A latency-tolerant MAC protocol for underwater acoustic sensor networks

Wireless networks with the shared media require Medium Access Control (MAC) protocol that provides contention resolution mechanism. The design of MAC protocol in underwater sensor networks is a challenging issue because of limited energy source and high propagation delay. The most important goal of the MAC design for underwater sensor networks is to resolve data packet collision efficiently with respect to energy consumption. So, selection of MAC protocol is an important task because it has significant impact on the system efficiency. A suitable MAC protocol must consider some factors such as fairness, energy consumption, latency and throughput based on various applications. The bandwidth in the acoustic links is very low because of the characteristics of underwater environment. To solve these problems, we propose a MAC protocol that is based on reserved time slot. A time slot is allocated to each node for sending data in a way that the data does not collide with another node´s data. Our protocol can tolerate latency while providing reasonable throughput with low energy consumption. A synchronization algorithm is employed to synchronize all nodes in a distributed manner. The listen/sleep periodic operation is used for saving energy due to long propagation delay and limited energy. The proposed protocol uses short ranges of underwater acoustic communication links to achieve higher throughput. The simulation results show that the proposed protocol increases the overall throughput of the network and reduces energy consumption.