Resilient Connectivity for Industrial IoT: How Sensor Platforms Become Realt Time and Ultra Low Power by Dr. Tolgay Ungan, endiio GmbH

1. Resilient Connectivity for Industrial IoT: How Sensor
Platforms become Real-Time und Ultra Low Power
Dr. Tolgay Ungan, Jorge Saez
6th M2M Alliance Academic Day 2017 Cologne

2. - 2 -
Agenda
 Motivation
 IoT Sensor Platform
 Wake-up Technology
 Differential FSK WuRx description
 Proof of concept using Visible Light Communications
 Development of an HF FSK WuRx prototype
 Tests and results
 Conclusions and outlook

3. - 3 -
Energy consumption in WSN
hikingresearch.wordpres
s.com
firescenes.net
• Energy saving is the most meaningful aspect in
Wireless Sensor Networks (WSN).
• WSN deployed in harsh environments.
• Difficult to replace energy source (battery).
WSN for Structural Health Monitoring
[Große et al, 2010]
Picture: Zeiss 3d AutomationPicture: BMBF Project smartWT
Smart Carrier for Industry 4.0
[Reindl et al, 2010]

4. System overview
- 4 -

5. Sensor Platform
- 5 -
Wireless Module
 Sub-GHz Transceiver
 µC with pre defined Sensor Application
 Software update over the air
 Wake-up Function
 UFL connector for external antenna
 Interfaces to digital and analog sensors
 Sensor library
Low Power Reference Design
 Energy management
 Battery Management (LiFePo) <150nA
 Energy Harvesting (Indoor Solar >150Lux)
 USB connector
 3 sensor interfaces (SPI, I²C and analog)
 3 sensor switches
 On/Off button
Certifications:
EN 300220-2 2.4.1
ETSI EN 300 220-2
V3.1.1.1 (2016-11)

6. Benefits of Endiio WuRx
- 6 -
fast
slow
weak strong
Energy Autonomy
OnDemand
Reactivity
Real Time and Low Power Area
ETSI: EN 300220

7. - 7 -
Wake-Up Receivers (WuRx)
hikingresearch.wordpress.comfirescenes.net
• Low power radio units
• Fully asynchronous communication(on-demand).
• Event driven applications.
Wake-up Scheme [Pletcher et al, 2008]

8. - 8 -
Standard OOK WuRx Design
hikingresearch.wordpress.comfirescenes.net
• OOK Demodulator
• Gain element either in RF domain or baseband domain.
• Envelope Detector using Schottky diode.
• Sensitivity as main parameter.
• Disadvantage
• Lack of robustness against noise and channel interference.
[Gebreyohannes, 2012]

9. Robustness with Endiio WuRx
- 9 -
-10
-120
800 000 15
Latency x Current Consumption
(ms x µA)
Interference
Resilience(dBm)
Robust, Real Time and Low Power Area
OOK
WuRx
FSK
WuRx

10. - 10 -
Differential FSK WuRx Approach
hikingresearch.wordpress.comfirescenes.net
• Main Features
 Two different frequency channels modulate
complementary signals.
 Differential wake-up signal.
• Goals
 Sensitivity increment.
 Enhanced noise/interferer resilience.
 Low power consumption

11. - 11 -
Prototype of the FSK WuRx
• Two high frequency channels (868 MHz and 838 MHz).
• Schottky diode HSMS-285C (zero-bias) for implementing
envelope detector.
• AS3933 as the Wake-Up IC.

12. - 12 -
Sensitivity results
Comparison between the OOK and the FSK WuRx for
the address-based detection mode of the AS3933.

13. - 13 -
Analysis of the noise resilience.
Measurement setup for analyzing the noise/interferer
resilience of the FSK WuRx.
 Generate an interferer and add it to the wake-up signals.

14. - 14 -
Results of the interferer resilience
analysis
• Interferer: pulsed signal of 200 Hz modulated on a 853 MHz.
• Difference Amplifier Gain = 20 V/V
• Wake-up modulating frequency = 20 kHz

15. - 15 -
Summary of the presented FSK
WuRx
Features of the FSK WuRx
 Sensitivity: [-54 dBm @120 kHz, -61 dBm @20 kHz ].
 Data rate: 8.1 kbps
 Current consumption: 11.2 μA
 Power consumption: 70.2 μW
 Noise/Interferer resilience:
-17/-16 dB CIR (in-band interferers)
 Up to -39 dB CIR for out-of-band interferers.

16. - 16 -
Outlook
Fully passive FSK WuRx
 Transformer instead of difference amplifier.
 Challenges:
 Find a transformer with an appropriated primary/secondary
impedance ratio.
 Size and frequency behavior.
Design of the FSK wake-up transmitter.
Integration of the FSK WuRx with the radio unit.

17. - 17 -
Comparison of the FSK differential
WuRx with another designs
Reference [6] [16] [17] [23] [25] FSK WuRx
Frequency
(MHz)
2400 403 2400 908-924
(dual tone)
433 924.4 838-868
(dual tone)
Power
Consumptio
n (μW)
99 0.116 63.5-121 54 45.5 70.2 μW
Type of
interferer
Sinusoidal
tone
N/A 10 kHz
random
interferer
N/A CW* Pulsed
signal
200 Hz
Frequency of
interferer
(MHz)
2395/2405 N/A 916/904/920 433 925.4/
923.4/
926.4
853/838/868
MHz
CIR (dB) -31/-27 3.3 1.7 -19/5.5/5.5 -30 -60
/18
/15
-39
/-16
/-17

18. Dr.-Ing. Tolgay Ungan
Tel.: +49 (0) 761 203 7224
Mobil: +49 (0) 179 749 19 09
ungan@endiio.com
endiio Engineering GmbH
Georges-Köhler-Allee 106
79110 Freiburg
Germany
endiio GmbH
Maria-Theresien-Str. 42a
6020 Innsbruck
Austria
www.endiio.com

19. - 19 -
Proof of concept using VLC
• Visible light communications (VLC)
• Light emitting diodes (LED) as senders and photodiodes as
receivers.
• Two different lights simulate the two frequency channels
of a FSK WuRx.
• Optical FSK WuRx

20. - 20 -
Scheme of the proof of concept
• Optical filters: films of the respective color.
• Blue and red LED
• Difference amplifier: operational amplifier with external
resistors.
• AS3933: Wake-Up IC with a sensitivity of 80 μV.

21. - 21 -
Results of the proof of concept
 Resulting differential signal and generation of the WAKE-Up
pulse (interruption).

22. - 22 -
Results of the proof of concept
 Maximum distance analysis in two different scenarios (with
and without interference).

23. - 23 -
Comparison with an optical OOK WuRx
 C. Carrascal et al, “A Novel Wake Up Communication System using Solar
Panel and Visible Light Communication”
 Off the shelf silicon amorphous solar cell (3.6 cm x 2.6 cm x 0.1 cm).
 10 W LED