A wireless communication system including a sender apparatus having a plurality of transmitting antennas that performs MIMO transmission of a plurality of data blocks; and a receiver apparatus that receives the plurality of data blocks. The sender apparatus transmits a process number via a control channel different from a data channel to the receiver apparatus, and wherein when the MIMO diversity transmission is performed, the receiver apparatus performs HARQ processing in the received data blocks based on not a process number which prevents the data blocks from competing but the received process number from the sender apparatus.