A channel capacity is increased by using MIMO (multiple input multiple output) radio relaying system.
A transmission is made from a transmitter 10 using a first antenna 111 and a second antenna 112 having polarization characteristics which are orthogonalized to each other. A reception is made in a repeater 201 using reception antennas 211 and 212 each having the same polarization characteristic as the first and the second antenna 111 and 112, respectively. Each signal received by the first and the second reception antenna 211 and 212, respectively, is passed through loop interference suppressors 271 and 272, respectively, and through amplifiers 241 and 242, respectively, to be transmitted from the first and the second transmission antenna 211 and 212 having the same polarization characteristics as the second and the first antenna 112 and 111, respectively. A reception is made in a receiver 30 by antennas 312 and 314 having the same polarization characteristic as the first antenna 111, and the reception is also made by antennas 311 and 313 having the same polarization characteristic as the second antenna 112. These received signals are subject to a signal separation processing in MIMO equalizer 32.