A method of reporting channel state information to a base station at a user equipment (UE) in a wireless communication system is disclosed. The method includes configuring a two-dimensional (2D) antenna array transmission mode of a downlink data channel via a higher layer, receiving an indicator corresponding to one of transmission schemes of the downlink data channel via the higher layer, calculating the channel state information on the assumption of one transmission scheme of the downlink data channel corresponding to the indicator, and reporting the calculated channel state information to the base station. The transmission schemes of the downlink data channel include a demodulation-reference signal (DM-RS) based large delay (LD) cyclic delay diversity (CDD) transmission scheme and a closed loop multiplexing transmission scheme in the 2D antenna array transmission mode.