The modified iterative detector/estimator algorithm for sparse channel estimation

Underwater acoustic channels exhibit very long delay spreads, but with limited multipath. In this paper, a novel strategy for the estimation of sparse underwater channels is developed. A modified iterative detector/estimator (IDE) algorithm is proposed by replacing the parallel thresholding approach in a previously developed IDE algorithm by an approach wherein a single threshold is varied for each iteration of the algorithm. The new method offers improved performance over the original IDE algorithm as well as the current state-of-art compressed sensing-based methods, such as the iterative hard thresholding (IHT), the Haupt-Nowak (HN) and the orthogonal matching pursuit (OMP) algorithms. A preliminary mean-squared error analysis of the MIDE algorithm provides insight as to its improved performance. Numerical results are provided to compare and contrast the various sparse estimation strategies.