Adaptive Exploitation of Residual Redundancy in Iterative Source-Channel Decoding

Iterative source-channel decoding (ISCD) aims at the exploitation of the time-variant residual redundancy of the source samples, e.g., source codec parameters, for error concealment and quality improvements. In most previous publications the receiver had perfect knowledge of the amount of residual redundancy. This assumption would require a reliable, i.e. highly redundant, transmission of side information. In contrast, in this paper we present a relatively simple scheme, yet efficient and robust, by which the residual redundancy at the receiver can be estimated accurately without any side information, and then can be exploited adaptively. We present the achievable performance gains in an ISCD system including the estimation of the residual source redundancy at the receiver for various scenarios. Several methods of different performance and computational complexity are proposed, with some of them even outperforming a system with perfect side information. The latter, not quite intuitive fact, is explained in the paper.