Low-complexity subband equalization of mobile underwater acoustic channels

The intersymbol interference (ISI) caused by multipath propagation becomes the major challenge for designing efficient equalization methods for underwater acoustic communications. Even at moderate bit-rates, the computational complexity of adaptive equalizers is high enough to challenge their realtime implementation. Hence, reducing their complexity by either low-complexity algorithms or efficient receiver structures is of paramount importance. In this work, we revisit the idea of joint subband equalization [9] and propose new receivers with reduced computational complexity that can cope with variable platform mobility within a signal packet, track rapid multipath fluctuations and maintain robustness under impulsive noise environments. The proposed subband equalizers are successfully tested in two experimental shallow water links by detecting quadrature phase-shift keying (QPSK) signals. In addition, results based on their performance-complexity tradeoffs are reported.