Power-measurement-based relative localization in GSM cellular networks

This position paper aims at proposing a new relative localization strategy for GSM cellular networks. We in particular consider a GSM network scenario where only a limited number of mobile phones is at known positions. This is the case of mobile phones which are equipped with satellite navigation receivers and know their absolute position. Such mobile phones will be referred to as located mobile phones. Mobile phones which either are not equipped with satellite navigation receivers or are out of coverage of their satellite navigation receivers do not know their absolute position and they will be referred to as un-located mobile phones. In both cases un-located mobile phones do not know their absolute position. Relative localization means then to locate the un-located mobile phones by exploiting the presence of neighbor located mobile phones and the communication capabilities of all GSM mobile phones. The idea arises from the observation that existing GPS-based positioning methods for GSM networks allow positioning only the GPS-enabled mobile phones that are in line of sight with at least four satellites. On the contrary, relative localization would allow locating both GPS-unequipped mobile phones and GPS-enabled mobile phones which are out of coverage. The proposed localization scheme is based on power level measurements, and it does not require network infrastructure changes, differently from positioning methods based on timing measurements. In this paper we identify and analyze the main related issues, and we sketch a possible solution.