Low Bit rate Ambient FM Backscattering for Low Cost and ...
16
AT-RASC 2018 1 Low Bit rate Ambient FM Backscattering for Low Cost and Low Power Sensing. Spyridon Nektarios Daskalakis, George Goussetis and Apostolos Georgiadis School of Engineering & Physical Sciences Heriot-Watt University EDINBURGH, SCOTLAND, UNITED KINGDOM [email protected]
Transcript of Low Bit rate Ambient FM Backscattering for Low Cost and ...
AT-RASC 2018 1
Low Bit rate Ambient FM Backscattering for Low Cost and Low Power Sensing.
Spyridon Nektarios Daskalakis, George Goussetis and Apostolos Georgiadis
School of Engineering & Physical SciencesHeriot-Watt University
EDINBURGH, SCOTLAND, UNITED [email protected]
AT-RASC 2018
Backscatter Principles (1/2) Commercial WSN Radios Cost and Power ConstraintsSolution: Backscatter Communication->RFIDsSingle transistor communicationAntenna load switching @ Ftag
μW Power Consumption!Low Cost!
2
AT-RASC 2018
Bistatic or Monostatic Architecture: CW Transmitter and Reader Collocated or not
Emitter: Dedicated CW TransmitterAmbient Signals
Tag: MCU (control unit)Multiple sensors Simple RF front-end
Reader: Software defined radioSmartphone
3
Backscatter Principles (2/2)
AT-RASC 2018
Ambient FM Broadcasting BackscatterCommunication using reflected ambient music signals.
Simplified scheme -> Only a receiver and a tag.
4
BBC 95.8 MHzTransmission power: 250 KW
Measured indoor max power: -60 dBm
AT-RASC 2018
Ambient Backscatter for Agriculture
5
Inkjet Printed Nanoparticle Inks
Resolution: 20 µm – 50 µm
Energy Assisted Prototype Tag
• Use FM broadcasting ambient signals.
• Temperature difference (Tleaf-Tair), relatedwith the meteorological event of rainfalls
AT-RASC 2018
OOK FM0 Receiver Algorithm
6
• RTL-GNU radio and MATLAB
• Received baseband signal
AT-RASC 2018
Binary Modulation Tag
7
• Indoor implementation of sensing system• Modulation ASK with FM0 encoding• Channel fluctuation Trade off: Bit rate and Efficient filtering
Tbit = 10 ms (50 bps)
Tbit = 1 ms (500 bps)
AT-RASC 2018
Some Receiver Plots!
8
Tag Packet Waves
Receiver Packet Waves
AT-RASC 2018
Real Indoor Demo Results
9
• Edinburgh Heriot-Watt University EMP lab• GOAL: increase the “tag-reader” distance
AT-RASC 2018
Battery-less uW Tag
10
8-bit PIC16LF1459 MCU-> 25uA/MHz @ 1.8 V32 kHz clockTsymbol=5.8 ms
DAC for RF front-end controlSolar panel + store capacitorADC for sensing
AT-RASC 2018
High Order Modulation Tag
11
High order modulation on ambient backscatter 4 PAM -> 2 Bits/symbolSpectrally efficient low power applicationsFM band 87.5 MHz- 108 MHzSingle transistor
AT-RASC 2018
4 PAM Receiver
12
Low cost RTL SDR (Cost: 18$) MATLAB+GNU RadioReal Time
Receiver Algorithm:Envelope DetectionCorrelation with square pulse (Duration=Tsymbol)Dynamically calculated thresholdsQuantize a signal to the nearest element of the set [-3, -1, +1, +3]
AT-RASC 2018
Receiver Results (1/2)
13
Tag waveform (MCU):PreambleTraining symbolsData
Packet: [10 00 10 00 10 11 11 00 01 01 11 10 00 11][ +3 -3 +3 -3 +3 -1 +1 -3 -1 -1 +1 +3 -3 +1]
Receiver Packet Waves, Bit rate: 345 bps
AT-RASC 2018
Receiver Results (2/3)
14
Packet data: [-1 +1 -3 -1 -1 +1 +3 -3 +1]
Calculate three thresholdsfrom preamble & training symbols
AT-RASC 2018 15
SummaryLow cost, low power backscatter sensing systemLow cost tag/receiver hardwareReal time indoor demos (Ambient Binary and High Order Modulation) 5 meters wireless communication
Future Goals
High order modulation measurementsBetter RF front end Increase rangeImprovement of receiver algorithm
AT-RASC 2018
Questions ?
Acknowledgment
Heriot-Watt University
ICON Foundation
EU COST Action IC1301 Wireless Power Transmission for Sustainable Electronics.
16
Thank you for your attention !
