Conflict-free MAC protocol for regional underwater observation networks

This paper designed a conflict-free Media Access Control (MAC) protocol for the regional underwater observation networks, which avoids channel contentions by using the top-down channel assignment. In this scheme, temporary channel access is assigned by the gateway or Autonomous Underwater Vehicle (AUV) using a require-data-send signal (RDS). RDS is used to wake up the specific node and can not be heard by the other nodes. We designed two types of acknowledgement (ACK) signal to shorten the poll duration and save energy. If data received correctly, ACK1 will be sent to sleep the transmitting node and wake up the next node to transmit data. Otherwise, ACK2 will be sent to require the error data to be retransmitted. Theoretical analysis and simulation results show that this protocol provides a better performance than ALOHA and CSMA protocols. Finally, we conducted a Lake Trails to validate the practicability of this protocol.