Abstract: An operating method of an access point (AP) multi-link device (MLD) is provided. The operating method includes: based on at least one non-AP MLD and at least one single link device (SLD) attempting channel access through a first link of the AP MLD, identifying a contention window of the at least one non-AP MLD, based on a ratio of, with respect to the first link, an idle time of the at least one non-AP MLD to an idle time of the at least one SLD; and transmitting a beacon frame including information about the contention window to the at least one non-AP MLD.