The present invention relates to a wireless communication system. A method for estimating a channel by a user equipment (UE) in a wireless communication system includes receiving information about at least one channel station information (CSI) configuration for reporting CSI of one of a plurality of serving cells, determining that the same precoding matrix is applied to a plurality of resource blocks when all of the at least one CSI configuration is configured to report a precoding matrix indicator (PMI) and a rank indicator (RI), and determining that the precoding matrix is applied to one resource block when CSI configuration configured not to report the PMI and the RI is present among the at least one CSI configuration, and estimating a channel based on a result of the determination.