A time reversal technique for minimizing equalizer complexity in high rate multi-antenna UWA link

High rate data transmission in an underwater link necessitates the use of multiple antennas. Intersymbol interference (ISI), one of the major issues in single antenna underwater acoustic (UWA) systems, becomes even more prominent while establishing a multi-antenna communication link. Deploying an adaptive equalizer to mitigate this ISI incurs huge computational complexity as the equalizer needs large number of taps. Also, this might require a compromise in data rate and/or error performance of the system. A solution to this is the time reversal (TR) technique which has been proven to be a computationally simpler approach to combat ISI and to provide high signal to noise ratio gains in a single antenna system. In this paper, we explore the possibility of the TR technique in improving error rate, and minimizing computational burden of the equalizer in a multi-antenna UWA link. We present an experimental demonstration which shows that while reducing the computational complexity, the TR technique also provides better error performance at higher data rate.