A relay to transmit data received from a transmitter to a receiver includes a reception unit to receive a first data frame including first data and a second data frame including first MAP information transmitted from a transmitter, and a determination unit to determine whether the received first data and first MAP information correspond to each other, and to determine that the reception unit has failed to receive second MAP information corresponding to the first data and second data corresponding to the first MAP information when the received first data and the first MAP information do not correspond to each other.