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[STDS-802-11] TGmd CIDs 2359 and 2394 - please review the proposed resolution

--- This message came from the IEEE 802.11 Working Group Reflector ---
All,

TGmd has agreed to the resolutions to these 2 CIDs during the July session. Motions will be brought in September. I was asked to post these to the reflector also - please review and let me know of any issues.

Thanks,

Dorothy
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Both CIDs: 2359 and 2394 have the same resolution, see https://mentor.ieee.org/802.11/dcn/19/11-19-1195-04-000m-assorted-crs.docx 

2359
10.24.2.2
1797.62

"NOTE---A STA can perform a PIFS recovery, as described in 10.24.2.8 (Multiple frame transmission in an EDCA TXOP), or perform a backoff, as described in the previous paragraph, as a response to transmission failure within a TXOP. How it chooses between these two is implementation dependent."

 

-- there is no normative statement that the STA must do one of these two things.

Change the cited text at the referenced location to

 

"A STA shall perform a PIFS recovery, as described in 10.24.2.8 (Multiple frame transmission in an EDCA TXOP), or perform a backoff, as described in the previous paragraph, as a response to transmission failure within a TXOP.

 

NOTE---How it chooses between these two is implementation dependent."

 

Revised - make changes shown under CID 2394 in 11-19-1195-04-000m-assorted-crs.docx.

 

There are three options defined in normative text,

for PIFS recovery, intra-TXOP backoff and waiting for the TXNAV timer to expire. The Note ties these three together, with the changes included.

 

In addition, the proposed changes remove a spurious reference to item f).

 

2394
10.24.2.2
1798.6

When RTS/CTS is successful, and the following PPDU fails, then the CW should not be increased.  This is because that failure cannot be due to a contention collision, i.e. any device that has received the RTS or CTS has updated its NAV so should not collide with us.  The reason for the failure is either bad (too high) rate, or interference. In both these case, increased backoff is unnecessary and it only exacerbates the effect of the interference. [xxmk]

In the referenced subclause at the end of bullet e) add

 

"However, the backoff procedure should not  be invoked by an EDCAF when the initial PPDU of the TXOP contained an RTS frame."

 

Revised - make changes shown under CID 2394 in 11-19-1195-04-000m-assorted-crs.docx.

 

Doubling CW for an intra-TXOP backoff may indeed not always be an optimal choice. However, PIFS recovery is also already an option. The group did not come to a consensus on whether additional (intermediate) options should be added.

 

In addition, the proposed changes remove a spurious reference to item f).


Agreed resolution:CID 2394

 

1797.33

 

The backoff procedure shall be invoked by an EDCAF when any of the following events occurs:

 

a)  An MA-UNITDATA.request primitive is received that causes a frame with that AC to be queued for transmission such that one of the transmit queues associated with that AC has now become nonempty and any other transmit queues associated with that AC are empty; the medium is busy on the primary channel as indicated by any of the following:

 

— physical CS;

— virtual CS;

— a nonzero TXNAV timer value;

— a mesh STA that has dot11MCCAActivated true and a nonzero RAV timer value, and the backoff counter has a value of 0 for that AC.

 

b)  The transmission of the MPDU in the final PPDU transmitted by the TXOP holder during the TXOP for that AC has completed and the TXNAV timer has expired, and the AC was a primary AC. (See 10.24.2.7 (Sharing an EDCA TXOP)).

 

c)  The transmission of an MPDU in the initial PPDU of a TXOP fails, as defined in this subclause, and the AC was a primary AC.

 

d)  The transmission attempt collides internally with another EDCAF of an AC that has higher priority, that is, two or more EDCAFs in the same STA are granted a TXOP at the same time.

 

In addition, the backoff procedure may be invoked by an EDCAF when:

 

e)  The transmission by the TXOP holder of an MPDU in a non-initial PPDU of a TXOP fails, as defined in this subclause.

 

NOTE—If the transmission by the TXOP holder of an MPDU in a non-initial PPDU of a TXOP failed, the A STA can perform either a PIFS recovery, as described in 10.24.2.8 (Multiple frame transmission in an EDCA TXOP), or perform a backoff, as described in item e) abovethe previous paragraph, or wait for the TXNAV timer to expire and invoke the backoff procedure per item b) aboveas a response to transmission failure within a TXOP. How it chooses between these two is implementation dependent.

 

A STA that performs a backoff within its existing TXOP per item e) above shall not extend the TXNAV timer value (see 10.24.2.8 (Multiple frame transmission in an EDCA TXOP)).

 

NOTE—In other words, the backoff is a continuation of the TXOP, not the start of a new TXOP.

 

If the backoff procedure is invoked for reason a) above, the value of CW[AC] shall be left unchanged.

 

If the backoff procedure is invoked for reason b) above, the value of CW[AC] shall be reset to CWmin[AC].

 

If the backoff procedure is invoked for reason c), d), or e), or f) above, the value of CW[AC] shall be updated as follows before invoking the backoff procedure:

 

etc.


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