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Multi-path Penalty Metric in Underwater Acoustic Communication for Autonomy and Human Decision-making

Bradli Howard, S.M., 2021
Henrik Schmidt, Advisor

A novel performance metric to improve underwater digital acoustic communication, called Multi- path Penalty (MPP), is proposed as an alternative to traditional signal-to-noise ratio (SNR) meth- ods in the context of the Arctic Beaufort Sea. MPP and SNR are compared alongside a third per- formance metric, Minimum Achievable Error (MAE), which replicates the operation of a channel estimate-based decision feedback equalizer in an acoustic modem. The three metrics are then tested in a hardware-in-the-loop Virtual Ocean simulator for an autonomous undersea vehicle (AUV) communicating with a collaborator. Using field data of modem statistics obtained during ICEX20 and expanded data supplied by the simulator, calibration of the three metrics to modem packet success is evaluated, resulting in a proposed recalibration for MAE. The AUV’s ability to communicate when adaptively choosing its depth is analyzed above and below the Beaufort Lens, and settings for MPP’s engineering variables are obtained. The results show MPP generally im- proves reception and demodulation of acoustic transmissions over SNR by approximately 5% within an operational range of 8 km, while achieving similar results to the more robust metric MAE. MPP is an improved utility for underwater digital acoustic communication in both marine autonomy and as a tactical decision aid.