Design And Verification Of Positioning System In IEEE802.11WLAN

IEEE802.11wireless network with traits of high speed, networking convenient,mobility, flexibility and so on, has been widely deployed and used since it appeared,and gradually become effective extension and replacement of the wired LAN. In802.11wireless network, users can access LAN and communicate with each other wheneverand wherever possible through mobile computing devices. Due to the mobility andflexibility of access nodes, managers need to realize real-time management of nodeposition, to meet the growing demands of target location, target tracking, searching andrescue and so on.Therefore, the wireless LAN node localization has become a hotresearch issue. But since it cannot receive the satellite signal indoor environment, GPSis not suitable for indoor positioning. For this reason the positioning technology basedon wireless LAN has become a hot research and development direction because of itswide deployment and low cost.On the base of through analysis aiming at the wireless network positioning, thepaper puts forward the improved centroid localization algorithm, and carrys outalgorithm simulation and performance analysis in OPNET Modeler network simulationsoftware, and verifies the effectiveness of the algorithm by realizing the algorithm in theself-designed " campus wireless positioning system ". At the same time, aiming at howto predict tracking node location problems, it is proposed that is weights optimizationalgorithm based on particle filter tracking, and the paper practices algorithm simulationin Matlab. The paper presents following main research results:(1) The characteristics of indoor wireless environment which are transmissionpower small, covering distance near, the environment changes greatly, cause thecalculated unknown node coordinate error large according to the centroid localizationalgorithm. In order to improve the positioning precision, reduce the localization error,the paper put forward centroid localization algorithm based on the weight update.Through simulation, in contrast to the traditional centroid localization algorithmsperformance of the new algorithm is improved about20%in a radius of2meterscommunication range.(2)Aiming at unknown node trajectory tracking problem in wireless network, onthe base of obtaining initial position information of the unknown node throughcalculation, synthesizing particle filtering and data association, the paper put forwardweight optimization algorithm based on particle filter tracking. In the simulationenvironment, the realization of the tracking algorithm proves it can track the unknownnode trajectory.(3) The paper designs and implements the positioning module and positiontracking module of the wireless positioning system. The fomer implements the location of unkown nodes which appear in the campus wireless local area network. The latterrealizes the unknown nodes trajectory tracking.