Patent ID: 7826346

Claim:
A multiple-input multiple-output transmission system having a transmit station for transmitting a plurality of data streams simultaneously from respective ones of separate transmit antennas, and a receive station for demultiplexing and outputting said data streams, which have been multiplexed in space, from signals received at a plurality of receive antennas, wherein said receive station comprises: a controller that detects whether or not there is an error in each data stream, estimates a state of a propagation path of each transmit antenna, and reports, to a transmitting side, re-transmission necessary/unnecessary information, for every data stream, created based upon whether or not there is an error, and the state of the propagation path of each transmit antenna; and said transmit station includes: a transmit antenna decision unit that decides plural transmit antennas, each of which transmits each data stream requiring re-transmission, based upon the reported state of the propagation path of each transmit antenna; and a re-transmission controller that controls re-transmission of the data streams requiring re-transmission from said plural decided transmit antennas, wherein the transmit antenna decision unit of said transmit station ranks the transmit antennas in order of descending superiority of the states of the propagation paths and, when data streams requiring re-transmission are to be re-transmitted, performs reallocation of the transmit antennas in an order that is reverse of the order of ranking in such a manner that a data stream requiring re-transmission transmitted a previous time from a transmit antenna for which the state of the propagation path is poorest will be transmitted from a transmit antenna for which the state of the propagation path is best.