Iterative Source-Channel Decoding with Delay Constraints

Iterative source-channel decoding (ISCD) exploits the residual redundancy of source codec parameters by using the Turbo principle. In most practical implementations of ISCD a delay constraint prohibits the utilization of future frames required for optimal soft decision source decoding if correlation between successive frames is exploited. In this letter we propose a novel receiver concept that attempts to partly overcome the receiver sub-optimality by refining the extrinsic information of past frames in order to improve the estimation of the parameters of the current frame. Simulation results show consistant performance improvements.