introduction to 802.11ac wlan technology and testing · mcs supported 0 to 7, 0 to 15 for access...

© 2013 Agilent Technologies

Wireless Communications

Introduction to 802.11ac WLAN

Technology and Testing

1



2 © 2013 Agilent Technologies


Agenda

• WLAN Market Update

• IEEE 802.11 Standards Evolution

• Overview of 802.11ac

– Performance Goals and Timeline

– Review of 802.11n

– New Enhancements for 802.11ac

• Design and Test Challenges

• Transmitter Tests

• Receiver Tests

• Summary of Measurement Solutions





WLAN Market Update

WLAN retail and enterprise market growth rate for 2010 estimated at 12%

(IDC) to 23% (Infonetics). For first 3 quarters of 2011, IDC estimated quarterly

growth rates of 16% to > 20% year-over-year.

Growth drivers:

• Integration of WLAN into more consumer products: smartphones,

digital cameras, e-readers, media players, gaming consoles, Blu-ray

players, HDTVs

• Increasing adoption and use of WLAN in companies, small office/home

office, hospitals, etc. Enterprise market growing faster than retail

market.

• Use of WLAN to offload data from cellular networks

• New applications: health/fitness, medical, smart meters, home

automation

Multi-format chipsets are increasingly common, mostly WLAN + Bluetooth or

WLAN + Bluetooth + FM today, some include cellular, WiMAX, and/or GPS:

need to test multiple technologies/formats and avoid interference

3





New Applications for WLAN

Growth of high-definition video and desire for wireless connections is driving need

for higher data rates for applications such as:

• Wireless display

• Distribution of video/media content throughout the home or office

• Rapid file upload/download (sync devices, movie kiosks)

Example data rates:

4

Application Data Rate (Mbps)

Interactive videoconferencing 0.38 to 0.5

Internet video streaming 2.5 to 8

HDTV 19.4 to 25

Blu-Ray 40

Uncompressed video, “good” quality

(8-bits/color, 1920x1080p, 24 fps, 4:2:2)

796

Uncompressed video, “best” quality

(10-bits/color, 1920x1080p, 60 fps, 4:4:4)

3730





IEEE 802.11 Standards Evolution

5

WLAN

802.11-1997

2 Mbps, DSSS, FHSS

802.11b 11 Mbps, CCK, DSSS

802.11a 54 Mbps,

OFDM, 5 GHz

802.11g 54 Mbps,

OFDM, 2.4 GHz

802.11n 600 Mbps with

4x4 MIMO, 20/40 MHz BW,

2.4 or 5 GHz

802.11ac

802.11ad

802.11p 27 Mbps, 10 MHz

BW, 5.9 GHz

802.11af

TVWS

Wireless Gigabit (WiGig)

Very High Throughput, 60 GHz

Very High Throughput, <6 GHz

TV White Spaces

Wireless Access for Vehicular Environment (WAVE/DSRC)

DSRC = Dedicated Short-Range Communications





Introduction to 802.11ac Standard: Enhancements for Very High Throughput (VHT)

• Minimum “very high throughput” goal of 1 Gbps

• Standard under development by IEEE 802.11ac Task Group (TGac)

- Draft 4.0 released in October 2012

- Standard completion planned for Nov. 2013

• Wi-Fi Alliance working on 802.11ac certification; plans to launch by early

2013

• Market research firms ABI Research and In-Stat expect 802.11ac products

to start shipping by late 2012 and to grow rapidly, becoming the dominant

Wi-Fi standard by 2014 or 2015

• 802.11ac routers now available from Asus, Belkin, Buffalo, D-Link, Netgear,

and EDIMAX for ~US$200. USB adapters from Netgear and D-Link for

~US$70. Products also support 802.11a/b/g/n.

• 802.11ac chipsets available from Broadcom, Qualcomm Atheros, MediaTek,

Marvell, Intel, Quantenna, some supporting 3x3 and 4x4 MIMO.

6





Review of 802.11n: Basis for 802.11ac

7

Feature Mandatory Optional

Transmission method OFDM

Channel bandwidth 20 MHz 40 MHz

FFT size 64 128

Data subcarriers / pilots 52 / 4 108 / 6

Subcarrier spacing 312.5 kHz

OFDM symbol duration 4 ms (800 ns guard interval) 3.6 ms (with 400 ns short guard interval)

Modulation types BPSK, QPSK, 16QAM, 64QAM

Forward error correction Binary convolutional coding (BCC) Low density parity check (LDPC)

Coding rates 1/2, 2/3, 3/4, 5/6

MCS supported 0 to 7, 0 to 15 for access points 8 to 76, 16 to 76 for APs

Spatial streams and MIMO 1, 2 for access points direct mapping

3 or 4 streams Tx beamforming, STBC

Operating mode / PPDU format

Legacy/non-HT (802.11a/b/g) Mixed/HT-mixed (802.11a/b/g/n)

Greenfield/HT-Greenfield (802.11n only)





Changes & Enhancements for 802.11ac

8

Feature Mandatory Optional

Channel bandwidth 20 MHz, 40 MHz, 80 MHz 160 MHz, 80+80 MHz

FFT size 64, 128, 256 512

Data subcarriers / pilots 52 / 4, 108 / 6, 234 / 8 468 / 16

Modulation types BPSK, QPSK, 16QAM, 64QAM 256QAM

MCS supported 0 to 7 8 and 9

Spatial streams and MIMO 1 2 to 8

Tx beamforming, STBC

Multi-user MIMO (MU-MIMO)

Operating mode / PPDU format Very high throughput / VHT

Data rates: Best case: 6.93 Gbps (160 MHz, 8 Tx, MCS9, short GI)

