Multiple RTS and DATA Receptions in a Loop-Based Underwater Propagation Delay Aware MAC Protocol

Due to the long underwater propagation delays, the underwater sink node may not receive all of the requests to send RTS and DATA frames from the various underwater sensor nodes, resulting in massive collisions. We proposed an underwater Medium Access Control (MAC) protocol that takes into account the long propagation delay to evaluate the performance of the carrier sense multiple access collision avoidance (CSMA/CA) protocol utilizing a loop-based single hope underwater sensor network. The proposed protocol is designed to restore multiple RTS control packets from n underwater sensor nodes to the underwater sink node in a single slot time. The sink node received multiple RTS frames without overlapping because the n underwater sensor nodes transmitted the RTS frames at the same time, but they were received at different times at the receiver end due to differences in propagation delays that depend on the distances between the n sensor nodes and the sink node. In this paper, by altering the number of underwater sensor nodes and the size of the contention window, the proposed MAC protocol throughput is evaluated by using the underwater propagation delay.