Layered space-time codes with iterative receiver and space-time soft-output decoding in a Rayleigh fading environment

In this paper, we propose a modified BLAST architecture which employs space-time trellis codes at each layer as constituent codes, and an iterative parallel interference canceller (PIC) at the receiver. The PIC performs both interference regeneration and cancellation; and furthermore, the scheme employs maximum-likelihood soft-output decoders, based on the Viterbi algorithm. These decoders calculate the a posteriori probabilities of the codewords in order to produce a soft output. Comparisons are drawn against the original BLAST architecture and simulation results are obtained. A significant gain is achieved in the case of Horizontal BLAST and a similar gain for the case of Diagonal BLAST, at a reduced computational complexity.