Time Reversal precoder: An efficient tool for more reliable underwater acoustic communication

Underwater acoustic communication has always been a challenging area of research where intersymbol interference (ISI) due to the complex multipath structure of the channel is one of the major issues in establishing a reliable communication link. In order to combat this ISI, the adaptive equalizer requires a large number of taps (equalizer length) and hence increases not only the computational complexity but also the delay in the system. Time Reversal (TR) precoder is another approach to mitigate ISI by means of its inherent property of spatio-temporal focusing of the transmitted energy at target location. It is also easier to implement as it does not incur much computational burden, unlike an equalizer. In this paper, we present a study on the performance of a UWA communication system using a TR precoder along with an equalizer. Experimental and simulation studies show that using a TR precoder not only reduces the required length of the equalizer but also performs reasonably well under severe channel conditions even at low signal to noise ratio (SNR).