802.

11ac Technical Overview & Design Ideas

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Agenda
Why do we need another 802.11 PHY? Technology Timelines Deployment ideas Questions

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802.11ac Categories of Usage

Wireless Display In Home Distribution of HDTV and other content Rapid Upload/Download of large files to/from server Backhaul Traffic (e.g. Mesh, Point-to-Point) Campus / Auditorium deployments Manufacturing Floor Automation

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Source: IEEE

Video requirements
Video type Uncompressed Description 720p (RGB) 1280x720 pixels; 24 bits/pixel, 60 frame/sec 1080i (RGB) 1920x1080/2 pixels; 24 bits/pixel, 60 frame/sec 1080p (YCrCb) 1920x720 pixel; 24 bits/pixel, 60 frame/sec 1080p (RGB) 1920x720 pixel; 24 bits/pixel, 60 frame/sec Lightly Compressed Motion JPEG2000 H.264 Compressed Blu-rayTM HD MPEG2 Rate 1.3 Gbps Packet error rate Jitter 5 msec Delay 5 msec

10-8

1.5 Gbps

10-8

5 msec

5 msec

1.5 Gbps

10-8

5 msec

5 msec

3.0 Gbps

10-8

5 msec

5 msec

150 Mbps 70 200 Mbps 50 Mbps 20 Mbps

10-7 10-7 10-8 10-7 3x10-7

10 msec 20 msec 20 msec 20 msec

10 msec 20 msec 20 msec 20 msec

Video bandwidth and error rate requirements

source: IEEE

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802.11n ENHANCEMENTS
Spatial streams

40 MHz channels Instead of 20 MHz

Improved OFDM

Reduced guard interval

Original 802.11 a, g OFDM

54 Mbps

65 Mbps

135 Mbps

150 Mbps

4 x 150 =
600 Mbps

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802.11ac Goals
Multi-station MAC throughput of at least 1Gbps, Single link at least 500Mbps Operation below 6GHz, but excluding 2.5 GHz Backward compatibility & coexistence with devices in 5 GHz band 256-QAM (optional)
Provides a 33% increase over 64-QAM

Wider Channel widths

80 MHz (mandatory support) & 160 MHz channels (optional) 80 MHz is contiguous 160 MHz can be either contiguous or in two non-contiguous 80 MHz slices

More Spatial Streams

Up to 8 spatial streams

Downlink Multi-user MIMO

One transmitting device, multiple receiving devices Allows for an AP to transmit to multiple stations simultaneously
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Sub-carriers for wider channels

26 carriers 26 carriers 28 carriers 28 carriers

-10MHz

fc

+10MHz

-10MHz

fc

+10MHz

52 subcarriers (48 usable) for a 20 MHz non-HT mode (legacy 802.11a/g) channel

56 subcarriers (52 usable) for a 20 MHz HT mode (802.11n) channel

57 carriers

57 carriers

-20MHz

-10MHz

fc

+10MHz

+20MHz

114 subcarriers (108 usable) for a 40 MHz HT mode (802.11n) channel

121 carriers

121 carriers

-40MHz

-30MHz

-20MHz

-10MHz

fc

+10MHz

+20MHz

+30MHz

+40MHz

242 subcarriers (234 usable) for a 80 MHz VHT mode (802.11ac) channel An 80+80MHz or 16MHz channel is exactly two 80MHz channels, for 484 subcarriers (468 usable)

OFDM subcarriers used in 802.11a, 802.11n and 802.11ac

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Channels
Band Edge 5150 Channel Frequency (MHz) 36 40 44 48 52 56 60 64 5320 Band Edge 5350 US U-NII I and U-NII II bands U-NII I: 5150-5250 MHz (indoors only) U-NII 2: 5250-5350 MHz 8x 20 MHz channels 4x 40 MHz channels 2x 80 MHz channels 1x 160 MHz channel U-NII II requires DFS (& TPC if over 500mW / 27dBm EIRP) US intermediate band (U-NII 2 extended) 5450-5725 MHz 12x 20 MHz channels 6x 40 MHz channels 3x 80 MHz channels 1x 160 MHz channel Requires DFS (& TPC if over 500mW / 27dBm EIRP) 5600-5650 MHz is used by weather radars and is temporarily not available in the U.S.

