The present invention relates to a wireless communication system. A method by which a user equipment reports a channel state information (CSI) in a wireless communication system, according to one embodiment of the present invention, can comprise the steps of: setting up a first CSI process in which a subframe pattern for a first subframe set, which uses an almost blank subframe (ABS), and a second subframe set, which does not use the ABS, is set; setting up a second CSI process in which the subframe pattern is not set; setting a second rank indicator (RI) of the second CSI process to be the same as a first RI corresponding to the second subframe set when the second CSI process is established so as to have the same RI as the first CSI process; and transmitting the CSI on the basis of the first CSI process and/or the second CSI process.