Research on WiFi Indoor Location Algorithm Based on RSSI Ranging

A weighted centroid algorithm of no height influence is proposed considering the influence of access point(AP) deployment height on positioning accuracy. Firstly, the received signal strength indication(RSSI) signal are collected and processed by Gaussian fitting and Kalman filtering, and the distance between terminal(such as phone) and AP is obtained according to indoor signal propagation model. Then, the vertical distance is eliminated by geometric method, and the plane distance between the AP and the terminal is obtained. Finally, the position coordinate is calculated by the weighted centroid algorithm of no height influence. For a multi-storey building, a Floor number recognition method is proposed, the two dimensional(2D) planar positioning and the Floor number recognition method are combined to construct a near three dimensional(N-3D) indoor location algorithm. In the laboratory building, the floor number was recognised with the above methods and the recognition rate is 100%. To do positioning experiments in the large classroom, the results showed that: compared to the traditional positioning algorithm, the improved algorithm have a certain increase on the accuracy and stability.