Proposed Modifications to 802.11e-D4.0 Group ACK January 2003 Proposed Modifications to 802.11e-D4.0 Group ACK Carlos Rios, RiosTek LLC

January 2003 D4.0 Group ACK Summary Group ACK per 802.11e-D4.0 is a relatively involved protocol to allow QSTAs to burst transmissions to another QSTA while deferring any and all corresponding ACKs until after a later (Group) ACK request. Upon association, sender QSTA gleans from (Association frame) Capabilities Info field that candidate receiver QSTA is capable of Group ACK Group ACK is set up, characterized and torn down with Action Frames: Sender transmits ADDGA Request to set up GA with receiver Receiver responds with ADDGA Response to announce its GA capabilities Sender and Receiver define Tx, Rx Buffer sizes and otherwise prep for GA DELGA Request lets the sender tear down previously established GA capability Once GA is set up, sender advertises any transmitted frames subject to GA by setting an appropriate flag in the packet MAC Header QOS Control field Keeps track of all buffer sizes, etc so to not send too many packets, etc Group ACKable frames are transmitted, separated by SIFS Done transmitting the burst, Sender issues GroupACK Request Control frame Receiver immediately responds with a Group ACK or an ACK The ACK lets him mark time until he’s done preparing a real Group ACK Needs to process Group ACK Req and correlate with his Rx buffer Real Group ACK ready, receiver QSTA transmits it as soon as possible Sender needs to ACK this Group ACK Sender can then initiate another burst at his convenience

D4.0 Group ACK Shortcomings January 2003 D4.0 Group ACK Shortcomings GA functionality should be available to all stations, not just QSTAs GAs should be allowed under DCF rules SIFS Burst packet separation hard requirement is too restrictive Indicates all GA packets need be queued at the sender SIFS should be a minimum, goal separation Don’t use QOS Control field to advertise GA parameters Replace “Order” bit (B15) in MAC Header Frame Control field with a “No Immediate ACK” bit always set upon a Group ACK transmission Modify Group ACK Request frame to simplify GA processing GAReq frame now contains a “Start Sequence Control” field Receiver and sender need calculate which sequence numbers were actually received from sender, which were actually sent to the receiver and, which, if any need be retransmitted Much easier for the GAReq to contain the list of seqnos actually sent, and the GA to contain the list of seqnos actually received

Proposed Group ACK Modifications January 2003 Proposed Group ACK Modifications Modified Group ACK is a relatively involved protocol to allow a STA to burst transmissions to another STA while deferring any and all corresponding ACKs until after a later (Group) ACK request. Upon association, sender STA gleans from (Association frame) Capabilities Info field that candidate receiver STA is capable of Group ACK Group ACK is set up, characterized and torn down with Action Frames: Sender transmits ADDGA Request to set up GA with receiver Receiver responds with ADDGA Response to announce its GA capabilities Sender and Receiver define Tx, Rx Buffer sizes and otherwise prep for GA DELGA Request lets the sender tear down previously established GA capability Once GA is set up, sender advertises any transmitted frames subject to GA by setting an appropriate flag in the packet MAC Header Frame Control field Keeps track of all buffer sizes, etc so to not send too many packets, etc Group ACKable frames are transmitted, separated at a minimum by SIFS Done transmitting the burst, Sender issues GroupACK Request Control frame Receiver immediately responds with a Group ACK or an ACK The ACK lets him mark time until he’s done preparing a real Group ACK Needs less time to process Group ACK Req, correlate with his Rx buffer Real Group ACK ready, receiver QSTA transmits it as soon as possible Sender needs to ACK this Group ACK Sender can then initiate another burst at his convenience

Proposed Group ACK Modifications Summary January 2003 Proposed Group ACK Modifications Summary The modified GA remains a relatively involved protocol, but now allows non-QoS STAs to burst transmissions to each other. No longer necessary to queue up packets at the sender prior to issuing a burst Better supports pseudo-streaming apps like MPEG2 MPTS distribution to multiple SPTS-processing STBs Reduced complexity sent/received/need-retransmit packet processing The herein modified Group ACK is a more robust solution Candidate normative text revisions to 802.11e-D4.0 are contained in document 03/052r0