Multiple-access communications for underwater acoustic sensor networks using OFDM-IDMA

In this paper, we present a novel multiple-access communications scheme that provides robust performance in the presence of large time-delay spread and the other channel impairments commonly encountered in shallow water acoustic sensor networks. The scheme is based on Orthogonal Frequency Division Multiplexing (OFDM) with an Interleave-Division Multiple Access (IDMA) overlay, where IDMA is a variant of Code-Division Multiple Access (CDMA). Simulations of various underwater acoustic sensor network scenarios show that the OFDM-IDMA scheme consistently outperforms other common multiple-access schemes in the shallow water environment.