RHNE-MAC: Random Handshake MAC Protocol Based on Nash Equilibrium for Underwater Wireless Sensor Networks

Underwater wireless sensor networks (UWSNs) have a long propagation delay; thus, when multiple nodes access the channel at the same time, the nodes cannot perceive the channel status in time, which causes access conflicts between nodes. To reduce multinode access conflicts and improve network throughput, a random handshake MAC protocol based on Nash equilibrium (RHNE-MAC) is proposed. In the RTS phase, RHNE-MAC regards nodes sending control packets to channels as competitive behavior and an incomplete information game. This paper firstly discusses the collision probability of two nodes sending data to the master node at the same time when the nodes are evenly distributed. Subsequently, according to the collision probability and the size of the network, the mathematical expectation concept is added to the payment function. Then, it uses the Nash equilibrium theory to solve the game, which allows the network to dynamically adjust the probability of nodes requesting access to a channel according to the number of nodes, thereby minimizing the problem of multinode access conflicts. Finally, the master node schedules the data transmission for each node according to the successful receipt of control packet information and propagation delay information of the network; therefore, multiple nodes can transmit data after a handshake period. The simulation results show that the throughput is increased by approximately 12% compared with prescheduling-based MAC and by 207% compared with TDMA; moreover, the end-to-end delay also has better performance.