1. A method of codebook transformation, in which, when a transmitter communicating with a first receiver interferes with an adjacent second receiver, the transmitter transforms a codebook for mitigating interference in the second receiver, the method comprising receiving a reference signal from the second receiver; estimating a channel with the second receiver through the received reference signal; calculating a receiving correlation matrix based on the estimated channel; calculating the inverse of the receiving correlation matrix from the calculated receiving correlation matrix; and transforming the codebook using the calculated inverse of the receiving correlation matrix.