Patent ID: 7756528

Claim:
An area estimation system, comprising: a radio signal transmitting terminal of which a presence area is unknown, the radio signal transmitting terminal including a radio signal transmitting unit configured to transmit a radio signal addressed to a radio signal receiving terminal; a radio signal capturing terminal of which a presence area is known, the radio signal capturing terminal including a radio signal capturing unit configured to capture the radio signal addressed to the radio signal receiving terminal, which is different from the radio signal capturing terminal, transmitted from the radio signal transmitting terminal, to obtain an RSSI for indicating a strength of the radio signal addressed to the radio signal receiving terminal; an area estimating unit including an RSSI receiver unit configured to receive the RSSI from the radio signal capturing terminal, an ID of the radio signal transmitting terminal, and an ID of the radio signal capturing terminal; an RSSI storage unit configured to store the RSSI from the radio signal capturing terminal, the ID of the radio signal transmitting terminal and the ID of the radio signal capturing terminal in association with one another; and a presence area estimating unit configured to estimate the presence area of the radio signal transmitting unit, by using the RSSI which is stored in the RSSI storage unit.