Abstract:

With the application and development of location-based service,outdoor and indoor positioning technology has been developing rapidly.Indoor positioning technology has been widely utilized especially in the continuous improvement of WiFi positioning technology.But two positioning methods of WiFi positioning technology are required to know the exact coordinates of the indoor network access points.This requirement cannot meet some emergency location requirements.Therefore,this paper presents an algorithm for automatically calculating the coordinate of indoor access points based on M estimation.The algorithm utilizes the satellite location information and the RSSI value of WiFi signal at the junction of indoor and outdoor,uses the segmented RSSI ranging algorithm to improve the accuracy of long distance RSSI distance and combines the residual absolute and minimum M estimation to improve distance intersection positioning algorithm.Finally the three-dimensional coordinates of the indoor access points were calculated,to achieve automated projection process.The experiment results show that the positioning accuracy of this method is 50% higher than conventional distance intersection least squares algorithm and the coordinates of the indoor access points can be calculated more accurately in real time,and the WiFi positioning technology is further improved.

Key words: WiFi positioning, RSSI distance measurement, distance intersection positioning, M estimation