In a multiuser MIMO system, entire system throughput achieved during
retransmission is significantly enhanced. When an interference signal
addressed to another user equipment (UE2) 200b has been demodulated
successfully, a user equipment (UE1) 200a holds the demodulated data
pertaining to the interference signal, and feeds back ACK information
about the UE2 and CQI information achieved after elimination of the
interference signal to a radio base station (BS) 100. When the UE2
performs retransmission after ended in a receiving failure and when the
UE1 has demodulated the interference signal addressed to the UE2
successfully, the BS changes the distribution of communication resources
in such a way that communication resources for the UE2 become larger than
those for the UE1. At the time of retransmission, the UE1 eliminates the
interference signal from a newly-received signal by use of
previously-held demodulated data pertaining to the interference signal,
and the UE2 combines data pertaining to the desired signal held during
previous receiving failure with data pertaining to the retransmitted
signal by means of soft combining.