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Page 1: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

387 Berlin Road, Bolton, MA 01740+1.978.222.3114 ๐ [email protected]

octoFade

Channel Emulation

January 2014

Page 2: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Outline

• What is channel emulation and why is it critical for MIMO

systems?

• Channel modeling standards

• octoFade-WiFi software

• octoFade—3GPP RTL

2

Page 3: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Wireless Channel

• Frequency and time variable wireless

channel

• Multipath creates a sum of multiple

versions of the TX signal at the RX

• Mobility of reflectors and wireless

devices causes Doppler-based fading

• Multiple antenna techniques are used

to optimize transmission in the

presence of multipath and Doppler

fading

3

Ch

an

nel

Qu

ality

MIMO=multiple input multiple output

Page 4: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Multipath and Flat Fading

• In a wireless channel the signal

propagating from TX to RX

experiences

Flat fading

Multipath/Doppler fading

4

Time

+10 dB0 dB Multipath fading component

-15 dB flat fading component

Multipath reflections occur in clusters.

Page 5: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Wireless Channel5

Per path angular spread

Composite angular spread

Composite angular spread

Multipath cluster

model

Multipath and Doppler

fading in the channel

Page 6: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Validating Radio DSP

• A variety of channel

conditions and complex

multiple-antenna algorithms

for adapting to these

conditions make a channel

emulator necessary for

developing and testing

radio DSP

6

TX RX

Controlled

programmable

channel

conditions

Multipath

Doppler

Noise

Channel Emulator

Page 7: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Development and Test of MIMO

• Development and test of MIMO

systems requires a channel emulator

to emulate multipath and Doppler

fading in a variety of wireless

channels.

• Adaptive multiple antenna techniques,

including TX and RX diversity, spatial

multiplexing and beamforming involve

sophisticated open and closed loop

algorithms that must be tested under a

range of controlled (emulated) channel

conditions.

• Traditional channel emulators connect

to DUTs conductively – without

antennas. Antennas and antenna

arrays are part of the channel models.

7

Channel

Emulator

DSP

RF

Fro

nt E

nd

RF

Front E

ndDigital IQ (CPRI/OBSAI)

RF or digital IQ coupling to

DUTs

Multiple RF

modules can

connect for

scalability

Page 8: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

SISO Channel Emulator

x

x

x

where K is the number of taps in the TDL

h1

h2

hK

+

Input

Output

Tapped Delay Line (TDL), H

TX

RX

Complex time-variable

coefficients, h

Delay 2

Delay 3

Delay K

Page 9: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

4x4 MIMO Channel Emulator Logic

9

N3

N4

+

+

+

+

N1

N2

H21

H31

H11

H41

H22

H32

H12

H42

H23

H33

H13

H43

H24

H34

H14

H44

M1

M2

M3

M4

Page 10: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

MIMO Channel

Emulation Logic

2 x 4 Example

H1,1

H2,1

H1,2

H2,2

H2,3

H1,3

+

+

+

+H1,4

H2,4N1

N2

M1

M2

M3

M4

[h1,11, h1,1

2, … , h1,1 T]

[h2,41, h2,4

2, … , h2,4 T]

[h2,11, h2,1

2, … , h2,1 T]

[h1,21, h1,2

2, … , h1,2 T]

[h2,21, h2,2

2, … , h2,2 T]

[h1,31, h1,3

2, … , h1,3 T]

[h2,31, h2,3

2, … , h2,3 T]

[h1,41, h1,4

2, … , h1,4 T]

Complex tap

coefficients

Tapped Delay Line, H n,m

Page 11: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Doppler spectrum

1,1k..K

Spatial

correlation

matrix

Polarization

matrix

Tap coefficient factors

1,1 h1,1k..K

Complex Tap Coefficient Generator

Tap coefficient factors

1,2 h1,2k..K

Tap coefficient factors

N,M hN,Mk..K

Tap coefficient factors

n,m hn,mk..K

… …

where k is the tap number, K is the maximum number of taps and h is the time-variable coefficient

Doppler spectrum

1,2k..K

Doppler spectrum

n,mk..K

Doppler spectrum

N,Mk..K

Page 12: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Doppler Spectrum Block

