Study On Medium Access Control Protocols For Underwater Acoustic Sensor Networks With A Dynamic Topology

In recent years,more and more underwater acoustic networks(UANs)use automation underwater vehicle(AUV)to carry underwater acoustic communication machine for constructing mobile nodes,which makes the protocol design for dynamic underwater acoustic network is becoming one of the research hotspots.In this paper,a contention-based MAC protocol called RA-SFAMA-MA is proposed for the hybrid underwater acoustic network with dynamic topological structure,in order to solve the specific problems such as prolonged propagation delay,low channel utilization and luxurious underwater energy storage in the underwater acoustic network with mobile nodes.First,the protocol avoids collision by scheduling the sending time of acknowledgement(ACK),and determines the suitable scenario of the ACK algorithm by calculating the optimal network capacity.Second,the receiving time sequence of each terminal node is determined by the multi-receiving mechanism based on RTS competition,and the network congestion is adjusted dynamically while the total delay of network propagation is reduced and the funnel effect is alleviated.Finally,experiments show that compared with the other two classical contention-based MAC protocols,RA-SFAMA-MA can achieve a higher throughput and a lower energy cost.Further more,in view of the dynamic topology and strict energy limitation of the hybrid underwater acoustic networks composed of mobile AUV nodes and underwater fixed nodes,this paper puts forward a cross layer protocol called RV-SFAMA-MA,which combines the RA-SFAMA-MA protocol in MAC layer with the VBF routing protocol in network layer.In RV-SFAMA-MA,the VBF routing protocol is integrated into the RTS competition algorithm to dynamically schedule the optimal routing of network,reduce the total length of propagation delay and greatly reduce the overall energy cost.The superiority of RV-SFAMA-MA are verified by the simulation of Mate2,which is based on the NS3 platform.Simulations show that compared with another mature cross-layer protocol DBR-MAC,RV-SFAMA-MA can achieve a higher throughput and a lower energy cost of.