Patent ID: 7579990

Claim:
A method of estimating a location of a target terminal by using a radio signal and a location of a plurality of anchor terminals, the radio signal being transmitted at least in either of directions from the target terminal to the plurality of anchor terminals and from the plurality of anchor terminals to the target terminal, comprising the steps of: using information required for location estimation derived from the radio signal and the location of at least one of the plurality of anchor terminals to obtain a first estimated location of the target terminal; calculating an estimated distance between the target terminal and the at least one anchor terminal based on the first estimated location, and calculating an expected value of a distance between the target terminal and the at least one anchor terminal based on the information required for the location estimation; comparing the estimated distance with the expected value to thereby select at least one of the plurality of anchor terminals as a nonuse terminal; and using the information required for the location estimation derived from the radio signal transmitted at least either of the directions except for the nonuse terminal, and the location of ones of the plurality of anchor terminals other than the nonuse terminal to obtain a second estimated location of the target terminal.