Patent ID: 7986972

Claim:
A method for transmitting data in a Multiple-Input Multiple-Output (MIMO) communication system, the method comprising: receiving feedback information including channel quality information of transmission antennas from terminals, wherein the feedback information comprises first feedback information for a multi-user mode and second feedback information for a single user mode; selecting one of the multi-user mode and the single user mode according to the channel quality information; extracting information for the selected mode from the feedback information; selecting at least one terminal and a precoding matrix of at least one transmission antenna through which data is transmitted according to the extracted information and the selected mode; and transmitting data using the selected precoding matrix and information of the selected terminal: wherein the first feedback information for the multi-user mode comprises a first index of an antenna among the transmission antennas, which maximizes a signal to noise ratio, and a single signal-to-noise ratio corresponding to the first index; wherein the second feedback information for the single user mode comprises a second index of an antenna among the transmission antennas, which is unused for the data transmission, and one or more signal-to-noise ratios each corresponding to an antenna excluding unused antennas; and wherein the second feedback information for the single user mode further comprises an indicator. wherein the indicator is turned off when all of the transmission antennas are selected in order to transmit data in the single user mode, and the indicator is turned on when fewer than all of the transmission antennas are selected.