A network device to function as an Access Point (AP) in a Wireless Local Area Network (WLAN) is provided. The AP is configured to acknowledge a data frame transmitted by a station (STA) in an uplink multi-user physical layer protocol data unit (UL MU PPDU). The AP includes one or more memories, a physical layer (PHY) processor, and a media access controller (MAC) processor. Each processor is coupled to the one or more memories, and is configured to receive the UL MU PPDU, decode an acknowledge (ACK) policy field within a data field of the UL MU PPDU, and determine whether an acknowledgement (ACK) policy indicated in the data field signals an implicit block acknowledgement (BlockAck) request. Responsive to a determination that the ACK policy indication signals an implicit acknowledgement policy, the AP is configured to transmit an ACK or BlockAck frame to the STA in either a single user (SU) or a multi user (MU) manner.