Patent ID: 8391394

Claim:
A transmission method using a codebook in a multiple-input multiple output system, comprising the steps of mapping multiple codewords to multiple layers; mapping the multiple layers to multiple antennas using a precoding matrix selected from a rank-3 codebook which is designed to map the codewords to different antennas; and transmitting the codewords through paths formed by mapping the layers and the antennas, wherein the precoding matrix of the rank-3 codebook is designed to equalize transmit power ratios between the antennas, the precoding matrix of the rank-3 codebook produces a transmission power ratio among the layers of 2:1:1, and the rank-3 codebook is: 1 2 ⁡ [ 1 0 0 1 0 0 0 1 0 0 0 1 ] 1 2 ⁡ [ 1 0 0 - 1 0 0 0 1 0 0 0 1 ] 1 2 ⁡ [ 1 0 0 0 1 0 0 0 1 1 0 0 ] 1 2 ⁡ [ 1 0 0 0 1 0 0 0 1 - 1 0 0 ] 1 2 ⁡ [ 0 1 0 0 0 1 1 0 0 1 0 0 ] 1 2 ⁡ [ 0 1 0 0 0 1 1 0 0 - 1 0 0 ] 1 2 ⁡ [ 0 1 0 1 0 0 1 0 0 0 0 1 ] 1 2 ⁡ [ 0 1 0 1 0 0 - 1 0 0 0 0 1 ] 1 2 ⁡ [ 1 0 0 0 1 0 1 0 0 0 0 1 ] 1 2 ⁡ [ 1 0 0 0 1 0 - 1 0 0 0 0 1 ] 1 2 ⁡ [ 0 1 0 1 0 0 0 0 1 1 0 0 ] 1 2 ⁡ [ 0 1 0 1 0 0 0 0 1 - 1 0 0 ] .