A novel scheme for underwater acoustic mobile communications

The underwater acoustic channel is a complicated and time-varying multipath channel, especially for the mobile applications in the littoral. To accommodate the execrable channel conditions, a robust communication scheme is proposed, which combines the differential frequency hopping (DFH) and multi-carrier technologies. Also a novel Doppler-shift estimation and synchronization method is presented, which utilizes the doppler-invariant hyperbolic frequency modulation (HFM) signal associating with the doppler-sensitive long single tone pulse. Simulation results demonstrate that the proposed communication scheme performs well for underwater acoustic mobile communications with relative velocity up to 30 knots at data rate about 300bps. Base on these preliminary results, the proposed scheme shows considerable promise for reliable underwater acoustic mobile communications.