1. A method of performing a random access by a user equipment in a wireless communication system using a mmWave band, the method comprising:obtaining information on a sequence set and a phase pattern vector set to use for a random access procedure;
selecting a phase pattern vector corresponding to a repetitive transmission count of a random access channel (RACH) signal among a plurality of phase pattern vectors included in the phase pattern vector set;
transmitting the RACH signal generated using a sequence selected among a plurality of sequences included in the sequence set and the selected phase pattern vector to a base station for time intervals amounting to the repetitive transmission count; and
receiving a RACH response signal indicating an estimated sequence and an estimated phase pattern vector from the base station,
wherein the RACH signal is generated by multiplying elements configuring the selected phase pattern vector by the selected sequence in each of the time intervals amounting to the repetitive transmission count.