WLAN IEEE 802.11ac Wide bandwidth high speed 802.11ac technology and testing

Hagen Heggenberger Regional Manager Customer Solutions Wireless Terminals

Agenda l

What is behind WLAN IEEE 802.11ac

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What has to be measured (Transmiter Specification)

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Market View

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Rohe&Schwarz testing solution

November 2012 | 802.11ac | 2

Facts about WLAN 802.11ac l

Backwards compatible to 802.11a and 802.11n and coexistence with 11a and 11n

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Frequency band: 5 GHz RF bandwidths: 20 MHz, 40 MHz, 80 MHz and 160 MHz Modulation types: BPSK, QPSK, 16QAM, 64QAM, 256QAM MIMO antenna support: 2x2, 4x4, 8x8 (new, compared to 802.11n)

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à Check out the R&S technology introduction white paper 1MA192

(written by Lisa Ward)

November 2012 | 802.11ac | 3

Facts about WLAN 802.11ac – OFDM l

OFDM Subcarriers Bandwidth (MHz)

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Number of Subcarriers

Subcarriers Transmitting Signal

20

64

-28 to -1 and 1 to 28, 4 Pilots

40

128

-58 to -2 and 2 to 58, 6 Pilots

80

256

-122 to -2 and 2 to 122, 8 Pilots

160

512

-250 to-130, -126 to -6, 6 to 126 and 130 to 250, 16 Pilots

80+80

256 per 80MHz Chan

-122 to -2 and 2 to 122, 16 Pilots

Bandwidth (MHz) 20 Subcarrier Rotation 40 80 reduces Peak to 160 Average Power Ratio 80+80 PAPR November 2012 | 802.11ac | 4

Rotated Subcarriers N/A ≥0 ≥-64 -192 to -1 and ≥64 Same as 80 MHz

Rotation Value 90 degrees (j) 180 degrees (-1) 180 degrees (-1) Same as 80MHz

Facts about WLAN 802.11ac – Channelization

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adjacent (contiguous) non-contiguous

Europe, Japan and Global Operating Class Channel Allocation 5170 MHz IEEE channel # 20 MHz

5330 5490 MHz MHz

40 MHz 80 MHz 160 MHz

November 2012 | 802.11ac | 5

5710 MHz

100 104 108 112 116 120 124 128 132 136 140

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Support of 20, 40, 80 MHz, 160 MHz channel bandwidth The 80MHz channel will consist of two adjacent, non-overlapping 40MHz channels. The 160MHz channels will be formed by two 80MHz channels

36 40 44 48 52 56 60 64

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Facts about WLAN 802.11ac – Frame Format

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All 802.11 devices (L= Legacy) to synchronize to the signal l l l

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L-STF (Short Training Field) L-LTF (Long Training Field) L-SIG (Signal).

New for 802.11ac: VHT (Very High Throughput.) l l l l

VHT-SIG-A field contains two OFDM symbols (BPSK, 90° rotated BPSK) VHT-STF VHT-LTFs.’. The VHT-SIG-B is the last field in the preamble

VHT auto-detection

November 2012 | 802.11ac | 6

Facts about WLAN 802.11ac – Modulation and Coding Schemes l l

802.11ac will use the 802.11n modulation, interleaving and coding architecture. 802.11ac adds an optional 256 QAM MCS 0 1 2 3 4 5 6 7 8 9

Modulation BPSK QPSK QPSK 16-QAM 16-QAM 64-QAM 64-QAM 64-QAM 256-QAM 256-QAM

November 2012 | 802.11ac | 7

Coding Rate 1/2 1/2 3/4 1/2 3/4 2/3 3/4 5/6 3/4 5/6

Facts about WLAN 802.11ac – Optional/Mandatory Properties

Mandatory

20 MHz, 40 MHz, 80 MHz channels

X

1 spatial stream

X

BPSK, QPSK, 16QAM, 64QAM

X

Optional

256QAM

X

80+80 MHz, 160 MHz channels

X

2 to 8 spatial streams

X

Multi-User MIMO (MU-MIMO)