5180 5200 5220 5240

5260 5280 5300

Band Edge 5470 Channel Frequency (MHz) 100 5500 104 108 112 116 120 124 128 5640 132 136 140 5700 144 5720

Band Edge 5725

5520 5540 5560 5580 5600 5620 Band Edge Band (U-NII)) Edge 5825 (ISM) 5850

5660 5680

Band Edge 5725 Channel Frequency (MHz) 149 5745 153 157 161

165

5765 5785 5805 5825

US U-NII 3 / ISM band 5725-5825 MHz 5x 20 MHz channels 2x 40 MHz channels 1x 80 MHz channel Slightly different rules apply for channel 165 in ISM spectrum

Channels defined for 5 GHz bands (U.S. regulations), showing 20, 40, 80 and 160 MHz channels
(channel 144 is now allowed in the U.S. for one additional 20 MHz, one 40 MHz and one 80 MHz channel)
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256-QAM Modulation
New 256-QAM options with coding of 3/4 and 5/6
Compared to 802.11n: 64-QAM 5/6

Provides a higher raw data top speed Higher order modulation leverages advances in radio technology, to better distinguish constellation points All the earlier options are still available, used if SNR is too low to sustain the highest rates

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Receive sensitivity requirements

Amplitude +1 Quadrature -1 Quadrature -1 Amplitude +1 Quadrature -1 Amplitude +1 Quadrature +1 Quadrature +1 Quadrature +1

Amplitude -1

Amplitude -1

Amplitude -1

16-QAM constellation

64-QAM constellation

256-QAM constellation

Constellation diagrams for 16-, 64-, 256-QAM

-40 -45 -50 -55 -60 -65 -70 -75 -80 -85 1/2 1/2 3/4 1/2 3/4 2/3 3/4 5/6 3/4 5/6 BPSK QPSK QPSK 16- 16- 64- 64- 64- 256- 256QAM QAM QAM QAM QAM QAM QAM Minimum sensitivity (20 MHz PPDU) (dBm) Minimum sensitivity (40 MHz PPDU) (dBm) Minimum sensitivity (80 MHz PPDU) (dBm) Minimum sensitivity (160 MHz or 80+80 MHz PPDU) (dBm)

Sensitivity, dBm

Required receive sensitivity for different modulation and coding rates

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More Spatial Streams

Up to 8 spatial streams in both single-user (SU) and multi-user (MU) (was 4 max in 802.11n)
8SS performance will only be possible where both devices have 8 antennas Without innovative antenna designs, this probably precludes handheld devices, but access points, set top boxes and the like will be able to use multiple streams

Adding spatial streams increases throughput proportionally . Assuming multipath conditions are favorable,
Two streams offer double the throughput of a single stream Eight streams increase throughput eight-fold Higher throughput only possible at shorter distances

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MIMO techniques, multi-antenna client

x x 400nsec x Ax + 1 x1, x2 y1, y2

1x SS
x 200nsec x 600nsec

1x SS

1x SS
Bx + 2 Cx + 3

1x SS

2x SS
-x2*, x2* -y2*, y2*

2x SS

Cyclic Shift Diversity (CSD, CDD)

Transmit diversity by blindly transmitting from each antenna with a fixed phase shift. Receiver picks best signal. Can be combined with MRC.

Transmit Beamforming (TxBF)

Transmitter receives channel state information from receiver (compressed V feedback matrix) and computes parameters to drive local signal maximum at receiver. The transmitter can form on several antennas if silicon allows.

Space Time Block Coding (STBC)

Transmitter codes a pair of symbols in successive timeslots from different antennas. Only works with even numbers of antennas, two per SS. All-ornothing, all SS must use STBC if any use it. Here combined with SDM. STBC halves the effective data rate.

2x SS

2x SS

Cx + 3

Combining Techniques Some combinations are disallowed by the equal modulation restriction, others by silicon implementation. Equal modulation requires all driven antennas to use the same MCS.

