Research And System Implementation Of WIFI Indoor Positioning Algorithm Based On Signal Strength

With the development of wireless technology and intelligence, the service based on location has been widely used in people's life as a strategic emerging industry. At present, in the outdoor environment, GPS and Beidou System can provide accurate positioning and navigation services. However, in the indoor areas, the satellite signal is too weak to achieve positioning service.The indoor positioning technology based on WIFI uses the principle that the wireless signal has been attenuated in the course of transmission. There are mainly two types of positioning algorithms: range-based positioning algorithms and range-free positioning algorithms. The range-based positioning algorithms mainly make use of a path loss model, transform the signal strength into the distance information, then use the trilateral localization algorithm and other methods to realize positioning, or other algorithms based on distance. The range-free positioning algorithms use signal intensity vector to establish the signal intensity fingerprint database, the real-time signal and the information in the fingerprint database can be mapped to get the position information. The method is suitable for the indoor area of slow scene change.This thesis mainly studies the indoor positioning technology based on WIFI.At first, the research status and development prospects of the domestic and international wireless indoor positioning technology are analyzed. Then it states the three aspects of the WIFI communication protocol, the mobile station how to access wireless local area network and several typical path loss models. Then it mainly introduces the indoor positioning technology based on WIFI. The simulations on MATLAB of the trilateral localization algorithm and the fingerprinting technique are respectively carried out, it analyzes performance, compares the two methods of the pros and cons and makes the strategy of positioning method selection. At the same time, the K value of the KWNN(the Weighted K Nearest Neighbor) of the fingerprint matching algorithm is studied. Finally the indoor positioning system is based on client/server mode, which is realized in the Windows environment to implement the server middleware system development and client development on Android platform. The system can provide real-time, relatively accurate location information and display information on the electronic map. The main work of this thesis is:1.The trilateral localization algorithm and the fingerprinting technique are simulated on MATLAB, and the performance of the two methods is analyzed.2.In the office, experiments and data simulations are carried out, and a strategy of K value in KWNN algorithm is proposed, which can reduce the blindness of the selection to a certain extent.3.On the basis of the theory and algorithm simulations, the client/server model is adopted to realize the development of the server middleware system in Windows environment, and realize the client development on the Android platform. It can realize the real-time display of the positioning information, which makes the user know the location of their own.