Doppler filter

Classical Specified for most 3GPP channel models; Classical = Jakes; Classical 3 dB and 6 dB

Bell Specified for 802.11n channel models; variations of this filter include Bell-spike, which is used by

802.11 model F to model a 40 km/hour spike in the spectrum

Static Models LOS on first tap; used in custom channel modeling

Flat Can also be implemented using RF attenuators via an identity matrix (i.e. connecting inputs to

outputs through attenuators)

Rounded Variations of this filter include Rounded 12 dB

Gaussian

Constant phase

Butterworth

Pure Doppler Rician LOS component only, no Reilly

Doppler filter

FIR or IIR

AWGN

Generator

Page 13: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Notes on Doppler Filter Implementation

• AWGN sources are connected to Doppler filters that provide the desired spectral shape of

the fading. The Doppler filter is IIR in the octoFade implementation.

• For 802.11n models, the filter is Bell-shaped for models A through F and Bell-Spike for

model F. The Bell spectrum models fading due to walking-speed motion in the environment

at an average speed of 1.2 km/hr. The spike in the Bell-Spike spectrum adds the effect of a

vehicle moving at an average speed of 40 km/hr.

• For 3GPP models, the Doppler spectrum is Classical.

Page 14: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Tap Coefficient Factors

+ x

𝑃𝑘Fluorescent

light

+

𝐾

1 + 𝐾𝑒𝑗𝜃𝑛,𝑚

1

1 + 𝐾

x

Tap coefficient factors

n,m

hn,mt

where t is the tap number, h is the time-variable complex coefficient, K is Rician K-factor

LOS component NLOS component

PDP weighting

Interpolation

to TDL clock

rate

Page 15: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Notes on Tap Coefficient Factors

• The parameter K (Rician K-factor) determines the relative strength of the LOS and NLOS

components and is set based on the chosen model.

• The 𝐾

1+𝐾term models the LOS component. The

1

1+𝐾term models the NLOS

component.

• The LOS component can only be present on the 1st tap. If the distance between the

transmitter and the receiver is greater than the distance to 1st reflector (typically a wall in the

indoor environment ) then LOS component is not present. The presence of LOS is a

configuration parameter that can be enabled or disabled.

• The first tap’s LOS component isn’t Doppler filtered. Thus, if LOS is present, the power

spectrum on the first tap deviates from the Bell spectrum since it includes both the LOS and

the NLOS components. If LOS is present, the PDF and CDF of the 1st tap are Rician. If

LOS is not present the PDF and CDF on the 1st tap are Rayleigh. On all other taps the PDF

and CDF are always Rayleigh.

• 𝑃 𝑡 represents the Power Delay Profile (PDP) weighting, summed over all the clusters that

contribute power for the tth tap. It reflects how strong the total power is at tap t.

Page 16: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

802.11n/ac Correlation Matrix

• The spatial correlation matrix is a function of the angular spread of each cluster, angle of arrival (AoA)

and angle of departure (AoD). 802.11n models assume that RX and TX antenna systems are uniform

linear arrays with equally spaced antenna elements.

• Spatial correlation is implemented using the Kronecker product of the transmit and receive correlation

matrices, Rtx and Rrx, respectively. These matrices are comprised of correlation coefficient terms,ρ, that

depend on the PAS, AoA, AoD, tap powers and distance D between antenna elements. Fox computes

the real and imaginary parts, RXX(D) and RXY(D), respectively, for each ρ. This allows spatial correlation

based on the complex field (i.e., using ρ =RXX(D)+jRXY(D)) or real power (i.e., using ρ =RXX2(D)

+RXY2(D)).

Rec

eive

r

Tran

smit

ter

AoA

AoD

Antenna element spacing, D

Angle of arrival (AoA),

Angle of departure (AoD)

Antenna spacing, D

Page 17: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

802.11ac Correlation and Polarization

• MU-MIMO modeled for AoD and AoA

• Polarization matrix added since 802.11ac devices are

expected to have cross-polarized antennas

17

AoA = angle of arrival

AoD = angle of departure

Page 18: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

4x4 Uni-directional Fader Block Diagram18

RFIQ

4 Quad

Atten 4

Quad

Atten

IQ

Fader logic

RF I/O RF I/OQuadQuad

Quad

circulator

Quad

circulator

RF

4

RF return path

Digitized

Page 19: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

4x4 Bi-directional Fader Block Diagram19

RFIQ

4 Quad

Atten 4

Quad

Atten

IQ

Fader Logic

RF I/O RF I/OQuadQuad

Quad Quad

Quad

circulator

Quad

circulatorFader Logic

RF

Digitized

Page 20: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Outline

• What is channel emulation and why is it critical for MIMO

systems?

