Sparse underwater acoustic channel estimation with adaptive delay filter

When estimating a sparse channel, the standard adaptive filter proposed by Widrow may require a great number of taps, but the Adaptive Delay Filter (ADF) with variable delay taps and variable gains need only a few elements since the delay taps can spread out to track the unknown system. For the purpose of further reducing the complexity of ADF, we adopt a polarity correlator to estimate the time delay, avoiding direct estimation of the mean square error function which is needed by the previously proposed MDRL (Maximum Deviation from Regression Line) algorithm, therefore resulting in much lighter computational load at little cost in performance. Computer simulations on the simulated underwater acoustic channel and data processing of channel measured at sea prove that our method is not only effective, but also has the ability of high resolution.