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.
Type:
Grant
Filed:
September 14, 1998
Date of Patent:
June 19, 2001
Assignee:
U.S. Wireless Corporation
Inventors:
Mati Wax, Oliver Hilsenrath, Abraham Bar
Abstract: A handoff technique for wireless communication systems uses pattern recognition of signal strength data to anticipate handoffs and reduce the total number of handoffs in the system. A criterion for system performance is used in determining the necessity for handoff. A window of signal samples from nearby base stations constitutes a pattern vector which is classified using a probabilistic neural network or other learning machine. The use of averaged signals and the sequencing of classes allow for a small number of training vectors for the pattern classifier. Substantially increased performance requires only one training vector per class. Simulation results indicate that, for a given probability of failure, the pattern recognition based handoff technique yields fewer handoffs than the conventional hysteresis rule.
Type:
Grant
Filed:
September 9, 1999
Date of Patent:
May 29, 2001
Assignee:
The Board of Trustees of the Leland Stamford Junior
University