1x or 2x SS

1x or 2x SS

Spatial Division Multiplexing (SDM)

Transmitter sends one spatial stream per antenna, chosen for best performance. Feedback from the receiver is not required: channel state is inferred by assuming reciprocity. Can be combined with STBC.

Maximal Ratio Combining (MRC)

Receive-only technique to combine multiple copies of the same signal at RF for best SNR. Can be combined with CSD, SDM or SDBC.

Transmit and receive techniques available for a multi-chain, multi-SS client

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Channel state information, implicit and explicit beamforming estimation

Request for sounding sounding frames Implied CSI Beamformed frames Actual CSI

Beamformer

Beamformee

Beamformer

sounding frames feedback from sounding Beamformed frames

Beamformee

Implicit feedback for beamforming (802.11n not 802.11ac) 1 (Beamformer) Send me a sounding frame 2 (Beamformee) Heres the sounding frame 3 OK, Ill pre-code assuming you hear me like I heard you

Explicit feedback for beamforming (802.11n and 802.11ac) 1 (Beamformer) Heres a sounding frame 2 (Beamformee) Heres how I heard the sounding frame 3 Now I will pre-code to match how you heard me

Implicit and explicit feedback for beamforming

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DL MU-MIMO
B 2 antenna client e.g. smartphone A AP D 4 antenna client e.g. PC 8 antenna AP

C single antenna client e.g. smartphone

2 antenna client e.g. smartphone

AP wins TXOP
Frame to A

Client TXOP
ack

AP wins TXOP
Frame to A Frame to D Frame to C

Client TXOP
ack

AP wins TXOP
Frame to A

AP

Frame to B Frame to D

Frame to B

Frame to C

A B C D

ack ack ack

Frame to AP

ack

ack

ack ack

Frame to AP

ack

time

Downlink Multi-user MIMO frame sequences

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MAC aggregation
Applications

P1

P2

P3

MSDU (MAC Service Data Unit)

P1

P2

P3

P1

P2

P3

MAC processing

MAC processing

MAC processing

MAC header

P1

P2

P3

MPDU (MAC Protocol Data Unit)

MAC header

P1

MAC header

P2

MAC header

P3

Aggregated MSDU format (A-MSDU)

PHY layer

Aggregated MPDU format (A-MPDU)

MAC frame aggregation in 802.11ac

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Preambles for legacy, mixed & non-HT modes

Key Short Training Field Long Training Field Signal Legacy (e.g. pre-802.11ac) High Throughput (e.g. 802.11n) Very High Throughput (e.g. 802.11ac)

Legacy preamble

VHT preamble

Data

STF LTF SIG L HT VHT

L-STF

L-LTF

L-SIG

VHT-SIG-A

VHT-STF

VHT-LTF

VHT-LTF

VHT-SIG-B

Repeated >= number of spatial streams Transmitted at 20MHz, in each underlying 20MHz channel Uses the VHT channel width

VHT preamble format

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Dynamic bandwidth operation

S20 RTS P RTS RTS S40 RTS

AP

CTS

CTS

CTS

CTS

client

Data

Data

Dynamic Bandwidth Operation, 80MHz channel

80MHz channel

80MHz channel

Secondary 20MHz

Primary 20MHz

Secondary 40MHz

Secondary 40MHz

Secondary 20MHz

Primary 20MHz

Dynamic Bandwidth and Channelization examples in 802.11ac, 80MHz channel

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802.11ac rates
Channel bandwidth 80 MHz Transmit Receive antennas 1x1 Modulation and coding etc 256-QAM 5/6, short guard interval 256-QAM 5/6, short guard interval 256-QAM 5/6, short guard interval 256-QAM 5/6, short guard interval 256-QAM 5/6, short guard interval 256-QAM 5/6 , short guard interval 256-QAM 5/6, short guard interval Typical client scenario Smartphone Throughput (individual link rate) 433 Mbps Throughput (aggregate link rate) 433 Mbps

