Research On MAC Protocol Of Underwater Mobile Sensor Network

Underwater Mobile Sensor Network(UWMSN)has important practical application value in the fields of ocean information monitoring and data collection.UWMSN consists of mobile nodes represented by autonomous underwater vehicles(AUVs)and ordinary underwater sensor nodes represented by anchor nodes.The AUV node can be used as a mobile aggregation node to collect the data of the anchor node in a single hop according to a certain route,so as to replace the traditional underwater wireless sensor network and send it to the surface aggregation node in a multi-hop manner.Multiple AUV nodes aggregate the data collected by each of them and send it to the main AUV node in a single hop,and the main AUV node transmits the data to the surface aggregation node.The mobility of AUV nodes leads to continuous changes in the network topology during communication,and it is necessary to design a suitable MAC layer protocol in single-hop communication to realize reliable transmission between AUV nodes,anchor nodes and AUV nodes to improve network transmission performance.The main work of this article is as follows:(1)An adaptive MAC protocol for dynamic backoff sending data frames is proposed for the scenario where AUV acts as a mobile aggregation node to collect information from ordinary sensor nodes.The MAC protocol is divided into a control phase and a data phase to address the issue of continuous updates,uncertain number and location of surrounding anchor nodes during the AUV movement process.In the control phase,control frame handshake is used to detect anchor nodes that can establish communication links and collect relevant information.In the data phase,the transmission order of anchor nodes is dynamically scheduled based on the distance between anchor nodes and AUV nodes.A data frame backoff transmission strategy based on dynamic distance is proposed to fully utilize propagation delay and improve channel utilization.The process model of MAC protocol was created using OPNET simulation software,and its excellent performance under different anchor node densities was verified.(2)In the scenario where multiple AUV nodes cover a large area of water to perform tasks and use the main AUV to perform secondary aggregation of information collected from the AUV,based on the MAC protocol of dynamic backoff sending data frames,the time synchronization and positioning technology of AUV is introduced,and a multi AUV cooperative MAC protocol based on position prediction is proposed.To address the issue of topology changes in the AUV network caused by mobility,a location prediction based AUV slot allocation strategy is proposed.During each control phase of the communication cycle,the slave AUV and the master AUV share their own position and movement trend,predict the position during the data phase,and schedule the transmission order from the AUV based on this information.Finally,OPNET simulation software is used to realize the process model creation,which verifies the excellent performance under the fixed number of AUVs and different network traffic loads.