A relative clock based and energy sense MAC protocol for underwater acoustic communication networks

TDMA is an ideal choice for solving the data collision in underwater acoustic communication networks, but it needs the global clock synchronization, which is hard to realize in underwater environment. Further, the asymmetrical energy consumption of the main node and the sub nodes will reduce the network lifetime. To address these problems, we presented a relative clock based and energy sense MAC protocol. In this protocol, global clock synchronization is not needed, all nodes mapped the network schedule on its local clock according to the relative propagation delay and worked on it. The gateway is changed dynamically according to its energy level, in order to prolong the network lifetime. The performance and the engineering feasibility of this protocol were demonstrated by simulations and lake trail.