WiFi Assisted GPS for Extended Location Services

This paper shows a lightweight technique for extending the positioning capabilities of a global navigation satellite system to areas characterized by reduced satellite visibility. This technique includes the presence of a WiFi coverage, used to implement the virtual satellite concept. In particular we assume that a customer terminal can receive both Global Positioning System (GPS) signals and WiFi beacons broadcasted by an access point (AP). We show that if such beacons include the georeferenced position of the relevant AP, the suitable usage of this information allows determining the GPS receiver position even if only three satellites are visible. Experimental results show that the achievable performance are similar to that obtainable by a plain GPS receiver using four visible satellites.