Hi Shubho,
I guess a counter-argument for second paragraph would that there is MU-EDCA for all the Trigger based UL data transmission mechanisms that a STA follows.
Regards,
Dibakar
From: Shubhodeep Adhikari <shubhodeep.adhikari@xxxxxxxxxxxx>
Sent: Sunday, January 4, 2026 11:22 PM
To: Das, Dibakar <dibakar.das@xxxxxxxxx>; stds-802-11-tgbn@xxxxxxxxxxxxxxxxx
Cc: Sindhu Verma <sindhu.verma@xxxxxxxxxxxx>
Subject: Re: [STDS-802-11-TGBN] 11bn LB291 CR request: 11-25-1934 -CR for MAPC fairness
Hi Dibakar,
There is no requirement that transmission power of non-APs is always lower than APs. Regulations too do not require that. Further, UL OFDMA,
MU-MIMO and DRU pack multiple non-APs in the UL and thus, multiply the total power transmitted in any given bandwidth/time resource as regulations limit the PSD per device only. These schemes have been designed to exploit precisely this aspect. In some cases,
the power transmitted totally by all UL devices can exceed that transmitted by the AP.
I think the discussion on fairness of CBF/CSR is somewhat misplaced given that the standard already has UL OFDMA , UL MU-MIMO, DRU, uncoordinated
spatial reuse, UL triggered access etc. In all these examples, one can come up with an argument that when a device A is transmitting, had device B not transmitted in parallel or in the same TXOP, a device C hidden from A could have transmitted in parallel.
Given the amount of overheads involved in these coordinated AP schemes, the focus should be to increase the efficiency of whatever opportunity exists. If the efficiency of resource utilization increases, it benefits all other devices too since they can get
more channel access time.
Regards,
Shubho
But transmission power of STAs are lower than APs.
Hi all,
As Shubho mentioned, in UL OFDMA/MU-MIMO, the collision domain has also been artificially extended when AP triggers multiple
STAs to transmit UL data, we can follow the same rule defined there. For Co-SR, although there’s no
sounding overhead, there’s still invite/response/ICF/ICR overhead, which is non-negligible, better
to keep it consistent with Co-BF.
Best,
Jason
Hi Dibakar, Shubho and Jason,
There is no sounding overhead in Co-SR. I think Co-SR shall follow the same rule as Co-TDMA regarding AC of traffics to transmit.
For Co-BF, we may take more discussion.
BR,
Xiangxin Gu
Institute of Communication Technology

Hi Shubho, Jason,
The concern is: CBF/CSR have the same issue as CTDMA regarding the collision domain being artificially extended when shared AP-2 transmits.
Regards,
Dibakar
Hi Dibakar,
I agree with Jason regarding the justification for CBF overhead. Also you have noted, option 3 in your email (as copied below) is automatically
satisfied by CBF.
Not exceed 67% of the time used for in-BSS communication i.e., at least 33% of TXOP used for sharing AP’s in-BSS communication.
This is automatically satisfied for CBF/CSR since the PPDUs are aligned. No new rule needed.
Further, CBF is no different from MU-MIMO, albeit from different transmission sources. There is no restriction on what AC should be used in
MU-MIMO transmissions and the only restriction is that the duration of the original transmission must not be exceeded. This is precisely what happens in CBF. Hence, I think the additional restrictions are not necessary.
Regards,
Shubho
Hi Dibakar,
Have you considered the sounding overhead as well as the Invite/Response/ICF/ICR overhead in Co-BF? If we limit the time and
AC to do Co-BF transmission, the gain of Co-BF may disappear. As you mentioned, the 3rd condition is always satisfied, the fairness issue in Co-BF is not that big comparing with Co-TDMA.
Best,
Jason
Hi,
On the fairness topic, there are CIDs asking to extend this to CBF/CSR. I received some feedback from few members that they would specifically like to align the rules with that
of CTDMA.
Now for CTDMA, the rules are broadly:
-
The allocated duration is limited to the min (VI TXOP limit, TXOP limit for the primary AC of the sharing AP)
-
This would be a new straight forward extension for CBF/CSR. However, it implies that CBF/CSR is also to serve low latency traffic similar to CTDMA.
-
The PPDUs transmitted during the allocated duration are of AC >= primary AC of sharing AP.
-
This rule would require sharing AP conveying this information to shared AP in the CBF Invite.
