MIMO underwater acoustic channel characterization based on a remotely operated experimental platform

In the framework of the development of a MIMO (Multi-input Multi-output) capable underwater acoustic modem, this paper describes on the one hand a remotely operated experimental platform at sea in real conditions able to transmit and receive real-time multi-streams signals and the other hand an analysis of the experimental channel capacity gain brought by the MIMO approach with respect to traditional single transmitter system. The original remotely operated generation/acquisition system provides an extensive characterization of the MIMO underwater acoustic channel for various transmission ranges and sea states. The capacity analysis extracted from real conditions channel estimates confirm that MIMO approach in experimental scenario leads to a substantial capacity gain with respect to single transmitter even by taking account signal overhead. As foreseen by theory, the MIMO capacity gain is also shown to be dependent from transmission range and transducers arrays configuration.