An embodiment of the present invention relates to a method by which a base station transmits a downlink signal in wireless communication system, the method including the steps of: transmitting a demodulation-reference signal (DMRS) approval; determining a long-term channel property from the DMRS of a first slot of an uplink sub-frame received by responding to the DMRS approval; receiving a first reference signal from a second slot of the sub-frame on the basis of the determined long-term channel property; determining a short-term channel property from the first reference signal; determining a pre-coding matrix from the long-term channel property and the short-term channel property; and transmitting a downlink signal through the determined pre-coding matrix.