On-demand Pipelined MAC for Multi-hop Underwater Wireless Sensor Networks

Recently, Underwater Wireless Sensor Networks (UWSNs) have attracted increasing attentions from the public as it enables a wide range of underwater applications. However, the long propagation delay and high error probability in UWSNs pose grand challenges for efficient and reliable protocol designs in time critical applications such as underwater pollution detection. In this paper, we propose a new medium access control (MAC) protocol, named On-demand Pipelined MAC (OPMAC), for time critical applications in UWSNs. The basic idea of this protocol is to establish an on-demand pipeline so that data could be transmitted from the source to the destination over multiple hops in a short time. A special acknowledgement mechanism is also designed to guarantee the reliability of the communication with low overheads. Analytical results show that OPMAC significantly reduces end-to-end delay and improves energy efficiency.