A method for receiving data in a closed-loop multi-antenna system that defines multiple antenna groups by antenna grouping on multiple antennas, and performs data transmission via each of the multiple antenna groups, the method comprising the steps of: estimating a channel characteristic associated with each data stream transmitted via each antenna group through channel estimation on a received signal; acquiring, from the received signal, channel quality information for each data stream transmitted individually via each antenna group based on the estimated channel characteristic and corresponding to a transmission mode, the transmission mode being one of a multi-user mode and a single-user mode selected depending on a comparison result between a sum rate, R_MU, in the multi-user mode and a sum rate, R_SU, in the single-user mode calculated by using a feedback information; determining, from the channel quality information acquired for each antenna group, maximum channel quality information, an antenna group index associated with the maximum channel quality information, rank information, and remaining channel quality information associated with the rank information; and transmitting the determined maximum channel quality information, antenna group index, rank information, and remaining channel quality information to a transmission apparatus as the feedback information, wherein the determining of maximum channel quality information comprises: calculating first channel quality information for each data stream using a first signal detection technique; and determining best channel quality information among the first channel quality information for each data stream as the maximum channel quality information, wherein the determining of the rank information is comprising: calculating second channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a second signal detection technique; calculating third channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a third signal detection technique; and determining the rank information depending on the second channel quality information and the third channel quality information. estimating a channel characteristic associated with each data stream transmitted via each antenna group through channel estimation on a received signal; acquiring, from the received signal, channel quality information for each data stream transmitted individually via each antenna group based on the estimated channel characteristic and corresponding to a transmission mode, the transmission mode being one of a multi-user mode and a single-user mode selected depending on a comparison result between a sum rate, R_MU, in the multi-user mode and a sum rate, R_SU, in the single-user mode calculated by using a feedback information; determining, from the channel quality information acquired for each antenna group, maximum channel quality information, an antenna group index associated with the maximum channel quality information, rank information, and remaining channel quality information associated with the rank information; and transmitting the determined maximum channel quality information, antenna group index, rank information, and remaining channel quality information to a transmission apparatus as the feedback information, wherein the determining of maximum channel quality information comprises: calculating first channel quality information for each data stream using a first signal detection technique; and determining best channel quality information among the first channel quality information for each data stream as the maximum channel quality information, calculating first channel quality information for each data stream using a first signal detection technique; and determining best channel quality information among the first channel quality information for each data stream as the maximum channel quality information, wherein the determining of the rank information is comprising: calculating second channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a second signal detection technique; calculating third channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a third signal detection technique; and determining the rank information depending on the second channel quality information and the third channel quality information. calculating second channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a second signal detection technique; calculating third channel quality information for a data stream transmitted via one of the multiple antenna groups based on the estimated channel characteristic using a third signal detection technique; and determining the rank information depending on the second channel quality information and the third channel quality information.