A method is described for transmitting, by a user equipment (UE), a demodulation reference signal (DMRS) for a physical uplink shared channel (PUSCH) in a wireless communication system. A cyclic shift field is received through a physical downlink control channel (PDCCH) from a base station. The cyclic shift field indicates first, second, third and fourth cyclic shifts, first orthogonal cover code (OCC) and a second OCC. A first DMRS sequences is generated by using the first cyclic shift and the first OCC. A second DMRS sequence is generated by using the second cyclic shift and the first OCC. A third DMRS sequence is generated by using the third cyclic shift and the second OCC. A fourth DMRS sequence is generated by using the fourth cyclic shift and the second OCC. The first, second, third and fourth DMRS sequences are transmitted to the base station.