Signaling data unit format parameters for multi-user transmissions

An apparatus, comprising:

• a network interface device associated with a first communication device, the network interface device implemented using one or more integrated circuits (ICs), wherein the network interface device includes:
• a media access control layer (MAC) processor implemented using the one or more ICs, and
• a physical layer (PHY) processor implemented using the one or more ICs;
• wherein the one or more ICs are configured to:
• determine one or more parameters related to a format of a MAC data unit for an uplink (UL) multi-user (MU) transmission, wherein the format of the MAC data unit for the UL MU transmission is different than a format of a MAC data unit for an UL single user (SU) transmission,
• generate one or more data units that include the one or more parameters, and
• cause the first communication device to transmit the one or more data units to a plurality of second communication devices to inform the plurality of second communication devices of the format of the MAC data unit for UL MU transmissions by the plurality of second communication devices to the first communication device.