• Channel modeling standards

• octoFade-WiFi software

• octoFade-3GPP RTL

20

Page 21: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

3GPP and 802.11 Channel Models

21

Parameter Model Name References and Notes

3GPP Models (RTL) LTE: EPA 5Hz; EVA 5Hz; EVA

70Hz; ETU 70Hz; ETU 300Hz;

High speed train; MBSFN

3GPP TS 36.521-1 V10.0.0 (2011-12)

3GPP TS 36.101 V10.5.0 (2011-12)

GSM: RAx; HTx; TUx; EQx; TIx 3GPP TS 45.005 V10.3.0 (2011-11) Annex C

3G: PA3; PB3; VA30; VA120;

High speed train; Birth-Death

propagation; Moving

propagation; MBSFN

3GPP TS 25.101 V11.0.0 (2011-12)

3GPP TS 25.104 V11.0.0 (2011-12)

3GPP TS 36.521-1 V10.0.0 (2011-12)

IEEE 802.11n/ac Models

(software)

A, B, C, D, E, F IEEE 802.11-03/940r4

IEEE 11-09-0569

Channel modelling

building blocks (RTL)

Tap: delay, Doppler, PDP weight

Path: list of taps

System: NxM, correlation matrix

Page 22: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Channel Emulation – Requirements Summary

22

802.11n802.11ac LTE (36-521 Annex

B)80 MHz 160 MHz

RF bandwidth

(no channel

aggregation)

40 MHz 80 MHz 160 MHz 20 MHz

EVM (avg down-

fading is -40 dB)

-28 dBm

(64QAM)

-32 dBm

(256QAM)

-32 dBm

(256QAM)

-22 dBm

(8% 64QAM)

TDL Taps 18 35 69 9

Delay resolution 10 ns 5 ns 2.5 ns 10 ns

Page 23: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Outline

• What is channel emulation and why is it critical for MIMO

systems?

• Channel modeling standards

• octoFade-WiFi software

• octoFade-3GPP RTL

23

Page 24: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

octoFade Software

24

802.11n/ac

channel emulator

Impairments: AWGN,

spurious, phase

noise, IQ imbalance,

frequency shift

Sample rate

conversion

Sample rate

conversion

Input file of sampled

IQ streams

Output file of

sampled IQ streams

4 x 4

4 streams 4 streams

Up to 4x4 MIMO configuration

AWGN = average white Gaussian noise

Page 25: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Use octoFade Software with Off-the-shelf Equipment

25

Off the shelf

VSG

DUT

Off the shelf

VSA

octoFade software

Running on a Linux or Windows PC

Page 26: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

802.11n Channel Models - Summary

26

Model [1] Distance to 1st

wall (avg)

# taps Delay

spread

(rms)

Max delay # clusters

A* test model 1 0 ns 0 ns

B Residential 5 m 9 15 ns 80 ns 2

C small office 5 m 14 30 ns 200 ns 2

D typical office 10 m 18 50 ns 390 ns 3

E large office 20 m 18 100 ns 730 ns 4

F large space

(indoor or outdoor)

30 m 18 150 ns 1050 ns 6

* Model A is a flat fading model; no delay spread and no multipath

The LOS component is not present if the distance between the transmitter and the receiver

is greater than the distance to 1st wall. The presence of LOS is a configuration parameter

that can be enabled or disabled.

