Bio-inspired secure underwater acoustic communication strategy by shifting the natural whale whistle phase

The bio-inspired secure underwater acoustic communication strategy camouflages the information with cetacean calls, tricking the enemy into mistaking the communication signals for natural marine mammal sounds to obtain communication security, showing distinct advantages over the conventional low probability of detection secure strategies. Inspired by this, a secure underwater acoustic communication strategy by shifting the whale whistle phase is proposed. It conveys the information by modulating the phase of natural whale whistles. The killer whale is served as an example of the bio-inspired models to illustrate the proposed method due to its wide distribution and high source level. To construct high performance and well camouflaged communication sequences, the autocorrelation, cross-correlation and Doppler tolerance of the killer whale whistles are analyzed first. Then the pulse shaping and varying symbol duration strategies are designed to alleviate the spectral leakage and the cyclostationarity problem brought about by the phase shifting to further improve the communication security. Experiments have been conducted and the effectiveness and security of the proposed method are verified by the experimental results.