Patent ID: 7885348

Claim:
A method performed by a transmitting station for transmitting two or more data streams through a channel, the method comprising: receiving a codeword of a full-manifold codebook, the codeword generated based on an initial channel matrix; subsequently receiving a codeword of a polar-cap codebook, the codeword of the polar-cap codebook representing deviations in the channel since receiving the codeword of the full-manifold codebook; and performing beamforming to transmit packets to a receiving station by applying beamforming coefficients derived from a codeword of the full-manifold codebook to an initial data transmission and by applying beamforming coefficients derived from a codeword of the polar-cap codebook to a subsequent data transmission, wherein the polar-cap codebook comprises a differential codebook that is smaller in size than the full-manifold codebook.