An access point may receive, from a set of electronic devices, one or more buffer status reports that indicate that at least a subset of the electronic devices have uplink data associated with one or more access categories. In response, the access point may create a group of uplink virtual queues for one or more electronic devices in the subset based on the one or more buffer status reports, where a given uplink virtual queue corresponds to a particular access category and a given electronic device. The access point may start one or more backoff counters with a one-to-one correspondence to uplink virtual queues in the group of uplink virtual queues. When a backoff counter for the given uplink virtual queue reaches zero, the access point may transmit a trigger frame to an electronic device in the subset that corresponds to the given uplink virtual queue.