Base station synchronisation

Method of providing synchronisation between a plurality of base stations in a telecommunication system, the system comprising a plurality of cells, each containing one of the base stations and at least one mobile station. In the method, each base station is able to transmit a synchronisation signal to other base stations within transmission range. The base station uses a channel in the local cell, preferably a random access channel (RACH), provided for usage in the plurality of cells. The base station can then calculate the time differences d a,b , d a,c , d b,a between it's own clock pulses, i.e. synchronisation signal, and those from other base stations. A base station may either use the set of time differences to autonomously adjust its clock pulses to minimise time differences or the base stations may transmit the differences to a radio network controller which calculates synchronising adjustments that are transmitted individually to each base station. Various methods, either central or local, are provided to schedule utilisation of RACH channels and mobile stations may be instructed over another channel, preferably a broadcast control channel, to be silent in the RACH timeslots. A method of locating a mobile station within a telecommunication cell of the system is also disclosed which involves a determination of the location of three base stations, scheduling synchronisation measurements for each of the base stations using a RACH, comparing a signal received from the mobile, preferably on the RACH, with timing signals in each base station and using the comparison to determine the mobile location.