Experiments for long-range high-rate underwater acoustic MIMO communication using adaptive passive time reversal

In this study, we apply the multiple-input/multiple-output (MIMO) underwater acoustic communication signal processing method based on the adaptive passive time reversal (APTR) to two different real sea experiment data, and report the results of evaluating the relationship between the effective communication data rate and the bit error rate (BER). The MIMO receiver system is based on rejection combining by APTR method which can suppress both co-channel interference and inter-symbol interference, which is followed by the Doppler shift compensation based on signal compression/dilatation correction and single-channel DFE. The channel was convolutionally coded at rate 5/6 and decoded by the soft-decision Viterbi algorithm. The experiments were conducted in water depths of 750 and 200 m, with communication distances of 12.5 and 13.5 km, and spatial multiplexing up to 4 and 5 channels, respectively. As a result, bit-error-free signal frame rate of over 97 and 98 % are achieved in both experiments with effective data rate of 20.0 and 27.0 kbps, respectively.