Example systems, methods, and devices for channel access in dense wireless networks are discussed. More specifically, methods may include transmitting one or more trigger frames from an access point to one or more communication stations, the one or more trigger frames comprising a plurality of components, the plurality of components indicating whether trigger frames within a beacon interval are scheduled in a periodic or aperiodic manner, and if periodic trigger frames are scheduled, then indicating a countdown to the next trigger frame, and if aperiodic trigger frames are scheduled, then indicating the time to the next trigger frame scheduled by the access point. Methods, apparatus, and systems described herein can be applied to 802.11ax or any other wireless standard.