Date Added: May 2012
UnderWater Acoustic (UWA) channel is typically sparse. In this paper, a complex Homotopy algorithm is presented and then applied for UWA OFDM channel estimation. Two enhancements that exploit UWA channel temporal correlation for the Compressed-Sensing(CS)-based channel estimators are proposed. The first one is based on a first-order Gauss-Markov (GM) model which uses the previous channel estimate to assist current one. The other is to use the Recursive Least-Squares (RLS) algorithm together with the CS algorithms to track the time-varying UWA channel.