A two-stage approach for the estimation of multiple input multiple output acoustic channels

Underwater acoustic communication (UWA) is a reliable way for data transmission in underwater environment, however, it is quite challenging due to its doubly spread characteristics as delay spread and Doppler spread. In this paper, a discrete-time channel input-output relationship for multiple-input-multiple-output (MIMO) single-carrier block transmissions is derived based on parameterization for amplitude and delay variations with polynomial fitting, where the mathematical model is characterized by a few parameter sets, transforming the estimation problem into estimation of the low-dimensional parameter sets. Then a two-stage sparse approach for delay-spread and Doppler-scale estimation of MIMO UWA channel is proposed, using orthogonal matching pursuit (OMP) algorithm to search on the delay-Doppler scale grid. The results of the proposed approach are further evaluated by simulations.