Patent ID: 8717994

Claim:
A method for transmitting reference signals for 8 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, wherein the downlink subframe has an extended cyclic prefix (CP) configuration; and transmitting channel state information-reference signals (CSI-RSs) for the 8 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 8 or fewer antenna ports to be mapped to two orthogonal frequency division multiplexing (OFDM) symbols in a data region of the downlink subframe, wherein the two OFDM symbols defined in the predetermined pattern for the CSI-RSs are second and third OFDM symbols of the second slot, and wherein the predetermined pattern for the CSI-RSs is used when the CRSs are configured for 2 or fewer antenna ports.