Parallel combinatory multicarrier modulation in underwater acoustic communications

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.