Patent ID: 8325595

Claim:
A method of transmitting a signal by a user equipment configured to use two antennas, the method comprising: obtaining transmission rank information; outputting a precoded signal by precoding a number of layer signals, the number corresponding to a transmission rank, and using a specific precoding matrix corresponding to the transmission rank, wherein the specific precoding matrix is selected from a two-antenna codebook; and transmitting the precoded signal, wherein the two-antenna codebook includes six precoding matrixes such as 1 2 ⁡ [ 1 0 ] , 1 2 ⁡ [ 1 1 ] , 1 2 ⁡ [ 1 - 1 ] , 1 2 ⁡ [ 1 j ] , 1 2 ⁡ [ 1 - j ] , 1 2 ⁡ [ 0 1 ] for the transmission rank 1 and one precoding matrix such as 1 2 ⁡ [ 1 0 0 1 ] for the transmission rank 2.