A user equipment of a wireless communication system is disclosed. The user equipment includes a communication module, and a processor. The processor is configured to perform a first type channel access, which is a channel access based on a random backoff, for an autonomous uplink (AUL) transmission when a predetermined condition is not satisfied, perform a second type channel access, in which channel sensing for a predetermined single time interval without backoff, for the AUL transmission when the predetermined condition is satisfied, and perform the AUL transmission based on a result of the first type channel access or a result of the second type channel access. The AUL transmission is performed by the user equipment without an uplink (UL) grant received from a base station.