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Simulation & Design ofSoftware-Defined Radios
Simulation & Design ofSoftware-Defined Radios
November 28, 2007
presented by:
David Leiss and Greg Jue, Agilent Technologies
Copyright 2007 Agilent Technologies, Inc.
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Agenda
SDRs: Overview, Challenges, and New Methodology
Evaluate an RF System with an FPGA based 16-QAM legacy
Waveform
Evaluate System Performance with a new Commercial Off the
Shelf (COTS) OFDMA Mobile WiMAX Waveform
Compare both Waveforms Susceptibility to RF Interference
FPGA Implementation and Test of an OFMDA Mobile WiMAX
Waveform
"WiMAX" is a trademark of the WiMAX Forum
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What Is a Software-Defined Radio?
Lots of definitions, but some key trends:
Radio where hardware is reconfigurable and will work with
multiple software-defined waveformsBaseband and digital IF may be implemented with FPGAs,
ASICs, DSP
New communications waveforms can be quickly introduced intothe system without requiring taking the hardware out of servicefor extended periods of time.
The Software Communications Architecture (SCA) enablesprogrammable radios to load waveforms, run applications, andbe networked into an integrated system.
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Ad-Hoc Network Operations and Impairments
Interference Sources
Overlapping
Wireless Network
Multi-
PathComms/Data
Network
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SDR Physical Layer Design & Test Challenges
Simulation is useful to evaluate waveform compatibility, butinvolves both baseband and RF. How can they be evaluated
together?
How can new waveforms, such as COTS WiMAX OFDMA, be
evaluated before implementing hardware?
How can new waveforms be evaluated with real-world fieldscenarios (e.g. interferers, jammers, etc..) before field
deployment?
How can custom waveform interoperability be tested with off-the-
shelf test solutions after hardware implementation?
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New SDR Design and Test Methodology Helps
Address these Challenges:
Capture and use baseband hardware waveforms* to design theSDR RF system. Evaluate baseband and RF together insimulation.
Leverage COTS reference waveforms* (such as WiMAX OFDMA)to evaluate RF system compatibility before implementing
hardware
Evaluate real-world scenarios (such as RF interferers) in
simulation before deploying hardware to the field
Test waveform* interoperability with off-the-shelf test solutions byleveraging simulation inside of test equipment
*Note: Waveforms shown in this presentation are physical layer
IQ waveforms, not full SDR DSP implementations
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Agenda
Overview
SDRs: Overview, Challenges, and New Methodology
Evaluate an RF System with an FPGA based 16-QAM legacy
Waveform
Evaluate System Performance with a new COTS OFDMAMobile WiMAX Waveform
Compare both Waveforms Susceptibility to RF Interference
FPGA Implementation and Test of an OFMDA Mobile WiMAXWaveform
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Addressing Physical Layer Design & Test Challenges
Challenge:
Simulation is useful to evaluate waveform compatibility, but
involves both baseband and RF. How can they be evaluatedtogether?
Solution:Capture and use baseband hardware waveforms to design the
SDR RF system. Evaluate baseband and RF together in
simulation.
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ADS Overview
Time Domain Based RF Envelope Co-Simulation
RF
Frontend
RF/Analog
Downconverter
Digital
Receiver
Digital
DeMod
System
Simulation
Level Behavioral RF/Analog Subsystem
CircuitCircuit CoSim
EM CoSim
TransistorNetwork
Analyzer
& IC-CAP
Verilog - A
Typically Models Describedby their Behavior, i.e. Gain,
NF, TOI, Mixer Spurs, etc.
Component Level Models,Lumped and Distributed
components, transistors, etc.
Measurement Based Models
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ADS OverviewNumeric Domain Based Co-Simulation
RF
Frontend
RF/Analog
Downconverter
Digital
Receiver
Digital
DeMod
Baseband Float, Fixed, Matrix, Cx
HDL / MATLAB / C++
Numeric models, FloatingPoint, Fixed Point, Complex,
Matrix, etc.
