Patent ID: 8724495

Claim:
A relay device that relays a wireless signal between a transmission device and a reception device, comprising: a receiver that receives the wireless signal from the transmission device; a transmitter that transmits, to the reception device, the received wireless signal subjected to processing via a first protocol that amplifies the received wireless signal or a second protocol that decodes and re-encodes data contained in the received wireless signal; and a controller that switches between the first protocol and the second protocol using an evaluating index including a first evaluating value related to a state of a transmission path between the transmission device and the relay device and a second evaluating value related to a state of a transmission path between the relay device and the reception device, wherein the first evaluating value is estimated by the relay device and is based on a monitoring result of a signal transmitted from the transmission device, and the second evaluating value is estimated by the reception device and is based on a result of monitoring a signal transmitted from the relay device to the reception device, the second evaluating value being received by the relay device; wherein the controller switches from the first protocol to the second protocol using a first threshold of the evaluating index, and switches from the second protocol to the first protocol using a second threshold of the evaluating index, the first threshold and the second threshold being different from each other; wherein the first protocol is Amplify-and-Forward (AF) protocol and the second protocol is Decode-and-Forward (DF) protocol.