Suggested Resolution on CID #10074 May 2006 doc.: IEEE 802.11-yy/xxxxr0 July 2006 Suggested Resolution on CID #10074 Date: 2006-07-19 Authors: Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair <stuart.kerry@philips.com> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <patcom@ieee.org>. Tomoya Yamaura (Sony) Tomoya Yamaura (Sony)

May 2006 doc.: IEEE 802.11-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 06-0886r0) CID#10074 : for implicit TxBF I would explain potential problem and proposed solution(s). Tomoya Yamaura (Sony) Tomoya Yamaura (Sony)

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)

CID #10074 : potential problem May 2006 doc.: IEEE 802.11-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)

CID #10074 : proposed solution May 2006 doc.: IEEE 802.11-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)

CID #10074 : proposed solution (cont’d) May 2006 doc.: IEEE 802.11-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. This another option would be discussed later, when we would find there would not be enough bits. Tomoya Yamaura (Sony) Tomoya Yamaura (Sony)

CID #10074 : Suggested Resolution-1a May 2006 doc.: IEEE 802.11-yy/xxxxr0 July 2006 CID #10074 : Suggested Resolution-1a 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 Estimation Capability ” in the figure shown in line-4 of page-47 (clause 7.3.2.47.6) of D1.0 Adding a new row to the Figure n19 CSI Estimation Capability Indicates the maximum number of space time streams (columns of the MIMO channel matrix) for which CSI can be simultaneously estimated. When staggered sounding is supported this limit applies independently to both the data portion and to the extension portion of the long training fields. Set 00 for maximum of 1 space time stream in estimation of CSI Set 01 for maximum of 2 space time streams in estimation of CSI Set 10 for maximum of 3 space time streams in estimation of CSI Set 11 for maximum of 4 space time streams in estimation of CSI (Note to TGn 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)

Note for this suggestion July 2006 Note for this suggestion There is no mention for implicit TxBF. It should be commonly used for explicit TxBF Difference from other capability bits for explicit TxBF This specifies estimation capability and other existing capabilities indicate the max number of rows in feedback. If this bits are ‘01’, for example, it means 2 STS supported in CSI estimation. Regular sounding up to 2 HT-LTFs ZLF sounding up to 2 HT-LTFs Staggered of 2+2 is supported. (But 1+3 or 3+1 are not) It does NOT mean the STA indicating this SHALL use all rows. It may choose 2 of them for further processing. Some “rules” should be added in other clause, related to this. And these would be covered by other submissions. For example, under 9.20.2, Sounding packets sent in response to a TRQ shall not set TXVECTOR.NUM_EXTEN_SS to a value greater than the limit indicated by the CSI estimation capability field of the STA that sent the TRQ. When the sounding packet is a ZLF the number of spatial streams corresponding to TXVECTOR.MCS shall not exceed the limit indicated by the CSI estimation capability field of the STA that sent the TRQ. Tomoya Yamaura (Sony)

CID #10074 : Suggested Resolution-1b May 2006 doc.: IEEE 802.11-yy/xxxxr0 July 2006 CID #10074 : Suggested Resolution-1b 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 Estimation Capability in implicit beamforming” in the figure shown in line-4 of page-47 (clause 7.3.2.47.6) of D1.0 Adding a new row to the Figure n19 CSI Estimation Capability in implicit beamforming Indicates the maximum number of space time streams (columns of the MIMO channel matrix) for which CSI can be simultaneously estimated by beamformer when implicit feedback of sounding frame is returned . When staggered sounding is supported this limit applies independently to both the data portion and to the extension portion of the long training fields. Set 00 for maximum of 1 space time stream in estimation of CSI Set 01 for maximum of 2 space time streams in estimation of CSI Set 10 for maximum of 3 space time streams in estimation of CSI Set 11 for maximum of 4 space time streams in estimation of CSI (Note to TGn 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)

CID #10074 : Suggested Resolution-2 May 2006 doc.: IEEE 802.11-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 7.3.2.47.6) 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. This option would be discussed later, when we would find there would not be enough bits. 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)

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

CID #10073 : potential problem May 2006 doc.: IEEE 802.11-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)

CID #10073 : proposed solution May 2006 doc.: IEEE 802.11-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)

CID #10073 : other consideration May 2006 doc.: IEEE 802.11-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)

CID #10073 : Suggested Resolution May 2006 doc.: IEEE 802.11-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 7.3.2.47.6) 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)