X

400 ns short guard interval

X

Space Time Block Coding (STBC)

X

Low Density Parity Check (LDPC)

X

Peak Data Rate

November 2012 | 802.11ac | 8

~293 Mbps ~3.5 Gbps

Facts about WLAN 802.11ac – Calculation of Data Rate l

Mandatory l l l l l l l l l

242 carrier – 8 pilot carriers = 234 carriers Sample Frequency 80 MHz Guard Interval 800 ns FFT 256 MCS7, 64 QAM (6 bits), Coding 5/6 Symbol time: 256/80 MHz + 800 ns = 4 µs Number of bits 6 x 234 x 5/6 = 1170 bits/symbol Maximum data rate: 1170 bits/symbol / 4 µs /symbol = 292.5 Mbit/s

November 2012 | 802.11ac | 9

Facts about WLAN 802.11ac – Transmiter Specifications l

Spectral Mask for 20, 40, 80 and 160 MHz Channels Channel Size 20 MHz

A

B

C

D

9 MHz

11 MHz

20 MHz

30 MHz

40 MHz

19 MHz

21 MHz

40 MHz

60 MHz

80 MHz

39 MHz

41 MHz

80 MHz

120 MHz

160 MHz

79 MHz

81 MHz

160 MHz

240 MHz

November 2012 | 802.11ac | 10

Facts about WLAN 802.11ac – Transmiter Specifications l

80 + 80 MHz Non Contiguous Channel Mask When the 80 MHz Channels Center Frequencies are separated by 160 MHz

November 2012 | 802.11ac | 11

Facts about WLAN 802.11ac – Market View l

Chips are planned by end of this year and beginning of next year

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First wave of chips will support: l l l

80 MHz bandwidth 256 QAM support expected MIMO support plans vary for customers – Some start with 2x2, some plan 3x3 initially

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Some plan MU-MIMO initially with 2 streams for 2 users

Next wave will support 160 MHz l l

Planned for end of this year to mid of next year Some indicating plans for 4x4 MIMO

November 2012 | 802.11ac | 12

Signal Generators IEEE 802.11ac

l Support for all mandatory physical layer modes l 80 MHz, 80+80 MHz, 160 MHz l For 80 MHz a SMBV100A can be used l For 80+80 MHz two SMBV100A with an external coupler can be used l For 160 MHz and 80+80 MHz the SGS100A and AFQ100A are ideal l Combination of SGS100A and AFQ100A provides excellent EVM

performance of -47 dBc

November 2012 | 802.11ac | 13

R&S Signal Generator Solution Signal Generator Setup Instrument:

SMBV100A AFQ + SGS or SMBV 802.11ac bandwidth: 80 MHz + 80 MHz Mode: contiguous

Instrument: SMBV100A 802.11ac bandwidth: 80 MHz + 80 MHz Mode: non-contiguous

Instrument: AFQ + SGS or SMBV 802.11ac bandwidth: 160 MHz Mode: contiguous

November 2012 | 802.11ac | 14

R&S Signal Generator Solution Features of –K86 and –K286 l

Support for all mandatory physical layer modes (VHT Preambles, Signal Fields, …)

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Very High Throughput (VHT) frames with 20, 40 and 80 MHz transmission bandwidth

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Frame Block Sequencer for alternating legacy (11a/b/g), 11n or 11ac frames within one ARB waveform

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Binary Convolutional Coding (BCC)

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Space Time Block Coding

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Cyclic Shift Diversity (CSD)

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MIMO modes with 4 transmit antennas

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BPSK, QPSK, 16-QAM, 64-QAM and 256QAM modulation

Additional features supported since October 2011 l

80+80 MHz and 160 MHz modes

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MIMO modes with up to 8 transmit antennas

