A method for reporting, by a user equipment, UE, a channel state information, CSI, to a base station, BS, based on a CSI-reference signal, CSI-RS, of a wireless communication system, the method comprising: receiving, from the base station, through a radio resource control, RRC, signaling, a CSI-RS resource configuration information indicating resource configuration of a CSI-RS using more than eight antenna ports and being related to indexes of a plurality of legacy CSI-RS resources using antenna ports up to 8 ports, wherein the plurality of legacy CSI-RS resources are aggregated to obtain the total number of antenna ports greater than eight antenna ports, and wherein the CSI-RS resource configuration information includes first resource configuration number and at least one second resource configuration number; and determining indexes of the plurality of legacy CSI-RS resources based on the received CSI-RS resource configuration information, wherein a first index of a specific CSI-RS resource among the plurality of legacy CSI-RS resources is matched to a first CSI-RS configuration number, and at least one second index of at least one CSI-RS resource except the specific CSI-RS resource among the plurality of legacy CSI-RS resources is matched to at least one second CSI-RS configuration number, wherein the first CSI-RS configuration number is resourceConfig-r11 indicated by csi-RS-ConfigNZPId-r11 of the CSI-RS resource configuration information according to standard documents disclosed by the 3rd generation partnership project, 3GPP, for a long term evolution/long term evolution-advanced, LTE/LTE-A, system, and the at least one second CSI-RS configuration number is nzp-resourceConfigList-r13 indicated by NZP-ResourceConfig-r13 of the CSI-RS resource configuration information according to standard documents disclosed by 3GPP for a LTE/LTE-A system; receiving, from the base station, the CSI-RS based on the plurality of legacy CSI-RS resources; and reporting, to the base station, the CSI based on the CSI-RS. receiving, from the base station, through a radio resource control, RRC, signaling, a CSI-RS resource configuration information indicating resource configuration of a CSI-RS using more than eight antenna ports and being related to indexes of a plurality of legacy CSI-RS resources using antenna ports up to 8 ports, wherein the plurality of legacy CSI-RS resources are aggregated to obtain the total number of antenna ports greater than eight antenna ports, and wherein the CSI-RS resource configuration information includes first resource configuration number and at least one second resource configuration number; and determining indexes of the plurality of legacy CSI-RS resources based on the received CSI-RS resource configuration information, wherein a first index of a specific CSI-RS resource among the plurality of legacy CSI-RS resources is matched to a first CSI-RS configuration number, and at least one second index of at least one CSI-RS resource except the specific CSI-RS resource among the plurality of legacy CSI-RS resources is matched to at least one second CSI-RS configuration number, wherein the first CSI-RS configuration number is resourceConfig-r11 indicated by csi-RS-ConfigNZPId-r11 of the CSI-RS resource configuration information according to standard documents disclosed by the 3rd generation partnership project, 3GPP, for a long term evolution/long term evolution-advanced, LTE/LTE-A, system, and the at least one second CSI-RS configuration number is nzp-resourceConfigList-r13 indicated by NZP-ResourceConfig-r13 of the CSI-RS resource configuration information according to standard documents disclosed by 3GPP for a LTE/LTE-A system; receiving, from the base station, the CSI-RS based on the plurality of legacy CSI-RS resources; and reporting, to the base station, the CSI based on the CSI-RS. <EOS>