Adaptive interference suppression and cancellation for underwater acoustic communications.

Abstract

An adaptive, time-reversal multichannel combiner is embedded within an iterative, successive interference cancellation framework to create a reduced-complexity, multiuser receiver with multiple-access interference suppression. The combined receiver achieves the goal of separating simultaneous, full-band transmissions from physically separated users transmitting to a base station in an underwater uplink setting. Although both receiver components could feasibly act alone, the combined receiver is shown to be more robust than its individuals, achieving both temporal and spatial interference mitigations in the presence of strong multiuser interference. Furthermore, with the addition of matching pursuit, a popular sparse channel estimation technique, and a block-by-block channel adaptation, the overall receiver is designed to be applicable to time-varying underwater acoustic environments. Analysis of experimental data collected during FAF-06 illustrates that for a two-user multiple-access system, multiuser separation can be achieved even in low signal-to-noise ratio (SNR) environments.