An Improved Delay Estimation Algorithm for Underwater Acoustic OFDM Sparse Channel

Traditional Orthogonal Matching Pursuit (OMP) method needs high oversampling factor and computational overhead to estimate off-grid path delays in underwater acoustic Orthogonal Frequency Division Multiplexing (OFDM) systems. In this paper, the idea of path compensation is introduced from multiple linear fitting theory, and an improved OMP path delay estimation method based on path compensation is proposed to reduce the energy leaking from off-grid paths to its surrounding grids. The compensation distance is used to evaluate compensation effect. The improved algorithm can improve the estimation performance by appropriate compensation distance without increasing the oversampling factor. Compared with the traditional OMP method, the proposed algorithm has lower computational complexity but better estimation performance. The results of simulations and sea trial data decoding show the superiority of the proposed method.