Radio relay apparatus and method

A disclosed radio relay apparatus 20 receives signals from a transmitter 10 via multiple receive antennas 21 and transmits relay signals derived from the received signals to a receiver 30 via multiple transmit antennas 22. The apparatus includes a channel estimation unit 26 configured to estimate a forward channel matrix H 1 representing radio channel characteristics between the transmitter 10 and the radio relay apparatus 20 and a loop channel matrix G representing interference occurring in the relay signals due to concurrently transmitting and receiving signals at the radio relay apparatus, a weight optimization unit 251 configured to derive a cancelling matrix C through iterative operations using the forward channel matrix H 1 , the loop channel matrix G and a backward channel matrix H 2 representing radio channel characteristics between the radio relay apparatus 20 and the receiver 30, and a feedback compensation unit 23 configured to subtract a signal weighted in accordance with the cancelling matrix C in a feedback path from a relay signal in a main signal path to adjust the relay signal.