US Patent 11027701 Location determination system

A location determination system is provided. The location determination system includes a vehicle device mounted in a vehicle, and a mobile terminal provided as a communication terminal to be carried by a user of the vehicle and set to transmit a radio signal including transmission source information at least once within a predetermined period of time. The vehicle device may receive the radio signal transmitted from the mobile terminal via an antenna disposed in the vehicle and detect a reception strength of the received radio signal. The vehicle device may determine, based on the reception strength of the radio signal detected by the reception portion, whether the mobile terminal is present inside a target area set in advance based on a position at which the antenna is disposed.