Typical case: 1.56 Gbps (80 MHz, 4 Tx, MCS9)

Items in red text below are changes compared to the 802.11n standard

• Wider channels

• Higher-order modulation

• More spatial streams and antennas (up to 8)

• Multi-user MIMO

• Operation in 5-6 GHz band only (not in 2.4 GHz band)





802.11ac Channelization

• Operates in 5-6 GHz band only, not in 2.4 GHz band

• Mandatory support for 20, 40, and 80 MHz channels

• 40 MHz same as 802.11n. 80 MHz has more than 2x data subcarriers: 80 MHz has 234 data

subcarriers + 8 pilots vs. 108 data subcarriers + 6 pilots for 40 MHz

• Optional support for contiguous 160 MHz and non-contiguous 80+80 MHz transmission and

reception. 160 MHz tone allocation is the same as two 80 MHz channels.

• U.S. region frequency allocation (shown below) includes 5710-5835 MHz channels not

available elsewhere. (Need to avoid weather radars in some areas)

9

These frequencies

are not available in

Europe, Japan and

other regions

Adapted from Specification Framework, IEEE 802.11-09/0992r15,

Updated based on 802.11ac/D1.0

245 MHz





802.11ac VHT PPDU Format:

New VHT Preamble

• L-STF, L-LTF, and L-SIG: • Similar to same fields in 802.11a/b/g (clause 17 in 802.11 standard)

• Transmitted first for backwards compatibility

• Fields are duplicated over each 20 MHz sub-band with appropriate phase rotation (see 22.3.7 in

standard). Subcarriers are rotated by 90 or 180 degrees in certain sub-bands to reduce PAPR.

• Cyclic shift delay applied to each transmit chain when applicable

• VHT-SIG-A • 1st symbol of VHT-SIG-A is BPSK, while 2nd symbol is BPSK with 90 degrees rotation (QBPSK) to

enable auto-detection of VHT

• Contains info required to interpret VHT packets (BW, number of streams, STBC used, guard interval,

BCC or LDPC coding, MCS, beamforming)

L-STF L-LTF L-SIG VHT-SIG-A VHT-STF VHT-LTFs VHT Data

2 symbols 2 symbols 1 sym BPSK,

1 sym QBPSK 1 symbol,

BPSK 1 symbol 1 symb/LTF,

8 LTFs max

VHT-SIG-B

1 symbol

802.11ac VHT PPDU

L-STF L-LTF L-SIG HT-SIG HT-STF HT-LTFs HT Data

2 symbols 2 symbols 2 symbols,

QBPSK

1 symbol,

BPSK 1 symbol 1 symbol/LTF,

4 LTFs max

802.11n PPDU

(Mixed Mode) 1 symbol = 4 ms

“PPDU” = PLCP Protocol Data Unit, “PLCP” = Physical Layer Convergence Procedure





802.11ac VHT PPDU Format:

New VHT Preamble

• VHT Short Training Fields (VHT-STF): – Used to improve automatic gain control estimation in MIMO transmission

• VHT Long Training Fields (VHT-LTF) – Long training fields: may include 1, 2, 4, 6, or 8 VHT-LTFs.

– Mapping matrix for 1, 2, or 4 VHT-LTFs (same as in 802.11n) or 6 or 8 VHT-LTFs (added for

802.11ac).

• VHT-SIG-B: – Describes length of data and MCS for multi-user mode. Bits are repeated for each 20 MHz sub-

band.

L-STF L-LTF L-SIG VHT-SIG-A VHT-STF VHT-LTFs VHT Data

2 symbols 2 symbols 1 sym BPSK,

1 sym QBPSK 1 symbol,

BPSK 1 symbol 1 symb/LTF,

8 LTFs max

VHT-SIG-B

1 symbol

802.11ac VHT PPDU

L-STF L-LTF L-SIG HT-SIG HT-STF HT-LTFs HT Data

2 symbols 2 symbols 2 symbols,

QBPSK

1 symbol,

BPSK 1 symbol 1 symbol/LTF,

4 LTFs max

802.11n PPDU

(Mixed Mode) 1 symbol = 4 ms





Diversity

Improve robustness

Spatial Expansion

(Transmit Diversity)

Receive Diversity

Multiple Antenna Techniques

in 802.11ac

Space-time block

coding (STBC)

X1, X2

-X2, X1*

y1, y2

Spatial division multiplexing

(direct mapping) Multi-user MIMO

Transmit Beamforming

Spatial multiplexing

Improve user throughput

Multi-user Increase system

efficiency

MIMO

MIMO (4x2)

Matrix

4 streams, 3 users X1

X2

y1

y2

Downlink only

Up to 4 users

Up to 4 streams/user

Total 8 streams max





Transmitter Block Diagram,

Single User

13

1 to 8 outputs BCC or LDPC

used, not both

1 to 8 inputs

From Figure 22-6, IEEE P802.11ac/D1.4

PH

Y P

ad

din

g

Scra

mb

ler

En

co

der

Pars

er

FE

C E

nco

der

FE

C E

nco

der

Str

eam

Pars

er

BCC

Interleaver

BCC

Interleaver

BCC

Interleaver

Constellation

mapper

Constellation

mapper

Constellation

mapper

LDPC

tone

mapper

LDPC

tone

mapper

LDPC

tone

mapper

Sp

ace t

ime b

lock c

od

ing

(S

TB

C)

CSD

CSD

Sp

ati

al M

ap

pin

g

IDFT

IDFT

IDFT

Insert GI

and

Window

Insert GI

and

Window

Insert GI

and

Window

Analog

and RF

Analog

and RF

Analog

and RF

. . .

. . .

. . .

. . .

