Combined multi-stage turbo decoding and precoding techniques for ISI channels

A multi-stage turbo decoding scheme combined with equalization using precoding for ISI channels is presented. The precoder and intersymbol interference (ISI) channel are jointly modeled as a finite-state probabilistic channel to provide the multistage turbo decoder with its statistics information. Both a priori and a posteriori probabilities are used in the metric function of the decoding scheme to improve the system performance. Structures of the combined turbo-encoder, interleaver and precoder in the transmitter and multi-stage turbo decoder in the receiver are presented. Performance of the introduced scheme in various ISI channels and different conditions are evaluated by simulation. The results indicate that the combined multistage turbo decoding and precoding techniques provide a considerable improvement.