a design workflow for software defined radios
TRANSCRIPT
A Design Workflow for Software Defined Radios
Frederick [email protected]
Presented August 22, 2007 to:Dr. Gary J. Minden
Dr. Joseph B. EvansDr. Alexander M. Wyglinski
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Acknowledgements• Defense Committee
• Dr. Gary J. Minden (Chair)• Dr. Joseph B. Evans• Dr. Alexander M. Wyglinski
• KU Agile Radio Group• Leon Searl and Dan DePardo• Jordan Guffey, Rory Petty,
Tim Newman, Brian Cordill, Dinesh Datla, RakeshRajbanshi, Qi Chen, and Megan Peck
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Outline• Background
• Software Defined Radios (SDR)• Dynamic Spectrum Access (DSA)
• Proposed Research• A workflow for SDRs
• Validation• Apply design workflow to KUAR• Generate systems
• Extension• Generic SDR API• Hardware Agnostic Cognitive Network
• Conclusion
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What is an SDR?• Ideal SDR
• Direct conversion between digital samples and analog waveform• Use only general purpose processors (GPP)• Unrealistic for high frequencies – cost, processor speed, algorithm complexity
• Practical SDR• Baseband processing, analog components translate to transmission band• Optimizations using digital signal processors (DSP) and field programmable
gate arrays (FPGA)
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Why do we need SDRs?• FCC “Command-and-
Control” Policy Limits• What can be transmitted• Who can transmit• Where they can transmit
• Results in apparent spectrum scarcity• Restricts research and novel
services• New York 13.1% utilization
3.0 MHz – 3.0 GHz• TV utilization often less than
50%
• Solution: SDRs
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Dynamic Spectrum Access• SDR detects unused frequencies (whitespace) and utilizes them• Cognitive Radio (CR)
• Radio which adapts to its environment• Cognitive algorithms implemented on SDR platforms
• Dynamic Spectrum Access (DSA)• Avoid licensed users• Utilize whitespace
Image From “Spectrum Pooling an Innovative Strategy for the Enhancement of Spectrum Efficiency,” by T. Weiss and F. Jondral
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Current SDR Technologies• Universal Serial Radio Peripheral (USRP)
• Generic RF front-end• Modular transmit/receive bands
• GNU Radio• Open source SDR software• Only supports general purpose processors• Based around USRP
• Global Mobile (GloMo) API• Generic radio modem API
• Software Communications Architecture (SCA)• CORBA based communications model for SDR modules
• Joint Tactical Radio System (JTRS)• SDR platform commissioned by Defense Advanced Research Projects
Agency (DARPA)• Built using SCA
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The KU Agile Radio (KUAR)• Digital Board
• 1.4 GHz Pentium M• 1 GB RAM & 8 GB microdrive• PCI Express, USB, 1 Gb ethernet• 160 MSPS Digital-to-Analog Converter (DAC)• 105 MSPS Analog-to-Digital Converter (ADC)• Xilinx Virtex II Pro 30 FPGA
• RF Front-End• Modular• 5.25 GHz – 5.85 GHz UNII Research Band• Receiver sensitivity -100 dBm• Transmitter power +25 dBm• Quadrature modulation & demodulation• Baseband bandwidth of 30 MHz
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SDR: A Federation of Components• Variety of components must work in unison to
transmit/receive• General purpose processors• Special purpose processors (FPGA, Microcontrollers)• Frequency synthesizers• Modulators/Demodulators• Attenuators
• Different types of design problems on SDR• Cognitive network design• Real time data management• Communication systems
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Development Domains• Break the problem into domains
• Reconfigurable hardware domain aimed at Communications Engineers
• Embedded software domain aimed at System Engineers• Radio management domain aimed at Network Engineers and
general radio maintenance
