Abstract

A system for locating a movable radio terminal within a cellular telephone network, or other radio network, which includes a plurality of base stations that transmit synchronized timing reference signals. A receiver in the network receives transmissions from the radio terminals to be located that include information compiled at the radio terminal indicating relative propagation delays in receipt of the timing reference signals from at least three base stations. A processor coupled with the receiver, processes the transmissions indicating relative propagation delays to identify a geographic location of the radio terminal. A complementary radio terminal receives the timing reference signals from base stations, including a designated base station and compiles information indicating propagation delays, relative to the propagation delay of the timing reference signal from the designated base station, from at least two additional base stations. The radio terminal transmits the information compiled so that a station receiving the transmission may locate the radio terminal in response to the information and the known locations of base stations in the network.

Other References

• Sweeney, Dan; "The Quest for Spectrum Efficiency", Cellular Business, Jun. 1991; pp. 24-26, 28, 32, 34, 3