High-rate multiple-input/multiple-output communication with adaptive time reversal demonstrated in tank experiments

Abstract

In our previous studies, it was shown that the method of adaptive passive time reversal (PTR) combined with decision feedback equalizer (DFE) is very effective in spatial division multiplexing for multiple-input/multiple-output (MIMO) or multiuser in underwater acoustic communication. In this study, tank experiments are carried out to compare the performance of adaptive PTR-DFE and orthogonal frequency division multiplexing (OFDM) for MIMO in the static environment under the condition that channel estimation is obtained clearly. As a result, the performance of adaptive PTR-DFE does not degrade regardless of increasing the number of transmitter channels, while that of OFDM deteriorates critically. In the experiment of 5 × 12 MIMO, adaptive PTR-DFE can achieve demodulation at the efficiency of 16.7 bps Hz−1 with 16 quadrature amplitude modulation easily with no errors, in contrast to that OFDM cannot achieve it even with quadrature phase shift keying.