Patent ID: 8532217

Claim:
A method for transmitting a signal in a multiple antenna system, the method performed by a transmitter and comprising: pre-coding the signal based on a codebook that includes first pre-coding matrices; and transmitting the pre-coded signal using a radio resource, wherein each of the first pre-coding matrices is decomposed into a diagonal matrix and a unitary matrix, wherein the diagonal matrix is configured in a form of [ W 0 0 0 W 0 ] ⁢ ⁢ or ⁢ [ W 0 0 0 W 1 ] , ⁢ wherein W 0 indicates a second pre-coding matrix included in the diagonal matrix as a diagonal entry, wherein W 1 indicates a third pre-coding matrix included in the diagonal matrix as a diagonal entry, and wherein the unitary matrix is configured in a form of [ 1 1 1 - 1 ] ⁢ ⁢ or ⁢ [ 1 1 j - j ] , wherein each of the first pre-coding matrices is for a first number of antennas divided into antenna clusters, wherein the second pre-coding matrix has a second number of rows, wherein a number of antennas belonging to one of the antenna clusters is set to the second number, and wherein the first number is greater than the second number.