Convergence properties of iterative decoders working at bit and symbol level

Abstract In this paper, we compare the convergence thresholds of parallel and serially concatenated codes with interleaver that employ iterative decoding algorithms working at bit or symbol level. The analysis technique is an extension to the symbollevel decoder of that presented in [1], and is valid for very large interleavers. The comparison shows that working at symbol level always yields a lower convergence threshold. In the serial concatenation, the advantage is quite significant.