Re: [STDS-802-11-TGBN] [EXT] Re: [STDS-802-11-TGBN] CID 15182: P-EDCA not enabled when long slot is used in a BSS

[Liwen Chu <liwen.chu@xxxxxxx>]

Hi Dmitry,

 

In current spec text, there is no normative text to disallow P-EDCA directly if  Short Slot Time field is set to zero.

 

However there is another issue with ICF operation which is required by P-EDCA, DPS, EMLSR, DSO.

 

In 2.4GHz band, when DSSS STAs, HR/DSSS STAs and ERP STAs are associated with the AP, the protection mechanism is required at the beginning of the TXOP. Under the assumption of DS-CTS and the following TXOP is not in the same TXOP, after backoff protected by DS-CTS until the RTS transmission, the TXOP holder needs to transmit another frame to protect the whole TXOP, i.e. CTS-to-Self or RTS to solicit CTS. The CTS-to-Self followed by RTS/CTS is not in line with the frame exchange sequence of P-EDCA. The  the replacement of ICF/ICR can’t satisfy the requirement of the other enabled feature, e.g. DPS, EMLSR, DSO,DUO. The reason is that the frame for TXOP protection needs to be carried in DSSS or HR/DSSS while the ICF needs to be carried in non-HT (duplicate) PPDU at 6, 12, 24 Gbps.

 

Best Regards,

Liwen   

 

NXP Confidential

From: Akhmetov, Dmitry <dmitry.akhmetov@xxxxxxxxx>
Sent: Wednesday, October 21, 2026 12:33 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: [EXT] Re: [STDS-802-11-TGBN] CID 15182: P-EDCA not enabled when long slot is used in a BSS

 

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Greeting’s P-EDCA followers,

 

Please post your questions/comments/suggestions regarding CID 15182 in this thread

 

Dmitry

 

From: Akhmetov, Dmitry
Sent: Thursday, October 15, 2026 2:29 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx; Ning Ning6 Gao <gaoning6@xxxxxxxxxx>; Yue Qi <yue.qi@xxxxxxxx>; Yonggang Fang <yonggang.fang@xxxxxxxxxxxx>
Subject: CID 15182: P-EDCA not enabled when long slot is used in a BSS

 

Hi all,

 

I’d like to start a discussion regarding CID 15182 (see below)

I was presented today and some members have some comments about the resolution, which is to add a NOTE saying that “NOTE: -  A UHR AP that sets Short Slot Time field to zero (see 9.4.1.4 (Capability Information field)) does not enable P-EDCA.”

 

It was proposed to change NOTE to normative text : “A UHR AP that sets Short Slot Time field to zero (see 9.4.1.4 (Capability Information field)) shall not enable P-EDCA.

 

Please let me know you if you have comments or questions

 

15182

Ning Gao

37.2.2

293

45

NOTE 1 justifies the fixed 81 us Duration value by "Duration + AIFS >= 81+25 = 106 > aSIFSTime + aSignalExtension + (AIFSN + CWmax) x aSlotTime = 97 us". The value 97 us assumes aSlotTime = 9 us, aSIFSTime = 16 us and aSignalExtension = 0. In the 2.4 GHz band with the long slot time (aSlotTime = 20 us, aSIFSTime = 10 us, aSignalExtension = 6 us) the maximum P-EDCA backoff countdown is 10 + 6 + (2+7) x 20 = 196 us, which greatly exceeds 106 us, so the NAV set by the DS-CTS frame does not protect the P-EDCA backoff.

Either restrict P-EDCA contention operation to cases where aSlotTime = 9 us, or define the Duration field value as a function of aSIFSTime, aSignalExtension, aSlotTime, P-EDCA AIFSN and P-EDCA CWmax instead of the fixed 81 us.

Revised.   Was deferred in 11-26/1671r1. No additional discussions followed Brought back same resolution:   Added : NOTE 2 — A UHR AP that sets Short Slot Time field to zero (see 9.4.1.4 (Capability Information field)) does not enable P-EDCA.   TGbn Editor: please apply changes marked (#15182) in 11-26/1671r6

 

             

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