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Hi All, During yesterday’s 11be MAC call, while discussing doc 11-21/0252, a few members had expressed concerns on the inclusion of the Basic variant Multi-Link element in the list
of events that qualify as critical updates (clause 11.2.3.15). I am initiating this thread to provide more details on the motive and answer any questions on the topic. Broadcast TIM is a legacy feature meant to facilitate power-save operation on client devices. An interested clients can negotiate with the AP to broadcast TIM frames. The
client is not required to monitor the beacon frames when operating in this mode (aids power-save). Furthermore, the client receives traffic indication and TSF information via the TIM frames. The TIM frame carries a Check Beacon field, which increments if there
is a BSS parameter update. An updated value of Check Beacon is an indication to the client to listen to the next the beacon frame to receive the new parameter. The MLO spec allows a non-AP MLD to monitor a single link and perform existing power-save operations such as negotiating TIM broadcast. Therefore, if there is an update
to the ML IE, a STA of a non-AP MLD must be prompted to go look for changes in the Beacon frame. Therefore, modifications to the Basic variant of ML IE must be added to clause 11.2.3.15 as a qualifier to increment Check Beacon field With respect to MLO operation, since the contents of the common portion of the ML IE are same across all links, a change to the Common Info field must not qualify as a criteria
for incrementing the CSN for the reporting AP. If CSN were to be incremented, all links would report an update – which is undesirable.
Similarly, a change to the per-STA portion of the ML IE must not cause the CSN to increment since the content in the per-STA profile applies to another AP of the AP MLD.
In this case too, the CSN for the reporting AP must not be incremented. Therefore, modification to Basic variant ML IE must qualify as a critical update in clause 11.2.3.15 (which results in Check Beacon field being incremented). However it
must not qualify as a criteria for incrementing the CSN for the reporting AP. Please let me know if you have a different view on the topic.
Happy to discuss further. Regards, Abhi To unsubscribe from the STDS-802-11-TGBE list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-11-TGBE&A=1 |