Group acknowledgement for multiple user communication in a wireless local area network

A method for simultaneously communicating with multiple communication devices in a wireless local area network, the method comprising:

• receiving, at a first communication device, a plurality of uplink data units simultaneously transmitted by multiple second communication devices;
• generating, at the first communication device, an acknowledgement data unit to acknowledge receipt of the plurality of uplink data units simultaneously transmitted by the multiple second communication devices, wherein the acknowledgement data unit includes a plurality of acknowledgment fields corresponding to ones of the multiple second communication devices, wherein each of at least some of the plurality of acknowledgment fields include:
• a first field that includes an indicator of a corresponding one of the multiple second communication devices,
• a second field that indicates whether the acknowledgment field corresponds to i) an acknowledgment corresponding to a single data unit received from the corresponding one of the second communication devices, or ii) a block acknowledgment corresponding to multiple data units received from the corresponding one of the multiple second communication devices,
• wherein when the second field indicates the block acknowledgment corresponding to a group of multiple data units, the acknowledgment field further includes a third field having a bitmap that indicates which of the multiple data units in the group are being acknowledged, and
• wherein when the second field indicates acknowledgment of a single data unit, the acknowledgment field does not include the third field;
• and
• controlling one or more transceivers of the first communication device to transmit the acknowledgement data unit;
• wherein a first acknowledgment field among the plurality of acknowledgment fields i) corresponds to the block acknowledgment corresponding to the multiple data units, and ii) includes the third field;
• and
• wherein a second acknowledgment field among the plurality of acknowledgment fields i) corresponds to the acknowledgment corresponding to the single data unit, and ii) does not include the third field.