Co-simulate with MATLAB
HDL and C++
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ADS OverviewInstrument Based Co-Simulation
RF
Frontend
RF/Analog
Downconverter
Digital
Receiver
Digital
DeMod
DUT MXA PSAESG / MXG Infiniium Logic Analyzer
ADS software and all these
instruments, and manyothers, use this 89600 series
VSA software.
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Using ADS with FPGA Hardware
From ADS one can read and write directly to & from instruments:
Download/Write
Digital Stimulus
from ADS to FPGA
Download/ Write
from ADS
ADS
16900 Logic Analyzer with
Pattern Generator Board
Capture/Read Digital
Output from
FPGA into ADS
16900 Logic AnalyzerCapture/Read
Into ADS
ADS
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FPGA QAM 16 Block Diagram
Digital IF/FPGA
+SymbolEncoder
BB Filter
BB Filter
0 deg
90 deg
IF LO
I
Q
Capture and read FPGA waveform into ADS to design RF system
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FPGA Test Setup
16900 series Logic
Analyzer with
89601 VSA
Software
FPGA Board
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Capture FPGA Waveform and Design Transmitter
Transfer capturedFPGA signal to ADS
EVM ~ 4.5 %
ORADS also has
HDL co-
simulate
capabilities
3rd Order
Spectral
Regrowth
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Add Channel Model and Design Receiver
Transfer captured
FPGA signal into
simulationEVM ~ 14.5 %
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Agenda
Overview
SDRs: Overview, Challenges, and New Methodology
Evaluate an RF System with an FPGA based 16-QAM legacyWaveform
Evaluate System Performance with a new COTS OFDMA
Mobile WiMAX Waveform
Compare both Waveforms Susceptibility to RF Interference
FPGA Implementation and Test of an OFMDA Mobile WiMAXWaveform
Add i Ph i l L D i & T t Ch ll
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Addressing Physical Layer Design & Test Challenges
Challenge:
How can new waveforms, such as COTS WiMAX OFDMA, be
evaluated before implementing hardware?
Solution:
Leverage COTS reference waveforms (such as WiMAX OFDMA)
to evaluate RF system compatibility before implementing
hardware
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802.16e Mobile WiMAX OFDMA COTS
OFDMA= Orthogonal Frequency Division Mult. Access
Data transmitted on multiple subcarriers for each
symbol- variable FFT sizes (512,1024,..)
Less susceptible to narrowband interference and
multipath
Parallel burst structure- multiple users (Multiple
Access) are assigned unique subcarrier mapping vs.time
Nulls create orthogonality
between subcarriers
0
1
2
34
5
6
7
8
9
10
k k+1 k+ 2 k+3 k+4 k+5 k+6
n+6 n+7 n+8
n n+1 n+2
n+3 n+4 n+5
Logical Sub-channelsSymbol number
Physical subcarriers
[[User 1
User 2
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Customizing COTS Technologies for SDRsParameterized Signal Sources and Receivers
Sources and
Receivers have
parameters which
can be modified
Bandwidth=20 MHzBandwidth=10 MHz
RateCode=4 (64 QAM)RateCode=3 (16 QAM)
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Customizing COTS Technologies for SDRsFlexible Parameterized Signal Sources and Receivers
Sources and Receivers
have parameters which
can be easily modified
Existing Sources and
Receivers can be modified
and saved to create custom
systems
Example: Replace
ADS Bit Source
with a customized
MATLAB source
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Wideband SDR has more susceptibility to
interference
A wide bandwidth means more noise at the
A2D Due to the transmitter inter-modulation
products the system EVM will be degraded
due to inter-channel interference (ICI)
Evaluate Performance with WiMAX COTS Waveform
As you watch the demonstration
think about potential performance
issues with the system and what
could be done very early in the
design process to fix them.
