1. A method for generating a hybrid codebook for a Multi-User Multiple-input Multiple-Output (MU-MIMO) system, comprising: generating a parent matrix set including a plurality of M×M unitary matrices when the number of transmitter antennas is M; and generating a child matrix set dependent on the parent matrix set by using training vectors included in a random training set and each column for each unitary matrix of the parent matrix set as an initial vector codebook.