06249680 is referenced by 197 patents and cites 13 patents.

A method and apparatus for location finding in a CDMA wireless communication system uses multipath signals in order to accurately determine a transmitter—s location. Direct path and multipath signals from a mobile transmitter arrive at an array of p antennas belonging to a cellular network base station. A location finding apparatus connected to the base station contains a multichannel receiver that uses PN sequence information provided by the base station receiver to despread the p signals and to separate each of the p signals into temporally distinct multipath parts. A signal processor calculates a signal signature for each active mobile. The signature is comprises a code correlation function, a set of temporal delays corresponding to the multipath parts and a set of signal subspaces. The signature is then compared to a database of calibrated signal signatures and corresponding locations, and a location whose calibrated signature best matches the measured signature is selected as the most likely location of the mobile transmitter. The location information can be used to increase the performance of a cellular telephone network and/or to provide useful services to cellular telephone customers.

Title
Radio transmitter location finding in CDMA wireless communication systems
Application Number
9/152916
Publication Number
6249680 (B1)
Application Date
September 14, 1998
Publication Date
June 19, 2001
Inventor
Abraham Bar
Palo Alto
CA, US
Oliver Hilsenrath
Alamo
CA, US
Mati Wax
San Ramon
CA, US
Agent
Lumen IPS
US
Assignee
U S Wireless Corporation
CA, US
IPC
H04Q 7/20
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