Underwater Acoustic Wireless Communications

The methods and the implementations of underwater acoustic (UWA) communications in the stochastic acoustic multipath propagation channels have been studied. The ocean underwater stochastic acoustic propagation channels with their time , space , and frequency varying multipath have demonstrated the great complexities and difficulties for wireless communications. In addition, there are many other problems encountered in UWA channels, such as large ambient noise, limited bandwidth, low carrier frequency, and extended propagation latency. All of these substantially limit the data rates of underwater digital communications. The paper describes the methods of underwater communications, as well as the key supporting technologies of the implementations based on the considerations to overcome the difficulties stated above. We have designed three different systems for the applications of audio, video and data underwater transmission respectively. The performance of the systems has been investigated on the experimental trials in real ocean environments. Presented results indicate the superior quality of the systems tested, and the systems have been proven to be suitable for the practical applications in real ocean environments. Of late, a great deal of valuable research work has gone into the field of UWA communications in a number of technologically leading nations. Nevertheless, it is only until lately, a very small number of them have reached the major breakthrough. It has been demonstrated that our research work results are equivalent to the current ones obtained in those leading nations.