• Each domain has its own workflow requirements• Different set of development tools• Each domain’s toolset must support designing, implementing,
and verifying modules• Domains interact but implementations are independent
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Reconfigurable Hardware Domain• Implement physical layer
communication systems• Direct access to ADC/DAC• Signal processing
optimizations possible in FPGA
• Generic memory elements need to be provided• Bus controller• Buffers (FIFOs, RAMs)• Registers (Status, Control)
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Embedded Software Domain• Manage hardware
interfaces and data streams
• Components• Dynamic Hardware Interface:
configure/communicate with reconfigurable hardware
• Static Hardware Interface: communicate with RF modules and sensors
• Spectrum Sensing: perform spectral sweeps
• Waveform Protocols: physical layer protocols
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Radio Management Domain• Radio Management
• Diagnostic tools• Network protocols• Spectrum access protocols
• User interface enables network tests• Control multiple radio nodes• Define co-operative tests• Display results
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Implementation on the KUAR• Reconfigurable Hardware Domain
• Xilinx Virtex II FPGA• PCI, PCIe, or USB bus
• Embedded Software Domain• 1.4 GHz Pentium M with 1 GB RAM
• Radio Management Domain• Remote KUAR interface
VGA
Xilinx Virtex IIPro FPGA
CPU/Mis.Memory
512k x 32 bit
OutputMemory
256k x 32 bit
InputMemory
256k x 32 bit
ADC
SDRAM1 GBPCI-eXpress
1 Lane
PCI
USB
IDE
GPS
Mouse
Monitor
Network
I2C
TemperatureSensor
I2C
CF Connector
CF+6 GB uDrive
DAC
AD9777Dual 16-Bit
Diff.
Diff.
Diff.
Diff.
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16
14
14
LTC2284Dual 14-Bit105 Msps
1000BaseT
Front Panel
AudioInput
AudioOutput
ADT7461
KontronETXexpress
1.4 Ghz Pentium-M
USB
USB
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USBPeripheralController
USB12
SPI
CypressCY7C68013A
3
USBUSB
I2C
FPGAConfiguration
LiBattery
RTC backuppower
FlashCarrier Cnfg
I2C
3 dBPOWERDIVDER
SMV3300A
LO 3
LNA
BASEBAND I
BASEBAND Q
SPI Bus
5.250-5.850 GHz
AD8347I-Q DEMODULATOR800 MHz - 2.7 GHz
GAINCONTROL
I DET Q DET
LNA
1.850-2.450 GHz
AD8349I-Q MODULATOR700 MHz - 2.7 GHz
090
BASEBAND Q
BASEBAND I
LR I
PA
ADF4360-1
ADF4360-2
TX LO 2
3.4 GHz
16.0 MHz
090
Σ
Lumped Microstrip
LR I
(-100dBm)
+8dBi
-4dB +19dB -5dB
-3dB
+19dB
-5dB+9dB-2dB
-10dB -5dB
(+3dBm)
-5dB+9dB
(+7dBm)
-10dB-5dB+17dB
(+9dBm)(+21dBm)
(+25dBm)
+8dBi
JumperSelect
BW=30 MHz
BW=30 MHz
-4dB
(+17dBm)
ADF4360-1
ADF4360-21.850-2.150 GHz
RX LO 1
AD56016 BIT DAC
RX IF GAINCONTROL
AD56016 BIT DAC
TX IF GAINCONTROL
Active TX Antenna Module
Active RX Antenna Module
2.150-2.450 GHz
1.850-2.150 GHz
2.150-2.450 GHz
3.4 GHz
1.850-2.450 GHz5.250-5.850 GHz
(-3dBm)
OPTIONALFor use with passive
antenna
(-8dBm)(-2dBm)(+15dBm)
ADF4113
MC68HC08MicrocontrollerI²C
DPB Input
Keyboard
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Communication Systems• Development tools
• Develop using Matlab/Simulink
• Implement using Xilinx VHDL• Verify with Simulink,
Modelsim, and hardware test bench
• Test cases translated down flow
• Verified components added to shared library
• Systems Built• BPSK, MQAM, OFDM,
Spectrum Analyzer, …
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Support Libraries• Development tools
• Implement using GCC & GNU Makefile
• User validation & cUnit• FPGA Library
• Configure bit file• Read from and write to hardware
configurations• RF Control Library
• Manage the RF front-end• Set and get frequencies and
gains• Query hardware capabilities
• Monitor Library• Monitor system temperatures
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The KUAR Control Panel• Control multiple radios
from one interface• Radio status• Configure radio profile• Control RF front-end
• Define network and single radio tests• Test definitions XML based
• Extendable interface• Java based remote KUAR
