Feedback method for mimo communication system

This feedback method for multiuser multiple-input multiple-output (MIMO) system is disclosed. The feedback method retrieves the step, an index mapped to the selected precoding matrix from a predetermined mapping table in which the terminal is to select one of the precoding matrix with the steps, the best SNR for measuring the received SNR for all transmit antennas and a step of transmitting the index, including SNR of the selected precoding matrix. According to the invention, since the feedback information is transmitted in the form of an index indicating the appropriate precoding matrix and the SNR, it is possible to reduce the amount of feedback information without the sum rate performance of the system decreases. Multiple-input multiple-output (MIMO), precoding (precoding), feedback