Iterative Symbol Decoding of Distributed Channel Encoded Fixed-Length Codes for Cooperative Communications

In this paper, we study the iterative decoding of distributed channel encoded fixed-length codes for power-efficient cooperative transmissions. By exploiting the technique of iterative source channel decoding (ISCD), the iterative decoding for cooperative transmissions exploits two types of the redundant information: the residual redundancy inherently remaining in the source codes, and the artificial redundant information provided by the distributed channel coder. To avoid the information loss on the bit-to-symbol conversion, we adopt symbol-level ISCD scheme consisting of the symbol-level channel decoder and the symbol-level source decoder. Our proposed iterative decoding can improve parameter signal-to-noise ratio (PSNR) performances by iteratively refining the extrinsic information for the source and the distributed channel decoders. Furthermore, the proposed source decoding algorithm based on the symbol-level BCJR algorithm enables the iterative decoding to efficiently exploit the extrinsic information conveyed by relay and source nodes. Simulation results show that the proposed iterative decoding scheme with the proposed source decoder and the symbol-level BCJR channel decoder delivers the robust power-efficient performance, and outperforms conventional decoding schemes.