. . .

. . .

. . .





Transmitter Block Diagram,

Multi-User MIMO

14

1 to 8 inputs

Str

eam

Pars

er

BCC

Interleaver

Constellation

mapper

Constellation

mapper

Constellation

mapper

LDPC

tone

mapper

LDPC

tone

mapper

ST

BC

CSD

CSD

Sp

ati

al M

ap

pin

g IDFT

IDFT

IDFT

Insert GI

and

Window

Insert GI

and

Window

Insert GI

and

Window

Analog

and RF

Analog

and RF

Analog

and RF

. .

. . .

.

. . .

. . .

. . . P

HY

Pad

din

g

Scra

mb

ler

En

co

der

Pars

er

BC

C

En

co

der

BC

C

En

co

der

BCC

Interleaver

Constellation

mapper CSD

PH

Y P

ad

din

g

Scra

mb

ler

LD

PC

En

co

der

Str

eam

Pars

er

ST

BC

. .

. . .

.

. .

.

User 1 (Using LDPC)

User N (Using BCC)

. .

.

1 to 4 users,

Up to 4 streams per user

Maximum 8 streams total From Figure 22-7, IEEE P802.11ac/D1.4





Design Challenges:

256QAM Modulation

15

256QAM requires better error vector magnitude (EVM) performance:

constellation points are closer together

Transmitter relative constellation error (EVM) spec for 256QAM is -32 dB

vs. -28 dB for 64QAM

Achieving better EVM requires better linearity and phase noise

Errors may be due to imperfections in IQ modulator, phase noise or error

in LO, or amplifier nonlinearity

Some phase noise can be removed by phase tracking in receiver, but

phase changes faster than a symbol period will not be tracked: will

impact EVM

Agilent design tools:

• SystemVue W1917 WLAN Baseband Verification Library can

simulate effects of various errors to assist in optimizing design

• 89600 VSA software can help identify causes of EVM





SystemVue W1917 WLAN Baseband

Verification Library

What’s included

• Simulation library of ~100 blocks for 802.11ac (a/b/g/n)

• Working MIMO TX/RX reference designs

• About 20 Testbenches (showing faded roundtrip BER)

Typical Applications

• System architecture validation, Fading, BB/RF, BER

• Algorithm development, Filtering, MIMO, CFR, DPD

• Troubleshooting & validation of partial hardware systems

• Component evaluation, modeling

Supported features:

• All channel BWs, mod types, and MCS including 256QAM

• BCC and LDPC coding, STBC

• 1-8 spatial streams, up to 8 Tx antennas

• Single-user and multi-user MIMO

• Spatial mapping: direct, spatial expansion, or user-defined

• WLAN TGac channel model

• Receiver supports timing and frequency sync, channel

estimation and phase tracking, demapping and decoding

SIMULATION

HARDWARE

VIRTUAL HW

Modeling platform follows into Test

for earlier, cross-domain validation

TX RX





• Option BHJ 802.11ac

Modulation Analysis supports

all bandwidths and modulation

types, up to 4x4 MIMO

• 89600 VSA software provides

flexible display for optimal

viewing of MIMO results:

– Up to 20 simultaneous traces

and up to 20 markers per

trace

– Arbitrary arrangement and

size of windows

• Supports variety of hardware

configurations for the

performance, bandwidth, and

number of channels you need

802.11ac Signal Analysis with

89600 VSA

17

EVM vs. Symbol

EVM vs.

Subcarrier

Metrics per STS Channel Matrix

Channel Frequency

Response





Example: Troubleshooting EVM with

89600 VSA

18

“V” shape of EVM vs.

carrier indicates

problem with IQ

timing skew

EVM improved from

-44.4 dB to -49.7 dB

after IQ skew

adjustment

OFDM Error

Summary display

shows IQ offset,

quadrature error,

gain imbalance, and

timing skew





Improving PA Linearity with

Digital Predistortion

19

SystemVue W1716 DPD Builder

simplifies and automates digital

predistortion (DPD) design for power

amplifiers

DPD requires 3-5 times the signal BW

of the PA under test: need wideband

signal generation and analysis

1. Stimulus waveform downloaded to

wideband AWG, upconvert to RF

with MXG or ESG signal generator

2. PA’s response captured using

M9392A and 89600 VSA software

3. W1716 compares PA’s response vs.

desired signal and creates DPD

model

4. W1716 creates waveform with DPD

and downloads to AWG. PA

response measured to verify DPD.

Green = original signal

Blue = PA without DPD

Red = PA with DPD

81180A Arbitrary

Waveform Generator





Test Challenge:

Generating Wider Bandwidth Signals

802.11ac Waveform Creation Software

• SystemVue W1917 WLAN Baseband Verification Library

– 2011.10 release includes 802.11ac reference designs for transmitter and receiver

– Supports BCC and LDPC coding, all channel bandwidths and MCS, SU-MIMO and MU-

MIMO with up to 8 spatial streams, channel model

• N7617B Signal Studio for WLAN

– Basic option for component test, advanced option for receiver test

– Supports BCC and LDPC coding, all MCS, up to 8 spatial streams, and single-user or multi-

user MIMO

– Create 20, 40, and 80 MHz BW signals with N5172B EXG, N5182A/B MXG, E4438C ESG,

E8267D PSG, N5106A PXB, and M9381A PXIe VSG

– Create 160 MHz BW signals with using N5182B MXG, M9381A PXIe VSG or N5106A PXB

– MIMO support: up to 4 ch with ESG, 6 ch with PXB, or 8 ch with EXG/MXG

– Create 80+80 MHz signals with two ESGs, EXGs, or MXGs (RF summing)

