Abstract: A method and apparatus reduces the ambiguities in the determination of cellular telephone locations in a location finding system based on the use of multipath signals. A location finding base station determines a signal signature from a subspace of an array covariance matrix. The signature is compared to a database of calibrated signal signatures and corresponding locations, and a set of likely locations whose calibrated signatures best match the measured signature is selected. A subset of most likely locations is selected from among the likely locations by comparing a function which represents how closely the measured signature matches the set of calibrated signatures with functions which represent how closely each likely signature matches the set of calibrated signatures. The locations corresponding to the best matching function are selected.

Abstract: A method and apparatus for location finding in a wireless communication system uses multipath signals in order to accurately determine a transmitter's location. Direct path and multipath signals from a mobile transmitter [74] arrive at an antenna array [80, 82, 84] of a base station receiver [76]. The base station determines signal signature from a subspace of an array covariance matrix. The signature is 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 transmitter location. The database of calibrated signal signatures and corresponding locations is generated by a calibration procedure in which a phone [74] transmits location data derived from a GPS receiver [88] and GPS satellites [90, 92, 94] to the base station [76] which records the location information together with the signal signature of the transmitter [74].

Abstract: In assigning features to nodes of a tree structured classifier and determining terminal nodes in response to a training set of objects each being determined by a plurality of features, a selected characteristic, such as a cost function based on the minimum description length, of the plurality of features unused at prior nodes is determined along the path from the root to the present node, a feature is then assigned to the node having a preferred value for the selected characteristic relative to the other features. Child nodes of the node are created in response to the assigned feature with features assigned thereto in a similar way. The preferred values for the selected characteristics of the assigned features for the child nodes of the node are combined and compared with the preferred value of their father node. Classification of the father node as a terminal is based upon such a comparison.