Patent ID: 6031490
Filing Date: 2000-02-29
Classification: G01S,H04W

Abstract:
A method for determining the geographical position of a first mobile radio terminal in a mobile radio system, said mobile radio system including a network controller and at least three radio base stations, each of said at least three radio base stations including an uplink TOA measuring unit operable to communicate with said network controller, a control unit, and a time reference unit operable to provide timing reference signals to said uplink TOA measuring unit, at least one of said at least three radio base stations colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio interface, and a service node operable to store known positions of at least two of said at least three radio base stations, the method comprising the steps of:receiving a request in said mobile radio system to determine the geographical position of said first mobile radio terminal;determining and reporting the position of said second mobile radio terminal to said service node;directing said first mobile radio terminal to transmit digital signals uplink on a traffic channel when said first mobile terminal is not transmitting or transmitting only analog signals;measuring in each uplink TOA measuring unit an uplink TOA of the digital signals transmitted by the first mobile radio terminal;receiving in said network controller said uplink TOA measurements from said at least three radio base stations and a traffic channel number to said traffic channel;translating said traffic channel number to an identity of said first mobile radio terminal;conveying said uplink TOA measurements and said first mobile radio terminal identity to said service node; andcalculating in said service node the position of said first mobile radio terminal using said known positions of said at least three radio base stations and said uplink TOA measurements.