Research On The Technologies Of Nodes Localization With RSSI Quantitative Models For Wireless Sensor Networks

With the development of sensor techniques, low-power electronic and radio techniques, low-power and inexpensive wireless sensors have been put into application, then the wireless sensor networks have appeared. Wireless sensor networks can be applied to many areas, such as military affairs, commerce, medical care, environmental monitoring, and have become a new research focus in computer and communication fields. Many applications of wireless sensor networks are based on sensor self-positioning, such as battlefield surveillance, environment monitoring, indoor user tracking and others, which depend on knowing the location of sensor nodes. Because of the constraint in size, power, and cost of sensor nodes, the investigation of efficient location algorithms which satisfy the basic accuracy requirement for WSN meet new challenges.The location techniques for WSN can be divided into two categories : Range-based approaches and Range-free approaches. Range-based methods have better accuracy, but require additional hardware at the sensor nodes, which are not available on regular application sensor networks. Acknowledging the requirement of hardware cost, the range-based solutions may be inappropriate in relation to the required location precision. Researchers have sought alternate range-free solutions to the localization problems in sensor networks. The range-free algorithms make no assumption about the availability or validity of range information. Because of the advantages on power and cost on sensor node, this thesis focuses the investigation on the range-free algorithms for WSN. The main research works are as below:(1) Analyzing the basic principles and key technologies of localization in wireless sensor networks, summarizing both advantages and disadvantages of the exiting algorithms.(2) The mechanism of DV-Hop algorithm is analyzed and a comparison with its improved version also presented in the paper.(3) Proposing a DV-Hop improved algorithm based on the RSSI quantitative model. The main principle of the new algorithm is the introduction of RSSI to improve the positioning accuracy. The Analysis and Simulation results show that the new algorithm can improve the accuracy of the localization.(4) Chan algorithm is introduced here to replace the triangulation algorithm. Refinement method is although introduced here to improve the accuracy of the sensor positioning. The simulation results show that: the new algorithm can improve the accuracy of positioning to some extent.(5) Extended the ad-hoc simulation platform of the University of Geneva -AlgoSenSim,Comparing and analyzing the characteristics of these two algorithms, the simulation results show that both improved algorithms have a better feasibility and practicability.