Method and system for determining position of a cellular mobile terminal

A method for determining the distance between a mobile radio station and a first radio base station, comprising the steps of:

• said mobile radio station and said first radio base station each determining a local time of transmission of an uplink signal and a downlink signal respectively;
• said mobile radio station and said first radio base station each determining a local time of reception of said downlink signal and said uplink signal respectively;
• calculating an apparent uplink air-time from said local time of transmission of said uplink signal and said local time of reception of said uplink signal;
• calculating an apparent downlink air-time from said local time of transmission of said downlink signal and said local time of reception of said downlink signal;
• adding said apparent uplink air-time and said apparent downlink air-time to obtain a round-trip air-time;
• and
• multiplying said round-trip air-time by the speed of light divided by two.

A method for determining the distance of a mobile radio station in a mobile communications system, comprising the steps of:

• setting up a connection between said mobile radio station and a first radio base station in said mobile communications system;
• calculating an apparent uplink air-time and apparent downlink air-time for said connection between said mobile radio station and said first radio base station utilizing a local time of transmission and a local time of reception measured from an associated local clock at said mobile radio station and said first radio base station;
• adding said apparent uplink air-time and said apparent downlink air-time for said connection to obtain a round-trip air-time for said connection;
• and
• determining a distance for said connection, by multiplying said round-trip air-time for said connection by the speed of light divided by two.

A method for determining the position of a mobile radio station, comprising the steps of:

• measuring a round-trip delay between at least one serving radio base station and said mobile radio station;
• said at least one serving radio base stations reporting said round-trip delay to a network processor;
• said mobile radio station measuring a respective local arrival time of a signal from each of a plurality of radio base stations;
• reporting said respective local arrival time of said signal from each of said plurality of radio base stations to said network processor;
• said mobile radio station transmitting a position data signal, and reporting to said network processor a local transmission time for said position data signal;
• each of said plurality of radio base stations measuring a respective local arrival time for said position data signal;
• each of said plurality of radio base stations reporting to said network processor a respective local transmission time for said signal from each of said plurality of radio base stations, and said measured respective local arrival time for said position data signal;
• and
• said network processor calculating said position of said mobile radio station with said reported local arrival times and said reported local transmission times for said position data signal and said signal from each of said plurality of radio base stations.

A system for determining the distance between a mobile radio station and a first radio base station, comprising:

• means for said mobile radio station to determine a local time of transmission of an uplink signal and said first radio base station to determine a local time of transmission of a downlink signal, and said first radio base station to determine a local time of reception of said uplink signal and said mobile radio station to determine a local time of reception of said downlink signal;
• and
• processing means for:
• calculating an apparent uplink air-time from said uplink local time of transmission and said uplink local time of reception;
• calculating an apparent downlink air-time from said downlink local time of transmission and said downlink local time of reception;
• adding said apparent uplink air-time and said apparent downlink air-time to obtain a round-trip air-time;
• and
• multiplying said round-trip air-time by the speed of light divided by two.