Combining OMP With a Superimposed Pilot Sparse Channel Estimation Method for Underwater Acoustic OCDM Systems

Recently, sparse channel estimation in underwater acoustic orthogonal chirp-division multiplexing (OCDM) communication has attracted increasing attention. However, the channel estimation method based on a superimposed pilot structure results in noise interference in the zero-coefficient term of the sparse channel, making it difficult to improve estimation performance. In this work, we propose an acoustic sparse channel estimation method that combines the orthogonal matching pursuit (OMP) with a superimposed pilot. A special frame structure is designed to achieve low-complexity carrier frequency offset estimation. The simulation demonstrate show that this method improves the accuracy of frequency offset estimation and reduces the normalized mean square error of the channel impulse response under the conditions of an underwater acoustic sparse channel from the Watermark dataset.