Research On Algorithm Of Ranging-based Localization In Wireless Sensor Networks

Wireless sensor networks are composed of a large number of sensor nodes which are in a mobile or static state. Hardware of the node costs low and it has a small volume-. They can be spread by machine or manual deployment in the monitoring area by random.The node itself carries sending and receiving device with wireless communication function can organize into a network with multi hop structure. Wireless sensor networks have a lot of fields of research, such as routing algorithm, the problem of information security, energy consumption, and data with acquisition and processing, and so on. Wherein, the localization technology of the sensor node is a very important basic core technology. This is because that the location information is very important in the surveillance activities with the sensor networks, and it is the prerequisite for taking measures and making decision by end-user in the network. Therefore, for the researchers both at home and abroad, it has become the focus of research discussion.This paper first discusses the basic definition of wireless sensor networks; the structure of the whole network and single node; and it also focuses on the localization technology of the wireless sensor networks, and explains the related notion of the location. In addition, the paper also introduces the main technology and algorithm in the research of location that generally divided into range-based and range-free. They have the tendency in the hardware overhead and positioning accuracy. In order to obtain higher positioning accuracy, this paper focuses on the study of the localization algorithm. Overall consideration of the hardware size, energy consumption, the cost of software and hardware and other practical factors, this paper is based on the ranging technology of RSSI as the research method of distance measurement between sensor nodes. Because of an impact on the measurement results by its geographical location, and environmental factors, it can be resulted a large error in the distance calculation by the model of RSSI. So in this paper, on the basis of in-depth study of the radio signal propagation path loss model, it improved the method of measurement data processing. Firstly, we can use Gauss fitting to manage the original location of the data in the experiment, that can eliminate error data, and then take the average value as RSSI measurement of the value with the current node, and then select beacon node basis, in order to reduce the measurement error, and finally through the MATLAB simulation. The simulation results show that, in this method, we can get more accurate location results, and then can improve the ranging error.In addition, this paper also gets a lot of theoretical research with localization, algorithm rang-based for wireless sensor networks. Considering the location accuracy and cost of each algorithm, we choose the triangle centroid location algorithm as the research object, and have carried on the theoretical analysis and experimental simulation in-depth analysis. The simulation results show that, this algorithm has reduced the positioning error with low efficiency and high positioning stability. Therefore, this paper will approximate PIT and the weighted impact factor to the original algorithm, in order to improve the algorithms, finally using MATLAB simulation. The simulation results show that:reducing the positioning error, and stability, the triangle weighted centroid localization algorithm which is improved has a higher efficiency and performance, and that can improve the positioning accuracy of the unknown nodes to a certain extent.