Page 27: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

802.11ac Channel Models

• 802.11ac channel models are an extension of 802.11n

models [2]

27

System Bandwidth

W

Channel Sampling

Rate Expansion

Factor

Channel Tap

Spacing

W ≤ 40 MHz 1 10 ns

40 MHz < W ≤ 80 MHz 2 5 ns

80 MHz < W ≤ 160 MHz 4 2.5 ns

W > 160 MHz 8 1.25 ns

Page 28: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

octoFade channel modeling

library

CLI application +

APIAPI

Model statistics

(Matlab)

octoFade Software Architecture

Page 29: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

National Instruments LabVIEW Console

29

National Instruments

LabVIEW application

Graphical

programming

environment

Page 30: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Viewing Input and Output Streams

30

National Instruments

TDMS file view

TDMS = TDM streaming

TDM = technical data management

Page 31: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Waveform Analysis

31

National Instruments WLAN Toolkit

Page 32: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Channel and Distortion Settings

32

Page 33: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

802.11ac RTL DSP Requirements

33

Parameter Requirement Notes

Number of IQ input paths 1-8 Unused inputs disabled where applicable

IQ input data format 18-bit

Number of IQ output paths 1-8 Unused outputs set to zero where applicable

IQ output data format 18-bit

Input/output sample rate Up to 400 MHz Current capability: 100 MHz

Channel bandwidth Up to 160 MHz Current capability: 40 MHz

Maximum number of total taps FPGA resources-dependent N x M x taps_per_TDL

Number of TDL blocks Up to 64

Number of taps per TDL block FPGA resources-dependent

Tap delay range FPGA resources-dependent Current capability: 30 usec

Minimum tap delay resolution 2.5 ns Current capability: 10 ns

Tap weight range 0 to -50 dB

Tap weight resolution 0.1dB

Doppler shift 2 kHz To support high speed train

SNR setting -10 to +35 dB, average+/- 0.1 dB accuracy

Noise filter bandwidth Up to 160 MHz Equal to preconfigured channel bandwidth

Subject to the availability of FPGA resources, octoScope can customize any of these specifications.

Page 34: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

RF Front End Considerations

Parameter Specification Notes

MIMO configuration 8 x 8 To support emerging

802.11ac and LTE

beamforming

configurations

Bidirectionality Important To support beamforming

Bandwidth 160 MHz To support emerging

802.11ac

Dynamic range

(RF dynamic range, converter

and DSP resolution)

Accommodate 52 dB of

output signal dynamic

range with little

distortion

Signal fluctuation:

+9 dB for PAPR

+3 dB for up-fade

-40 dB for down-fade

EVM About 6 dB higher than

EVM required for RF

signal

For example, channel

emulator’s EVM should be

at least 36 dB over the

entire dynamic range to

minimize distortion of a 30

dB EVM 802.11n signal

34

Page 35: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

octoFade-Wi-Fi Verification Examples

35

Page 36: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Doppler Spectrum – 802.11n Model F

• Example of Doppler

spectrum plots for IEEE

802.11n model F

Environment velocity is

1.2 km/hour and is

modeled on all taps for

all models

Tap 3 for model F

includes automotive

velocity spike at 40

km/hour

36

-40 -20 0 20 40

100

Tap h111

-40 -20 0 20 40

100

Tap h112

-40 -20 0 20 40

100

Tap h113

-40 -20 0 20 40

100

Tap h114

-40 -20 0 20 40

100

Tap h115

-40 -20 0 20 40

100

Tap h116

-40 -20 0 20 40

100

Tap h121

-40 -20 0 20 40

100

Tap h122

-40 -20 0 20 40

100

Tap h123

-40 -20 0 20 40

100

Tap h124

-40 -20 0 20 40

100

Tap h125

-40 -20 0 20 40

100

Tap h126

-40 -20 0 20 40

100

Tap h211

-40 -20 0 20 40

100

Tap h212

-40 -20 0 20 40

100

Tap h213

-40 -20 0 20 40

100

Tap h214

-40 -20 0 20 40

100

Tap h215

-40 -20 0 20 40

100

Tap h216

-40 -20 0 20 40

100

Tap h221

-40 -20 0 20 40

100

Tap h222

-40 -20 0 20 40

100

Tap h223

-40 -20 0 20 40

100

Tap h224

-40 -20 0 20 40

100

Tap h225

-40 -20 0 20 40

100

Tap h226

Theoretical

Simulated

The Doppler spread is 3 Hz at 2.4 and 6 Hz at 5.25 GHz for

environment speed of 1.2 km/hour

Frequency, Hz

Page 37: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Doppler Spectrum – 802.11n Model F, Tap 3