80 MHz

2x2

Tablet, PC

867 Mbps

867 Mbps

160 MHz

1x1

Smartphone

867 Mbps

867 Mbps

160 MHz

2x2

Tablet, PC

1.73 Gbps

1.73 Gbps

160 MHz

4x Tx AP, 4 clients of 1x Rx 8x Tx AP, 4 clients with total of 8x Rx 8x Tx AP, 4 clients of 2x Rx

Multiple smartphones

867 Mbps per client

3.47 Gbps

160 MHz

Digital TV, set-top box, tablet, PC, smartphone Multiple set-top boxes, PCs

867 Mbps to two 1x clients 1.73 Gbps to one 2x client 3.47 Gbps to one 4x client 1.73 Gbps to each client

6.93 Gbps

160 MHz

6.93 Gbps

802.11ac achievable link rate scenarios

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802.11ac rates
MCS Lowest rates Mbps (20MHz channel, 1x SS) Long GI 0 1 2 3 4 5 6 7 8 9 6.5 13.0 19.5 26.0 39.0 52.0 58.5 65.0 78.0 (86.7) Short GI 7.2 14.4 21.7 28.9 43.3 57.8 65.0 72.2 86.7 (96.3) x2.1 for 40MHz x4.5 for 80MHz x9.0 for 160MHz x2 for 2 SS x3 for 3 SS x4 for 4 SS x5 for 5 SS x6 for 6 SS x7 for 7 SS x8 for 8 SS Channel width Spatial streams Highest rates Mbps (160MHz channel, 8x SS) Long GI 468.0 939.0 1404.0 1872.0 2808.0 3744.0 4212.0 4680.0 5616.0 6240.0 Short GI 520.0 1040.0 1560.0 2080.0 3120.0 4160.0 4680.0 5200.0 6240.0 6933.3

Data rates for various 802.11ac configurations

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Mandatory and optional features

Feature
Channel width Modulation & coding Spatial streams Guard interval Beamforming feedback Space-time block coding Parity check MU-MIMO Encryption cipher Counter Mode with Cipher-block chaining Message authentication code Protocol (CCMP) Binary Convolutional Coding (BCC) 20, 40, 80MHz MCS 0 7 (BPSK, QPSK, 16-QAM, 64-QAM, 1/2, 2/3, 3/4, 5/6) 1 Long (800nsec)

Mandatory
80+80, 160MHz

Optional
MCS 8, 9 (256-QAM, 3/4, 5/6) 2-8 Short (400nsec) Respond to beamforming sounding Transmit and receive STBC Transmit and receive Low Density Parity Check (LDPC) Up to 4 spatial streams per client, with same MCS Galois/Counter Mode Protocol (GCMP)

802.11ac mandatory and optional features

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802.11ac vs 802.11n
802.11ac enhancement 80 MHz, 160MHz channel 8 Spatial streams Notes Medium-term improvement over current 802.11n ~ 2.1x (80MHz over 40 MHz) ~ 2x (4SS over 2SS) Max theoretical improvement over max 802.11n 4.2x (160MHz over 40MHz) 2x (8SS over 4SS)

Over 40MHz in 802.11n (but how often is a 160MHz channel practical?) Over max 4 spatial streams in 802.11n (but only just seeing 3SS) Over 64-QAM 5/6 in 802.11n No explicit BF in current 802.11n systems due to complexity Over single-user MIMO in 802.11n

256-QAM 3/4 and 5/6 modulation Beamforming (implementable BF) Multi-user downlink MIMO Total improvement

~ 1.2, 1.33x ~1.5x ~1.5x ~10x

~ 1.2, 1.33x ~2x ~2x ~40x

802.11ac throughput improvement over 802.11n (estimates only - performance depends on clients, traffic profiles, neighboring WLANs etc.)

