gnu radio as a research and development tool for rfid ... · • gnu radio provides a flexible...

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GNU Radio as a Research and Development Tool for RFID Applications

25 September 2012

Christopher R. Valenta


•  Overview of RFID and applications •  RFID/RFID-enabled sensors development •  GNU Radio as a research and educational tool •  Conclusions •  Demonstration

Agenda

Electro(Op+cal-Systems-Laboratory-|-EOSL--(-2-


Where is RFID?



Background on RFID


•  RFID reader transmits continuous wave (CW) signal to environment

•  Tags in range digitally modulate CW signal by changing their ‘size’ via radar cross section ! 15.5 pJ/bit!

•  Tags’ modulated data include identification and sensing information

•  Reader demodulates the backscattered data

RF-Front-End-

So<ware-Defined-Radio-

TX-

RX-

RFID-Reader- RFID-Tag-


•  Variety of frequencies (USA – FCC ISM Bands) •  135 kHz, 13.56 MHz, 433 MHz, 900 MHz, 2.4 GHz, 5.8 GHz

•  Most work concentrated at UHF •  Digital and analog sensing •  Recent interest in RFID sensors

•  Intel WISP •  GE chemical sensor •  Southern States CMD II

RFID Vs. RFID-enabled Sensors & WSN


GE-Chemical-Sensor-

Southern-States-CMD-II-


•  Large number of tags ! Cheap ! Very simple •  Increased complexity in reader (transceiver)

Background on RFID


RF-Front-End-

So<ware-Defined-Radio-

TX-

RX-

RFID-Reader-


•  Lots of developments in RFID technology •  Novel antennas, sensors, modulation schemes,

computation •  Hardware specific ! Software implications

•  Usually entire tag designed with one in mind •  Integration of technologies is difficult (or impossible)

•  Revisions •  Expensive •  Time intensive

Motivation



•  Availability of DSP blocks •  Low time to implementation/Rapid prototyping •  Ease of debugging/Code readability

•  Modularity

•  Flexibility •  Protocol, data rate, frequency

•  Reusable code •  Low latency data processing •  No other COTS 5.8 GHz RFID systems

•  Lots of freedom

Why GNU Radio?



•  Development board allows the rapid prototyping of RFID •  Sensors •  Microwave structures •  Antennas •  Coding/Telecommunications

Protocols •  4 identical ports allow inter-

changable daughtercards •  Daughtercards are controlled

via programmable microcontroller on Motherboard

•  Modular hardware and software

Semi-Passive RFID Development Board


Semi(Passive-Motherboard-

(Microcontroller,-oscillator,-power-circuitry,-USB-debugger,-etc.)-

RF-Front-End-

(Switches)-

Antenna-

Analog-Sensor-(ADC)-

Digital-Sensor--(I2C,-SPI)-

Demodulator-


R.E.S.T. Layout


Programming-Port-

Reset-BuZon-

ADC-Voltage--Reference-

Power-Circuitry-Select-Source-(Programmer-(BaZery-(External-Select-Des+na+on-(MSP430-(Ports-

Daughtercard-Port-

Status-LEDs-

Configurable-BuZon-

Microcontroller-TI-(-MSP430F5419-

10-cm-

10-cm-


Daughterboards


•  5.8 GHz RF front end •  With antenna •  Without antenna

•  Motion capture board •  Temperature board •  Gas sensor array


Integrated Motion Capture System



Dedicated Motion Capture Tag


Microcontroller-

RF-Switch-

Gyrometer-

Accelerometer-


Tag Software Flow Diagram


Query-Sensors-

-

Insert-Tag-ID-&-Header-

-

Calculate-CRC--

Manchester-Encode-

-

BackscaZer--


•  Bi-static arrangement •  5.8 GHz Direct Down

Conversion Transceiver •  120 dB dynamic range •  12 dB noise figure

•  Ettus Research USRP N200 •  LFRX Daughtercard (DC

– 30 MHz) •  Manchester-encoded

BPSK •  Variable data rate

•  Custom telecomm. protocol

Motion Capture System


Header%(3%byte)%

Tag%ID%(2%byte)%

Accel_Data%(3%byte)%

Gyro_Data%(3%byte)%

CRC%%%%%(1%byte)%


Transceiver Schematic



Receiver Software Flow Diagram


Channel-Filter--

Automa+c-Gain-Control-

-

Timing-Recovery-

-

Constella+on-Receiver-

-

Unpack-k-bits--

Correlator--

Framer-sink--

I/Q-Data-

Packet-Received-Flag-


Screenshot



•  Backscatter channel is unique •  Experiments with different modulations

•  Sensor development •  Passive multiple access •  Cognitive radio •  Simulated and real-world data

Research Tool


Flicker-noise- Thermal-noise-

DC-Block-

Frequency-

|S(f)|-


Power-Optimized Waveforms (POWs)


•  Benefits:-Increased-range-and-reliability,-mul+ple-access-techniques,-ranging-•  Challenges:-Genera+on-and-demodula+on-


POW Efficiency Improvement



•  Remove complexities of C++ and Verilog •  Students interact primarily with Python

•  Coding, sensors, headers, modulation

Educational Tool



•  GNU Radio provides a flexible platform for developing RFID technologies

•  Users •  Research Labs •  Industry •  Hobbyists •  Undergraduate/Graduate instruction

•  Modular nature allows development of a single piece of hardware/software without significant understanding of system

Conclusions



•  Funding •  Shackelford Fellowship from GTRI •  Thingamagigawerks •  NSF Career Grant #0546955

•  People •  Marcin Morys •  Bashir Akbar •  Dr. Greg Durgin

Acknowledgements


Questions? [email protected]

Demonstration

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