Turbo decoding of multiple description source and channel codes
We address the joint use of a heterogeneous source of redundancy in a coding chain: multiple description coding and channel coding where the redundancy on the source symbols and on the transmitted bits is generated by quantized frame expansions and convolutional coding, respectively. The received signal is viewed as the noisy output of a serial concatenated coding system, and a turbo-type decoder that relies on a soft information exchange between its decoding blocks is proposed to iteratively reconstruct the source signal. EXIT charts are used to characterize the convergence behavior of the proposed iterative receiver, which in turn is used to select system parameters such as the channel code. The turbo receiver is simulated for 2 /spl times/ 5 frame expansions where the results indicate a significant gain achieved by the decoding iteration both in the erasure and no erasure cases.