On the hyperbolic positioning of GSM mobile stations

This paper presents a method for locating GSM mobile stations (MSs) using a hyperbolic position location technique. The proposed solution makes use only of GSM functions, avoiding additional GPS (Global Positioning System) equipment. The algorithm is implemented with an extended Kalman filter (EKF) that, processing the time delay difference of arrival (TDOA) measurements, allows one to estimate both the position and the speed vectors of the MS. The TDOA estimates from at least three base transceiver stations (BTSs) are obtained from OTD (observed time difference) and RTD (real time difference) parameters yet defined by ETSI for a GSM Phase 2 network. Computer simulations are provided to show the feasibility of the proposed approach.