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Hi Carlos and All, Thank you for the discussion today on clause 10.13.2, I have copied clause 10.13.2 below for reference.
(Note: the text in this e-mail has underlined text for additions and
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10.13.2 A-MPDU length limit rules
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Change the first paragraph as follows
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A STA indicates in the Maximum A-MPDU Length Exponent field in its HT Capabilities element the
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maximum A-MPDU length that it can receive in an HT PPDU. A STA indicates in the Maximum A-
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MPDU Length Exponent field in its VHT Capabilities element the maximum length of the A-MPDU pre-
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EOF padding that it can receive in a VHT PPDU. A DMG STA indicates in the Maximum A-MPDU
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Length Exponent field in its DMG Capabilities element the maximum A-MPDU length that it can receive.
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An EDMG STA indicates in the Maximum A-MPDU Length Exponent field in its EDMG Capabilities
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element the maximum A-MPDU length that it can receive.
The encoding of these fields is defined in Table
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9-163 for an HT PPDU, in Table 9-249 for a VHT PPDU, and in Table 9-229 for a DMG STA
that is not
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an EDMG STA, and in Table 1 for an EDMG STA.
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Insert a new paragraph at the end as follows
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An EDMG STA shall not transmit an A-MPDU that is longer than the value indicated by the Maximum A-
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MPDU Length Exponent field in the EDMG Capabilities element received from the intended receiver. I have several point to make regarding this text:
1)
The purpose of the text in the first paragraph is to require a STA to report the maximum A-MPDU length that the STA can receive.
2)
The text requires the STA to report this value in the HT Capabilities element, the VHT Capabilities element, and the DMG Capabilities element. This text does not require the STA to send the capabilities
element, nor does it specify when the capabilities element should be sent. It only specifies that if the STA sends the element it should include the maximum A-MPDU length the STA can receive.
3)
Note the for the HT Capabilities element and VHT Capabilities element the requirement to report is for all STAs. To me this means that all STAs which will send the HT Capabilities element must report
their maximum A-MPDU length in the HT Capabilities element. Likewise for all STAs which send the VHT Capabilities element.
4)
When DMG was added to the specification the way reporting was required was changed. I believe that this is an error that TGmd should consider fixing this by simplifying the language to state that
a STA indicates the maximum A-MPDU Length in the DMG Capabilities element and not try to make the requirement specific to DMG STAs. But I don’t think this is something TGay needs to fix, this is probably a TGmd issues.
5)
Based on the above: I don’t think that the addition of the EDMG Capabilities element should complicate this section by trying to indicate which STAs send the DMG Capabilities element is sent by or
where the fields are defined. Given the above discussion, I suggest the following for the changes to the first paragraph (note the changes to the DMG requirement should probably be made by TGmd):
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A STA indicates in the Maximum A-MPDU Length Exponent field in its HT Capabilities element the
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maximum A-MPDU length that it can receive in an HT PPDU. A STA indicates in the Maximum A-
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MPDU Length Exponent field in its VHT Capabilities element the maximum length of the A-MPDU pre-
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EOF padding that it can receive in a VHT PPDU. A
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Length Exponent field in its DMG Capabilities element the maximum A-MPDU length that it can receive
in a DMG PPDU.
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A
In addition to the above suggestions I suggest changing the inserted new paragraph to be changed in the following way:
1)
The requirement for a STA not to send a DMG PPDU larger than the intended receiving STA can receive was appended to the paragraph that contains the similar requirements for HT and VHT. Hence it
the EDMG requirement should also be appended to the last paragraph in this clause and not a standalone paragraph.
2)
There is no reason to restrict sending STA to be an EDMG STA, or for that matter an DMG STA for the DMG case. Including the STA type restriction builds into the specification an issue going forward,
which is illustrated by the current DMG requirement. The issue is that the current DMG STA requirement does not restrict an EDMG STA from sending a DMG PPDU which is larger than that can be received by the intended STA (which has sent a DMG maximum length),
it only restricts DMG STAs from doing so. Therefore I believe I believe the last paragraph in section10.13.2 should read as follows: Change the last paragraph as follows: A STA
shall not transmit an A-MPDU in an HT PPDU that is longer than the value indicated by the Maximum A-MPDU Length Exponent field in the HT Capabilities element received from the intended
receiver. MPDUs in an A-MPDU carried in an HT PPDU shall be limited to a maximum length of 4095 octets. A STA shall not transmit an A-MPDU in a VHT PPDU where the A-MPDU pre-EOF padding length is longer than the value indicated by the Maximum A-MPDU Length
Exponent field in the VHT Capabilities element received from the intended receiver. A
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