-
@Guoyuchen (Jason Yuchen Guo)
@Sherief Helwa please let me know if you are fine with this approach. If so, I will add a field in the CBF Invite frame.
-
Not exceed 67% of the time used for in-BSS communication i.e., at least 33% of TXOP used for sharing AP’s in-BSS communication.
-
This is automatically satisfied for CBF/CSR since the PPDUs are aligned. No new rule needed.
CBF TTT members: Please share your thoughts on this.
Regards,
Dibakar
Hi,
Thanks Yanjun. I will change the resolution as
“Reject”
for now but may defer them if I get more objections. So far most of the feedback asks to reject it.
Regards,
Dibakar
Hi Dibakar,
Current spec text allows background and best effort traffic to use the shared TXOP, which is against the design principle for Co-TDMA to help low-lat traffic. So it doesn’t
make sense to reject 6628 and 10376. If you still see split views and want to make progress, can you defer them for now?
Based on the feedback, it seems there is strong preference not to make major changes to the CTDMA design. As such, would reject CID 6628, 10376.
Regarding CIDs that are asking for fairness rules for CBF, CSR (e.g., 10187), if we compare with the rules we have for CTDMA, then CBF/CSR automatically satisfy the 33% proportional
constraint on allocated time since the PPDUs transmitted by the two APs are aligned in time. We could add the other part of CTDMA constraint that limits maximum allocated duration to min (VI TXOP limit, TXOP limit of the primary AC used to obtain that TXOP
by sharing AP) if there is interest. Please let me know your thoughts.
I would like to provide a feedback on 11-25-1934
-CR for MAPC fairness, specifically on
-
comment 6125:
·
a minor editorial suggestion, please consider using
“just above” or
“as described directly above”
-
comments 6628 and 10376
:
·
we have already a general rule in 11bn for coordinated AP(s) (i..e, AC_{shared_AP} >= primary AC)
that is flexible for coordinated AP(s) to follow without violating EDCA requirements for the gained TXOP by coordinated APs.
Why to revisit now (when we already have 1.0draft) the basic C-TDMA framework what members have discussed intensively at early stages of C-TDMA development and agreed upon in the
past ?
C-TDMA is intended for LL traffic, and coordinated APs will prioritize AC VO/VI to serve during the shared portion of TXOP.
Ironically, the section on fairness (Section 37.27) on which members spent a good amount of time was discussed/developed to support the current model (without additional rules/and
constraints on coordinated APs).
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External email : Please do not click links or open attachments until you have verified the sender or the content.
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Please note that I have uploaded 1934r0 to
the mentor.
All members who are interested in that section please review.
Please add the following CR documents to the MAC queue:
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11-25-1934 -CR for MAPC fairness
– Technical (31 CIDs)
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11-25-1935- CR for SCS related text
– Technical (34 CIDs)
Can you please help queue the following CR docs to the TGbn MAC agenda?
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11-25/1912 LB291 - CR for MAPC element - Editorials 1 (14 CIDs)
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11-25/1913 LB291 - CR for 37.15.1 MAPC common procedures - Editorials 2 (18 CIDs)
Can you please help queue the following CR docs to the TGbn MAC agenda?
11-25/1835 LB291: CR for CIDs assigned to Abhi - Part 4
11-25/1836 LB291: CR for CIDs assigned to Abhi - Part 5
Can you please help queue the following CR docs to the TGbn MAC agenda?
11-25/1826 LB291: CR for CIDs assigned to Abhi - Part 2
11-25/1834 LB291: CR for CIDs assigned to Abhi - Part 3
WARNING: This
email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
Can you please help queue the following CR doc to the TGbn MAC agenda?
11-25/1825 LB291: CR for CIDs assigned to Abhi - Part 1
WARNING: This
email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.
Please help add the CR document to the MAC queue. It resolves 1 CID. Thank you!
23-Oct-2025 ET 2025 1859 0 TGbn 11bn LB291 CR for CID 4983 Kaidong Wang (Huawei)
Please help to add following to the PHY queue, it has 8 CIDs.
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PHY-lb291-CIDs_subclause_38.3.15.12_ELR_SIG
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Pls add the following to the MAC queue. It resolves 15 CIDs.
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2025
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1820
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0
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LB291: CR for CIDs on UHR Parameters Update element - part 1
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All, please let me know if you have any feedback.
Please add the following CR document to the MAC queue. It resolves 23 CIDs.
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2025
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1816
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0
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LB291: CR for CIDs on UHR Mode Change element - part 1
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