An access point transmits a trigger frame to a set of electronic devices in a wireless local area network (WLAN). The access point receives, from one or more electronic devices in a set of electronic devices, one or more requests to send data. In response, the access point transmits the trigger frame, which includes information specifying an ordered list of electronic devices in the set of electronic devices that are allowed to transmit. Subsequently, the access point sequentially receives one or more frames from the ordered list of electronic devices. After receiving a frame from the last electronic device in the ordered list of electronic devices or after an unused transmit opportunity of the last electronic device in the ordered list of electronic devices, the access point transmits a block acknowledgment to the ordered list of electronic devices.