Methods of operating a wireless communication device for adaptive beamforming of a base station according to a state of a channel are provided. The methods include receiving a sounding packet from the base station through the channel; obtaining channel quality about the channel, using the sounding packet; selecting a feedback mode out of a plurality of feedback modes based on the channel quality; generating a matrix to be a basis of the adaptive beamforming, based on the selected feedback mode; and transmitting channel state information including information on the matrix to the base station.