to the generic factor node modeling the channel is related to the basic branch metric used in the Viterbi algorithm when MAP sequence detection is applied or in the BCJR algorithm implementing MAP symbol detection. This fact suggests that all the previously proposed solutions for those algorithms can be systematically extended to LDPC codes and graphbased detection. When the sumproduct algorithm works on the derived factor graphs, the most demanding computation is in general that performed at factor nodes modeling the channel. In fact, the complexity of the computation at these factor nodes is in general exponential in a suitably defined channel memory parameter. In these cases, a technique for complexity reduction is illustrated. In some particular cases of practical relevance, the above mentioned complexity becomes linear in the channel memory. This does not happen in the same cases when detection is performed by using the Viterbi algorithm or the BCJR algorithm, suggesting that the use of factor graphs and the sumproduct algorithm might be computationally more appealing. As an example of application of the described framework, the cases of noncoherent and flat fading channels are considered. Index Terms — Factor graphs, sumproduct algorithm, channels with memory, phasenoise, flat fading, lowdensity paritycheck codes, iterative detection/decoding. I.
Noncoherent and mismatchedcoherent receivers for distributed STBCs with amplifyandforward relaying
 IEEE Trans. Wireless Commun
, 2007
"... Abstract — Cooperative diversity is a transmission technique where multiple nodes in a network cooperate to form a virtual antenna array realizing the benefits of spatial diversity in a distributed fashion. The coherent scenario considered in most existing work on cooperative diversity assumes the a ..."
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Cited by 18 (4 self)
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Abstract — Cooperative diversity is a transmission technique where multiple nodes in a network cooperate to form a virtual antenna array realizing the benefits of spatial diversity in a distributed fashion. The coherent scenario considered in most existing work on cooperative diversity assumes the availability of perfect channel state information at the relay and destination terminals and is highly unrealistic in practical applications. In this paper, we investigate noncoherent and mismatchedcoherent receivers for a cooperative diversity scheme assuming both quasistatic and timevarying fading channels for the underlying cooperative links. Specifically, we consider a distributed spacetime block coded (STBC) system in a singlerelay scenario operating in the amplifyandforward relaying mode. Exploiting the orthogonal structure of distributed STBC, we first derive a noncoherent decoding rule which can be implemented in practice by a Viterbitype algorithm. Although this decoding rule has been derived assuming quasistatic channels, its inherent channel tracking capability allows its deployment over timevarying channels with a promising performance as a suboptimal solution. As a possible alternative to noncoherent detection, we investigate the performance of mismatchedcoherent receiver (i.e., coherent detection with imperfect channel estimation) within the considered relayassisted transmission scenario. We further compare the performance of noncoherent and mismatchedcoherent receivers to reveal their robustness under various mobility scenarios. Index Terms — Cooperative diversity, spacetime block coding, noncoherent detection, imperfect channel estimation, fading channels. I.
Adaptive Bayesian and EMbased detectors for frequencyselective fading channels
 IEEE Transactions on Comm
, 2003
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Optimal Joint Detection/Estimation in Fading Channels with Polynomial Complexity
 IEEE Trans. Inform. Theory
, 2003
"... The problem of sequence detection in frequencynonselective/timeselective fading channels, when channel state information (CSI) is not available at the transmitter and receiver, is considered in this paper. The traditional belief is that exact maximum likelihood sequence detection (MLSD) of an ..."
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Cited by 11 (1 self)
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The problem of sequence detection in frequencynonselective/timeselective fading channels, when channel state information (CSI) is not available at the transmitter and receiver, is considered in this paper. The traditional belief is that exact maximum likelihood sequence detection (MLSD) of an uncoded sequence over this channel has exponential complexity in the channel coherence time.
Extended MLSE diversity receiver for time and frequency selective channel
 IEEE Trans. Commun
, 1997
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