A new block-coded modulation scheme for Rayleigh fading channel, soft output decoding issues

Abstract

We investigate the application of the sum-product algorithm to the decoding of a q-ary block-coded modulation (BCM) scheme which is based on extending the parity check equations of a binary block code to q-ary symbols. This is achieved by decomposing the code into a sub-code with an acyclic Tanner graph and its cosets which are represented by a trellis diagram. The combination of these two cycle-free graphs are used to develop an efficient soft output decoding algorithm for the given code.