Key Technology Of Node Localization And Target Tracking Based On UWSNs

With the decrease of the land resources,human beings are paying more and more attention to the marine resources.As the key technology of the development and utilization of marine resources,target tracking based on Underwater Wireless Sensor Networks(UWSNs)has become a hot topic.Since underwater nodes provide data for target tracking,the locations of nodes are crucial to target tracking based on UWSNs.In this dissertation,the node localization problem is first studied.On this basis,underwater target tracking based on UWSNs is then studied.The main work and contributions of this dissertation are as follows:At first,as for the network with poor communication ability and without any auxiliary equipment,a topdown positioning scheme is proposed.By defining the node confidence coefficient,introducing the gradient method,and designing a new three dimension twohop distance estimation method,the localization coverage is increased while keeping a proper localization error.Secondly,considering the challenge of clock synchronization of underwater nodes,a clock synchronization independent localization scheme is proposed.The distance differences between an unknown node and anchors are obtained by using local clocks,then the distance-difference based least squares estimation is designed to compute node location.In addition,considering the limited storage and computing ability of a node,the problem of underwater target tracking based on the local inforrmation is studied.To overcome the limitation of global node selection,a local node selection scheme is proposed.To insure the realtime requirement of underwater target tracking,the distributed Kalman filter with feedback fusion method is adopted and a distributed target tracking algorithm based on the local node selection scheme is designed,which results in decreasing computational complexity.Thirdly,the effect of node topology on target tracking based on UWSNs is studied.Based on the relation between Posterior Cramer-Rao Lower Bound(PCRLB)and node location,a new underwater target tracking algorithm based on the multi-sensor particle filter is designed.Based on above results,the effect of the imperfect channel between a node and the fusion center on target tracking is also studied and a new target tracking scheme considering the imperfect channel is also designed.The sea trial data can verify the validity of our algorithm.Finally,considering the mobility of underwater nodes,the problem of underwater target tracking with node location uncertainty is also studied.On the basis of the relation between PCRLB and node estimated location,a new underwater target tracking scheme considering node location uncertainty is designed,which results in improving the tracking accuracy.