Reduction of decoding complexity of trellises for BCM

Block-coded modulation (BCM) combines bandwidth-efficient modulation techniques with error-correction capabilities to allow efficient data transmission over communication channels. The disadvantage of this technique, however, is the complexity of the trellis used in the Viterbi decoding process. The authors address this problem and propose a method for the reduction of decoding complexity. Optimal sectionalisation has been identified as an appropriate technique and it is applied to trellises of BCM schemes based on a set of new objective functions. The resulting sectionalisation algorithm has been applied to various BCM schemes including 4-PSK, 8-PSK and 16-PSK and a complexity reduction of approximately 20% is achieved. Extensive simulation has shown that both original and sectionalised trellises have the same performance over Rayleigh, K=6 Rician and K=10 Rician fading channels. Furthermore, a comparison between the considered BCM schemes and ring-TCM is provided in terms of code performance and decoding complexity