– 802.11ac channel models can be added to waveform files for MIMO receiver testing

20





Hardware for Generating

80 MHz Signals Sampling rate limitations

• Max sample rate for many RF signal generators cannot support 2x oversampling

for 80 MHz bandwidth signals

• 1x oversampling results in images at band edges from aliasing: need to use

fractional oversampling to allow filtering of images

• Recommended HW: N5172B EXG, N5182A/B MXG, or M9381A PXIe VSG (better

EVM performance than E4438C ESG)

21

1x OSR Matlab Waveform from N5182A MXG with images at band edges

N7617B Signal Studio Waveform from N5182A MXG: no images





Hardware for Generating

160 MHz Signals

22

N5182B MXG

RF Vector Signal Generator

• 9 kHz to 6 GHz

• Up to 1 GSamples baseband memory

• 160 MHz modulation BW with internal

baseband generator

• ~200 MHz BW using external I/Q

inputs

• Opt. 012 provides LO in/out for phase

coherency for MIMO

• Enhanced phase noise option

• Excellent EVM: ~ 0.4% or -47 dB for

160 MHz 802.11ac signal

M9381A PXIe

RF Vector Signal

Generator

• 1 MHz to 6 GHz

• Up to 1 GSample baseband memory


baseband generator

• Excellent RF I/Q Flatness: <± 0.2 dB for

100 MHz and <± 0.3 dB for 160 MHz

• EVM: ~0.64% or -44 dB for 160 MHz

802.11ac signal

• Single channel configuration





Additional Hardware for Generating

160 MHz Signals

Use wideband arbitrary waveform generator

(AWG) to create analog I/Q signal, apply

to external I/Q inputs in RF signal

generator

Need I/Q adjustments (example: IQ skew,

gain balance)

Recommended Agilent wideband AWGs:

• 81180A/B: 12 bits, up to 4.2 Gsa/s, 1 GHz

BW/channel, 64MSa memory

• M8190A: 12 or 14 bits, up to 12 Gsa/s, 5

GHz analog BW, 2GSa memory, AXIe

form factor

23

81180A/B M8190A

160 MHz signal from 81180A and N5182A MXG

Use wideband AWGs with SystemVue waveform files. M8190A support with N7617B Signal Studio planned February 2013.





Test Challenge:

Analyzing Wider Bandwidth Signals

Analyzer hardware needs to support 40, 80, and 160 MHz BW signals

Digital predistortion may require measuring 3 to 5 times the BW of

desired signal: up to 800 MHz for 160 MHz signal

Software: all channel BWs supported by 89600 VSA

Hardware for single-channel measurements:

• N9030A PXA signal analyzer: up to 160 MHz demodulation BW, best

performance

• N9020A MXA signal analyzer: up to 40 MHz demod BW

• M9392A PXI VSA: up to 250 MHz BW

• Infiniium or Infiniivision oscilloscopes: 1 GHz or wider BW

24





Test Challenge: Analyzing Wider Bandwidth Signals (MIMO)

Hardware for MIMO measurements:

• N7109A PXIe Multi-Channel Signal Analysis System: 2,

4, or 8 channels, 40 MHz demodulation BW, 20 MHz to 6

GHz

• M9392A Dual Channel PXI VSA: 2 channels, up to 250

MHz BW

• Wideband MIMO PXI VSA: up to 4 channels of

synchronous downconversion, 800 MHz BW

• Infiniium or Infiniivision oscilloscopes: 1 GHz or wider BW,

4 channels

25





N9077A-4FP 802.11ac Embedded

Application • For PXA, MXA, and EXA signal analyzers

• New option for the N9077A WLAN application that

also supports 802.11a/b/g (opt. 2FP) and 802.11n

(opt. 3FP).

• Opt. 4FP for 802.11ac will require opt. 2FP and

3FP

• Supports 20, 40, 80, 160 MHz, and 80+80 MHz BW

signals depending on hardware demodulation

bandwidth

• I/Q demodulation measurements including:

- Modulation accuracy with Burst Info view & results

- Power vs. time with Burst and Rise & Fall views

- Spectral flatness

- Power Stat CCDF

• Swept spectrum measurements including:

- Spectrum emission mask

- Spurious emissions

- Occupied bandwidth

- Channel power

* CXA with W9077A supports 802.11a/b/g/n, but the CXA does not support

the 802.11ac option due to its demodulation bandwidth limitation of 25 MHz.





802.11ac Signal Analysis Solutions

N7109A Multi-Channel

Signal Analysis System

Infiniium

Oscilloscopes

PXA/MXA/EXA

Signal Analyzers 20 or 40

MHz BW

>40 MHz

BW

Single Channel 2x2 MIMO 3x3, 4x4 MIMO

PXA Signal Analyzer

(160 MHz BW)

N7109A Multi-Channel

Signal Analysis System

Infiniium

Oscilloscopes

MXA/EXA

(40 MHz BW)

Infiniium

Oscilloscopes

Infiniium

Oscilloscopes

Wideband MIMO PXI VSA

(800 MHz BW)


(800 MHz BW)

M9392A PXI VSA

89600 VSA

SystemVue W1917 WLAN

• Support all 802.11 formats

and channel BWs

• Multiple HW platforms

• Up to 8x8 MIMO

N9077A X-series App

• X-series analyzers only

• Support all 802.11 formats

and channel BWs

• Single channel only

Software Hardware





Transmitter Tests

Section 22.3.19 in 802.11ac Standard

Transmit spectrum mask

Spectral flatness

Transmit center frequency tolerance

Packet alignment

Symbol clock frequency tolerance

Modulation accuracy

• Transmit center frequency leakage

• Transmitter constellation error (EVM)

