Underwater acoustic communications in time-varying dispersive channels

Underwater acoustic communication (UAC) system designers tend to transmit as much information as possible, per unit of time, at as low as possible error rate. However, the bit rate achieved in UAC systems is much lower than for wire or radio-communication systems. This is due to disadvantageous properties of the UAC channels, namely the sea and inland waters. Estimation of UAC channel transmission properties is possible within a limited bandwidth and temporal resolution. Thus, the UAC physical layer of data transmission is designed on the basis of roughly estimated channel parameters, or assuming the worst possible conditions. The paper presents the methodology of adapting UAC signaling schemes to tough underwater propagation conditions, through an example of two communication systems designed and developed at the Gdansk University of Technology.