Patent ID: 8325843

Claim:
A method comprising: accessing a codebook related to a Multiple Input Multiple Output (MIMO) system having four transmit antennas, the codebook being stored in a storage medium and having entries for rank 1 through rank 4, each rank denoting a particular spatial multiplexing order; using the entries in rank 1 of the codebook construct entries for rank 1 through rank 8 of two base matrices for a MIMO base codebook related to eight transmit antennas; performing transmissions for the MIMO system using said MIMO base codebook, and providing feedback operations indicating an entry index of said MIMO base codebook, and wherein the two base matrices for said MIMO base codebook are defined as V8(:,:,4) and V8(:,:,5) having a form of: V ⁢ ⁢ 8 ⁢ ( : , : , 4 ) = 1 4 ⁡ [ 1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1 1 0 - 1 0 j 0 - j 0 0 1 0 - 1 0 j 0 - j 1 0 1 0 - 1 0 - 1 0 0 1 0 1 0 - 1 0 - 1 1 0 - 1 0 - j 0 j 0 0 1 0 - 1 0 j 0 j ] V ⁢ ⁢ 8 ⁢ ( : , : , 5 ) = 1 4 ⁡ [ 1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1 1 + j 2 0 - 1 - j 2 0 - 1 + j 2 0 1 - j 2 0 0 1 + j 2 0 - 1 - j 2 0 - 1 + j 2 0 1 - j 2 j 0 j 0 - j 0 - j 0 0 j 0 j 0 - j 0 - j - 1 + j 2 0 1 - j 2 0 1 + j 2 0 - 1 - j 2 0 0 - 1 + j 2 0 1 - j 2 0 1 + j 2 0 - 1 - j 2 ] .