Patent ID: 8917681

Claim:
A method for transmitting reference signals for eight or fewer antenna ports at a base station, the method comprising: transmitting common reference signals (CRSs) for four or fewer antenna ports in a downlink subframe including a first slot and a second slot and having a normal cyclic prefix (CP), wherein the downlink subframe has 14 orthogonal frequency division multiplexing (OFDM) symbols and the OFDM symbol index starts from 0; and transmitting channel state information-reference signals (CSI-RSs) for the eight or fewer antenna ports, the CSI-RSs being mapped to the downlink subframe according to a predetermined pattern; wherein the predetermined pattern defines the CSI-RSs for the eight or fewer antenna ports to be mapped to two OFDM symbols in a data region of the downlink subframe, the two OFDM symbols being separated by one OFDM symbol, and wherein the predetermined pattern for the CSI-RSs is used when the CRSs are configured for two or fewer antenna ports.