Research On Three Dimensional Distributed Range-free Localization In WSN

How to realize self-localization for sensor nodes in wireless sensor networks (WSN) is one of the most important problems. The realization of node localization in WSN can give support to area monitoring that needs accurate position information.First, the basic concept, feature and applications of WSN are introduced. Then development status of localization problem of WSN at home and abroad is depicted. Finally relative merits of each algorithm are summed up and challenges faced by localization problem in WSN are listed. But in some situations sensor nodes are deployed in3D space, so research on localization algorithms in3D space with high accuracy is becoming an important topic.Second, a range-free distributed three dimensional optimum space step distance localization scheme (OSSDL) in WSN is proposed by analyzing classic DV-Hop algorithm. An anchor selection method is added into OSSDL which means optimum anchors are selected in communication range. In this way location accuracy is improved and can also be used in WSN with random communication range. Another method called CF_OSSDL is introduced by supplying an overall correction factor for each unknown node which can offset distance error and increase accuracy. Meanwhile Kalman filtering model is also added and a new algorithm called OSDKF is formed. This method can mainly deal with much uncertain position information and find optimum value by filtering lots of data. At last a scheme called VCN which is based on virtual central node is also introduced.Finally we set up simulation environment using MATLAB software and make validations of these algorithms mentioned above. From simulation results the significance of these algorithms can be deduced. Also we analyze and study the defects of them and optimum working status can be found.