A method is provided in a wireless communication system, in which configuration information of a channel state information-reference signal (CSI-RS) is transmitted to a terminal. The CSI-RS is included in a first set or a second set. A resource not used for mapping downlink data symbols is identified based on a first resource of CSI-RS included in the first set without consideration of a second resource of CSI-RS included in the second set. The downlink data symbols are mapped to a resource except the resource not used for mapping the downlink data symbols. Downlink data is transmitted on a physical downlink shared channel (PDSCH) to the terminal.