A MAC protocol based on flexible RWT for underwater mobile ad-hoc networks

In this paper, we propose an underwater media access control (MAC) protocol based on flexible request-to-send waiting time (RWT) with a three-way handshaking mechanism. To support underwater mobile ad-hoc networks where each node has one-hop communication, our proposed MAC protocol is designed for data reliability, energy efficiency, node mobility, and network scalability. First, the order of transmission is decided by prioritizing messages to ensure data reliability. We determine the priority of messages based on the messages' content and urgency levels. We can also receive multiple RTS during an RWT and then reserve a channel to send data by transmitting one clear-to-send (CTS). This results in high energy efficiency by reducing the number of data transmissions in harsh underwater environments. Our proposed MAC protocol ensures a scalable, efficient network to accommodate extended or reduced networks with node mobility. Then we can manage efficiently underwater environment monitoring system based on underwater mobile ad-hoc networks.