A self adaptive MAC layer protocol for delay-tolerant underwater wireless sensor networks

The propagation speed of an acoustic signal is much slower than the speed of a terrestrial radio signal due to the physical characteristics of an underwater acoustic channel. This large delay can impact the throughput of the channel. There is also a very high delay variance which presents unique challenges to the designs of efficient MAC protocols. The long and inconsistent delay renders many traditional protocols insufficient since they rely on multiple handshakes and accurate estimations of the round trip time (RTT) between two nodes. We proposed a novel approach to develop a Cluster based delay-tolerant protocol (CBDTP) to address these problems by eliminating RTS/CTS and ACK handshaking while avoiding collision. In addition, our CBDTP protocol uses a self-adaptive algorithm to address the inconsistent delay problem and its impact on RTT estimation. Our simulation study shows that CBDTP can improve channel throughput and resource utilization in a volatile deployment environment for many underwater wireless sensor network applications.