The present invention provides data transmission capacity that is optimized in a communication environment by iteratively modifying a beamforming vector by linearly coupling selfish beamforming with unselfish beamforming using feedback information. The transmitter for modifying the beamforming vector iteratively includes: a feedback receiving module that receives feedback information from a receiver: and a vector determination module that determines an initial beamforming vector by coupling a first vector for the selfish beamforming with a second vector for the unselfish beamforming at the time of initial beamforming, and corrects a coupling ratio of the first vector and the second vector of the beamforming vector with reference to the received feedback information whenever the beamforming is modified.