Signal transmission method and apparatus using codebook in wireless communication system supporting multiple antennas

摘要

The present invention relates to a method for transmitting, by a base station, a downlink signal using a plurality of transmission antennas comprises the steps of: applying a precoding matrix indicated by the PMI, received from a terminal, in a codebook to a plurality of layers, and transmitting the precoded signal to the terminal through a plurality of transmission antennas. Among precoding matrices included in the codebook, a precoding matrix for even number transmission layers can be a 2×2 matrix containing four matrices (W1s), the matrix (W1) having rows of a number of transmission antennas and columns of half the number of transmission layers, the first and second columns of the first row in the 2×2 matrix being multiplied by 1, the first column of the second row being multiplied by coefficient “a” of a phase, and the first column of the second row being multiplied by “−a”.

主权项

1. A method for transmitting a downlink signal using 2·N (N is a natural number) transmit (Tx) antennas by a base station (BS), the method comprising:
receiving a first precoding matrix index (PMI) and a second precoding matrix index (PMI) from a user equipment (UE); determining a precoding matrix on the basis of a combination of the first PMI and the second PMI in a prestored codebook; performing precoding by applying the determined precoding matrix to the downlink signal mapped to R layers (where 1≦R≦8); and transmitting the precoded signal to the user equipment (UE) through 2·N Tx antennas, wherein the prestored codebook includes precoding matrices configured in the form of [⁢W1W1a⁢⁢W1-a⁢⁢W1]when R is an even number, where W1 is an N×(R/2) matrix and a is a coefficient of a phase.