A new tandem source-channel coding scheme

The authors present a novel tandem source-channel coding scheme consisting of a trellis source coder and a trellis coded modulation (TCM) channel coder. Motivation for the use of TCM, instead of conventional channel coding schemes such as convolutional codes, arises from the fact that, by using TCM, improvement in signal-to-quantization-noise ratio (SQNR) is achieved without bandwidth expansion. Criteria for the choice of TCM codes are discussed, and TCM schemes suitable for this application are presented. Simulation results for both a Gauss-Markov source and speech samples indicate that the use of the present scheme results inconsiderable improvement not only over uncoded transmission but also in comparison to joint source-channel trellis coding. The disadvantage is the additional computational effort and corresponding delay resulting from the use of the Viterbi algorithm at the receiver