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[STDS-802-11-TGAX] CID 24468 (on A-MPDU aggregation rules)

Hi Liwen,

 

Here is my proposed reject reason for the following CID:

 

_  24468

 

 

There is no reason to require all Trigger frames to be first in the A-MPDU (after any immediate ack).  The point of having multiple Trigger frames is to mitigate corruption, but having them all bunched up means they are more vulnerable to periodic interference.  The AP should be allowed to decide where best to place multiple Trigger frames, if it decides to include them.  The resolution to CID 22276 claims that this "can gave the destinated STAs more time to prepare the HE TB PPDU" but this is bogus because (a) all but the last Trigger frame might be corrupted (not received) and so (b) the way a STA ensures it has enough time to prepare is to specify its needs in the Trigger Frame MAC Padding Duration subfield of the HE MAC Capabilities Information field

Delete "The Trigger frames are the first MPDUs of the A-MPDU unless the A-MPDU also

carries an Ack or BlockAck frame in which case the Trigger frames are included

immediately after the Ack or BlockAck frame." in the tables in the referenced subclause

 

REJECTED

There is a reason to require all Trigger frames to be the first in the A-MPDU: it simplifies the receiver design. If it is known that a Trigger frame will always be received before a frame requiring acknowledgment, then the receiver design is simplified in the sense that it has two possible response paths. If, at the time the receiver comes across an frame requiring acknowledgement it will either already have received a Trigger frame, in which case the response is format is an HE TB PPDU or it will not have received a Trigger frame and the response format is known to be an SU PPDU (or no response at all if the ack policy is HTP Ack). Allowing Trigger frames to appear anywhere in the A-MPDU would complicate the receiver design: the receiver would not know the response PPDU format (and timing) or whether to respond at all until the last frame of the A-MPDU had been processed.

 

-Robert

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