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VHT Link Adaptations. Date: 2011-1-18. Authors:. FLA Categories. Solicited MFB MRQ with NDP Sounding that requests beamforming/MU FB, MFB sent with sounding FB frame. MRQ that is not tied up with beamforming exchange, MFB sent in regular uplink frame. Unsolicited MFB

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vht link adaptations
VHT Link Adaptations

Date: 2011-1-18

Authors:

fla categories
FLA Categories
  • Solicited MFB
    • MRQ with NDP Sounding that requests beamforming/MU FB, MFB sent with sounding FB frame.
    • MRQ that is not tied up with beamforming exchange, MFB sent in regular uplink frame.
  • Unsolicited MFB
    • Unsolicited MFB with Sounding FB.
    • Unsolicited MFB sent in regular uplink frame.
solicited link adaptation in 11n
Solicited Link Adaptation in 11n

MRQ shall be sent in HTC along with sounding (see 9.18.2).

+HTC MRQ=1

NDPA

NDP

MFB

  • MRQ is sent with sounding, so that the Rx can fully derive MIMO channel est and compute appropriate Mod/rate/Nss.

Slide 3

difference in 11ac
Difference in 11ac
  • NDPA+NDP sequence is tied up with SU-BF or MU-MIMO sounding.
    • Refer to NDPA frame definition
  • Therefore it is not possible to send a VHT MRQ in NDPA that only requests MFB and not request BF feedback.
    • i.e. MRQ in NDPA has to be tied up with BF.
    • Note that MRQ in NDPA means MFB has to be measured based on NDP.
mcs versus snr fb
MCS versus SNR FB
  • It is arguable whether the Rx or Tx should compute the MCS.
    • Tx needs to offset its power difference on sending different MCSs, the Rx does not know the Tx power control.
    • Rx does not know whether Tx will apply optional PHY modes such as STBC, LDPC, TxBF, or other proprietary technology.
  • Desirable to feedback both MCS and SNR.
    • SNR is defined as 8bit 2’s complement number, averaged over all the tones and all the space-time streams

Represent [-10, 53]dB, same as SNR report in Compressed V FB (11n, 11ac)

example of vhtc format
Example of VHTC Format
  • Details refer to [1].
link adaptation with su bf
Link Adaptation with SU BF
  • We already have rule on MFB in SU BF feedback frame: MFB+SNR assumes the same CV will be applied, and Nsts=Nc.
  • Need a rule for responding MRQ with NDPA.
  • Proposal: if the MRQ is in NDPA that requests SUBF feedback, BFMee SHALL include the MFB only in SU-BF feedback.
    • Reason: SU-BF FB already has SNR and Nsts ready, it is just one step from computing MCS, easy to implement. Delayed MFB in this case will complicate the situation.

MRQ

NDPA

NDP

MFB+SNR

SUBF FB

Slide 7

pre motion 1
Pre-Motion 1
  • Do you agree to add the following sentence in spec frame work

6.x VHT Link Adaptation

MRQ in VHT Control Field could be sent with any frame (i.e. not only with NDPA).

    • Yes
    • No
    • Abstain
pre motion 2
Pre-Motion 2
  • Do you agree to add the following sentence in spec frame work

6.x VHT Link Adaptation

An SNR Feedback field is included in VHT Control Field, which is defined as 8bit 2’s complement number, averaged over all the tones and all the space-time streams.

    • Yes
    • No
    • Abstain
pre motion 3
Pre-Motion 3
  • Do you agree to add the following sentence in spec frame work

6.x VHT Link Adaptation

If the MFB requester sends MRQ in an VHT NDP announcement frame requesting only SU-BF Feedbacks, then the MFB responder shall include the corresponding MFB and SNR feedback in the VHT Compressed Beamforming frame that is the response of the same NDP-A and NDP sequence.

    • Yes
    • No
    • Abstain
references
References

[1] 11-11-0040-00-00ac-VHT-Control-and-Link-Adaptation.pptx

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