Device and method using adaptive codebook for dual beamforming feedback and wireless communication system including the same

A beamformee device comprising:

• a processor configured to implement:
• a channel estimator configured to receive a null data packet (NDP) from a beamformer device through a channel, and to obtain a plurality of channel information associated with a plurality of subcarriers of the channel based on the NDP;
• a feedback mode selector configured to select one of a first feedback mode, a second feedback mode or a third feedback mode as a selected feedback mode based on a characteristic of the channel;
• a first beamforming matrix provider configured to generate a plurality of wideband beamforming matrices by performing a singular value decomposition (SVD) and compressing the plurality of channel information based on the selected feedback mode being the second feedback mode, and to select and output one of a plurality of first codebooks as a selected first codebook based on the plurality of channel information as one of the plurality of wideband beamforming matrices based on the selected feedback mode being the first feedback mode or the third feedback mode;
• a dimension reduction unit configured to generate a plurality of equivalent channel information corresponding to the plurality of channel information based on the plurality of wideband beamforming matrices;
• and
• a second beamforming matrix provider configured to generate a plurality of subcarrier beamforming matrices by performing an SVD and compressing the plurality of equivalent channel information based on the selected feedback mode being the first feedback mode, and to select and output one of a plurality of second codebooks as a selected second codebook based on the plurality of equivalent channel information as one of the plurality of subcarrier beamforming matrices based on the selected feedback mode being the second feedback mode or the third feedback mode,
• wherein the processor is further configured to feed the plurality of wideband beamforming matrices and the plurality of subcarrier beamforming matrices back to the beamformer device, and
• wherein a codebook index corresponding to the selected first codebook and the selected second codebook is fed back to the beamformer device.

A beamforming feedback method comprising:

• obtaining a plurality of channel information associated with a plurality of subcarriers of a channel based on a null data packet (NDP) that is received from a beamformer device through the channel;
• providing a plurality of wideband beamforming matrices based on the plurality of channel information;
• generating a plurality of equivalent channel information corresponding to the plurality of channel information based on the plurality of wideband beamforming matrices;
• providing a plurality of subcarrier beamforming matrices based on the plurality of equivalent channel information;
• and
• feeding the plurality of wideband beamforming matrices and the plurality of subcarrier beamforming matrices back to the beamformer device,
• wherein any one or any combination of the plurality of wideband beamforming matrices and the plurality of subcarrier beamforming matrices are selected from a plurality of codebooks that are stored in memory.