Research, Based Localization Algorithm For Wireless Sensor Networks

Wireless sensor networks, which integrate microelectromechanism technologies, 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.The research of this dissertation is focused on how to improve the location accuracy under the premise of a moderate complexity in the algorithm:1) After analyzed the system architecture and key technologies of wireless sensor network system based on IEEE 802.15.4, the principles and methods of wireless sensor network system location algorithm are also described.2) Ranging technology combining reference nodes, using the constraint relation between transfer matrix and observation matrix, the CTLS algorithm based on TDOA are presented in this dissertation. This location algorithm is transformed into the criteria total least square algorithm issue, and then, the criteria total least square algorithm is equaled to the non criteria total least square algorithm, target location can be estimated by Newton iterative.3) In wireless systems, the LOS path is often blocked and the communications is conducted through reflected, diffracted and scattered rays due to the interaction with objects in the propagation environment. This phenomenon leads to big bias in the TOA, TDOA estimations and finally causes errors in location estimation. To resistance the NLOS impact on the location error, combing Centroid and TDOA. Comparing with the single TDOA algorithem, the performance of location is improved obviously.4) The Range-free algorithm demonstrates greater advantages than the range-based algorithm in anti-NLOS, small coverage radius. In contrast to the disadvantages of the Centroid algorithm, the non-linear modified method is used to make the location precision controllable.