The present invention relates to a wireless communication system. Particularly, the present invention relates to a method for performing communication by a terminal in a TDD-based wireless communication system, and an apparatus therefor. The method comprises the steps of: configuring a PCell and an SCell, wherein the PCell and the SCell have different UL-DL configurations from each other; receiving information indicating a reference UL-DL configuration; and performing a signal processing operation according to a transmission direction indicated by the reference UL-DL configuration, in only a cell having the same transmission direction as the transmission direction indicated by the reference UL-DL configuration from among the PCell and the SCell, as for subframe # k1 in which transmission directions of the PCell and the SCell are different from each other.