28

Most tests are similar to 802.11n; next slides will review

some differences and specification changes





Transmit Spectrum Mask

Spectral mask for 20 and 40 MHz are same as for 802.11n, except as shown in table

80 MHz spectral mask is an extension of 40 MHz mask

Measured with 100 kHz resolution bandwidth, 30 kHz video bandwidth

29

dBr = dB relative to maximum spectral density of the signal

Signal BW Offset Frequency 802.11n 802.11ac

20 MHz > 30 MHz Max of -45 dBr or -53 dBm/MHz Max of -40 dBr or -53 dBm/MHz

40 MHz > 60 MHz Max of -45 dBr or -56 dBm/MHz Max of -40 dBr or -56 dBm/MHz

80/160 MHz > 120/240 MHz Not applicable Max of -40 dBr or -59 dBm/MHz

40 MHz Channel

80 MHz Channel





Transmit Spectrum Mask for

160 and 80+80 MHz

160 MHz spectral mask is an extension of 40 and 80 MHz masks

For 80+80 MHz, mask is linear sum of the separate 80 MHz masks for values from

-20 dBr to -40 dBr. For values from 0 to -20 dBr, use higher value.

30

Example spectral mask for 80+80 MHz signals, with center frequencies separated by 160 MHz

160 MHz Channel





Spectral Flatness

Specified as deviation in power of each tested subcarrier from the average power

over a set of subcarriers with specified range of indices (same method as 802.11n)

Limits relaxed by 2 dB from the max/min values allowed for 802.11n: allows more in-

band filter ripple for better out-of-band rejection for transmitters

±2 dB +2,

-4 dB

±4 dB +4,

-6 dB

802.11ac 802.11a/n

middle ~70% of subcarriers

160 MHz

20,40,80 MHz





Transmitter Relative Constellation Error

(RCE) or Error Vector Magnitude (EVM)

Test method same as 802.11n:

• Channel estimation (equalizer training) based on preamble only

• Pilots used for phase tracking

• Minimum 16 data symbols in frame, RMS average over at least 20 frames

32

Modulation Coding Rate 802.11n RCE (dB)

802.11ac RCE (dB)

BPSK 1/2 -5 -5

QPSK 1/2 -10 -10

QPSK 3/4 -13 -13

16QAM 1/2 -16 -16

16QAM 3/4 -19 -19

64QAM 2/3 -22 -22

64QAM 3/4 -25 -25

64QAM 5/6 -28 -27

256QAM 3/4 N/A -30

256QAM 5/6 N/A -32





Receiver Tests Section 22.3.20 in 802.11ac Standard

Minimum input level sensitivity

Adjacent channel rejection

Nonadjacent channel rejection

Receiver maximum input level

Clear Channel Assessment (CCA) sensitivity

Again, most tests are similar to 802.11n; focus on key differences

33





Receiver Minimum Input Level

Sensitivity

At input levels listed below, packet error rate shall be less than 10% for a PSDU

length of 4096 octets.

Applies to non-STBC modes, 800 ns guard interval, BCC coding.

Specs same as 802.11n, with additions for 802.11ac MCS and bandwidths.

34

Modulation Coding Rate

Minimum Sensitivity Level (dBm)

20 MHz 40 MHz 80 MHz 160 or 80+80 MHz

BPSK 1/2 -82 -79 -76 -73

QPSK 1/2 -79 -76 -73 -70

QPSK 3/4 -77 -74 -71 -68

16QAM 1/2 -74 -71 -68 -65

16QAM 3/4 -70 -67 -64 -61

64QAM 2/3 -66 -63 -60 -57

64QAM 3/4 -65 -62 -59 -56

64QAM 5/6 -64 -61 -58 -55

256QAM 3/4 -59 -56 -53 -50

256QAM 5/6 -57 -54 -51 -48





Adjacent & Nonadjacent Channel

Rejection

Test procedure:

• Desired signal set to 3 dB above minimum sensitivity level.

• Apply interfering signal of same BW in adjacent or nonadjacent channel. Interferer

is a conformant OFDM signal that is unsynchronized with desired signal, with

minimum duty cycle of 50%.

• Interfering signal power increased until 10% PER occurs for PSDU length of 4096

octets.

• Power difference between interfering and desired signal is the rejection.

For 80+80 MHz, test done for channel below lower 80 MHz segment and

channel above higher 80 MHz segment; use smaller rejection value.

35





Adjacent & Nonadjacent Channel

Rejection

36

Modulation Coding Rate Adjacent Channel Rejection (dB)

Nonadjacent Channel Rejection (dB)

20/40/80/160 MHz

80+80 MHz 20/40/80/160 MHz

80+80 MHz

BPSK 1/2 16 13 32 29

QPSK 1/2 13 10 29 26

QPSK 3/4 11 8 27 24

16QAM 1/2 8 5 24 21

16QAM 3/4 4 1 20 17

64QAM 2/3 0 -3 16 13

64QAM 3/4 -1 -4 15 12

64QAM 5/6 -2 -5 14 11

256QAM 3/4 -7 -10 9 6

256QAM 5/6 -9 -12 7 4

Minimum Adjacent and Nonadjacent Channel Rejection Levels

Specs same as 802.11n, with additions for 802.11ac MCS and bandwidths.





Summary

802.11ac new PHY features will include:

• Wider channel bandwidths: 40 and 80 MHz mandatory, 160 and 80+80

MHz optional

• Higher order modulation: 256QAM

• More spatial streams and antennas: up to 8

• Multi-user MIMO on downlink: up to 4 users, up to 4 streams per user, 8

streams total

Design challenges to deal with wider BW signals that require better EVM to

support 256QAM

Transmitter and receiver tests mostly the same as 802.11n with additions for

new bandwidths and modulation/coding rates

Agilent tools are available to address challenges from system simulation and

design to test, covering all 802.11ac bandwidths including 160 MHz.

