BER Improvements With Multilevel Coded Modulation

Abstract

The paper compares some new methods for coded modulation constructions using
multilevel codes obtained by combining channel coding and digital modulation. As reference
examples are presented schemes based on phase shift keying. The comparison parameter is the bit
error rate and consequently structures for optimal receivers are discussed. In particular it is
shown how multistage decoding can be improved by using interleaving blocks between the three
levels of the decoding structure and which are the advantages obtained - the increase in
reliability, additional coding gains, a modest complexity of the structure, but with an undesired
increased decoding delay. Finally the role of time diversity encoding in improving transmission
performances on nongaussian channels is presented.