1. GroupID in VHT-SIG Field
January 2010
doc.: IEEE /0073r0
May 2010
GroupID in VHT-SIG Field
Date:
Authors:
Joonsuk Kim, Broadcom Corp.
Joonsuk Kim

2. January 2010
doc.: IEEE /0073r0
May 2010
Background
With resolvable LTFs for MU-MIMO transmission, we need a mechanism to identify which streams are for which user [1].
GroupID was proposed to identify users and space-time streams in MU-MIMO operation [1]
PagingID mechanism also reaches the same goal if AP can collect the channel correlation information from STAs [2]
We have reached a consensus to agree on having GroupID field in VHT-SIG A and keep working on the GroupID management (e.g., how to define and signal groups)
Joonsuk Kim, Broadcom Corp.
Joonsuk Kim

3. Location Indication for MU-Streams in VHT-SIG A
January 2010
doc.: IEEE /0073r0
May 2010
Location Indication for MU-Streams in VHT-SIG A
VHT-SIG A tells the number of columns of Qk (steering matrix for user k) in the order of assigned user number in the group.
All STAs can listen to VHT-SIG A, so each participating user knows when to start to detect its own stream.
VHT-SIG A includes following fields
GroupID is used to indicate which group of STA(s) to receive MU-MIMO transmissions in the order of assigned user number
Some of these bits may be reused for SU-MIMO packet
Detail of GroupID management (e.g. How to assign & signal groups with GroupID) is TBD
How to manage the GroupID field to support a large network of STAs is under investigation
K is the max number of users to support with MU-MIMO
y bits
x bits
Group ID
# of columns of Qk (Nsts_k) for k=1,2,…,K
Qk is the steering matrix
for user k
x>0, y >0
Nsts field
x bits indicate the number of columns of Nsts for user 1,2,…, K. Details are TBD
It is possible Nsts_k = 0 for certain k if STA k is not a recipient of MU-MIMO packet.
Joonsuk Kim, Broadcom Corp.
Broadcom Proprietary & Confidential. © 2009 Broadcom Corporation. All rights reserved. 3
Joonsuk Kim

4. January 2010
doc.: IEEE /0073r0
May 2010
Strawpoll
Do you support adding a GroupID field (TBD bits) and an Nsts field (TBD bits) to VHT-SIGA of the 11ac preamble, and editing the spec framework document, , accordingly?
Yes: 57
No: 0
Abstain: 14
It passes
Joonsuk Kim, Broadcom Corp.
Broadcom Proprietary & Confidential. © 2009 Broadcom Corporation. All rights reserved. 4
Joonsuk Kim

5. Reference [1] “11-10-0073-02-00ac-GrpID-for-DL-MU-Transmission.ppt"
January 2010
doc.: IEEE /0073r0
May 2010
Reference
[1] “ ac-GrpID-for-DL-MU-Transmission.ppt"
[2] “ ac-mu-mimo-sta-scheduling-strategy-and-related-phy-signaling.ppt”
Joonsuk Kim, Broadcom Corp.
Joonsuk Kim