Characterization of delay and doppler spreads of underwater particle velocity channels using zero crossing rates

Communication in acoustic particle velocity channel using vector sensors is recently proposed for the underwater medium. Due to the presence of multiple propagation paths, a mobile receiver collects the transmitted signal with different delays and Doppler shifts. This introduces certain delay and Doppler spreads in particle velocity communication channels. In this paper, these channel spreads are characterized using the zero crossing rates of channel responses in frequency and time domain. Useful expressions for delay and Doppler spreads are derived in terms of the key channel parameters, mean angle of arrivals and angle spreads. Closed-form expressions for the temporal correlations of underwater acoustic particle velocity channels are presented as well. These results are needed for design and performance predication of communication systems in time-varying and frequency-selective underwater particle velocity channels.