37



Agilent: First to Market with 802.11ac Test Solutions

89600 VSA Software

EXG/MXG Signal Generator

E4438C ESG Signal Generator

N5106A PXB Baseband Generator and Channel

Emulator

PXA/MXA/EXA Signal Analyzers

N7109A Multi-Channel Signal

Analysis System

Infiniium & Infiniivision

Oscilloscopes

N7617B Signal Studio

81180B Wideband AWG

M8190A Wideband AWG

Signal

Creation SW

Signal Analysis

Hardware

38

Signal Generation

Hardware

Signal

Analysis SW

Configurations available for: • 20, 40, 80, 80+80, or 160 MHz channel bandwidth

• Single channel, 2x2, 3x3 or 4x4 MIMO.


N9077A X-series Embedded Application

M9381A PXIe RF VSG

SystemVue W1917 WLAN Library W1716 DPD Builder

SystemVue W1917 WLAN Library

M9392A PXI VSA





For More Information

Agilent Resources

• 802.11ac application and product info: www.agilent.com/find/802.11ac

• MIMO application and product info: www.agilent.com/find/mimo

• 89600 VSA product information: www.agilent.com/find/vsa

• Additional Webcasts and events: www.agilent.com/find/events

IEEE 802.11ac Standard

• Task group updates: http://www.ieee802.org/11/Reports/tgac_update.htm

• 802.11 working group project timelines:

http://www.ieee802.org/11/Reports/802.11_Timelines.htm

• 802.11ac working group documents:

https://mentor.ieee.org/802.11/documents?is_group=00ac

39

http://www.agilent.com/find/802.11ac

http://www.agilent.com/find/mimo

http://www.agilent.com/find/vsa

http://www.agilent.com/find/events



Appendix:

Additional Product Information

40



N5182B MXG and N5172B EXG X-series

RF Vector Signal Generators

N5172B EXG

• 9 kHz to 6 GHz

• Up to 512 MSamples baseband memory


baseband generator

• ~200 MHz BW using external I/Q inputs


coherency for MIMO

• Excellent EVM: ~0.35% or -49 dB for 80

MHz 802.11ac signal

41

• 9 kHz to 6 GHz

• Up to 1 GSamples baseband memory


baseband generator


inputs


coherency for MIMO

• Enhanced phase noise option

• Excellent EVM: ~ 0.4% or -47 dB for

160 MHz 802.11ac signal

N5182B MXG

EVM measured with equalizer training on preamble only



N5182A MXG and E4438C ESG

RF Vector Signal Generators

E4438C ESG

• 250 kHz to 6 GHz

• 64 MSa baseband memory

• 80 MHz modulation BW with

internal baseband generator


inputs

N5182A MXG

• 100 kHz to 6 GHz

• 64 MSa baseband memory

• 100 MHz modulation BW with

internal baseband generator


inputs

• Opt. 012 provides LO in/out for

phase coherency for MIMO

42





81180B 12-bit Arbitrary Waveform

Generator

43

• Variable sample rate from 10 MSa/s to 4.6 GSa/s

• 1 or 2 channels, coupled and phase coherent or uncoupled

• 1 GHz modulation bandwidth per channel (2 GHz IQ

modulation)

• 1.5 GHz carrier frequency

• Up to 64 MSa memory

• Advanced sequencing capabilities

• 2 markers with adjustable width and levels





M8190A 12 GSa/s Arbitrary Waveform

Generator

44

Precision AWG with two DAC settings - 14-bit resolution up to 8 GSa/s

- 12-bit resolution up to 12 GSa/s

• Variable sample rate from 125 MSa/s to 8 / 12 GSa/s

• Spurious-free-dynamic range (SFDR) up to 80 dBc typical

• Harmonic distortion (HD) up to-72 dBc typical

• Up to 2 GSa arbitrary waveform memory per channel with

advanced sequencing

• Analog bandwidth 3 GHz (direct DAC out)

• Analog bandwidth 5 GHz (AMP out -> DC and AC)

• AXIe modular form factor





M9330A and N8241A Arbitrary

Waveform Generators

45

M9330A: PXI, 15-bits, 1.25 GSa/s

N8241A: LXI module, 15-bits, 1.25 GSa/s or 625

MSa/s

• Up to 500 MHz BW per channel for 1.25 Gsa/s, 250

MHz per channel for 625 Msa/s

• < -65 dBc spurious-free dynamic range

• 8 or 16 Msamples waveform memory per channel

• Supports sequencing

M9330A

N8241A

Note: These products are not recommended for

802.11ac due to lack of an adjustment for IQ skew,

resulting in poor EVM in the RF signal.



Wideband AWGs: Choose the Performance You Need!

