Underwater acoustic communication channel capacity: A simulation study

Acoustic communication channel capacity determines the maximum data rate that can be supported (theoretically) by an acoustic channel for a given source power and source/receiver configuration. In this paper, broadband acoustic propagation modeling is applied to estimate the channel capacity of a shallow water waveguide for a single source-receiver pair, both with and without source bandwidth constraints. Initial channel capacity estimates are obtained for a range-independent environment defined by the mean (time-averaged) sound speed profile measured at a site in the 1995 SWARM experiment. Without bandwidth constraints, estimated channel capacities approach 10 megabits per second at 1 km range, but after 2 kin range they decay at a rate consistent with that of estimates by Peloquin and Leinhos [1], which were based on a sonar equation analysis for a generic underwater channel. Channel capacities subject to source bandwidth constraints are approximately 30-90% lower than the upper bounds predicted by the sonar equation analysis, and exhibit a significant wind speed dependence. Simulations of internal wave effects on channel capacity show minimal effects at low frequencies but, at 2500 Hz, show a significant increase in the channel capacity at longer ranges. Implications for underwater acoustic communication systems are discussed.