Research On Time Synchronization Technology Of Wireless Sensor Networks

Wireless sensor network is a special Ad-hoc network,which is a distributed network that communicates by a large number of nodes in a wireless self-organizing manner.It is highly valued by academia and industry because of its advantages of low cost,self-organization,and ability to work in harsh environments.Time synchronization technology is an important supporting technology for wireless sensor networks.In wireless sensor network applications,if there is no guarantee of time consistency,the data collected by the sensor nodes will be meaningless.Applications such as data fusion,location,target tracking,and network management require clock synchronization between sensor nodes.Due to the constraints of energy,price and volume of sensor nodes,traditional time synchronization mechanisms such as NTP and GPS are not suitable for wireless sensor networks.Therefore,it is very important to modify or redesign the time synchronization mechanism of wireless sensor networks to meet actual needs.Firstly,this thesis summarizes the research status of time synchronization technology of wireless sensor network,and then expounds the basis technology related to time synchronization,including the clock model of the node,the key factors causing the synchronization error of the node and the basic principle of achieving synchronization,etc.Several typical time synchronization algorithms are analyzed and compared,and the performance indicators of the time synchronization algorithm are summarized.Secondly,a clustering-based multi-hop TPSN time synchronization algorithm,(Timing-Sync Protocol for Sensor Networks of Chain,C-TPSN)is proposed,which can solve the problem that when number of levels increases,local clock offset difference also increase to multi-hop TPSN,based on the analysis and research of the existing time synchronization algorithms.This thesis proposes to divide the WSN into a number of clusters so that the TPSN can therefore provide synchronization among the cluster roots first then the cluster roots can synchronize asynchronously and explores how to set the cluster depth,in order to better achieve the synchronization error and message overhead balance.Aiming at the problem of high energy consumption of large-scale sensor network nodes,the Timing-Sync Protocol for Sensor Networks of Adaptive Interval Synchronization(Adapt-TPSN)is proposed.The idea of the algorithm is to set a desired synchronization different threshold firstly.When the last synchronization result of a node is less than the threshold,the next synchronization interval of the node will be increased.Otherwise,the next synchronization interval is decreased.Reduce unnecessary message overhead by adjusting the synchronization period of the nodes.Finally,the algorithm is implemented on the NS-2 simulation platform,and the performance of the algorithm is tested from the aspects of synchronization error and message overhead.The results show that the improved algorithm C-TPSN can solve the problem that when number of levels increases,local clock offset difference also increase to multi-hop TPSN,and achieve better synchronization.The Adapt-TPSN algorithm can reduce the message overhead while satisfying the synchronization accuracy.