Improving the performance of variable-length encoded systems through cooperation between source and channel decoders

Systems employing variable-length source codes are prone to error propagation. Several techniques that involve varying levels of cooperation between the channel decoder and source decoder are considered for improving the performance. At one extreme, conventional tandem decoding performs channel decoding and source decoding independently; at the other extreme, joint source-channel MAP decoding combines the two into a single decoder. Simulation results indicate that joint source-channel list decoding with “trellis pruning” can result in significant improvement over conventional tandem decoding