Iterative decoding with erasures in a concatenated system with diversity

We study error correcting codes, which are constructed by using "permutation" and "iterative decoding" in conjunction with "concatenation". These codes include "concatenated codes", "product codes" and "turbo codes" as special cases. We then extend our approach to a continuous channel, by adopting AZD (ambiguity zone detection) at the receiver, which introduces generalized erasures. Iterative decoding can significantly improve the performance of a coded system that contains a channel with memory (e.g., spectral shaping, ISI, multipath delay), modulation with memory (e.g., trellis coded modulation, continuous phase modulation) and/or diversity. Moreover, it is implementable with low decoding complexity and requires a small decoding delay. Using this framework, we propose two architectures for iterative receivers in an existing wireless packet transmission system. These receivers are fully backward compatible with the existing transmitter, have low decoding complexity and delay, and offer a decoding improvement of several dBs.