Method and apparatus for multi-user concurrent random access for wireless local area networks (WLANs)

A method, implemented in a wireless transmit/receive unit (WTRU), the method comprising:

• detecting a trigger frame for uplink (UL) multi-user (MU) transmission, the trigger frame including an assignment of resource units (RUs) for random access in upcoming UL MU physical layer protocol data units (PPDUs) and an indication that the trigger frame is one of a plurality of trigger frames in a cascading sequence of trigger frames in an MU transmission opportunity (TxOP);
• selecting one of the RUs in the assignment of RUs for a random access transmission;
• and
• sending the random access transmission on the selected one of the RUs.

An access point (AP) comprising:

• a processor and a transmitter, the processor and the transmitter being configured to generate and transmit a trigger frame for uplink (UL) multi-user (MU) transmission to a plurality of stations (STAs), the trigger frame including an assignment of resource units (RUs) for random access in upcoming UL trigger-based physical layer protocol data units (PPDUs) and an indication that the trigger frame is one of a plurality of trigger frames in a cascading sequence of trigger frames in an MU transmission opportunity (TxOP);
• and
• a receiver, the receiver and the processor being configured to receive the UL trigger-based PPDUs, the received trigger-based PPDUs including at least one frame from at least one of the plurality of STAs on one of the assigned RUs,
• wherein the transmitter and the processor are further configured to transmit an acknowledgement for the at least one frame, the acknowledgement being aggregated with one of the plurality of trigger frames in the sequence.