Page 1Version 1.0 IEEE802.11-11-865r0 IEEE Perspectives on Document N14746 EEE 802 IEEE 802.11...

Page 1Version 1.0 IEEE802.11-11-865r0 IEEE Perspectives on Document N14746

EEE802

IEEE 802.11 IEEE802.11 Perspectives on document 6N14746 (NB of China’s contribution on the MAC and PHY Specs for Wireless high data rate application - 5.4.2 in 6N14603 WG 1 Agenda)


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This document provides a preliminary response from the IEEE 802.11 Working Group on the proposal contained in document 6N14746

Abstract


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Topics

• Context and Introduction• Overview of IEEE802.11ac• Potential areas of overlap and incremental techniques• Potential technical issues with China NB proposal• Potential marketplace issues with China NB proposal• Preliminary conclusions• Invitation


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Context and Introduction• IEEE Taskgroup 802.11ac has been working on the development of a new

standard for Very High Throughput for <6GHz (practically the 5GHz band) since September 2008– Currently status is Working Group Letter Ballot on draft 1.0

• Document N14746 from the China National Body contains a MAC/PHY proposal which targets the same frequency bands and usages and includes many of the same technical concepts as 802.11ac

• However this proposal embodies key differences which would make devices that implement the proposed standard incompatible and non-coexistent with 802.11 based devices in the same frequency band

• This document outlines:– A brief overview of IEEE802.11ac– Potential technical issues with the proposal in doc N14746– Potential marketplace issues with the proposal in doc N14746– Possible way forward


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Purpose, Scope and Timeline of IEEE802.11ac

Purpose:• Provide significantly higher network throughput for existing WLAN

application areas

• Enable new market segments for operation below 6 GHz including distribution of multiple multimedia / data streams and rapid synchronization

Scope:Updates to both PHY and MAC to enable:

• A multi-station network throughput of at least 1 Gbps

• A maximum single link throughput of at least 500 Mbps

• Below 6GHz carrier frequency operation, excluding 2.4GHz operation

I.e. 5 GHz operation generally, using same spectrum in use for .11a and .11n

Timeline:– Taskgroup started Q3, 2008– Currently in stage of Working Group ballot of draft 1.0– Standard Finalization anticipated in Q4, 2013


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802.11ac Market Drivers• Industry cadence of new physical layer (PHY) technology introduction

– Approximately every 3-4 years, the Wi-Fi industry launches a program with a major upgrade to PHY capabilities

• 2000: 11b, 11 Mbps; 2003: 11g, 54 Mbps; 2007: 11n, 300 Mbps

– The IEEE 802.11ac taskgroup is currently developing a standard for new PHY capabilities, targeting Gbps link rates in the 5 GHz band

• Higher Throughputs are highly compelling for enabling technologies such as Wi-Fi Direct, 802.11z/TDLS and Wi-Fi Display;

– Widens the ecosystem of Wi-Fi enabled devices– GigE routers and storage devices are expected to complement the ecosystem

• 802.11ac technology will be highly relevant for several High Value Use Cases, among which:

– Compressed Video streaming throughout the home– Wi-Fi Display– ‘Rapid Synch and Go’ and Back Up file transfer– Wireless Networking for Home and Small Office– Manufacturing Floor Automation


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New technologies in 802.11ac

• Wider channel bandwidths:• 80 MHz and 160 MHz channel bandwidths• 80 MHz mandatory for STA, 160 MHz optional

• More spatial streams:• Support for up to 8 spatial streams (vs. 4 as in 11n)

• Multi-user MIMO (MU-MIMO)• A technique where multiple STAs, each with potentially multiple antennas,

transmit or receive independent data streams simultaneously• “Space Division Multiple Access” (SDMA): streams not separated by frequency, but

instead resolved analogously to 11n-style MIMO

• Downlink MU-MIMO (one transmitting device, multiple receiving devices) included as an optional mode

• Modulation• 256-QAM, rate ¾ and 5/6, added as optional modes

• Other elements/features:• Single sounding and feedback format for beamforming (vs. multiple in 11n)• MAC modifications (mostly to adapt to above changes)• Coexistence mechanisms for 20/40/80/160 MHz channels, 11ac and 11a/n devices


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Current spectrum availability for 802.11ac operation in select geographic markets

US

Europe &Japan

India

China


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Examples of new configurations enabled by .11ac

Scenario* Typical Client Form-factor

Link Rate AggregateCapacity

1 Tx AP, 1 Rx, 80MHz Handheld 433 Mbps 433 Mbps

2 Tx AP, 2 Rx, 80 MHz Tablet, Laptop 867 Mbps 867 Mbps

1 Tx AP, 1 Rx, 160MHz Handheld 867 Mbps 867 Mbps

2 Tx AP, 2 Rx, 160 MHz Tablet, Laptop 1.73 Gbps 1.73 Gbps

4 Tx AP, 4 1-Rx STAs,160 MHz Handheld 867 Mbps to each STA

3.47 Gbps

8 Tx AP; 160MHz•1 4-Rx STA•1 2-RX STAs•2 1-RX STAs

DTV, STB, Tablet, PC, Handheld

3.47 Gbps to 4-RX STA; 1.73 Gbps to 2-RX STA; 867 Mbps to each 1-RX STA

6.9 Gbps

8 Tx AP; 4 2-Rx STAs, 160 MHz DTV, Tablet, Laptop, PC

1.73 Gbps to each STA

6.9 Gbps

* All scenarios assume 245 QAM Modulation, and rate 5/6 coding


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Taskgroup IEEE 802.11ac has active participation from a large number of companies, originating from all over the globe

