Determining a position of a mobile communication device

A method of determining a position of a mobile telecommunication device which transmits a cellular signal to base stations connected by a data link and having known locations, the method comprising the steps of:

• receiving the cellular signal at two or more base stations having known locations wirelessly;
• providing a WLAN reference signal to the base stations;
• correlating the cellular signal and the WLAN reference signal so as to produce a correlation for each base station as received by a receiver outside the base stations and coupled to the base stations via the data network, by correlating the cellular signal received at a first base station with a first WLAN reference signal so as to produce a correlation for the first base station, detecting a maximum in the correlation, which maximum is indicative of a time of arrival of the cellular signal from the mobile telecommunication device at the first base station;
• correlating the cellular signal signals received at a second base station with a second WLAN reference signal so as to produce a correlation for the second base station, detecting a maximum in the correlation, which maximum is indicative of a time of arrival of the cellular signal from the mobile telecommunication device at the second base station;
• deriving from the times of arrival respective distances to the mobile communication device;
• and
• using the respective distances and the respective known locations of the base stations to derive a location of the mobile telecommunication device.