In a method for communicating in a wireless communication network a trigger frame is generated to trigger simultaneous uplink transmissions by multiple communication devices. The trigger frame includes a padding portion having a length determined based on respective time duration requirements of the multiple communication devices, the respective time duration requirements for preparing uplink transmission by the corresponding second communication devices. The trigger frame is transmitted to the multiple communication devices. The simultaneous uplink transmissions, triggered by the trigger frame, are received from the multiple communication devices.