Research On Localization Algorithms In Wireless Sensor Networks

Wireless sensor networks (WSN) integrates various techniques, such as Micro Electro Mechanical systems technology, embedded technology, distributed information processing technology, computer network technology and wireless communication technology,WSN can real-time monitor, sense, collect and process all kinds of information, then, send it to the users. It is a new information acquisition and processing technology, and has been widely used in military and civilian fields.In WSN, node localization technique is the premise of target identification, tracking, monitoring and many other applications, Which is an important support technology for WSN. Therefore, node positioning becomes a hot issue with the development of WSN.In this paper, localization algorithms for WSN are discussed. Firstly, the research status and significance of the WSN localization technology are given, followed by the basic principles of node localization. Moreover, several typical distributed localization algorithms are discussed to conclude that each algorithm has its own range of application. Based on these analysis, a general model of the distributed localization algorithm is given. Secondly, focus on the DV-distance algorithm. Through simulating and analyzing this algorithm, One can find that the positioning accuracy of this method is effected by the zig-zag error and ranging error seriously. Therefore, combining with the proposed general model, a novel RSSI-based distributed localization algorithm is presented. The new scheme set the Time To Live (TTL) of the WSN to 2 for reducing the Zig-zag error, and includes two stages:initial location stage and iterative refinement stage. In the initial stage, for improving the positioning coverage, a location method based on two anchor nodes is used; while, in the iterative stage, the estimated location from the initial stage is as the original position of EKF to attain high accuracy.The present algorithm is simulated by MATLAB 7.0, and the simulation results show that the new algorithm achieves high localization accuracy even when anchor ratio is less. Comparing with DV-distance algorithm, The proposed algorithm performs better in localization accuracy and coverage.