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Low-complexity iterative receivers for multiuser space-time block coding systems

dc.contributor.advisorShwedyk, Edwarden_US
dc.contributor.advisorNguyen, Ha H.en_US
dc.contributor.committeeMemberSaadat Mehr, Aryanen_US
dc.contributor.committeeMemberDinh, Anh vanen_US
dc.contributor.committeeMemberDaku, Brian L.en_US
dc.contributor.committeeMemberZhang, W. J. (Chris)en_US
dc.creatorYang, Yajunen_US 2006en_US
dc.description.abstractIterative processing has been shown to be very effective in multiuser space-time block coding (STBC) systems. The complexity and efficiency of an iterative receiver depend heavily on how the log-likelihood ratios (LLRs) of the coded bits are computed and exchanged at the receiver among its three major components, namely the multiuser detector, the maximum a posterior probability (MAP) demodulators and the MAP channel decoders. This thesis first presents a method to quantitatively measure the system complexities with floating-point operations (FLOPS) and a technique to evaluate the iterative receiver's convergence property based on mutual information and extrinsic information transfer (EXIT) charts.Then, an integrated iterative receiver is developed by applying the sigma mappings for M-ary quadrature amplitude modulation (M-QAM) constellations. Due to the linear relationship between the coded bits and the transmitted channel symbol, the multiuser detector can work on the bit-level and hence improves the convergence property of the iterative receiver. It is shown that the integrated iterative receiver is an attractive candidate to replace the conventional receiver when a few receive antennas and a high-order M-QAM constellation are employed. Finally, a more general two-loop iterative receiver is proposed by introducing an inner iteration loop between the MAP demodulators and the MAP convolutional decoders besides the outer iteration loop that involves the multiuser detection (MUD) as in the conventional iterative receiver. The proposed two-loop iterative receiver greatly improves the iteration efficiency. It is demonstrated that the proposed two-loop iterative receiver can achieve the same asymptotic performance as that of the conventional iterative receiver, but with much less outer-loop iterations.en_US
dc.subjectmutual informationen_US
dc.subjectiterative receiveren_US
dc.subjectSpace-time block codeen_US
dc.subjectEXIT charten_US
dc.titleLow-complexity iterative receivers for multiuser space-time block coding systemsen_US
dc.type.materialtexten_US Engineeringen_US Engineeringen_US of Saskatchewanen_US of Science (M.Sc.)en_US


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