A New Cooperative Localization Method for UMTS Cellular Networks

The ETSI/3GPP standardization body has defined a general location services (LCS) UMTS architecture which i) provides assistance data for mobile phones equipped with satellite navigation receivers and ii) is able to localize mobile phones not equipped with satellite navigation receivers or out of coverage. Nevertheless, the most of the already deployed systems for location-based services either assume that UMTS mobile phones are equipped with satellite navigation receivers and limit themselves to collect and transmit assistance data, or derive the position of mobile phones from the identifier of the serving cells. As the accuracy of methods based on cell identifiers depends on the size of the serving cell and it may drop to even few kilometers in case of macrocells, this paper considers the localization problem still unsolved for the UMTS mobile phones not equipped with satellite navigation receivers or out of coverage. To solve this problem, this paper proposes a new cooperative localization method for UMTS cellular networks. The idea arises from the observation that an ever increasing number of UMTS mobile phones will have an integrated satellite navigation receiver and will be able to position themselves. Thus, the proposed method consists in using the ETSI/3GPP LCS architecture to allow mobile phones without satellite navigation receivers or out of coverage to estimate their position by performing power measurements on signals emitted by mobile phones with satellite navigation receivers and known-position¹.