Apparatus and method for precoding using channel orthogonalization in multi user multi antenna system

PURPOSE: An apparatus for precoding using a channel orthogonalization method in a multi user multi antenna system and a method thereof are provided to reduce the complexity by reducing amount of calculation. CONSTITUTION: A transmitter determines K user terminal candidate group about a user terminal. The transmitter determines each channel matrix within the candidate set based on the channel estimation(300). The transmitter initializes the quadrature-channel matrix about each channel matrix of K user terminal(302). The transmitter determines the quadrature-channel matrix of selected user terminal(304).