37

-200 -150 -100 -50 0 50 100 150 20010

-4

10-2

100

102

Frequency

Dopple

r S

pectr

aTap h

113

FFT-based power

estimation using entire

long realization

length 1024

periodograms with

50% overlap

speed of light Frequency, Hz

Page 38: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Doppler Spectrum – 802.11n Model E, Tap 3

38

-600 -400 -200 0 200 400 600

10-8

10-6

10-4

10-2

100

102

Frequency

Dopple

r S

pectr

a

Tap h113

Fluorescent light effects at 120, 360, and

600 Hz – harmonics of the power line

frequency of 60 Hz

Frequency, Hz

Page 39: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Cumulative Distribution Function (CDF)

• IEEE 802.11n, Model F, CDF for 18 taps

39

-40 -20 0 20-4

-3

-2

-1

0Tx#1 - Rx#1

log

10 C

DF

-40 -20 0 20-4

-3

-2

-1

0Tx#1 - Rx#2

-40 -20 0 20-4

-3

-2

-1

0Tx#2 - Rx#1

log

10 C

DF

20 log10

(h) [dB]

-40 -20 0 20-6

-4

-2

0Tx#2 - Rx#2

20 log10

(h) [dB]

Tap 1 with LOS component

Page 40: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

www.octoscope.com

Power Delay Profile (PDP) – Model F

• Power decreases with increasing tap delay.

• Red points are for the normalized PDP under NLOS conditions. Blue points are simulated normalized

PDP under LOS conditions.

40

5 10 15 20-30

-20

-10

0

10Tx#1 - Rx#1

Pow

er

[dB

]

5 10 15 20-30

-20

-10

0

10Tx#1 - Rx#2

5 10 15 20-30

-20

-10

0

10Tx#2 - Rx#1

Pow

er

[dB

]

Tap index

5 10 15 20-30

-20

-10

0

10Tx#2 - Rx#2

Tap index

Tap 18

Tap #, 1-18

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Channel Impulse Response

• Impulse response, IEEE 802.11n model F

41

0 1 2 3 4 5 610

-6

10-5

10-4

10-3

10-2

10-1

100

101

time (s)

abs(H

)

Page 42: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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Outline

• What is channel emulation and why is it critical for MIMO

systems?

• Channel modeling standards

• octoFade-WiFi software

• octoFade-3GPP RTL

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Page 43: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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octoFade System Architecture

VST = vector signal transceiver

Emulator API

octoFade LabVIEW GUI

LVlib wrapper

GSM

Profile

API

802.11n/ac

Profile API

LTE

Profile

API

WCDMA

Profile

API

Gen

eric

mod

els

SCME

Profile

API

Altera FPGA board

Host instrument

hardware platform

D/A and A/D

RF Front End

FPGA based DSP

43

Page 44: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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octoFade Demo Configuration

Emulator API

DLL Library VIs

GSM

Profile

API

WCDMA

Profile

API

LTE

Profile

API

Gen

eric

mod

els

Altera FPGA board

PDP Verification VI Doppler Verification VIoctoFade Demo VI

Emulator HAL (PCIe)

44

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Demo Setup

45

Page 46: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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Supported Models and Building Blocks

46

Parameter Model Name References and Notes

3GPP Models (RTL) LTE: EPA 5Hz; EVA 5Hz; EVA

70Hz; ETU 70Hz; ETU 300Hz;

High speed train; MBSFN

3GPP TS 36.521-1 V10.0.0 (2011-12) Annex B

3GPP TS 36.101 V10.5.0 (2011-12) Annex B

GSM: RAx; HTx; TUx; EQx; TIx 3GPP TS 45.005 V10.3.0 (2011-11) Annex C

3G: PA3; PB3; VA30; VA120;

High speed train; Birth-Death

propagation; Moving

propagation; MBSFN

3GPP TS 25.101 V11.0.0 (2011-12) Annex B

3GPP TS 25.104 V11.0.0 (2011-12) Annex B

IEEE 802.11n/ac Models

(software)

