British Telecommunications Public Limited Company

Stephen M Gannon

Ian Goetz

Peter R Munday

The location of mobile unit cellular radio system is determined by determining the differences in timing of a characteristic feature of the transmission of the control channel of each of a plurality of base stations as measured at the mobile unit. The characteristic feature may, for example, be the training signal already used by the mobile unit in a cellular system to measure signal strength in handover operations. By determining the differences between time of arrival of transmissions from four base stations, location in two dimensions can be derived without prior knowledge of the actual distance to any of the base stations. A fifth base station allows location in three dimensions to be determined.

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Buckinghamshire, United Kingdom

Stephen M Gannon