Patent ID: 8229457

Claim:
A positioning system for estimating a location of a mobile communication terminal, comprising: a processor; a distance information acquiring unit configured to acquire information indicating distances between at least one radio wave source and the mobile communication terminal, the distances being calculated based on radio waves transmitted and received between said at least one radio wave source and the mobile communication terminal; a direction information acquiring unit configured to acquire a plurality of pieces of information indicating directions of radio waves transmitted from the at least one radio wave source and received by the mobile communication terminal; a direction range calculating unit configured to calculate a range of directions from the at least one radio wave source to the mobile communication terminal from the pieces of information indicating the directions of the acquired radio waves based on a range calculation rule stored in advance; a location calculating unit configured to calculate the location of the mobile communication terminal based on the distances acquired by the distance information acquiring unit and the range of directions calculated by the direction range calculating unit for the at least one radio wave source; a reliability evaluating unit configured to evaluate reliabilities of the radio waves for positioning of the mobile communication terminal, for the at least one radio wave source, from the distances acquired by the distance information acquiring unit and the range of directions calculated by the direction range calculating unit, based on a reliability calculation rule stored in advance; and a determining unit configured to determine a radio wave source associated with information to be used for calculation of the location of the mobile communication terminal, based on the reliabilities evaluated by the reliability evaluating unit.