Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: [STDS-802-11-TGBE] [CR-MAC] Multi-link Retransmission

Hi Yongho,

 

You are right, I made a mistake. The note should have been as below:

 

NOTE – In order to prevent the receiver from discarding a newer frame as a replayed frame due to an older retransmitted frame, the PN used to protect the frame is not incremented when the frame is retransmitted.

 

Consider the following simple scenario:

  • 1st frame (SN=1, PN=1) and 2nd frame (SN=2, PN=2) are transmitted together
  • 1st frame fails while 2nd frame is successfully received
  • 1st frame is retransmitted on a different link with a new PN (3) and is successfully received.
  • Both frames are forwarded up by the Rx Reorder buffer in order of their SNs.
  • Replay counter becomes 3 due to 1st frame => 2nd frame is discarded as replayed frame since its PN = 2 < 3.

 

I agree with you that this requirement is similar to the one in baseline, however it is not apparent that the baseline rule covers the case of retransmission on a different link since the A1/A2 may be different. Alternatively, I can add a simpler note based on the baseline text:

 

NOTE—Retransmitted MPDUs are not encapsulated with a new PN when retransmitted on another link.

 

What do you think?

 

Regards,

Rojan

 

From: Yongho Seok <yongho.seok@xxxxxxxxx>
Sent: Wednesday, March 17, 2021 2:38 PM
To: Rojan Chitrakar <rojan.chitrakar@xxxxxxxxxxxxxxxx>
Cc: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] [CR-MAC] Multi-link Retransmission

 

Hi Rojan, 

Regarding "NOTE 2 – In order to prevent the receiver from discarding a retransmitted frame as a replayed frame, the PN used to protect the frame is not incremented when the frame is retransmitted. (#2598)"

Isn't this conflicted with the following baseline rule?
"The receiver shall discard any Data frame that is received with its PN less than or equal to the value of the replay counter that is associated with the TA and priority value of the received MPDU."

If you increase the PN of the retransmitted frame, why is it discarded? The PN is greater than the value of the replay counter. 

 

I understand the PN of the retransmitted MPDU should not be changed. The baseline also has the following text.

(#4613)NOTE—Retransmitted MPDUs are not modified on retransmission.

But, I am not sure whether "To prevent something" is correct in your NOTE 2. 

 

Thanks, 

Yongho

 

2021년 3월 15일 (월) 오전 1:18, Rojan Chitrakar <rojan.chitrakar@xxxxxxxxxxxxxxxx>님이 작성:

Dear all,

 

Please help to review the following CR document and let me know if there is anything:

 

https://mentor.ieee.org/802.11/dcn/21/11-21-0302-00-00be-crs-for-d0-3-multi-link-retransmission-cids.docx

 

It resolves the following 8 CIDs related to Multi-link retransmissions:

 

CIDs: 1064, 1687, 2503, 2598, 2714, 3338, 3381, 3382 (8 CIDs)

 

Regards,

Rojan

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

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