46

M8190A 81180B N8241A / N6030A / M9330A

Max Sample Rate 8 GSa/s and 12 GSa/s

(variable)

4.6 GS/s (variable) 1.25 GS/s (fixed)

Resolution 14-bit 8 GSa/s, 12-bit 12 GSa/s 12 bit – 4 Markers 15 bit – 4 Markers

Sample Memory 128 MSa, 2 GSsa 16 / 64 MSa 8 / 16 MSa

Max. Bandwidth per

channel

5 GHz 1 GHz (1.5 GHz RF) 500 MHz

Spurious-free

Dynamic Range

<-80 dBc , (fout = 100 MHz,

measured DC to 1 GHz)

-68 dBc (fout = 10-3000 MHz)

< -50 dBc

(up to 500 MHz, with optional

reconstruction filter)

< -75 dBc (1 kHz - 500 MHz)

Harmonic Distortion <- 72 dBc (fout = 100 MHz, fs

= 7.2 GHz, 700 mVpp direct

DAC output)

< -58 dBc (SClk 4.6 GHz, 32 pt

sine waveform)

< -65 dBc (DC - 500 MHz)

Phase Noise / Floor - 90 dBc/Hz -100 dBc/Hz @10 kHz -115 dBc/Hz @10 kHz

Output

amplitude/Offset

DAC: 700 mVpp

DC: 1 Vpp, in – 1 V to + 3 V

window

AC: + 10 dBm

500 mVpp; +/- 1.5 V Offset,

DC amp: 2 Vpp

500 mVpp; +/- 0.2 V Offset

Sequencing 256K segments, 4M loops

granularity: 48/64,

2 loop levels

16K Segments, 1M loops

16K Sequences,

1K Scenario Table

512K Segments, 1M loops

32K Sequences, Infinite

16K Scenarios Table

Form factor Modular, AXIe Stand-alone instrument Modular, PXI, LXI

Price range $76K (1ch, 128MSa, no SEQ,

AMP)

$148K (2ch fully loaded)

$62.5K (2ch, 16 MSa memory)

$73.3K (2ch, 64 MSa memory)

$40K (2 ch, 8MSa)

$68K (2 ch, 16MSa, Seq,

DDS)





Modular PXI Solutions for

Signal Analysis

47

Wideband MIMO PXI VSA:

• 4 channels of synchronous downconversion

• 10 MHz to 26.5 GHz frequency range

• 800 MHz bandwidth per channel

• 2 GSa/s or 420 MSa/s digitizer

• Scalable and upgradable from 1 to 4 channels

with 89600B VSA software

• EVM -42 dB for 80 MHz 802.11ac signal, 5.8 GHz

• Small form factor for MIMO system

Wideband MIMO PXI System

www.agilent.com/find/pxi-vsa-MIMO

Note: This solution is intended for R&D and design and verification test applications. It is not

a manufacturing test solution.

http://www.agilent.com/find/pxi-vsa-MIMO









Infiniium High Performance

Oscilloscopes

48

• Up to 33 GHz frequency range/bandwidth

• Scalable from 1 to 4 channels with 89600B VSA

software

• EVM ~ -40 dB for 80 MHz 802.11ac signal, 5.8

GHz

• 4 phase-coherent inputs: allows troubleshooting

of timing and issues related to beamforming

• Analog IQ, IF, or RF analysis

http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-34711.749314&imageindex=1



Agilent Multi-channel SA Solutions

49

~ $138,000 ~ $113,500 (~$138,500 for 3 channels)

N7109A

Applications 802.11n, WiMAX,

LTE Advanced, MIMO,

Beamforming R&D

Freq Range 20 MHz to 6 GHz

# Channels/Chassis 2, 4, or 8 channels

Maximum Analysis

BW

40 MHz

Ind. Channel Tuning Across RF Freq Range

Minimum Frequency

for Widest BW

20 MHz

(always up to 40MHz BW)

89600 VSA Support Full Hardware Support

Swept Measurements No (except VSA macros)

Streaming Support 132MSa capture

Typical EVM

(w/ EQ set to preamble,

pilots, data )

-43 to -47dB

depending on signal

Synchronization/

phase coherent

Yes, also

independently tunable

Pricing 2-ch $ 84.9K

4-ch $105.5K

8-ch $208.5K

PXA Signal Analyzer N7109A

Applications 802.11ac, LTE-Advanced 802.11n, WiMAX,

LTE Advanced, MIMO,

Beamforming R&D

Freq Range 3 Hz to

3.6/8.4/13.6/26.5/44/50 GHz

(IQ and IF/RF)

20 MHz to 6 GHz

# Channels/Chassis 1 (up to 160 MHz BW)

2 (up to 40 MHz BW) [H2’12]

2, 4, or 8 channels

Maximum Analysis

BW

160 MHz (1-ch)

40 MHz (2-ch) [H2’12]

40 MHz

Ind. Channel Tuning N/A (Single Channel) Across RF Freq Range

Minimum Frequency

for Widest BW

3 Hz ? 20 MHz


89600 VSA Support Full Hardware Support Full Hardware Support

Swept Measurements Yes No (except VSA macros)

Streaming Support No 132MSa capture

Typical EVM


pilots, data )

-49 to -51dB, 80MHz BW

-47 to -51dB, 160MHz BW

-43 to -47dB

depending on signal

Synchronization/

phase coherent

Yes Yes, also


Pricing 8.4 GHz Model

1-ch $ 60K ?

2-ch $120K ?

2-ch $ 84.9K

4-ch $105.5K

8-ch $208.5K

90000SeriesScopes PXA Signal Analyzer N7109A

Applications 2 to 4 Channel MIMO

802.11ac, LTE, WiMAX

Beamforming R&D

Troubleshoot multi-channel

timing errors, GP debug

802.11ac, LTE-Advanced 802.11n, WiMAX,

LTE Advanced, MIMO,

Beamforming R&D

Freq Range DC to 33 GHz

(IQ and IF/RF)

3 Hz to

3.6/8.4/13.6/26.5/44/50 GHz

(IQ and IF/RF)

20 MHz to 6 GHz

# Channels/Chassis 4 phase coherent channels 1 (up to 160 MHz BW)

2 (up to 40 MHz BW) [H2’12]

2, 4, or 8 channels

Maximum Analysis

BW

DC to 33 GHz 160 MHz (1-ch)

40 MHz (2-ch) [H2’12]

40 MHz

Ind. Channel Tuning N/A N/A (Single Channel) Across RF Freq Range

Minimum Frequency

for Widest BW

33 GHz 3 Hz ? 20 MHz


89600 VSA Support Full Hardware Support Full Hardware Support Full Hardware Support

Swept Measurements N/A Yes No (except VSA macros)

Streaming Support No No 132MSa capture

Typical EVM


pilots, data )

~ -40dB, 80MHz BW

~ -40dB, 160MHz BW


-47 to -51dB, 160MHz BW

-43 to -47dB

depending on signal

Synchronization/

phase coherent

Yes Yes Yes, also


Pricing 13 GHz Model, 4 ch $123K 8.4 GHz Model

1-ch $ 60K ?

