A communication system is configured that includes a mobile terminal, one or more relay devices, and a base station for communicating with the mobile terminal via any of the one or more relay devices, where the mobile terminal includes a reception unit for receiving a reference signal transmitted from the one or more relay devices, a determination unit for determining a relay device to be used for communication with the base station based on the reference signal received by the reception unit from the one or more relay devices, and a transmission unit for transmitting to the base station information indicating the relay device determined by the determination unit.