IEEE 802.11-21/0262r0 Critical Updates Discussion Summary
The document discusses critical updates related to IEEE 802.11-21/0262r0, focusing on changes in system information for APs within an AP MLD. It addresses scenarios where non-AP STAs receive Beacon frames with direct inclusion events, potential issues with updating critical information, and proposes solutions to handle critical updates effectively. The content delves into specific cases like Extended Channel Switch Announcement and Quiet element inclusion. Various options are explored to manage critical updates and ensure proper handling of system changes within wireless networks.
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2/17/2021 Doc.: IEEE 802.11-21/0262r0 Critical Update - Follow Up Date: 2021-2-17 Authors: Affiliations Address Phone email Name Young Hoon Kwon Liwen Chu Manish Kumar Hongyuan Zhang Yan Zhang Rui Cao Sudhir Srinivasa Hui-Ling Lou NXP Submission Slide 1 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Recap: The following concepts regarding critical updates were agreed: 802.11be supports that an AP within an AP MLD shall include in the Beacon and Probe Response frames it transmits the Change Sequence fields that indicate changes of system information for the transmitting AP and other APs within the same AP MLD, where the change sequence field value for each AP is initialized to 0, and is incremented when there is a critical update to the operational parameters for that AP. Also, there has been a discussion on cases that some critical updates are directly included in Beacon and/or Probe Response frames on other links: Inclusion of (Extended) Channel Switch Announcement Inclusion of Quiet element NOTE: For the simplicity, let s use the term Direct inclusion event for this case Submission Slide 2 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Issues When a non-AP STA receives a Beacon frame from AP1 on link1 that has Direct inclusion event for AP2 on link2, where AP1 and AP2 are affiliated with the same AP MLD: Change Sequence value corresponding to AP1 in the Beacon frame is updated such that this value is higher than the saved Change Sequence value from the non-AP STA. Even though the Change Sequence value has been updated, the non- AP STA is not supposed to access link2. What if there are other critical updates happened together with the direct inclusion event? For example: Inclusion of a Quiet element Insertion of a Broadcast TWT element As the non-AP STA does not access link2, the non-AP STA does not update the other critical updates properly. Submission Slide 3 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Possible Solutions Option 1 When a direct inclusion event happens, the Change Sequence value is not updated. Or a direct inclusion event is not considered as a critical update. In this case, a non-AP STA will only check Beacon/Probe Response frames when a critical update that is not a direct inclusion event happens. Quiet IE, Cnt=1 bTWT element Quiet IE, Cnt=2 bTWT element Quiet IE, Cnt=3 Quiet Period link1 CS = 102 Quiet IE, Cnt=1 CS = 100 Quiet IE, Cnt=3 CS = 101 Quiet IE, Cnt=2 CS = 102 CS = 100 link2 Submission Slide 4 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Possible Solutions Option 2 There are two fields defined: Critical update field: As in current definition Indication of other critical updates included in this update 0 : Only direct inclusion event happened in the critical update indicated by the Critical update field. 1 : Critical update other than the direct inclusion happened in the critical update indicated by the Critical update field. Quiet IE, Cnt=1 bTWT element Quiet IE, Cnt=2 bTWT element Quiet IE, Cnt=3 Quiet Period link1 CS = 103, OCU=1 Quiet IE, Cnt=1 CS = 101, OCU=0 Quiet IE, Cnt=3 CS = 102, OCU=1 Quiet IE, Cnt=2 CS = 103, OCU=1 CS = 100, OCU*=X link2 *OCU: Other Critical Update Submission Slide 5 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Possible Solutions Option 3 When a direct inclusion event happens together with other critical updates on a Beacon frame of an AP affiliated with an AP MLD, all the critical updates are included in a Beacon and/or Probe Response frames of other APs affiliated with the same AP MLD. Quiet IE, Cnt=1 bTWT element Quiet IE, Cnt=2 bTWT element Quiet IE, Cnt=3 Quiet Period link1 CS = 103 Quiet IE, Cnt=1 bTWT element CS = 102 Quiet IE, Cnt=2 bTWT element CS = 101 Quiet IE, Cnt=3 CS = 100 CS = 103 link2 Submission Slide 6 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 Conclusions Critical updates when direct inclusion event happens is discussed, and some possible solutions were discussed. Option 1: Excluding direct inclusion case from critical update Option 2: Having separate field for indicating direct inclusion Option 3: Including all events when direct inclusion event happens Submission Slide 7 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 SP1 Do you agree that The following events are not considered as critical updates: Inclusion of a Channel Switch Announcement element Inclusion of an Extended Channel Switch Announcement element Inclusion of a Quiet element Submission Slide 8 Young Hoon Kwon et al (NXP)
2/17/2021 Doc.: IEEE 802.11-21/0262r0 SP2 Do you agree that When more than one critical update is included in a Beacon frame of an AP that is affiliated with an AP MLD, and if any of the critical updates needs to be directly included in a Beacon and/or Probe Response frame of other APs that is affiliated with the same AP MLD, all critical updates shall be included in the Beacon and/or Probe Response frame of other APs that is affiliated with the same AP MLD. Submission Slide 9 Young Hoon Kwon et al (NXP)
