Research On WiFi Network Location Algorithm Based On RSSI Value

Wireless location technology is widely used in civil commercial, military communications and other fields. With the rapid development of the "wireless city", the layout of the Wi Fi network also increases. The access points of Wi Fi network throughout are spread in public places such as shopping malls, schools,hospitals, and stations. The Wi Fi network can make up the shortages of the GPS and Bei Dou navigation system, which have application restrictionsin built-up area and indoor, at the same time, it can improve the positioning accuracy. The research of Wi Fi network location algorithm which based on RSSI values has important practical significance.In this thesis, at first, the research of network positioning technology at home and abroad and the advantages of Wi Fi network have been introduced.Compares the advantages and disadvantages of ranging localization algorithmwhich commonly used, and so does their application scope. Analyzes the main factors affecting location and typicalthe spread of several models.According to theoretical and experimental data analysis, the writer judges that the environment has great influence on the positioning system, and from this,raise the secondary positioning algorithm which based on received signal strength. The algorithm uses the log distance path loss model, the path loss values are determinedby the environment of the positioning system; at the receiving end, use the improved t test and median arithmetic average filtering method to deal with the error signals; every two adjacent AP nodes communicates and computes path loss values, the path loss values of each AP node location for the first time are used for this AP node and the average value of adjacent AP node path loss; after that, use the improved least-square method to locate for the first time. Combiningthe resultof pending locating nodesat firsttime, the path loss value can be updated, and use the Chan algorithm to locate secondary which has higher positioning accuracy.In the Matlab simulation platform, setting up a simulation system to proof in the two-dimensional space and three-dimensional space. The results show that the proposed localization algorithm can significantly improve the positioning accuracy. The positioning algorithm has a good stability, andcan adapt to different environment, soit has the very high value in use. Revised the system properly, it also can be used in other areas, such as wireless intelligent warehouse management, hospital intelligent monitoring system, etc.