A Hybrid Localization System In Wireless Sensor Networks

The development of MEMS, RF technology and network technology promotes wireless sensor nodes towards the direction of small size, intelligence and multi-function, which endows wireless sensor networks (WSNs) a prosperous growing space and tremendous value in application. WSNs have applied extensively in military, environment monitoring, medicine care and transportation control. Position information is of vital importance in the various applications in WSNs. The information gathered by sensors should be meaningful only with the presence of position information. Besides, position information helps to improve routing efficiency, coverage performance, etc. Therefore, the dissertation concentrates on the research of localization in WSNs.In the beginning, the dissertation describes the research background in WSNs, summarizes categories of localization models in WSNs and the typical localization methods. Then the dissertation analyzes the features of localization methods considering both precison and energy consumption and proposes the idea of hybrid localization system (HLS). HLS is composed of coarse-grained localization system (CLS) and fine-graind localization system (FLS). CLS takes the wireless signal strength as the reference for distance and gets the rough area the target located. According to the trade-off of position precision and energy consumption, FLS is in charge of optimization. FLS takes image to localize target. When FLS is informed, it takes picture, binarized, connected component labeled and calculates the coordinates by homography matrix. The homography matrix is derived in the calibration process beforehand. Finally, the dissertation provides the detaied test results of both CLS and FLS. Meanwhile, it provides solution to the problems occured in the test process. The test shows that HLS outperforms in both position precision and energy consumption. Then the dissertation summarizes the work done and suggests future work.