Radio transmitter location finding in CDMA wireless communication systems
First Claim
1. In a spread-spectrum CDMA wireless communication system comprising a mobile transmitter and a receiver connected to an antenna array, a method for estimating the location of the mobile transmitter, the method comprising:
- receiving at the antenna array signals originating from the mobile transmitter;
determining from the received signals a signal signature corresponding to the mobile transmitter, wherein the signature comprises a spatial signature and a code correlation signature;
comparing the signal signature to a database comprising calibrated signal signatures and corresponding location data; and
selecting from the database a set of likely calibrated signal signatures and a corresponding set of likely calibrated locations, wherein a difference between the likely calibrated signal signatures and the signal signature is minimized.
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Accused Products
Abstract
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.
361 Citations
13 Claims
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1. In a spread-spectrum CDMA wireless communication system comprising a mobile transmitter and a receiver connected to an antenna array, a method for estimating the location of the mobile transmitter, the method comprising:
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receiving at the antenna array signals originating from the mobile transmitter;
determining from the received signals a signal signature corresponding to the mobile transmitter, wherein the signature comprises a spatial signature and a code correlation signature;
comparing the signal signature to a database comprising calibrated signal signatures and corresponding location data; and
selecting from the database a set of likely calibrated signal signatures and a corresponding set of likely calibrated locations, wherein a difference between the likely calibrated signal signatures and the signal signature is minimized. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification