Disclosed are a method for adjusting a downlink listen-before-talk (LBT) parameter by a base station, in a licensed assisted access (LAA) system for execution of LBT-based signal transmission by a base station or a terminal, and a device for supporting same. More particularly, disclosed are a method for uplink operation by a terminal, in a multi-carrier environment, a method for uplink transmission on the basis of same, and a device for supporting the methods.