Serial concatenation of simple linear block codes and differential modulations

In this paper, binary linear block codes with very low encoding and decoding complexity (therefore, "simple" codes) are introduced as outer codes in a serially concatenated coding scheme employing multilevel differential phase-shift keying, i.e., differential modulations, as inner codes. Such a concatenated coding scheme is particularly suitable for power- and bandwidth-efficient transmission over channels with phase ambiguities or completely unknown phase at the receiver. Using extrinsic information transfer chart based analysis and optimization, the performance of the new concatenated codes is found to be within less than 1 dB of the pertinent capacity limit for the additive white Gaussian noise channel. This compares favorably with more complex benchmark schemes using e.g. outer low-density parity-check codes proposed recently in the literature. Simulation results confirm the predicted performance advantages for the proposed simple codes.