Patent ID: 8576822

Claim:
A method for transmitting a Channel State Information-Reference Signal (CSI-RS), the method comprising: generating a CSI-RS sequence for antenna ports of a maximum of N (N being an integer larger than or equal to 1) number for transmission of the CSI-RS; mapping the generated CSI-RS sequence to Resource Elements (REs) for transmission of the CSI-RS; and generating an Orthogonal Frequency Division Multiplexing (OFDM) signal including the mapped CSI-RS sequence and transmitting the generated OFDM signal to a User Equipment, wherein, in the mapping the generated CSI-RS sequence to the REs: the CSI-RS sequence is mapped to REs corresponding to one sub-carrier at every 12 sub-carriers for each antenna port with respect to two OFDM symbols within a sub-frame by which the CSI-RS is transmitted, for ┌N/2┐ antenna port sets, each of which includes either both an M th (M≦N, and M being an odd number) antenna port and an (M+1) th antenna port or only the M th antenna port if the (M+1) th antenna port does not exist and is used as an antenna port set for transmission of the CSI-RS, the CSI-RS of antenna ports within each of the antenna port sets are allocated to REs having the same time-frequency resource and are discriminated from each other by orthogonal codes, and the CSI-RS allocated for two adjacent antenna port sets within a resource block are spaced apart from each other with an interval of 3 REs in the frequency axis.