doc.:ieee 802.11-09/0789r1 submission robert stacey, intel july 13, 2009 slide 1 technology and use...

doc.:IEEE 802.11-09/0789r1

Submission Robert Stacey, Intel

July 13, 2009

Slide 1

Technology and Use Cases for TGac

Authors:

Date: 2009-07-13

Name Company Address Phone email Robert Stacey Intel 2111 NE 25th Ave

Hillsboro, OR 97124 +1-503-724-0893

[email protected]

Eldad Perahia Intel 2111 NE 25th Ave Hillsboro, OR 97214

[email protected]

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Introduction

• We look at various technologies for TGac, map the technologies to use cases and conclude that most of the gain is achieved with simple extensions to TGn

• For use cases, we reference – WiFi Alliance (WFA) VHT Study Group Usage Models presented

in 07/2988r4

Slide 2

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Possible technologies

• Wider channels • Higher order modulation and code rate• More spatial streams• Multi-user MIMO• OFDMA

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Wider Channels• Possible approaches

– Bond adjacent channels to form 80 MHz channel– Simultaneous transmission on non-adjacent channels

• Advantage– Doubles the PHY data rate (sticker on the box still sells)– Negligible increase in cost over 11n

• Issues– Bonding

• Coexistence with 11n 20MHz & 40MHz– Non-adjacent channels

• Significant receiver complexity to deal with OBSS– Frequency reuse

• The number of available non-overlapping bonded channels will be lower

– One 80MHz channel in 5.15-5.25 GHz band– One 80MHz channel in 5.25-5.35 GHz band

• Can increase co-channel interference– Unknown whether a single channel can span multiple regulatory bands

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Higher order modulation and code rate

• Higher order modulation– 256 QAM (was almost adopted in 11n)– 1024 QAM

• Higher code rate– 7/8 (was almost adopted in 11n)

• Advantage– Architecturally simple addition to the standard

• Issues– Reduces robustness– Requires tighter Tx and Rx specs (e.g. phase noise)

doc.:IEEE 802.11-09/0789r1


July 13, 2009

More Spatial Streams

• Go beyond four steams in 11n, perhaps eight• Advantage

– data rate increases as a function of number spatial streams• Issues

– Size/power constrained devices may not be capable of supporting additional antennas

– Antenna correlation/coupling if antennas need to be packed closer together

– As we have seen in 11n, mobile/portable devices unlikely to support a large number of antennas

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Multi-user MIMO• 11n MIMO

– Spatial division multiplexing (SDM) – STA simultaneously transmits multiple streams to another STA

• Multi-user MIMO– STA simultaneously transmits multiple streams to several other STAs

• E.g. 4 antenna AP transmits two streams to STA1 and two streams to STA2

• Advantage– Increases network capacity with client devices that only have few antennas

• Issues– Multi-user MIMO on the downlink from AP to STA has higher complexity than

11n Tx Beamforming– Multi-user MIMO has very high complexity on uplink - would require precise

transmit packet synchronization between STAs and transmit power control (similar to that required in CDMA cellular system)

– Scheduling– As yet not well know how time variant is the channel

doc.:IEEE 802.11-09/0789r1


July 13, 2009

OFDMA

• Subdivide OFDM subcarriers to several STAs– Used in cellular systems like Wimax

• Advantage– More efficient method in usages with multiple lower rate clients, e.g.

voice– Efficient uplink technique for ACK packets in response to downlink MU-

MIMO packet• Issues

– Has very high complexity on uplink - would require precise transmit packet synchronization between STAs and transmit power control

– Scheduling– Does not increase maximum data rate or network capacity, only improves

efficiency with multiple lower rate clients

doc.:IEEE 802.11-09/0789r1


July 13, 2009

3a 1c

1b2a 2b

1d 3b 1a

6a 2d3d

4a4b

3e

2c 1f5b

1e 5a

2e 3c

WFA VHT Usage Models mapped to market volume and timing*

Anticipated Market Timing For Mainstream Market

Mar

ket V

olum

e

Rela-tivelyLow

Sooner

RelativelyHigh

Later

Key1a Desktop Storage & Display1b Projection to TV or Projector in Conf Rom1c In room Gaming1d Streaming from Camcorder to Display1e Broadcast TV Field Pick Up1f Medical Imaging Surgical Procedure Support2a Lightly compr. video streaming around home2b Compr. video streaming in room or t.o. home2c Intra Large Vehicle (e.g. airplane) Applications2d Wireless Networking for Small Office2e Remote medical assistance3a Rapid Sync-n-Go file transfer3b Picture by Picture viewing3c Airplane docking3d Video Content Download to car3e Police / Surveillance Car Upload4a Multi-Media Mesh Backhaul4b Point-to-Point Backhaul5a Video demos / telepresence in Auditorium5b Public Safety Mesh6a Manufacturing floor automation

Highlight these use cases on the next slide

* from 07/2988r4

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Slide 10

WFA VHT Usage Models mapped to technologies

Category # Usage model MCS Wider channel

MU-MIMO OFDMA More SS

1. Wireless Display 1a Desktop Storage & Display X X ?

1b Projection to TV or projector in conf room (lightly compressed video) X X X

1c In room gaming (lightly compressed video) X X X

1d Streaming from camcorder to display (lightly compressed video) X X

1e Broadcast TV field pick up X

1f Medical Imaging and Surgical Procedure Support X X

2. Distribution of HDTV 2a Lightly compressed video streaming around the home X X X

2b Compressed video streaming around home X X X X

2c Intra large vehicle (e.g. airplane) applications X X X ?

2d Wireless networking for office X X X

2e Remote medical assistance X X

3. Rapid upload/download 3a Rapid sync-n-go file transfer X X

3b Picture by picture viewing X X

3c Airplane docking X X

3d Movie content download to car X ?

3e Police / surveillance car upload X ?

4. backhaul 4a Multi-media mesh backhaul ? ? X

4b Point-to-point backhaul X X

5. Outdoor campus / auditorium 5a Video demos / tele-presence in auditorium X X

5b Public safety mesh ? ? X

6. Manufacturing floor 6a Manufacturing floor automation ? ? ?

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Short range applications

• Some of the most important usage models are short range– 1a: Desktop storage and display– 1b: Projection to TV or projector– 1c: In-room gaming– 1d: Streaming from camcorder to display– 3a: Rapid sync-and-go file transfer– 2d: Wireless networking for office

• These applications benefit from MCS enhancement (in addition to wider channels)

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Video streaming around home• Most video streaming

applications are best supported using direct links

• Relay through AP is unlikely to be as efficient even with MU-MIMO

• In some scenarios, downlink MU-MIMO may be beneficial for multiple streams (but again using direct link)

TV

TVTV

TV

DVR

DVR

PC

doc.:IEEE 802.11-09/0789r1


July 13, 2009

Summary• Wider channel benefits almost all applications

– 2x improvement• MCS enhancements benefit short range, direct link applications

– Almost 2x improvement possible• Downlink MU-MIMO provides increased network efficiency for

some applications– Only when long term, simultaneous traffic flows are present (e.g. video)– < 2x improvement; dependent on uplink/downlink traffic mix– Not clear that 2 hop MU-MIMO is better than direct link

• More spatial streams may provide some benefit in certain environments

– Cost and form factor prohibitive for most devices due to antenna requirements

• Downlink OFDMA provides little benefit– Power saving and performance gain questionable

• Uplink space/frequency multiplexing techniques– No compelling use case, especially considering complexity

doc.:ieee 802.11-09/0789r1 submission robert stacey, intel july 13, 2009 slide 1 technology and use...

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