The Research Of Position Algorithm For Wireless Sensor Networks

Wireless sensor networks, which integrate technologies of micro-electromechanism sensing , embedded computing, distributed information processing and wireless communication, lead to a new pattern of information gathering and processing, can be wildly used in many areas such as national defense, environmental supervision, medical treatment, outer space exploration, counter-terrorism and disaster retrival. Itis considered as one of the most important techniues of the 21^st century. But for most applications, data without location information has limited use. Localization has become one of the indispensable supporting techniques in wireless sensor networks, and has widely drawn attention of domestic and foreign scholars.Existing localization algorithms can be roughly divided into two categories: range-based localization algorithm and range-free localization algorithm. For the limitations of battery, cost and volume in wireless sensor networks, the range-free localization algorithm has higher practicability. This paper mainly fouses on the localization algorithms for WSN. First of all, the research significance and research status of target localization are presented; then, the type of the localization algorithms, the criterion of performance evaluation and the method of computing coordinate. In this article we introduce the range-free localization algorithms, and analyize the performance of some kinds of typical range-free algorithms. The most existing range-free localization algorithms require high ratio beacons. It will enhance the cost of network, and make the communication collision seriously. So we introduce two types of range-free localization algorithms base on studying existing algorithms. The two algorithms are not require deploy many beacons. The one algorithm of we introduce can achieve localization that make use of power control. In this algorithm, the beacons which can broadcast single with different power. The unkown node estimate distance between the beacon and the unknow node base on whether the single which broadcast by the beacon was received. The unknow node calculate it's coordinate when they get enough distance. The algorithm can calculate the coordinate without measure equipment. But for making the result more precise, we amend the distance between the beacon and unknow node use RSSI. If the power of the beacon is enough, this algorithm could finish the localization use only three beacons. Forthermore, we also introduce a algorithm finish localization use a mobile beacon. A mobile beacon with GPS move in the deploy area, and broadcast their's coordinate with fixed interval. The localization will finish when the unknow node receive enough coordinate.The two algorithms which introduced in this paper have good performance in algorithm complication and ratio of covering without more beacons. So the cost of the algorithm is lower. The simulation results show that the algorithms have good performance in precise and complex.