MIMO-UAC for Rate Enhancement and Range Extension

Abstract

Abstract : Our research focuses on the horizontal underwater acoustic communications. During this year, our research on multi-input multi-output underwater acoustic communications (MIMO-UAC) can be categorized into two thrusts: (1) Robust MIMO-UAC with Low-Complexity Receivers and (2) Enhanced Channel Estimation and Symbol Detection for High Speed MIMO-UAC. In terms of MIMO-UAC with low-complexity receivers, we have established a simple windowed least squares (LS) channel estimator, developed a differential MIMO scheme obviating channel estimation, and analyzed the effects of different doubly-selective channel models in UAC scenarios. For high-speed MIMO-UAC, we have focused on the channel estimation and symbol detection problems in MIMO-UAC. We have presented a cyclic approach approach for designing training sequences with good auto- and cross-correlation properties. Iterative adaptive approach (IAA) coupled with Bayesian information criterion and RELAX has been presented as an approach for estimating the channel impulse response. We also proposed a new detection method called RELAX-BLAST. Our proposed schemes are tested via both simulations and field data from the acoustic communications experiment (RACE'08) conducted by the Woods Hole Oceanographic Institution (WHOI).