DIFFERENTIAL FEEDBACK SCHEME FOR CLOSED-LOOP MIMO BEAMFORMING

摘要

A first NxM codebook of a first rank M may be used to generate a second Nx(N-M) codebook of a second rank (N-M). This second codebook is both orthogonal and complementary to the first codebook. In practice, this may reduce storage requirements in closed-loop MIMO beamforming, because the second codebook may be dynamically generated as needed by a base station and/or a mobile station. In some cases, a higher rank beamforming matrix or precoding matrix may be formed from a lower rank (e.g., one or two) beamforming matrix or precoding matrix. Also, a novel way to generate the rotation matrix is disclosed.