Combined Iterative Demapping and Decoding for Coded MBOK DS-UWB Systems


IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E87-A    No.10    pp.2621-2629
Publication Date: 2004/10/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Wide Band Systems)
ultra wideband,  iterative decoding,  M-ary biorthogonal keying(MBOK),  multipath fading channels,  

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This paper presents a novel decoding strategy called combined iterative demapping/decoding (CIDD), for coded M-ary biorthogonal keying-based direct sequence ultra-wideband (MBOK DS-UWB) systems. A coded MBOK DS-UWB system consists of a convolutional encoder, an interleaver, and an MBOK DS-UWB pulse mapper. CIDD improves the error rate performance of MBOK DS-UWB systems by applying the turbo principle to the demapping and decoding processes at the receiver side. To develop the CIDD, a soft-in/soft-out MBOK demapping algorithm, based on the max-log-MAP algorithm, was derived. Simulation results showed that using CIDD siginificantly improved the error rate performance of both static and multipath fading channels. It was also shown that the computational complexity of CIDD is comparable to that of the Viterbi decoding used in [133,171]8 conventional convolutional coding.