A Low Complexity Iterative Receiver for Multiuser Space-Time Coding System

In multiuser space-time coding system the research already made is almost focused on STTC and STBC scheme. For this reason, a multiuser space-time coding system combined with Turbo-BLAST scheme is investigated. Iterative processing has been shown to be very effective in multiuser space-time coding systems, where each user employs channel coding and iterations are performed between the soft-output channel decoders. The complexity of an iterative receiver depends heavily on how the log-likelihood ratios (LLRs) are computed for users´ coded bits in order to implement the iterations. The bit-level cancellation (BLC) scheme is proposed in this paper to ease the computation of the LLRs and allow bit-level interference cancellation in the iterative processing. It is demonstrated that the proposed iterative receiver performs very close to the conventional one, but with a much less computational complexity. Also the high spectral efficiency of the system from BLAST is retained.