Method and device for transmitting reference signal in wireless communication system

A method for transmitting a reference signal in a wireless communication system, the method comprising:

• mapping demodulation reference signals (DMRSs) of a first plurality of layers to a first resource element (RE) set and a second RE set, the first RE set and the second RE set each including four REs occupying four orthogonal frequency division multiplexing (OFDM) symbols within a subframe;
• mapping DMRSs of a second plurality of layers that is different from the first plurality of layers to a third RE set and a fourth RE set each including four REs occupying four OFDM symbols within the subframe;
• allocating a first orthogonal cover code (OCC) having a length of 4 to each of the DMRSs mapped to the first RE set;
• allocating a second OCC having a length of 4 to each of the DMRSs mapped to the second RE set;
• allocating a third OCC having a length of 4 to each of the DMRSs mapped to the third RE set;
• allocating a fourth OCC having a length of 4 to each of the DMRSs mapped to the fourth RE set;
• and
• transmitting the mapped DMRSs,
• wherein the subframe includes two slots each including six OFDM symbols,
• wherein the fourth OCC is obtained by swapping positions of bits constituting the third OCC, and
• wherein the second OCC is obtained by swapping positions of bits constituting the first OCC.