Research On Range-Free Location Algorithms Based On Wireless Sensor Network

In recent years, along with the economic development, science and technology has improved continuously, the applications of wireless sensor networks(WSN) was becoming more and more widely, it can be used for emergency services, navigation systems, traffic control monitoring and healthcare monitoring, and also can be used for military industry and other fields, the location of the wireless sensor network node sensor is the key issue. If the sensor node does not know their location, then the data acquired from node about the perceived environment is meaningless, for example, in emergency, one second position location delay from the identification of the injured victims may result in life-threatening situations. For a node positioning, Global Positioning System(GPS) is the easiest way, but since its high cost of energy consumption, the large number of sensor networks nodes, the GPS deployed on each node is unrealistic.With the development of embedded technology and communication technology, many WSN positioning methods were emerged, such as received signal strength, time of arrival, time difference of arrival based on distance and angle of arrival positioning method, centroid location, DV-Hop, APIT and other Rang-free positioning method. Wherein the range-free positioning does not need to directly measure the distance, by positioned through the network connectivity information and hops, this positioning method was simple and with high positioning accuracy. This paper studies the range-free localization algorithm, the following key elements are:1)WSN structural principle, the main features of key technologies, problems and applications are presented first, and range based localization algorithm and range-free algotithm were discussed. The principle, strengths and weaknesses of the locations were also discussed, then several basic position calculation method were introduced, such as DV-hop, the final selection of the range-free positioning method was the main method in this study.2)Two typical range-based WSN localization algorithm were introduced, namely centroid location algorithm and DV-Hop localization algorithm, the basic principles of the process of the two algorithms were discussed, and the results of its simulation experiments were analyzed and we find out the reasons for the positioning error.The centroid algorithm was effected mainly by anchor node density, the larger the network topology, however, the DV-Hop algorithm was depended on the average distance per hop and the number of hops, in addition, the anchor node distribution network structure is also required.3)The positioning accuracy of the DV-Hop algorithm is not high, an improved scheme with the weighted average distance per hop error processing, and allowing multiple nodes participating positioning beacons was proposed, the weighted algorithm is named as WDV-Hop algorithm, using MATLAB simulation platform, we verified the location results, and the results were compared with the traditional DV-Hop algorithm localization error.4)On the basis of DV-Hop algorithm, further improvement was proposed based on genetic optimization algorithm thinking, to further reduce positioning errors, and to improve accuracy. The weighted genetic algorithm was named as GWDV-Hop algorithm The simulation experiment was carried out with the traditional algorithms, WDV-Hop localization algorithm and GWDV-Hop algorithm. The parameters which may affect the latation accuracy such as the ratio of anchor nodes and the total number of nodes were simulated.5)This section concludes the whole paper, points out deficiencies and looks forward to the unsolved.