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802.11ad-2012 Very High Throughput 60GHz

Requirements Throughput > 1 Gbps @ 10 metres Management plane from 802.11 Fast Session Transfer to 802.11n & ac Coexistence with 802.15.3c (WPAN) Applications Room-scale uncompressed HD video Set-top boxes & projection to TVs DVRs, game consoles, other video Rapid sync-&-go file transfer

60GHz Access Point

60GHz

M A C

transparent (same MAC addr)

5GHz 5GHz

M A C

client

Access Point

M A C M A C

60GHz

60GHz

non-transparent
5GHz 5GHz

M A C M A C

client

MAC & PHY differ from other 802.11 Based on WiGig PHY uses SC for 385 4620 Mbps Or OFDM for 693 6756 Mbps 2.16 GHz channels Beamforming required Scheduled and contention access Discovery with/out beamforming

Milestones Jan 2009 IEEE task group started Jul 2012 Final Approval for IEEE 802.11ad-2012 Jan 2013 WFA and WiGigAlliance consolidate activity Dec 2013 WFA certification
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Spectrum Unlicensed Worldwide spans 57 67 GHz USA & Canada 57 64 GHz Europe 57 67 GHZ Japan 57 66 GHz

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Chipset shipments (802.11n)

Wi-Fi chipset shipments and penetration of 802.11n (actual & forecast)

source: iSuppli

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Chipset forecast

2,500 802.11n (2.4 GHz) 2,000 802.11ac (5 GHz) 1,500 802.11n/802.11ac 802.11n (dual-band)

1,000

500

0 2010

2011

2012

2013

2014

2015

2016

Wi-Fi chipset forecast for 802.11ac chipsets (millions)

source: ABI research

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802.11ac Adoption Timeline

Wi-Fi Alliance specification Gen I enterpriseclass APs up to 1.3Gbps Critical mass enterprise infrastructure Critical mass clients

IEEE Standard ratified

2012
Consumer 802.11ac products

2013

2014

2015

2017

First embedded client products

Gen II enterpriseclass APs up to 7 Gbps

Replacement of 802.11n

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Phases of 802.11ac Pre and Post IEEE Ratification

CY 2013/2014: Draft 802.11ac
Max data rate 1.3Gbps - 4x performance compared to 2x2 802.11n 5GHz only Up to 3 spatial streams, up to 80MHz wide channels reduced number of overall channels in 5GHz Client devices start shipping mid2013; Mass adoption early-2014

CY 2014/2015: IEEE ratified 802.11ac

Max data rate of 6.93Gbps 10x performance & 50% better range compared to 2x2 802.11n Up to 8 spatial streams &160MHz wide channels even fewer 5GHz channels Multi-User MIMO - Increased Capacity with simultaneous transmit to multiple receivers Mass adoption mid-2015

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Expected Real World Performance

Mobile Device 802.11n 802.11ac

Smartphone Tablet Laptop

150 Mbps 150 Mbps 450 Mbps

200 Mbps 450 Mbps 600 Mbps

Deployment Assumptions
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40MHz channels Short distance to AP (high density design)

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When to Move to 802.11ac?

Get your network ready first Migration Planning Wired Network Audit - PoE+, Gigabit Ethernet RF planning for 5.0GHz and capacity Continue to invest in 802.11n 11n is not going away anytime soon 11n client devices are here today, 6x the performance of 11abg 11n is at a good price point today

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Summary - 802.11ac Features

802.11ac Standard Update (IEEE and WFA)
5 GHz only Draft (2.0) published Jan 2012 IEEE Standards Board ratification is targeted for December 2013. Wi-Fi Alliance - WFA certification under development. Initial WFA certification program, planned for 1H 2013

Provides up to 7 Gbps of throughput (eventually)

1.3 Gbps data rates in phase 1 Higher orders of modulation (256-QAM, 3/4, 5/6) Wider Channel bandwidth
80MHz 160MHz

Up to 8 streams (3-4 streams in first generation) Multi-user MIMO

* Second generation features estimated late CY 2014/1H CY 2015

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Summary 802.11ac Transition

11ac is an evolution not a revolution It will be very similar to the 11n roll out
First APs based on draft standard Similar coverage areas Extensions of 11n technologies
Wider channels More streams Better modulation

Future generations will require hardware upgrades

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CONFIDENTIAL Copyright 2012. 2013 Aruba ArubaNetworks, Networks,Inc. Inc. All rights reserved