Research Of WSN Location Technology Based On ZigBee Research Of WSN Location Technology Based On ZigBee

Wrieless sensor networks,which integrate technologies of micro-electro-mechanism sensing, embedded computing, distributed information processing and wireless communication, lead to a new pattern of information gathering and processing. The fundamental problems of sensor networks are deployment and coverage, localization, and networking protocols. And localization, which has been focused as a basic problem, is the precondition of many applications of sensor networks, such as target identification,surveillance and tracking. Therefore,we discuss the several of today's mainstream positioning algorithm: Time Difference of Arrival positioning algorithm, DV_Distance positioning algorithm, the reference node based on mobile positioning mechanism.First of all, the research status of wireless location techniques and positioning systems for WSN are summarized based on the study of a lot of related literatures. In this thesis, the criterion of performance evaluation and algorithms, the taxonomy for wireless sensor networks localization systems are described, the principles and characteristics of recent representative localization approaches are discussed and presented.Secondly, we further study based on the multi-hop wireless sensor network location algorithm.we presented a novel EKF-based positioning scheme using TDOA for sensor networks. Our scheme which is based on time measurement requires no global time synchronization in the wireless sensor networks and minimal extra hardware in sensor construction. We firstly utilize the TDOA measurements to locate target sensor node, and then make use of the estimated values which is educed from the algorithm as observed values for Extended Kalman filtering and estimation, then we analyze the results of simulation based on three anchor sensors.Thirdly, aiming at the enhanced positioning accuracy of wireless sensor network node location, an improved DV_Distance positioning algorithm, which uses a differential error correction scheme for reducing cumulative distance error and node location error accumulated over the multiple hops, is proposed. In this thesis, we discuss the proper situation of using the algorithm, the factor of localization error, communication and computation cost, and whether the error can be forecasted.Finally,the most important problem of the localization algorithm with a mobile beacon is the problem how we choose the path of the mobile beacon, and when the beacon broadcasts its position. We propose a feasible scheme using virtual force, which assures the beacon's coverage of the surveillance area, and makes the beacon's path shortest.