A, B, C, D, E, F IEEE 802.11-03/940r4; IEEE 11-09-0569

Static Models (software

and RTL)

Identity matrix Static bypass

Butler matrix Static, minimum correlation

Channel modelling

building blocks (RTL)

Tap: delay, Doppler, PDP weight

Path: list of taps

System: NxM, correlation matrix

Page 47: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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octoFade-3GPP RTL DSP SpecificationsParameter Specification

Digital IQ inputs (N) Up to 8 (16-bit)

Digital IQ outputs (M) Up to 4 (16-bit)

MIMO channels Up to 2 independently configured MIMO channels

Maximum number of TDL paths 16 paths

Maximum number of taps per TDL 18 taps per TDL

Maximum number of taps 144 taps total

Tap specifications

0 to -40dB; 0.1dB resolution

10ns delay resolution

30us max delay range

3GPP channel models

LTE: EPA 5Hz; EVA 5Hz;EVA 70Hz; ETU 70Hz; ETU 300Hz; MBSFN

GSM: RAx; HTx; TUx; EQx; TIx

UMTS: PA3; PB3; VA30; VA120; MBSFN

Moving propagation, birth-death, high-speed train

Custom channel modelsArbitrary fading profiles can be implemented in software and loaded into the FPGA via

register interface.

Distortion Better than -50dBc

AWGNSNR: -10 to +25dB; 0.1dB resolution

Bandwidth: Up to 20MHz, per 3GPP standard requirements

Fading

Types: Rician/Rayleigh

Spectrum: Classical Doppler

Shift: 0.1 – 1000Hz; 1Hz resolution

Control Interface 32-bit register memory map

47

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octoFade-module

48

Formfactor PCIe

IQ interface DDR HSMC Ports A and BClock rate: 61.44 MHzBit resolution: 16 bits I, 16 bits Q

FPGA resources*Stratix IV EP4SGX530KH40C2

Logic ALUTs: 97,616 used; 424,960 available (23% used)memory bits: 7,760,493 MB used; Available 21,233,664 (37% used)18-bit DSP Blocks: 296 used; Available 1,024 (29% used)

Board memory DDR3/SSRAM x36*

0 MB used; 512 MB available

PCI Express Interface x4 PCI Express4-lane interface to host PC for configuration and verification

octoFade-module hardware is based on off-the-shelf Altera Stratix-IV FPGA board with

octoFade-3GPP RTL integrated into the on-board FPGA

- Highly efficient implementation with only 1/3rd of the FPGA resource used

Page 49: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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FPGA Resource Estimate

49

Altera

Stratix IV EP4Sx360

Xilinx

Virtex 6 XC6VLX195T

Logic

104K ALUTs, 62K Regs

73K ALMs 88K - 173K LUT-6 44-87%

MEMORY 235 256x36 = 9kb blocks 235 18Kb blocks 34%

48 2K x 72= 148kb blocks 192 36 Kb blocks 56%

DSP 296 dual multiply/add blocks 592 DSP slices 93%

Page 50: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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octoFade-3GPP Logic Verification Examples

50

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3GPP LTE PDP MIMO 4x4 Example

51

2 4 6 8 10-10

-5

0

Tx#1 - Rx#1

Pow

er

[dB

]

2 4 6 8 10-10

-5

0

Tx#1 - Rx#2

2 4 6 8 10-10

-5

0

Tx#1 - Rx#3

2 4 6 8 10-10

-5

0

Tx#1 - Rx#4

theo

sim

2 4 6 8 10-10

-5

0

Tx#2 - Rx#1

Pow

er

[dB

]

2 4 6 8 10-10

-5

0

Tx#2 - Rx#2

2 4 6 8 10-10

-5

0

Tx#2 - Rx#3

2 4 6 8 10-10

-5

0

Tx#2 - Rx#4

2 4 6 8 10-10

-5

0

Tx#3 - Rx#1

Pow

er

[dB

]

2 4 6 8 10-10

-5

0

Tx#3 - Rx#2

2 4 6 8 10-10

-5

0

Tx#3 - Rx#3

2 4 6 8 10-10

-5

0

Tx#3 - Rx#4

2 4 6 8 10-10

-5

0

Tx#4 - Rx#1

Pow

er

[dB

]

