In wireless communications for multi-users, an access point may generate a trigger frame, which may include a trigger indication. The trigger indication may indicate whether a second trigger frame will be transmitted during a time interval. The trigger indication may use a single bit. The trigger frame may also include resource allocation for one or more stations. When the access point transmits the trigger frame, the station(s) may transmit an uplink frame(s) in response to the trigger frame. The access point may transmit a second trigger frame in the time interval. In response to the second trigger frame, the station(s) may transmit additional uplink frame(s) to the access point. The station(s) may save the resource allocation included in the trigger frame and utilize the same resource allocation for the uplink frame(s) and the additional uplink frame(s). Other methods, apparatus, and computer-readable media are also disclosed.