A method for, at a transmitter, transmitting a signal to a receiver in a wireless communication system is disclosed. The method includes transmitting a first reference signal for omni-directionally providing a uniform reference beam to the receiver, transmitting a second reference signal for providing beams respectively corresponding to a predetermined number of sectors to the receiver, receiving, from the receiver, sector information selected based on the second reference signal and information about a beam gain difference between a beam corresponding to the selected sector and the reference beam, and performing beamforming for transmitting a signal to the receiver based on the sector information and the information about the beam gain difference.