1. TGn Meeting Report - June 02 ‘09
doc.: IEEE /0669r0
June 2009
TGn Meeting Report - June 02 ‘09
Date: 2009-June-02
Authors:
Name
Company
Address
Phone
Bruce Kraemer
Marvell +1 -
321 4 27
4098
marvell
.com
5488 Marvell Lane,
Santa Clara, CA, 95054
Bruce Kraemer, Marvell
Bruce Kraemer, Marvell

2. June 2009 Bruce Kraemer, Marvell
As a result of previous ballot round comments, the latest set of TGn changes (for recirc 3) include some enhancements for TGn wrt to 1SS devices. Those changes are a welcome improvement to the TGn draft. The inclusion of those changes has caused me to further consider several trends in the WLAN marketplace and how well TGn is supporting those trends. When the TGn project started, the general view what that TGn would be a "high thruput addition" to the current popularly deployed phys (TGa, b, g). It is well known that "draft TGn" devices have been shipping since before the TGN Sponsor ballot process started. This has provided an opportunity to get real world information about what features of TGn are being adopted in the industry. Market activity is confirming that TGn is (and will continue to) displacing prior generation PHYs rather than supplanting them. This is becoming particularly significant at the lower end of the TGn performance spectrum where as 1SS TGn devices are increasingly replacing TGg devices. However, the TGn draft still contains some (IMO, no longer needed or desired) restrictive requirements for SS support. These requirements are impeding the expansion of the market in the value / low cost market segments. 1SS "non-AP" stations are currently part of the TGn draft, yet APs are required to support 2SS as minimum finctionality. This hinders the use of TGn technology for value segment APs. Given the realities of the market, I believe that the minimum requirements for AP vs SSs should be changed. I suggest that APs be allowed to be 1SS as a minimum. 1SS AP devices are going to exist in significant volume in the market (in fact they already exist). The TGn amendment to should encompass and encourage the uses of TGn that are already being seen in the field.
1) Change the wording in clause from "An HT AP shall support all equal modulation rates for 1 and 2 spatial streams (MCSs 0 through 15) using 20 MHz channel width." to "An HT AP shall support all equal modulation rates for 1 spatial stream (MCSs 0 through 7) using 20 MHz channel width." 2) Also change the note in section from "NOTE--Support of 20 MHz Non-HT Format and 20 MHz HT Format with one and two spatial streams is mandatory at APs." to "NOTE--Support of 20 MHz Non-HT Format and 20 MHz HT Format with one spatial stream is mandatory at APs." 3) These are the two references to this restriction that I could find in the draft. Also correspondingly change any other references which may exist that require 2SS support for APs.
Bruce Kraemer, Marvell

3. SB3 CID 3017 (11-09-0024 r11) Comment Proposed Change June 2009
Bruce Kraemer, Marvell

4. June 2009
Discussion (1 of 2)
The pertinent text in the draft expressing the restriction is located in two places
1. the last paragraph of section “Introduction to the HT PHY”
An HT non-AP STA shall support all equal modulation rates for 1 spatial stream (MCSs 0 through 7) using 20 MHz channel width. An HT AP shall support all equal modulation rates for 1 and 2 spatial streams (MCSs 0 through 15) using 20 MHz channel width.
2. A note at the end of section “Effect of CH_BANDWIDTH, CH_OFFSET and MCS parameters on PPDU format”
NOTE—Support of 20 MHz Non-HT Format and 20 MHz HT Format with one and two spatial streams is mandatory at APs. Support of 20 MHz Non-HT Format and 20 MHz HT Format with one spatial stream is mandatory at non-AP STAs.
Bruce Kraemer, Marvell

5. June 2009
Discussion (2 of 2)
At the time the project was started (2002) the goal of TGn was significantly higher throughput than what was available from existing options (b,g,a).
Functional Requirements were drawn up to refine technical goals and serve as a review criteria for proposals. Multiple versions of were developed during 2003 and early 2004 ( r12 was posted March 2004).
In May of 2005 Document r0 introduced handset requirements and asked for certain exceptions to be considered.
Primary concerns were handset market size, extended range, device size, power consumption, smaller number of antennas, efficient support for small packet size
Subsequently, in July 2005 the Functional Requirements were modified ( r13 posted July 2005).
During the TGn CRC call of June 01, 2009 the proposed change was discussed with strawpoll results for 1/against 5/abstain 5 indicating it had far less than the 75% approval required to become a change.
Conclusion: The TGn requirements were and are driven by a need for higher throughput. During 2005, after several months of debate the requirements and draft contents were modified but have remained stable since then. The opportunity to significantly alter the project goals would appear to be behind us. The calendar time required to discuss the change and its implications is limited as is the motivation within the WG11. While the suggestion is not without merit, it would be best to explore methods to accomplish the stated change at another time and within another venue such as a future P baseline revision.
Bruce Kraemer, Marvell

6. Proposed Resolution Disagree June 2009
The rationale behind P802.11n has been its unique identity as a high throughput amendment. Some accommodation for small, handheld stations has previously been incorporated. The opportunity to significantly alter the project goals has passed. The proposed change to allow HT-APs operate with only one spatial stream is not supported by the majority of participants.
Bruce Kraemer, Marvell