Research On Time Synchronization And Node Localization Algorithms In Underwater Sensor Networks

With the increasing demand for the development of marine resources,underwater sensor networks are widely used in the marine field.The time synchronization technology and node localization technology of underwater sensors have attracted much attention as the application foundation of underwater sensor networks.Due to the significant differences in network latency and deployment between underwater sensor networks and terrestrial sensor networks,the mature time synchronization technology and node localization technology of the vast majority of terrestrial sensor networks cannot be directly used in underwater sensor networks.Therefore,This article studies the time synchronization technology and node localization technology of underwater sensors.The main work of this article is as follows:(1)Aiming at the problem that the traditional MU-Sync(A cluster-based Synchronization algorithm for Underwater acoustic Mobile networks)time synchronization algorithm ignores the change of round-trip propagation delay,resulting in poor accuracy,an underwater sensor time synchronization algorithm based on Kalman filter(KF-Sync)was studied,That is,the system State-transition equation and the system observation equation are established by using the temporal and spatial correlation of the underwater sensor nodes,and the Kalman filter is used to estimate the node clock skew and clock offset,so as to achieve time synchronization between the two sensor nodes.Simulation shows that the time synchronization accuracy of this algorithm is superior to traditional algorithms.(2)Aiming at the problem that the traditional underwater sensor DV-Hop(Distance VectorHop)localization algorithm has large errors caused by the minimum hops,average hop distance and least square estimation of coordinates,an improved DV-Hop localization algorithm for underwater sensors based on weighted hyperbola(IWH-DV-Hop)was studied,That is,the minimum hop number is improved by the double communication radius method,the average hop distance is improved by the normalized weighted processing method,and the coordinates of unknown sensor nodes are estimated by the weighted hyperbola method,so as to realize the positioning of unknown sensor nodes.Simulation shows that the positioning accuracy of this algorithm is superior to traditional algorithms.(3)Aiming at the problem that the traditional underwater sensor DV-Hop localization algorithm has large errors caused by the minimum hop number,average hop distance and least square estimation of coordinates,an improved DV-Hop localization algorithm for underwater sensor based on particle swarm optimization(IPSO-DV-Hop)was studied,That is,the minimum hop number is improved by using the double communication radius method,the average hop distance is improved by using the normalized weighted processing method,and the coordinates of unknown sensor nodes are estimated by using the Particle swarm optimization algorithm,so as to achieve the positioning of unknown sensor nodes.Simulation shows that the positioning accuracy of this algorithm is superior to traditional algorithms.Compared with IWH-DV-Hop,this algorithm has slightly higher positioning accuracy but requires longer positioning time.