Blind Decision-Feedback Equalization of Shallow Water Acoustic Channels

In this paper, blind receivers for signals transmitted through shallow water are proposed. After having introduced the used modulation scheme and its favorable properties, three different blind receiver structures are studied. The first processing step in all cases is explicit non-data-aided timing recovery. Then, blind adaptive-decision feedback equalization and phase recovery is performed. The adaptive setting of the nonlinear equalizer is attained by using the constant modulus algorithm for the feed-forward section and various strategies for the feedback section. All structures have been successfully tested with measured shallow water data gathered during the ROBLINKS 1999 sea trial. The obtained results suggest that blind decision-feedback equalization is possible and may speed up convergence compared to linear CMA.

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