An iterative decoding technique and architecture for RS concatenated TCM coding systems

In this paper, we propose a soft value modification (SVM) algorithm, based on which we further propose a new low-complexity iterative decoding technique for the conventional serial concatenated coding system which consists of Reed-Solomon (RS) code and Trellis coded Modulation (TCM) scheme with an interleaver in between. In our decoding technique, the RS decoder is based on Berlekamp-Massey (BM) algorithm, and the TCM decoder is based on Viterbi (VB) algorithm. After each iteration, the data bits and the err-flag information generated from the output of RS decoder can be fed back to the input of VB decoder as reference information, which combined with the SVM algorithm helps the VB decoder to decide whether and how to modify the corresponding soft values from the channel output. This modification approach makes the soft value more reliable than the previous version and, thus, increases the VB and RS decoder´s correction capacity. Extensive simulation results in different systems highlight the proposed scheme´s coding gain over the conventional two-stage decoding algorithm. Finally, a low-complexity architecture for hardware implementation of this novel iterative decoding technique is suggested, and the comparison with the pipeline architecture found in the literature shows the advantages of our proposal.