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Multi-user (MU)-MIMO modes

November 2012 | 802.11ac | 15

Signal Analysis with Signal Analyzers

Max. bandwidth 80 MHz R&S FSQ

Max. bandwidth 160 MHz

R&S FSW

November 2012 | 802.11ac | 16

WLAN 802.11ac Analysis with R&S FSW Results available

l Result list EVM, IQ offset etc l Power versus time l Magnitude capture l EVM versus symbol & EVM versus carrier l Spectrum & spectrum masks l ACP l FFT spectrum l Spectrum flatness & group delay l Constellation diagram & constellation versus carrier l Signal content and statistics, signal field, bit stream

NASM 2012 November 2012 | 802.11ac | 17

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WLAN 802.11ac Analysis with R&S FSW Transmiter Specifications – Spectrum Measurements with R&S FSW l

Spectral Mask for 20, 40, 80 and 160 MHz Channels

November 2012 | 802.11ac | 18

WLAN 802.11ac Analysis with R&S FSW Modulation Analysis l

Transmitter Constellation Error

MCS

Modulation

Coding Rate

RCE (dB)

0

BPSK

1/2

-5

1

QPSK

1/2

-10

2

QPSK

3/4

-13

3

16-QAM

1/2

-16

4

16-QAM

3/4

-19

5

64-QAM

2/3

-22

6

64-QAM

3/4

-25

7

64-QAM

5/6

-27

8

256-QAM

3/4

-30

9

256-QAM

5/6

-32

November 2012 | 802.11ac | 19

For error < 1dB a residual EVM of < -38 dB for T&M is needed

WLAN 802.11ac Analysis with R&S FSW Modulation Analysis – R&S FSW-K91/91ac

Bandwidth 160 MHz

November 2012 | 802.11ac | 20

WLAN 802.11ac Analysis with R&S FSW Modulation Analysis – R&S FSW-K91/91ac

DUT EVM: -33 dB With -45 dB res. EVM, the result is -32.7 dB

Constellation diagram R&S FSW-K91ac Residual EVM < -45 dB at 5 GHz

R&S FSW quality is needed, because with e.g. -35 dB res. EVM, the result is -30.9 dB, which does not meet the spec.

November 2012 | 802.11ac | 21

802.11ac MIMO Signal Analysis

Simultaneous Analysis: l Each Analyzer captures one MIMO stream l Better analysis of interferences and dynamic scenarios

November 2012 | 802.11ac | 22

Application firmware R&S FSQK91ac l

MIMO is supported l l l

Sequential MIMO Sequential MIMO using OSP box Support of more analyzers

Signal Source

November 2012 | 802.11ac | 23

802.11ac MIMO Signal Analysis

l One Analyzer (Master) displays all results

November 2012 | 802.11ac | 24

802.11ac MIMO Sequential Analysis

l Different antennas are routed automatically by

R&S®OSP Switch Box to the analyzer l Analyzer combines results to form a „quasi-simultaneous“ reception l Automatic switching control by analyzer Switching Control LAN

RF R&S®OSP Switch Box R&S®FSW

Tx

Rx November 2012 | 802.11ac | 25

WLAN 802.11ac – Test Solutions Signal Generation

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802.11ac (80 MHz) is supported by all vector signal generators of R&S For 160 MHz a combination of R&S AFQ100A/B and vector signal generator is needed l R&S SGS100A shows the best performance l WinIQSIM2 (2.20.230.162) is needed l Calibration of generator setup is recommended to get EVM < -40 dB – SMx RF and Baseband Correction Toolkit

IQ

RF

DUT

November 2012 | 802.11ac | 26

Test Solutions for 80MHz and 160 MHz Max. bandwidth 80 MHz R&S SMU

R&S FSQ

R&S SMBV

R&S FSW

Max. bandwidth 160 MHz R&S AFQ100A/B +

R&S SMU R&S SMBV R&S SGS

November 2012 | 802.11ac | 27

R&S FSW + R&S FSW-B160

R&S Signal Generator Solution Application note 1GP94 l Solution overview l Capabilities of 11ac options l Step by step guidelines l Signal quality optimization for AFQ setups l Measurement examples

R&S 11ac technology introduction white paper 1MA192 YouTube: WLAN 802.11ac measurements using the R&S®FSW signal and spectrum analyzer November 2012 | 802.11ac | 28