1. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 1 VHT SG Considerations 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, 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@ok-brit.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.http:// ieee802.org/guides/bylaws/sb-bylaws.pdf stuart@ok-brit.compatcom@ieee.org Date: 2007-06-20 Authors:

2. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 2 Use cases and scenarios Compared to initial TGn purpose along the standardization path a strong interest has grown up towards inserting technology features for supporting various class of devices: –PC (core original Wi-Fi use) –CE equipment (for HQ video streaming) –Handhelds (e.g. VoIP) Go beyond an 11n on steroids: –vht gives an opportunity to consider new use cases & expand further our traditional way of thinking! –Be the next PHY/MAC that new SG will use such as DLS and VTS! Reality of the market: –Wi-Fi penetration in the home/enterprise/outdoor is growing –Need to face diversity of device classes and features in a robust way –Need to support multiple connections: throughput shouldn’t drop when increasing the number of devices (in the home simultaneous support for IPTV/MP3 streaming & VoIP calls is a reality) –A larger number of CE&handhelds devices are expected to become capable of peer-to-peer gaming, content sharing, and VoIP/video communication in residential, office, and public access networks. –Public access networks and office/enterprise communication solutions are growing. Higher capacity enhanced with higher throughput will be needed. –Interference management/overlapping BSS for efficient deployments and different bandwidth management need to be supported in a robust fashion (20/40MHz is still a major challenge in TGn!) –Outdoor operation is a reality: hotspots and mesh products. Outdoor specificities need to be accounted for (cf. PHY section). –Multimedia handheld PDAs with WiFi access (e.g. Lido, A910) are in high demand and require improved power save mechanisms.

3. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 3 Spectrum usage Statement: 11vht PAR should not be coupled to IMT-Adv timeline, but in our opinion, should address IMT-Adv requirements: –1Gbps nomadic + interworking with MAN technologies. IMT-Adv is above all a tremendous opportunity for accessing new spectrum where 1Gbps WLAN nomadic use is explicitly identified in the req. document It is thus likely that WLAN will have access to a new pool of spectrum other than the legacy 2.4 and 5GHz current bands –possibly >1GHz in total, with the largest chunk between 3.4-4.2GHz TBC by WRC07 –There is a definitive value to have a clean migration path to greenfield operation –Need support for dynamic adaptive bandwidth to fit within available spectrum –Need for interference avoidance as well as spectrum coexistence technologies IMT-Adv deals also with providing a global heterogeneous convergence vision bundling cellular and nomadic technologies: –IEEE802 as a whole is very well positioned with.16/.11/.21 to provide a complete solution through.18 –We need to ask ourselves if it is time to go beyond simple coexistence and consider tighter integration/cooperation between MAN and LAN technologies

4. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 4 MAC efficiency and features During the 802.11HT SG various presentation dealt with 11 MAC efficiency limitations that led to the proposal of efficient aggregation mechanisms (AMPDU/AMSDU) in TGn –Is this enough? (i.e. quantify inherent overhead MAC limitations vs. infinite rate PHY) How to support various BW devices without too much overhead? Is there a value to have several devices transmitting at the same time? –OFDMA exists and provides solutions to: Unbalanced link budgets Improved spectral efficiency/higher capacity through more optimal resource scheduling –Dynamic adaptive bandwidth enables spectrum allocation to be sized to traffic need PSMP TGn mechanisms introduce in a sense an aggregation mechanism implicitly forging a kind of TDM access scheme with a kind of downlink and uplink: –Is TDMA a natural evolution to.11 or can we still build upon the flexibility of CSMA? Compatibility with core requirements of other WG (e.g. TGs) and IMT- Advanced should be maintained to support proposed use cases and to avoid obsolescence Power saving modes for nomadic devices is becoming increasingly important: –Are the 11e/11n mechanisms sufficient? –Should target cellular-like handheld battery performance (talk and standby times)

5. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 5 Some PHY considerations The big question: how to design the PHY to increase the rate: –Information theory tells that capacity grows linearly as a function of the bandwidth and MIMO targets SNR improvements C=B log(1+SNR) –Larger bandwidth of operation will be a must (e.g. 80MHz for gaining >4x over 20MHz operation) in order not to require to large numbers in terms of spectrum efficiency. Shall it be mandated to all devices classes? Rule of thumb exercise on spectral efficiency: –Assumptions: 64/256QAM i.e. 6/8 bits/symbol, FEC R=5/6, 52/108 useful carriers out of 64/128 in 20/40MHz, 16 samples GI –Spectral efficiency const.FEC.carrier_ration.cp_ratio.N_ss=6x5/6x52/64x64/80= 3.25bit/s/Hz for 64QAM in 20MHz for a single stream –1Gbps over 80MHz requires 12.5bit/s/Hz and 10bit/s/Hz in 100MHz –Conclusion: might be feasible with 3/4 spatial streams over 80MHz i.e.: >13bit/s/Hz with 3ss 256QAM and with 4ss 64QAM Better outdoor operations: –Tolerance to larger RMS delay spread: expand the duration of the cyclic prefix to absorb larger delay spreads –Support for moderate mobility (environment): is this a standard issue or receiver differentiator? Should we strive to increase commonalities with.16 OFDMA PHY to go beyond passive coexistence to real cooperation between MAN and LAN? In terms of advanced MIMO technologies, Multi-User MIMO (e.g. SDMA) is getting part of all the major standards (3GPP LTE, IEEE802.16e/m) as a mean to increase aggregated user throughput (e.g. number of VoIP calls supported): –Is this a natural addition to IEEE802.11n for VHT?

6. doc.: IEEE 802.11-07/0721r1 Submission June 2007 Marc de Courville, MotorolaSlide 6 Scoping out 11n enhancements Proposed items that we believe deserve consideration for potential inclusion in the PAR (note: this is a non exhaustive list to be expanded along the process): –Import technical IMT-Adv requirements to be sure to address this opportunity, and not to be alienated to external body evolution –Spectrum efficiency –Below 6GHz spectrum operation –MAC&PHY features to ease interoperability with WMAN –Better outdoor support –Talk time constraints –Enhanced peer to peer capabilities –Simultaneous transmitting devices support