Research Of Localization Technology In Wireless Sensor Networks

Wireless sensor networks(WSN) are multi-hop self-organized network systems in which massive sensor nodes are randomly deployed to communicate with each other, and it can be wildly used in many areas such as national defense, environmental monitoring, medical treatment and outer space exploration. The performance of node localization which is regarded as one of the sustainable techniques in WSN has been the basis of most applications in WSN. Self-localization of sensor node is to get the position information of node by using information of some known nodes and some special mechanisms. Correct self-localization of sensor nodes in the promotion of monitoring events normally.There is unpractical shortcoming in the node localization, such as great impacted by circumstances, high algorithm complexity and huge energy-costs. It is obviously that the technology of wireless sensor networks will go-ahead very quickly and its applications will be wider and wider in the coming future. Thus it can be seen that designing practical localization technology is a very essential and challenging research issue in WSN, and it is of great significance as well.In this thesis, we study the localization technology of wireless sensor networks completely and in depth. At first, we introduce the basic concepts and key techniques of WSN. Then, we investigate the basic theory of localization technology in WSN. We classify the existing typical localization technology, and represent the performance standard.This thesis mainly focuses on the research of the localization technology of sensor nodes in WSN and proposes two range-free localization algorithms. The main achievements of this paper are listed as follows:(1) To solve the limitation that DV-Hop algorithm can't locate accurately when the twisted path exists in wireless sensor networks due to the barriers, we introduces the concept of Trusty-Degree, and proposes a Trusty-Degree based localization algorithm—TDDV-Hop, which can filter the appropriate average distance per hop by estimating the value of Trusty-Degree. Simulation result demonstrates that TDDV-Hop algorithm can reduce the localization error by twisted path, and improve the accuracy of localization. (2) In order to use less anchor nodes to achieve more precise localization, we propose a range-free localization algorithm which is based on three mobile anchor nodes, the algorithm can guarantee that each unknown node can choose the anchor nodes which are not far away from itself to implement localization, and construct an optimization model to maximize the area of double overlay regions in the network. The results of simulation show that this algorithm can improve the precision of localization.For the node localization algorithm is such a complicated problem, this paper just researches some points of it. There still remains a lot of awkward problems. In order to design a perfect algorithm, we have to think over and study from various orientations and angles. Meanwhile, we should consider the factors of power cost, time waste, etc. It will be need to be studied more in depth in future work.