Research On Node Localization And Target Tracking In Wireless Sensor Networks

Wireless sensor network(WSN)has widely used in military,environment,medical,home,transportation and other aspects.The node localization problem is the most basic and key problem in the research area of WSN,and the target tracking is also one of the most important applications of WSN.There are some important theoretical and practical problems in the technology of node localization and target tracking in WSN.In the node localization problem,obtain higher localization accuracy under the limited hardware resources is an important research hotpot.In the target tracking system of WSN,making reasonable dormancy strategy and cooperation mode of nodes according to the predicted state of target to balance the energy consumption and prolong the network live-time while ensure the accuracy of target tracking is also the current research focus.Therefor the main contents of this paper are as follows:Firstly,the node localization algorithm and target tracking algorithm in WSN are studied,based on the application requirements,organizational structure and network characteristics of WSN.In terms of node localization algorithm,the principle,advantages and disadvantages of range-based localization algorithm and non-range localization algorithm are analyzed respectively.In terms of target tracking in WSN,the framework of target tracking is given,the target tracking algorithm based on tree network structure,Kalman filter and particle filter,cluster network structure is introduced respectively.Secondly,in order to improve the positioning accuracy of node localization algorithm based on RSSI-ranging,the maximum likelihood estimation equation of unknown nodes is established according to the logarithmic shadow fading model of RSSI measurement.The grasshopper optimization algorithm is introduced into the node localization algorithm based on RSSI-ranging,combining with the characteristics of nodes localization problem in WSN,the initial strategy of grasshopper population is optimized,the individual movement strategy of grasshopper is improved and the elite mutation strategy is introduced,and the proposed algorithm is verified by simulation.Finally,in order to ensure the target tracking accuracy,balance the energy consumption and prolong the network lifetime,a target tracking algorithm based on dynamic cluster is proposed,the dynamic cluster is formed by the information of PCRLB and the residual energy of nodes.The proposed algorithm uses particle filter to predict the state of the target at the next time.According to the prediction position of the target,the prediction covariance matrix and the sensing radius of the sensor nodes,the region of candidate nodes is determined at the next time.In the region of candidate nodes,several sensor nodes are selected to form a cluster to track the target by comprehensive considering the information of PCRLB and the residual energy of nodes.The simulation results show that the proposed algorithm is effective.