Patent ID: 8750402

Claim:
A method for transmitting a reference signal (RS) by a Base Station (BS) that supports a Long-Term Evolution (LTE) system supporting N number of transmitting antennas among a total of M number of transmitting antennas and an LTE Advanced (LTE-A) system supporting M number of transmitting antennas where M is greater than N, the method comprising: creating, by the BS, a subframe supporting both the LTE system and the LTE-A system; and transmitting the subframe to a User Equipment (UE), wherein, in the subframe, Common Reference Signals (CRSs) for antenna ports 0 to N−1 are mapped, and CRSs for antenna ports N to M−1 are mapped, wherein a power level of the CRSs for antenna ports 0 to N−1 and a power level of the CRSs for antenna ports N to M−1 are independently controlled, and wherein the power level of the CRSs for antenna ports 0 to N−1 is greater than the power level of the CRSs for antenna ports N to M−1.