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System Simulation Results with
WiMAX OFDMA COTS Waveform
EVM ~ 5.6% versus
~ 14.5 % for uncoded 16 QAM
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Other COTS Wireless Libraries in ADS
CDMA
GSM
DTV
3GPP WCDMA
CDMA2000
EDGE
WLAN
CDMA2000 1XEV
TDSDMA
HSPA
http://eesof.tm.agilent.com/products/wireless_libraries.html
Other possible sources of signals and measurements:
The ADS MATLAB Co-Simulation
Elements: Agilent Instruments:
Fixed WiMAX
Mobile WiMAX
802.11n
WiMedia
3GPP LTE
Agenda
http://eesof.tm.agilent.com/products/wireless_libraries.htmlhttp://eesof.tm.agilent.com/products/wireless_libraries.html8/23/2019 Simulation & Design of Software-Defined Radios
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Agenda
Overview
SDRs: Overview, Challenges, and New Methodology
Evaluate an RF System with an FPGA based 16-QAM legacyWaveform
Evaluate System Performance with a new COTS OFDMA
Mobile WiMAX Waveform
Compare both Waveforms Susceptibility to RF Interference
FPGA Implementation and Test of an OFMDA Mobile WiMAXWaveform
Addressing Physical Layer Design & Test Challenges
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Addressing Physical Layer Design & Test Challenges
Challenge:
How can new waveforms be evaluated with real-world field
scenarios (e.g. interferers, jammers, etc..) before field
deployment?
Solution:
Evaluate real-world scenarios (such as RF interferers) in
simulation before deploying hardware to the field
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Evaluate Effects of Interferers on QAM16 System
Transmitter Receiver
DSP
16QAM
DeMod
DSP
16QAM
Source
Channel
Model
Interference
Source
3.4 GHz
Transmitter Receiver
DSP
16QAM
DeMod
DSP
16QAM
Source
Channel
Model
Interference
Source
3.4 GHz
Transmitter Receiver
DSP
16QAM
DeMod
DSP
16QAM
Source
Channel
Model
Interference
Source
3.4 GHz
Effects of Interferers on QAM16
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Effects of Interferers on QAM16
Swept QPSK Interference Frequency and Power using VSA Software
Channel
Model
Receiver
Interference
Source
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Next: Evaluate Effects of Interferers on OFDMA
System
DSP
OFDMA
Source
Transmitter
Channel
Model
Receiver
DSP
OFDMA
DeMod
Interference
Source
3.4 GHzOFDMA SrcBW=10 MHz
Fctr=25 MHz
Pwr 0 dBm
Path Model
Length=200M
Loss103 dB
Suburban Env.
Interference
Type=QPSK
Fc=3385 to 3415 MHz
Pwr= -150 to -70 dBm
~30 dBmChannel
Model
Receiver
DSP
OFDMA
DeMod
Interference
Source
3.4 GHz
Effects of Interferers on WiMAX OFDMA
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Effects of Interferers on WiMAX OFDMA
Receiver
Effects of Interferers on WiMAX OFDMA
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Effects of Interferers on WiMAX OFDMA
Interference Frequency Sweep
Channel
Model
Receiver
Interference
Source
QPSK Interference Source
Freq = 3380 to 3420 MHz
Power = -100 dBm
ADS 802.16e (WiMAX)
EVM Measurement
Component
Channel
Model
Interference
Source WiMax
16 QA
Effects of Interferers on WiMAX OFDMA
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Effects of Interferers on WiMAX OFDMA
Interference Power Level Sweep
Channel
Model
Receiver
Interference
Source
QPSK Interference Source
Freq = 3402 MHz
Power = -120 to -95 dBm
Note: The 16 QAM based waveform
system had an EVM of
approximately 15% in this region.
Agenda
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Agenda
Overview
SDRs: Overview, Challenges, and New Methodology
Evaluate an RF System with an FPGA based 16-QAM legacyWaveform
Evaluate System Performance with a new COTS OFDMA
Mobile WiMAX Waveform
Compare both Waveforms Susceptibility to RF Interference
FPGA Implementation and Test of an OFMDA MobileWiMAX Waveform
Addressing Physical Layer Design & Test Challenges
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g y y g g
Challenge:
How can custom waveform interoperability be tested with off-the-
shelf test solutions after hardware implementation?
