Signal Transmission in Underwater Using Passive Time Reversal for Single and Multiuser

Abstract

This paper describes passive time reversal communications, which enables multiple users to send information simultaneously to the time reversal array. Experimental results at 3.5 kHz with a 1 kHz bandwidth demonstrate that as many as six users can transmit information over a 4 km range in a 120 m deep water using quaternary phase-shift keying (QPSK) modulation, achieving an aggregate data rate of 6 kb/s. Moreover, the same data rate has been achieved at 20 km range by three users using 16-quadrature amplitude modulation (16-QAM).