According to the present disclosure, a user equipment (UE) selects a carrier among a plurality of carriers, receives information on a channel busy ratio (CBR) threshold from a network, and triggers a carrier reselection. When a CBR of the carrier satisfies the CBR threshold, e.g. the CBR of the carrier is below than the CBR threshold, the UE keeps using the carrier. That is, the carrier reselection is not performed when the CBR of the carrier satisfies the CBR threshold. On the other hand, when a CBR of the carrier does not satisfy the CBR threshold, the UE performs the carrier reselection.