DEVICE AND METHOD IN A CELLULAR MOBILE TELEPHONE SYSTEM

摘要

PURPOSE: An apparatus in a cellular mobile telecommunication system is provided to determine the geographical position of a mobile station. CONSTITUTION: A distance between the mobile station and a radio base station is estimated from the propagation delay. The propagation delay is determined according to the present method where the mobile station sends access bursts to the base station which measures the access delay of the arrived bursts in the same way as an ordinary hand over. No confirmation on received access bursts is sent from the base station to the mobile station and therefor the hand over attempt is terminated. The connection between the mobile station and the previous base station is re-established. The measured access delay is proportional to the propagation delay and thereby also to the distance to the mobile station. The mobile position can be determined with good accuracy if values from at least three base stations are obtained, although with less accuracy if only two values are obtained. Also an access delay measured by earlier known methods can be used together with measurements achieved with the present method to determine the mobile position.