Indoor Positioning Based On WiFi Signal Strength And Its Application Research

Now there are more and more demands for indoor positioning.Usually, use electrical, magnetic, optical, acoustic, mechanical and other means to determine the location of the relevant parameters. Due to the popularity and development of wireless networks, indoor wireless positioning has become a hot spot in recent years. Many kinds of indoor positioning technology based on wireless signal were produced, such as ultrasonic, infrared, Bluetooth, radio frequency, WiFi, etc. In recent years, WLAN's large scale laying, indoor wireless location technology based on WiFi is becoming a hot spot of the research of location service.In this paper, the main work is as follows:1. The attenuation factor N in signal attenuation model is not always stay in constant value,it changes during propagation process because the difference between indoor environment.Therefore, using the three spline interpolation on the attenuation factor n interpolation processing. After receiving the signal strength, the location node can solve the dynamic value of the attenuation factor n according to the interpolation node sent by the server side, and then the distance between the node and the hot spot is replaced by the model, and the error compensation of the universal model is realized. In this paper, select a wide range of indoor corridor environment to validate the proposed three spline interpolation, confirmed that the dynamic path loss after the interpolation, fit more in the actual measured data, and more conducive to the replacement of the precise distance.2.The premise of the classic three edge location algorithm is based on the signal attenuation model to replace the signal intensity with high precision, and the model error is inevitable due to the complexity of the indoor environment. Based on the multiple pre location calculation, the prior knowledge of the specific location environment is screened and the mean value is changed, and the mean value is taken as the three-dimensional coordinates of the location node. The improved algorithm can obviously reduce the positioning error and improve the positioning accuracy, and it can extend from the plane to the three-dimensional space.3.In view of the situation that the server side load is too large in the location system, the positioning calculation is transferred from the background server to the corresponding positioning node, which reduces the calculation pressure and the communication cost of the background server, and realizes the distributed positioning. In the process of positioning the server does not need to participate in the calculation, just need to listen to the client's request, after the decision to send saved parameters after the judgement. The positioning process is carried out at the end of the positioning node, which greatly reduces the limit of the capacity of the server to locate the nodes in the system, and can meet the requirements of large users and high real-time requirement in complex environment.