Adaptive acoustic underwater communications based on generalized multi-carrier interleave-division multiplexing

In this contribution, an adaptive underwater acoustic modem with high bandwidth and power efficiency is proposed. Key features include interleave-division multiplexing (IDM) in time and frequency domain (and optionally in the spatial domain) in conjunction with generalized (non-orthogonal) multi-carrier (MC) transmission. IDM is a special form of superposition coded modulation. At the receiver side, joint intersymbol interference (ISI) and adjacent channel interference (ACI) cancellation is performed, in addition to iterative decoding. Adaptation (with respect to variable data rates, variable signal power, variable signal bandwidth, variable range, variable channel conditions, variable service requirements, etc.) is supported to an extend, which is currently unknown in the area of underwater communications. The communication signal can be used for navigation/positioning purposes without modification at the transmitter side. The system design is easily applicable in underwater networks, and extendable to an arbitrary number of transducers (MIMO processing). The modem is implemented by means of software-defined radio. A wide range of potential applications is targeted.