Systems and techniques relating to wireless communications are described. A described technique includes obtaining data for a transmission to a wireless communication device. The wireless communication device can be configured to process incoming transmissions based on an aggregate data unit format that specifies signaling for aggregating multiple medium access control (MAC) data units. The technique includes, in a physical (PHY) frame, an aggregate data unit that is based on the data and the aggregate data unit format, the aggregate data unit including a single MAC data unit. The technique includes, in the PHY frame, an indication to signal that the MAC data unit in the aggregate data unit is singular and to cause the wireless communication device to accept the aggregate data unit without a corresponding block acknowledgement agreement.