D-MAC: Hybrid Media Access Control for Underwater Acoustic Sensor Networks

Physical properties of hydroacoustic communication channels differ essentially from those of conventional terrestrial radio channels, the former being characterized by the long propagation delays, limited bandwidth, extremely complex and quickly varying reverberation, and the half-duplex nature of underwater acoustic modems. This motivates a substantial redesign of the algorithms and techniques of the underwater data transfer concerning both physical and data link layers, especially concerning the development of underwater acoustic sensor networks. The recent studies of underwater acoustic sensor networks have caused the appearance of a variety of data link and network layers protocols intended to solve particular tasks for various types of networks. In this paper, we present a new media channel access protocol architecture combining two media access algorithms for the transfer of different data types, notably burst data and short instant messages, in order to provide the network layer with additional capabilities to solve problems in a wider range.