Solution:
Test waveform interoperability with off-the-shelf test solutions by
leveraging simulation inside of test equipment
FPGA Implementation
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FPGA Implementation
and Test Flow
ADS HDL Co-Simulation of SystemVue HDL
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ADS HDL Co Simulation of SystemVue HDL
Agilent SystemVue
Generate
HDL with
HDS3
Co-Simulate with
HDL in ADS
and VSA SW
ADS HDL Co-Simulation Results : EVM ~ 1.1%
FPGA Implementation Test Setup
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FPGA Implementation Test Setup
16900
LogicAnalyzer
with VSA
SW and
ADS
FPGA
Board
(DUT)
MXA
SignalAnalyzer
with VSA
SW and
ADS
ESG to
Clock
FPGA
Board
Close-Up of Mobile WiMAX Measurement
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p
Measured EVM~1.1%
(versus ~1.1%
simulated)
OFDMA
Constellation
Spectrum
Software-Defined Instruments with ADS
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Software Defined Instruments with ADS
ADS AddsSimulated RF
Interferer to
FPGA Signal
Spectrogram
Showing
Interferer Freq. &
Intensity vs.
Time
Interferer in
WiMAX Spectrum
ADS Slider toControl Interferer
Freq. Offset and
Power
Other Waveforms Implemented
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p
3GPP LTE Downlink (OFDMA)
HSPA TestModel5(Wideband Code Domain
Spread Spectrum)
3GPP
WCDMA
Summary
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Capturing baseband hardware waveforms to design the SDR RFsystem was shown. Baseband and RF were evaluated togetherin simulation.
A COTS WiMAX OFDMA reference waveform was used toevaluate RF system compatibility before the hardwareimplementation
An RF interferer scenario was evaluated in simulation beforeimplementing and deploying hardware
The FPGA hardware implementation was testing using Software-Defined Instruments, leveraging simulation inside of off-the-shelftest equipment
Additional References
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Web Links:
Agilent EEsof EDA Home Page:http://eesof.tm.agilent.com/
EEsof SDR Applications:
http://eesof.tm.agilent.com/applications/sdr.html
EEsof Aerospace Defense Applications:
http://eesof.tm.agilent.com/applications/aerospace-b.html
EEsof Connected Solutions:
http://eesof.tm.agilent.com/products/connected_solutions_main.htmlApplication Notes:
Software Defined Radio Measurement Solutions:
http://cp.literature.agilent.com/litweb/pdf/5989-6931EN.pdf
Connected Simulation and Test Solutions Using ADS:http://literature.agilent.com/litweb/pdf/5988-6044EN.pdf
RF/IF-to-Digital Connected Solutions BER Using ADS:
http://literature.agilent.com/litweb/pdf/5989-0024EN.pdf
http://eesof.tm.agilent.com/http://eesof.tm.agilent.com/applications/sdr.htmlhttp://eesof.tm.agilent.com/applications/aerospace-b.htmlhttp://eesof.tm.agilent.com/products/connected_solutions_main.htmlhttp://eesof.tm.agilent.com/products/connected_solutions_main.htmlhttp://cp.literature.agilent.com/litweb/pdf/5989-6931EN.pdfhttp://literature.agilent.com/litweb/pdf/5988-6044EN.pdfhttp://literature.agilent.com/litweb/pdf/5989-0024EN.pdfhttp://literature.agilent.com/litweb/pdf/5989-0024EN.pdfhttp://literature.agilent.com/litweb/pdf/5988-6044EN.pdfhttp://cp.literature.agilent.com/litweb/pdf/5989-6931EN.pdfhttp://eesof.tm.agilent.com/products/connected_solutions_main.htmlhttp://eesof.tm.agilent.com/applications/aerospace-b.htmlhttp://eesof.tm.agilent.com/applications/sdr.htmlhttp://eesof.tm.agilent.com/8/23/2019 Simulation & Design of Software-Defined Radios
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Thank You !