Capacity of MIMO Systems in Shallow Water Acoustic Channels

UnderWater Acoustic (UWA) channels are typically characterized by a multipath structure with large delay spread, where only a few propagation paths carry significant energy. Each path exhibits time variability, which, together with the transmitter and receiver motion, induces Doppler spreading and shifting of the signal. In this paper, the authors analyze the limits on the information rate achievable through Multiple-Input Multiple-Output (MIMO) communications over UWA channels. Assuming full Channel State Information (CSI) at the receiver, they evaluate the ergodic capacity in two scenarios: one with partial CSI at the transmitter, and another with no CSI.