Analysis and Estimation of the Underwater Acoustic Millimeter-Wave Communication Channel

A millimeter-wave frequency band in underwater acoustic communication is proposed and analyzed in this paper. The millimeter-wave frequency ranged from 150 kHz to 1500 kHz. The wavelength of underwater sound waves is about 1-10 mm, so using the millimeter-wave frequency band as proposed can improve communication performance efficiently. Simulations of the measured sound velocity profile collected in the South China Sea prove that the communication channel of the millimeter-wave frequency is characterized by the sparsity or cluster-sparsity when the launch angle is large. Using this phenomenon, we propose a novel form of cluster-sparsity l(2,0)-norm shrinkage LMS algorithm which can identify the millimeter-wave communication channel. The l(2,0)-norm constraint takes advantage of the sparse properties and the shrinkage denoising method improves the tracking ability in the time-varying sparse channel, so the proposed algorithm can achieve high channel estimation accuracy. Both the simulation results and experimental data processing confirm that the proposed algorithm achieves better performance than the previous algorithm.