Research On Indoor Mobile Node Location Based On Wireless Sensor Networks

WSN(Wireless Sensor Network)is a self-organizing network composed of a large number of sensor nodes with sensing,computing and communication capabilities.In WSN,localization technology can make each node obtain its own position coordinate and it can ensure monitor targets,collect,share and predict data in the network.Localization technology is the key technology of WSN.Under indoor environment,under the influence of obstacles the signal transmission of mobile nodes is usually the NLOS(Non-Line-of-Sight),which leads to more localization errors.Therefore,it has more practical significance if we know how to reduce the localization error,improve the localization accuracy of the node and use WSN to study indoor mobile nodes localization.Based on WSN,this paper focuses on two localization algorithms,the initial state motion state,when mobile nodes into network under indoor NLOS environment.Meanwhile,an effective method to suppress the NLOS errors is put forward,so as to improve the localization accuracy of the mobile nodes.In addition,this paper proposes a modified algorithm according to the Maximum likelihood estimation which is commonly applied to calculate node coordinates in WSN.The main results are as follows:Firstly,this paper is based on the research and analysis of the commonly used WSN node ranging technology.The author puts forward a multi-signal localization algorithm aiming at solving the problems,such as limited ranging range,low localization success rate of TDOA,susceptibility to signal interference and low ranging accuracy of RSSI.The algorithm which selects the appropriate anchor nodes through the RSS participates in the location computed,in order to narrow the area located in an unknown area and improve the node localization accuracy.Then aiming at the problem of NLOS errors caused by indoor localization,this paper proposes a method of suppressing NLOS.This method selects anchor nodes with low errors through introducing suppressing factor,in order to reduce the impact of NLOS on the localization results and improve the localization accuracy.Secondly,aiming at the problem of motion state of mobile nodes,this paper proposes a mobile node localization algorithm which is based on HISL(Historical Information State Localization).This method locates the mobile nodes according to the number of anchor nodes around the unknown nodes and the unknown nodes' historical localization information.In addition,the paper also involves the method of calculating the node coordinates through introducing a modified values for making the coordinate value of the nodes more closer to the true value.Finally,the author uses MATLAB simulation tool to simulate the above-mentioned findings and the results show that the algorithms proposed in this paper can effectively improve localization accuracy and have good adaptability,using.