Node Localization For Wireless Sensor Networks Based On Mobile Anchor

The application of network technology has made wireless sensor networks (WSN) node which is consisted of sensing, data processing, and communicaiting components not only to be a sensor unit, but also to be a combination unit which can exchange information, collaborate and control. As a new information acquisition and process platform, Wireless sensor networks possess wide application prospects in military, industry, medical treatment, environment monitoring and other fields. Wireless sensor networks have widely used in the areas of poor conditions, to achieve the monitoring and tracking tasks. In these applications, the location of nodes play an important role in wireless sensor networks. Therefore, the study of node location method has important theoretical and practical value. This thesis focuses on the study of localization algorithm and path planning of the mobile anchor for wireless sensor networks based on the analysis of related literatures.First of all, the research status of wireless location techniques for wireless sensor networks at home and abroad are summarized based on the analysis of a lot of related literatures. The classification methods of localization systems and algorithms for wireless sensor networks are introduced and the principles and characteristics of recent representative localization algorithms are analyzed and discussed.Secondly, as sensor nodes are randomly deployed in two-dimensional applications, in the localization algorithm with a mobile beacon, how to choose the appropriate beacon trajectory is very important. At present relatively little research has been made. In this paper, a new dynamic path planning method is proposed. When mobile anchor nodes receive messages sent from neighbor nodes, the path that the mobile anchor should travel along is determined according to the information of neighbor nodes based on this search algorithm.Then, several semi-definite programming relaxation models are analyzed, the advantages and the disadvantages of several location algorithms in these fields are researched based on the simulation. Focus on the computation costs of semi-definite programming, in this thesis a new convex position estimation algorithm is studied. In this algorithm, a mobile anchor broadcasts packets with multi-power level on its trajectory. Simulation results show that this algorithm can greatly reduce the computational complexity and also perform well.Finally, a new distributed multi-coordinate localization algorithm using multi-power mobile anchors is proposed based on the study of a lot of recent representative localization algorithms. The algorithm can achieve very good positioning performance when it using triangle path. Based on the study of a distributed mobile anchor localization algorithm, aim at the defect of node beeline movement and using dynamic path planning method, a improved localization algorithm is proposed for the case of nodes non-uniform distribution. The simulation results show that this improved algorithm can obtain higher localization precision compared with the original algorithm in the network environments where the sensor nodes are non-uniform deployed and obstacles still occur in the area.