API• Programmable test window
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Achievements
• Developed design workflows to handle• Reconfigurable hardware• Embedded software• Radio management
• Implemented on the KUAR• Communications systems
– BPSK, QPSK, OFDM• KUAR API
– RF Control, FPGA Control, Monitoring libraries• Analytical systems
– Whitespace detector, spectrum analyzer
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Enabling Generic SDR Development• Physical layer implementations often tailored to
system• Dependent on sampling rates• Optimized for parallel and signal processing• Hard real-time deadlines
• Cognitive algorithms are complex but more generic• Wide variety of issues: whitespace, battery life, channel
characteristics, noise power, …• Complex solutions: frequency selective modulation, expert
systems, genetic algorithms, ontology based systems, …
• Should be able to re-use cognitive algorithms
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Hardware Agnostic Network Stack• SDR Platform API
handles the physical layer implementations
• Unifying Layer exposes generic SDR interface
• Traffic Scheduler manages access to shared RF front-end
• Cognitive Network Layer is independent of SDR implementation platform
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Unifying Layer• Hardware Manager
• List hardware capabilities• Control RF front-end
• Protocol Manager• List waveform protocols• Manage waveform protocols
• Spectrum Sensor• Handle spectral sweeps
• Data Stream Manager• Similar to GloMo API• Interact with configured
waveform protocols
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Traffic Scheduler• Schedule packets to channels
• Channel is a hardware digital/analog chain• Scheduled packet includes protocol, frequency, power, and time frame• Each channel has an allocation list
• Packets are scheduled in a sliding window• Packets may be scheduled periodic or single-shot• Call back interface for error states and packet completion
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Conclusion• Achievements
• Developed a design workflow for SDRs• Workflow used to develop systems for KUAR• Proposed generic SDR API (Unifying Layer)• Described infrastructure to support hardware agnostic cognitive
networks
• Future work• Implement hardware agnostic network stack• Develop more robust cognitive algorithms for KUAR• Apply workflow to another SDR platform
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Resources• SDR Resources
• SDR Forum: http://www.sdrforum.org/• Wikipedia Article: http://en.wikipedia.org/wiki/Software-defined_radio
• Publications• G. J. Minden, J. B. Evans, L. Searl, D. DePardo, R. Rajbanshi, J. Guffey, Qi Chen, T.
Newman, V. R. Petty, F. Weidling, M. Lehnherr, B. Cordill, D. Datla, B. Barker, A. M. Wyglinski, A. Agah, "An Agile Radio for Wireless Innovation" IEEE Communications Magazine, Vol. 45, Issue 5, pp 113-121, May, 2007.
• V. R. Petty, R. Rajbanshi, D. Datla, F. Weidling, D. DePardo, P. J. Kolodzy, M. J. Marcus, A. M. Wyglinski, J. B. Evans, G. J. Minden, J. A. Roberts, "Feasibility of Dynamic Spectrum Access in Underutilized Television Bands" in Proceedings of the 2nd IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySpan 2007), (Dublin, Ireland), April 2007.
• G. J. Minden, J. B. Evans, L. Searl, D. DePardo, V. R. Petty, R. Rajbanshi, T. Newman, Q. Chen, F. Weidling, J. Guffey, D. Datla, B. Barker, M. Peck, B. Cordill, A. M. Wyglinski and A. Agah, "KUAR: A Flexible Software-Defined Radio Development Platform" in Proceedings of the 2nd IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySpan 2007), (Dublin, Ireland), April 2007.
• F. Weidling, D. Datla, V. Petty, P. Krishnan, and G. J. Minden, “A Framework for RF Spectrum Measurements and Analysis,” in Proceedings of the 1st IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySpan 2005), (Baltimore, MD, USA), pp. 573– 576, Nov. 2005.
• Questions?