Method and apparatus for transmitting reference signal in multi-antenna system

A base station (BS) in a wireless communication system, the BS comprising:

• a radio frequency (RF) unit for transmitting or receiving a radio signal;
• and
• a processor coupled to the RF unit, and configured to:
• receive first, second, third and fourth DMRS sequences, which are respectively associated with first, second, third, and fourth layers, from a user equipment (UE),
• wherein the first, second, third and fourth DMRS sequences are generated, by the UE, by using first, second, third, and fourth values assigned for the first, second, third and fourth layers respectively,
• wherein the first and second values are separated by a maximum value corresponding to a total number of possible cyclic shifts, and
• wherein the third and fourth values are separated by the maximum value corresponding to the total number of possible cyclic shifts, and
• wherein the first, second, third and fourth DMRS sequences are mapped, by the UE, to resource elements (REs) in two slots,
• wherein the first and second DMRS sequences mapped in a second slot among the two slots are multiplied by 1, and
• wherein the third and fourth DMRS sequences mapped in the second slot among the two slots are multiplied by −1.