• In taskgroup IEEE802.11ac, engineers who work for a large international group op Companies and Research Institutes are collaborating to develop a global industry standard

• 802.11ac has active participants from:– Australia - Germany - Netherlands– Belgium - Great Britain - Singapore– Canada - India - South Korea– China - Israel - Taiwan– France - Japan - USA– Finland

• For example the recent submission for the creation of Draft 1.0 of 802.11ac (doc 11/1361) lists participants from the following companies:

– Broadcom (USA) - Marvell (USA)– Celeno (Israel) - Mediatek (Taiwan)– Cisco (USA) - Qualcomm (USA)– ETRI (South Korea) - Radrix (Japan)– Huawei (China) - Realtek (Taiwan)– Intel (USA) - Samsung (South Korea)– Kyushi Institute (Japan) - ST Ericsson (Italy / France)– LG Electronics (South Korea) - ZTE (China)


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Potential Areas of Overlap and Incremental Features in N12746

• A high level comparison of the China NB proposal and 802.11ac highlights the following areas of overlap:

– Targeted frequency (<6GHz)

– 20/40/80 MHz modes

– MU-MIMO

– 256 QAM

– LDPC

• The proposal introduces a set of incremental features which, in theory, can lead to higher throughputs, e.g.:

– Code rate 7/8 for 256 QAM

– Non-contiguous 20 MHz channels

– Denser carrier spacing for OFDM (4x)

– Up to 8 SS support of DL MU-MIMO

– Unequal Modulation

– Uplink MU MIMO

– Expanded LDPC Matrix

– Scheduled TDMA MAC

Note: Document N14746 contains a high level overview of the proposed standard and no detailed analysis of the overlap and differences can be provided at this time


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Potential Technical IssuesPreliminary analysis of the proposal points to some high level issues:

1. The scheduled TDMA MAC will cause coexistence issues with 802.11 devices operating in the same frequency band in overlapping networks– In situations where the overlapping networks operate in different administrative

domains, as is typically the case in residential and SMB settings

2. The proposed preamble is likely to cause coexistence issues with 802.11 based devices– May lead to false detects and wrong defer on .11a/n/ac and degraded performance

3. Significantly higher sensitivity to frequency error and phase noise compared to .11ac– Unclear how the preamble can work for 40 ppm combined with Tx/Rx frequency

offset

4. Complexity Issues:– Proposal introduces new techniques that add significant complexity to a device with

questionable benefits (e.g. 7/8 coding for 256 QAM, large LDPC matrix)– It is non-trivial to build a combo 80211/N14746 device that actually works


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Potential Marketplace Issues• The dynamics inside the 802.11 based ecosystem are highly competitive,

which leads to rapid innovation and scale advantages for 802.11 based devices• The 802.11 / Wi-Fi Alliance ecosystem has emerged as the winning ecosystem

for WLAN applications, ‘outcrowding’ other efforts like ETSI HiperLAN2, Home RF and others

• IEEE802.11ac benefits from all other elements of the 802.11 standards family, e.g:

– Backwards compatibility and coexistence with .11a and .11n– MAC functionality such as QoS, security, TDLS, Mesh, .11v Powersave, .11aa Video-

streaming, Fast Session Transfer with 60GHz, interworking with cellular etc, etc.

• Wi-Fi Alliance Impact– Wi-Fi Certification plays a key role in customer adoption of new WLAN technology (especially

for Large Service Providers, Enterprises and Global equipment OEMs);• WFA plans to certify 802.11ac based devices

– WFA creates its own value added industry specifications (e.g. Wi-Fi Direct for Peer to Peer, Wi-Fi Display)

• 802.11ac will be compatible with these specifications and programs


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Preliminary Conclusions• Document N14746 contains a set of valuable advanced concepts for a High

Throughput WLAN system• The proposal in N14746 and IEEE802.11ac are targeting similar frequency

bands, usages and largely similar techniques.• The China NB includes some incremental and different techniques from

802.11ac, however 802.11ac has the following significant advantages:– Full compatibility and coexistence with the installed base of .11a / .11n systems– Leverages all QoS, Security and other value added MAC features of the 802.11

family of standards– Spec is developed, and peer-reviewed by the global experts in the field– Contributions and support from participants and companies from all over the world– Wi-Fi Alliance Interop Certification and WFA value added industry specs– First to market advantage in terms of implementations

• It is very difficult to establish the need for an additional Global standard that tries to address the same frequency bands, usages and techniques, but is faced with significant technical and marketplace drawbacks


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Invitation

• Inserting (some of) the concepts included in N14746 into the discussion for subsequent additions to the IEEE802.family of standard will be highly appreciated!

• IEEE802.11 initiates new taskgroups on a regular basis, and some of the technologies identified in N14746 have already been identified as potential extensions to IEEE802.11

• IEEE802.11 is open for anyone to join, to participate in technical discussions and to make contributions

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