Hi Dmitry,
Thank you for your reply.
See my response in line.
BR,
Xiangxin Gu
Communication Standards Devision
From: Akhmetov, Dmitry <Dmitry.Akhmetov@xxxxxxxxx>
Sent: Tuesday, April 1, 2025 1:46 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBN] P-EDCA questions and answers from the chat
For the first question:
Unfortunately no.
To obtain a TXOP a STA shall follow baseline EDCA procedure as in 10.23.2.4 which involve AIFSN deference and random backoff. That is required by both IEEE and ETSI channel access procedures
DS transmission does not follow that procedure - there is no backoff. So, technically, after TXing DS (CTS) STA did not initiate the TXOP. DS only provides protection for the following
contention which we see to follow 10.23.2.4 procedure.
[// Xiangxin Gu] To my understanding, DIFS guarantees that no break for frame exchange in a TXOP and priority access for Beacon frame. Here I
don’t see these will happen in P-EDCA.
For the second question:
I’m not sure why STAs around should lose medium sync because they miss L-STF of the next PPDU… STA1 send DS (CTS), it frame set NAV=97us on some STA2. STA1 chose random BK=7 (for example)
and start contention. After sifs + 2*aSlotTime+ 7*aSlotTime = 34+63=97 us STA1 initiates TXOP with RTS frame. Why in this example STA2 should miss L-STF of RTS frame?
[// Xiangxin Gu] If P-EDCA STA1 chose random BK other than 7, for example 6, it would send RTS frame after SIFS + 2*aSlotTime+ 6*aSlotTime.
An around STA would start to detect next PPDU after the protected period, i.e. SIFS + 2*aSlotTime+ 7*aSlotTime. So the around STA would miss the
RTS frame and lose medium sync.
Dmitry
From:
顾祥新 (Xiangxin Gu) <Xiangxin.Gu@xxxxxxxxxx>
Sent: Monday, March 31, 2025 8:03 PM
To: Akhmetov, Dmitry <Dmitry.Akhmetov@xxxxxxxxx>;
STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: RE: P-EDCA questions and answers from the chat
Hi Dmitry,
For the following question: After P-EDCA DS CTS frame, it’s in TXOP of the CTS duration. So AIFSN[2] is not correct. It should be SIFS.
Another question is: The STAs around would lose medium synchronization because they missed the L-STF of the next PPDU at the end of the protected duration by DS CTS frame. What
do you think on it?
Xiangxin Gu
Why AIFSN[2] is needed in P-EDCA contention? It's in protected duration.
Answer :
The value of AIFSN[AC] shall be greater than or equal to 2 for non-AP STAs
BR,
Xiangxin Gu
Communication Standards Devision
From: Akhmetov, Dmitry <Dmitry.Akhmetov@xxxxxxxxx>
Sent: Thursday, March 27, 2025 11:04 PM
To: STDS-802-11-TGBN@xxxxxxxxxxxxxxxxx
Subject: [STDS-802-11-TGBN] P-EDCA questions and answers from the chat
Hi,
Please find below answers to the questions I captured from the chat of Webex regarding document 2007r5:
Binita Gupta :
"A P-EDCA eligible STA may start a P-EDCA contention to deliver buffered traffic" —> "A P-EDCA eligible STA may start a P-EDCA contention to deliver buffered traffic if the TBD conditions are met". Need to include
reference to conditions in this 'may requirement'
Patrice NEZOU:
Agree with Binita. P-EDCA eligible STA shall have LL traffics to deliver in AC_VO
Answer: If I got the comment correctly, it is about sentence on p3L34. In fact, the following lines (36-40) completely cover that:
To start P-EDCA contention the P-EDCA eligible STA shall transmit [#339] CTS frame if the following conditions are satisfied:
·
A PEDCA is enabled by the AP in the BSS
·
P-EDCA eligible STA has AC_VO traffic buffered traffic
·
Other TBD conditions
Gaius Wee:
“ p4L28. "did not to receive CTS frame". Should delete "to"
Answer: Ack, corrected
Liwen Chu, Mohamed Abouelseoud
this (setting to AP's MAC address) is not optimized solution.
Answer: Ok , we can definitely discuss this further. Leaving “RA field set to MAC address of an AP…” TBD for now.
Binita Gupta
"A P-EDCA eligible STA that did not initiate a TXOP (see
10.23.2.4) using P-EDCA contention or did not to receive CTS frame in response to the RTS frame used to initiate the TXOP obtained using P-EDCA contention may transmit CTS frame without invoking backoff procedure as in
10.23.2.4 to start another P-EDCA contention, for up to TBD retries."
On this part there is no motion, so need more discussion
Answer: this is motioned as a part of the motion 272
Xiangxin Gu
Why AIFSN[2] is needed in P-EDCA contention? It's in protected duration.
Answer :
The value of AIFSN[AC] shall be greater than or equal to 2 for non-AP STAs
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