Performance analysis of digital acoustic communication in a shallow water channel

High data rate acoustic transmission is required for diverse underwater operations such as the retrieval of large amounts of data from bottom packages and real time transmission of signals from underwater sensors. The major obstacle to underwater acoustic communication is the interference of multipath signals due to surface and bottom reflections. High speed acoustic transmission over a shallow water channel characterized by small grazing angles presents formidable difficulties. The reflection losses associated with such small angles are low, causing large amplitudes in multi-path signals. In this paper we propose a simple but effective model for multipath interference, which is then used to assess the performance of a digital communication system operating in a shallow water channel. The results indicate that transmission rates in excess of 8 k-bits/s are possible over a distance of 13 km and channel depth of only 20 meters. Such a system offers improved performance in applications such as data collection from underwater sensors.