Channel access method for performing transmission in unlicensed band, and device using same

A user equipment (UE) for use in a wireless communication system, the UE comprising:

• a communication module;
• and
• a processor controlling the communication module,
• wherein the processor is configured to:
• attempt to transmit a transmission using a first channel access procedure, the first channel access procedure including a channel sensing for a time interval of 16 μs before the transmission;
• and
• if the first channel access procedure for the transmission is failed, and the transmission is in a set of contiguous transmissions prior to a last transmission of the set, attempt to transmit a next transmission in the set using a second channel access procedure, the second channel access procedure including a channel sensing for a time interval of 25 μs before the next transmission.