Parallel combinatory multicarrier modulation in underwater acoustic communications

Abstract

Parallel combinatory multicarrier (PCMC) modulation is a generalisation of the legacy multicarrier frequency shift keying (FSK) scheme, where for each group of M subcarriers, more than one (say L) subcarriers are chosen for simultaneous transmission. The PCMC scheme provides an effective way to increase the spectral efficiency while maintaining non-coherent detection at the receiver. This study provides an in-depth study of the PCMC scheme with emphasis on how to couple with binary or non-binary channel coding. One favourable system configuration is identified, having parameters (L,M) = (4,8), which increases the spectral efficiency by 50% relative to the most efficient FSK scheme from the FSK family. Coupled with non-binary low-density parity-check (LDPC) coding over the Galois field GF(64), the PCMC scheme with (L,M) = (4,8) is shown to have robust performance in multipath fading channels.