Tap index

2 4 6 8 10-10

-5

0

Tx#4 - Rx#2

Tap index

2 4 6 8 10-10

-5

0

Tx#4 - Rx#3

Tap index

2 4 6 8 10-10

-5

0

Tx#4 - Rx#4

Tap index

LTE ETU model

Source: octoFade Verification ReportPDP = power delay profile

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3GPP Doppler Spectrum – Matlab Model

52

-0.048 0.048

-10

0

10

20

30

40

50

60

h1,1

Norm. Freq.

Spe

ctr

um

sim

theory

Source: octoFade Verification Report

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3GPP Tap Coefficients CDF Example

53

-30 -25 -20 -15 -10 -5 0 5 10 15

-3

-2.5

-2

-1.5

-1

-0.5

0

Rayleigh

Tx#1 - Rx#1

log

10 C

DF

20 log10

(h) [dB]

CDF – cumulative distribution function

Source: octoFade Verification Report

Page 54: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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3GPP Moving Propagation Example

54

0 20 40 60 80 100 120 140 160100

150

200

250

300

350

400

450

500

550

600

time (s)

tap i

nde

x

Moving Propagation - Tap 2

Source: octoFade Verification Report

Page 55: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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3GPP Birth-Death Example

55

0 100 200 300 400 500 600 700 800 900 10000

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000histogram of path 0

tap index

num

ber

of

occurr

ence

s

Source: octoFade Verification Report

Page 56: octoFade Channel Emulation · 2014-01-13 · octoFade Channel Emulation January 2014. ... Bell Specified for 802.11n channel models; variations of this filter include Bell-spike,

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References1. IEEE, 802.11-03/940r4: TGn Channel Models; May 10, 2004

2. IEEE, 11-09-0569 , “TGac Channel Model Addendum Supporting Material”, May 2009

3. IEEE, 11-09-0334-08-00ad-channel-models-for-60-ghz-wlan-systems

4. Schumacher et al, "Description of a MATLAB® implementation of the Indoor MIMO WLAN channel model proposed by the IEEE 802.11 TGn Channel Model

Special Committee", May 2004

5. Schumacher et al, "From antenna spacings to theoretical capacities - guidelines for simulating MIMO systems"

6. Schumacher reference software for implementing and verifying 802.11n models -

http://www.info.fundp.ac.be/~lsc/Research/IEEE_80211_HTSG_CMSC/distribution_terms.html

7. TS 25.101, Annex B, “User Equipment (UE) radio transmission and reception (FDD)”, file: 25101-b00-AnnexB.doc

8. TS 36.101, Annex B, “Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception”, file: 36101-a50-

AnnexB.doc

9. TS 36.521-1, Annex B, “Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) conformance specification Radio transmission and

reception Part 1: Conformance Testing”, file: 36521-1-a00_s09-sAnnexB.doc

10. TS 45.005, Annex C, “GSM/EDGE Radio Access Network; Radio transmission and reception”, file: 45005-a30-AnnexC.doc

11. TS 51.010-1, “Mobile Station (MS) conformance specification; Part 1: Conformance specification”, file: 51010-1-980_s00-s11.doc

12. 3GPP TR 25.996, "3rd Generation Partnership Project; technical specification group radio access networks; Spatial channel model for MIMO simulations“

13. IST-WINNER II Deliverable 1.1.2 v.1.2, “WINNER II Channel Models”, IST-WINNER2, Tech. Rep., 2008 (http://projects.celtic-

initiative.org/winner+/deliverables.html)

14. 3GPP TS 34.114: “User Equipment (UE) / Mobile Station (MS) Over The Air (OTA) Antenna Performance Conformance Testing”

15. CTIA, “Test Plan for Mobile Station Over the Air Performance - Method of Measurement for Radiated RF Power and Receiver Performance”, Revision 3.1,

January 2011

56

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Thank you!

• octoFade web page

http://www.octoscope.com/English/Products/octoFade/octoFade.html

• Contact

Fanny Mlinarsky

Mobile: 978.376.5841

Email: [email protected]

57