1. Suggested Resolution on CID #10074
May 2006
doc.: IEEE yy/xxxxr0
July 2006
Suggested Resolution on CID #10074
Date:
Authors:
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Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

2. May 2006
doc.: IEEE yy/xxxxr0
July 2006
Abstract
I submitted two comments to improve D1.0 for TxBF at asymmetric antenna configuration.
CID#10073 : for explicit TxBF
(Treated as ‘for your reference’ in this document, and this is
covered in r0)
CID#10074 : for implicit TxBF
I would explain potential problem and proposed solution(s).
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

3. Some definitions Beamformer Beamformee Beamformer Beamformee
July 2006
Some definitions
Beamformer
STA that transmits steered frame
It has N-antennas
Beamformee
STA that receives steered frame
It has M-antennas
N-antennas
M-antennas
steered
Frame
Beamformer
Beamformee
Tomoya Yamaura (Sony)

4. CID #10074 : potential problem
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10074 : potential problem
implicit TxBF
N<M
Beamformee
M=3
Beamformer
N=2
TRQ in HTC
[3x2 channel： <3 streams]
This is 2 streams device but;
have to estimate/buffer
2x3 channel
- have to calculate
steering matrix from
2x3 matrix
(ch estimation)
Sounding
[2x3 channel: <3 streams]
(derive V)
steered
frame
[3x2 channel： <3 streams]
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

5. CID #10074 : proposed solution
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10074 : proposed solution
Add capability field for Beamformer (not only for beamformee)
To allow low cost solution at beamformer
capability exchange prior to beamforming
Beamformee
M=3
Beamformer
N=2
TRQ in HTC
[3x2 channel： <3 streams]
(ch estimation)
Sounding
[2x2 channel: <3 streams]
Dimension of sounding is limited based on announced capability of beamformer
+Smaller overhead
(derive V)
steered
frame
[3x2 channel： <3 streams]
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

6. CID #10074 : proposed solution (cont’d)
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10074 : proposed solution (cont’d)
How to add this capability indicator ?
Just define new capability indicator as current draft has for explicit TxBFs
Pros : much simpler to understand
Cons : requires more bits Or
Reuse capability field for beamformee for explicit TxBF, such as CSI feedback
Pros : no additional bits required
Cons : overloading bits may be misunderstood by the beginners
Even if the node doesn’t support explicit feedback, this field shall be set correctly.
BTW, current draft doesn’t mention how to set these fields if these features are not supported.
There is no problem if the node support explicit also.
Same meaning = maximum training dimension.
If beamformer has capability to estimate streams more than antenna numbers, it would be indicated in this field as well.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

7. CID #10074 : Suggested Resolution-1
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10074 : Suggested Resolution-1
Instruct the TGn editor to allocate two bits from a reserved field of the Transmit Beamforming Capability field in the HT Capability element and insert appropriate references to these bits in the description below.
Replacing two reserve bits with “Number of beamformee antennas in implicit feedback” in the figure shown in line-4 of page-47 (clause ) of D1.0
Adding a new row to the Figure n19
Number of beamformee antennas support in implicit feedback
Indicate the maximum number of beamformee antennas the beamformer can support when implicit feedback of sounding frame is returned
Set 00 for single Tx antenna sounding
Set 01 for 2 Tx antenna sounding
Set 10 for 3 Tx antenna sounding
Set 11 for 4 Tx antenna sounding
(Note to editor)
The terminologies of “beamformer” and “beamformee” may be changed depending on the result of comment resolution for CID #472.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

8. CID #10074 : Suggested Resolution-2
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10074 : Suggested Resolution-2
Instruct the TGn editor to change definition of “CSI number of beamformer antennae” field in the Transmit Beamforming Capability field in the HT Capability element in the description below.
Replacing the field name of “CSI number of beamformer antennas” (now B19, 20) in the figure shown in line-4 of page-47 (clause ) of D1.0 with “CSI number of beamformer antennas / Number of beamformee antennas in implicit feedback”
Changing row of Figure n19 (shown at the bottom of page-49) as follows.
Number of beamformer antennas support in implicit feedback / Number of beamformee antennas in implicit feedback
When “Explicit BF CSI feedback” doesn’t indicate “incapable”, this field means;
The maximum number of beamformer antennas the beamformee can support when CSI feedback is required.
When “Implicit TxBF capable” doesn’t indicate “incapable”, this field means;
The maximum number of beamformee antennas the beamformer can support when implicit feedback of sounding frame is returned.
Set 00 for single Tx antenna sounding
Set 01 for 2 Tx antenna sounding
Set 10 for 3 Tx antenna sounding
Set 11 for 4 Tx antenna sounding
(Note to editor)
The terminologies of “beamformer” and “beamformee” may be changed depending on the result of comment resolution for CID #472.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

9. For your reference July 2006 May 2006 doc.: IEEE 802.11-yy/xxxxr0
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

10. CID #10073 : potential problem
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10073 : potential problem
explicit TxBF using CSI feedback
N<M
Beamformee
M=3
Beamformer
N=2
No problem for channel estimation and packing
CSI, because it would be
capable for 3-streams
CSI FB-RQ
with sounding
[3x2 channel： <3 streams]
This is 2 streams device but;
have to receive/buffer 3x2
CSI feedback
have to calculate
steering matrix from
3x2 matrix
(ch estimation)
CSI data
[2x3 channel: <3 streams]
(derive V)
steered
frame
[3x2 channel： < 3 streams]
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

11. CID #10073 : proposed solution
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10073 : proposed solution
Add capability field for Beamformer (not only for beamformee)
To allow low cost solution at beamformer
Beamformee
M=3
Beamformer
N=2
capability exchange prior to beamforming
CSI FB-RQ
with sounding
[3x2 channel： <3 streams]
(ch estimation)
CSI data
[2x3 channel: <3 streams]
Dimension of CSI feedback is limited based on announced capability of beamformer
+Smaller overhead
(derive V)
steered
frame
[3x2 channel： <3 streams]
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

12. CID #10073 : other consideration
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10073 : other consideration
Why only for CSI feedback ?
For steering matrix feedback (compressed or uncompressed), this doesn’t occur.
Because the dimension of steering matrix would become NxN.
How about N>M case in explicit feedback ?
Current draft has capability indicators of beamformee.
If beamformer would honor capabilities at beamformee, there would be no problem.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)

13. CID #10073 : Suggested Resolution
May 2006
doc.: IEEE yy/xxxxr0
July 2006
CID #10073 : Suggested Resolution
Instruct the TGn editor to allocate two bits from a reserved field of the Transmit Beamforming Capability field in the HT Capability element and insert appropriate references to these bits in the description below.
Replacing two reserve bits with “CSI row number from beamformee” in the figure shown in line-4 of page-47 (clause ) of D1.0
Adding a new row to the Figure n19
CSI row number from beamformee support
00 supporting single row of CSI
01 supporting 2 rows of CSI
10 supporting 3 rows of CSI
11 supporting 4 rows of CSI
The maximum number of rows of CSI explicit feedback from beamformee the beamformer can support when CSI feedback is required
(Note to editor)
The terminologies of “beamformer” and “beamformee” may be changed depending on the result of comment resolution for CID #472.
Tomoya Yamaura (Sony)
Tomoya Yamaura (Sony)