Patent ID: 6329948
Filing Date: 2001-12-11
Classification: G01S

Abstract:
A method of determining a position of a wireless communication terminal in a wireless communication system including a plurality of mobile stations each having a wireless communication terminal installed therein, a plurality of base stations each being arranged at known positions on a plane and a communication control station controlling communication between said plurality of wireless communication terminals and said plurality of base stations, comprising the steps of:measuring times of receipt at which a radio wave emitted by a wireless communication terminal provided in a mobile station whose position is to be determined are received by at least three base stations which are substantially synchronized with a standard time;deriving calculated wave emitting times for each of said at least three base stations by replacing a position of the mobile station in equations by a plurality representative positions within a position calculation area set in a simultaneous communication area in which said at least three base stations can simultaneously communicate with the mobile station, said equations being obtained by modifying equations in which products of a velocity of light and differences between an actual wave emitting time at which the radio wave is emitted from the wireless communication terminal of the mobile station and said measured times of receipt become equal to distances between said mobile station and said at least three base stations;deriving a sum of unsigned differences between two calculated wave emitting times in all combinations of two calculated wave emitting times obtained from at least three calculated wave emitting times for each of a plurality of representative points; anddetermining a position of the mobile station at one of said plurality of representative points at which said sum becomes minimum.