Improved reliability and data rates for AUV acoustic communications

The availability of parallel channels in a point-to-point communication system may be exploited to increase data rate and reliability, without additional power, beyond that possible with a single channel. The severe power and bandwidth constraints imposed on an autonomous underwater vehicle acoustic telemetry link motivate the use of spatial modulation techniques to achieve these benefits, particularly for missions requiring real time sensor data transmission. Theoretical performance improvements for coherent modulation schemes yielding the equivalent of 6 dB or greater signal-to-noise ratio gain are shown. Experimental results from an underwater range near the Bahama Islands are given. Inclusion of a modest horizontal line array on the vehicle and a remote transceiver on the surface are the sole additional requirements beyond a conventional telemetry system.