Iterative Source-Channel Decoding: Design of Redundant Index Assignments

The exploitation of the residual redundancy of source codec parameters by using the Turbo principle is known as iterative source-channel decoding (ISCD). The concept of redundant index assignments was proposed as a powerful improvement for ISCD. In this contribution design and optimization guidelines for such redundant index assignments are presented. Commonly, the redundant index assignment is based on a simple block code. Using extrinsic information transfer (EXIT) chart we demonstrate that weak block codes such as a repetition code should be preferred. Simulation results show significant performance improvements with redundant index assignments based on this guideline.