Patent ID: 8891650

Claim:
A method for transmitting downlink Reference Signals (RSs) wireless communication system, the method performed by a base station having a plurality of antenna ports and comprising: transmitting, by the base station, a first Orthogonal Frequency Division Multiplexing (OFDM) symbol in which first RSs and second RSs are allocated in a predetermined order along a frequency axis, the first RSs for a plurality of a first group of antenna ports among the plurality of antenna ports, the second RSs for a second group of antenna ports among the plurality of antenna ports, and the first RSs multiplexed in Code Division Multiplexing (CDM) with the second RSs by pairing each of the first group of antenna ports with one of the second group of antenna ports; and transmitting, by the base station, a second OFDM symbol in which the first RSs and the second RSs are positioned in an RS pattern that is a frequency-domain shift of an RS pattern of the first OFDM symbol.