2-ch $120K ?

2-ch $ 84.9K

4-ch $105.5K

8-ch $208.5K

Dual channel PXI VSA 90000SeriesScopes PXA Signal Analyzer N7109A

Applications Environment recording with

wide bandwidths and

multichannel to support 80 +

80 MHz 802.11ac

2 to 4 Channel MIMO


Beamforming R&D

Troubleshoot multi-channel



LTE Advanced, MIMO,

Beamforming R&D

Freq Range 50MHz to 26.5 GHz DC to 33 GHz

(IQ and IF/RF)

3 Hz to

3.6/8.4/13.6/26.5/44/50 GHz

(IQ and IF/RF)

20 MHz to 6 GHz

# Channels/Chassis 1 or 2 channels 4 phase coherent channels 1 (up to 160 MHz BW)

2 (up to 40 MHz BW) [H2’12]

2, 4, or 8 channels

Maximum Analysis

BW

250 MHz DC to 33 GHz 160 MHz (1-ch)

40 MHz (2-ch) [H2’12]

40 MHz

Ind. Channel Tuning Across RF Freq Range N/A N/A (Single Channel) Across RF Freq Range

Minimum Frequency

for Widest BW

2.25 GHz 33 GHz 3 Hz ? 20 MHz


89600 VSA Support Full Hardware Support Full Hardware Support Full Hardware Support Full Hardware Support

Swept Measurements No (except VSA macros) N/A Yes No (except VSA macros)

Streaming Support Yes (Up to 100 MHz) No No 132MSa capture

Typical EVM


pilots, data )


-41 to -43dB, 160MHz BW

~ -40dB, 80MHz BW

~ -40dB, 160MHz BW


-47 to -51dB, 160MHz BW

-43 to -47dB

depending on signal

Synchronization/

phase coherent

Synchronized

(not phase coherent)

Yes Yes Yes, also


Pricing 2-ch $138K 13 GHz Model, 4 ch $123K 8.4 GHz Model

1-ch $ 60K ?

2-ch $120K ?

2-ch $ 84.9K

4-ch $105.5K

8-ch $208.5K

Wideband MIMO PXI VSA Dual channel PXI VSA 90000SeriesScopes PXA Signal Analyzer N7109A

Applications 80 + 80 MHz and 160 MHz

802.11ac R&D / DVT, MIMO

Environment recording with

wide bandwidths and

multichannel to support 80 +

80 MHz 802.11ac

2 to 4 Channel MIMO


Beamforming R&D

Troubleshoot multichannel



LTE Advanced, MIMO,

Beamforming R&D

Freq Range 2.25 GHz to 26.5 GHz

(lower with external LO)

50MHz to 26.5 GHz DC to 33 GHz

(IQ and IF/RF)

3 Hz to

3.6/8.4/13.6/26.5/44/50 GHz

(IQ and IF/RF)

20 MHz to 6 GHz

# Channels/Chassis 2 to 4 channels (1 chassis)

Up to 8 channels (2 chassis)

1 or 2 channels 4 phase coherent channels 1 (up to 160 MHz BW)

2 (up to 40 MHz BW) [H2’13]

2, 4, or 8 channels

Maximum Analysis

BW

800 MHz 250 MHz DC to 33 GHz 160 MHz (1-ch)

40 MHz (2-ch) [H2’13]

40 MHz

Ind. Channel Tuning Only within IF bandwidth Across RF Freq Range N/A N/A (Single Channel) Across RF Freq Range

Minimum Frequency

for Widest BW

2.25 GHz with M9302A PXI

LO

10 MHz with External LO

2.25 GHz DC 3 Hz 20 MHz


89600 VSA Support Digitizer Control Only Full Hardware Support Full Hardware Support Full Hardware Support Full Hardware Support

Swept Measurements No (except VSA macros) No (except VSA macros) N/A Yes No (except VSA macros)

Streaming Support Yes (Up to 100 MHz) Yes (Up to 100 MHz) No No 132MSa capture

Typical EVM


pilots, data )


-41 to -43dB, 160MHz BW


-41 to -43dB, 160MHz BW

~ -40dB, 80MHz BW

~ -40dB, 160MHz BW


-47 to -51dB, 160MHz BW

-43 to -47dB

depending on signal

Synchronization/

phase coherent

Synchronized


Synchronized


Yes Yes Yes, also


Pricing 2- ch $113K

3-ch $138K

4-ch $163K

2-ch $138K 13 GHz Model, 4 ch $123K 8.4 GHz Model

1-ch $ 60K

2-ch $120K

2-ch $ 84.9K

4-ch $105.5K

8-ch $208.5K

http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&nid=-34711.749314&imageindex=1



3-Channel Wideband MIMO PXI Vector Signal

Analyzer

50

M9362A-D01

Downconverter

100 MHz Out1

100 MHz Out2

Video Trigger This Channel

M9352A

Amp Attenuator M9168C uW

Attenuator

Notes:

With M9302A LO, minimum RF frequency is 2.25 GHz

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