A transmit node receives a transformed correlation matrix or a correlation matrix of a channel coefficient matrix, or a correlation matrix of an interference channel coefficient matrix from each of receive nodes sharing a radio resource. The transmit node determines a precoder based on a value maximizing values determined by the transformed correlation matrix or the correlation matrix of the channel coefficient matrix, or a value minimizing values determined by the correlation matrix of the interference channel coefficient matrix, and precodes a transmit signal by using the determined precoder.