10 years of battery life and 10 km of range? Not impossible with Mbed OS and LoRaWAN. Presentation from Alessandro Grande and me during IoT DevFest in Tempe, Arizona.

1. Jan Jongboom & Alessandro Grande
IoT DevFest 2019
Low-power IoT nodes
with Mbed and LoRaWAN

2. © 2019 Arm Limited 2
Jan Jongboom
Principal Developer Evangelist
jan.jongboom@arm.com
Alessandro Grande
Developer Advocate
alessandro.grande@arm.com

3. © 2019 Arm Limited 3
IoT Networks
Powerconsumption/Bandwidth
Range

4. © 2019 Arm Limited 4
10kilometers range years of battery life

5. © 2019 Arm Limited
The range
© 2019 Arm Limited

6. © 2019 Arm Limited 6
High link budget
RX
Derived from work by Thomas Telkamp
TX Power
Connector loss
Antenna gain
Connector loss
Antenna gain
RX Power
Path loss and fading
Receiver sensitivity
-137 dBm
14 dBm151 dBm link budget

7. © 2019 Arm Limited 7
Link budget
Wi-Fi
Sub-GHz 6LoWPAN
LoRa
TX Power RX Sensitivity Link budget
20 dBm -75 dBm 95 dBm
11 dBm -110 dBm 121 dBm
14 dBm -137 dBm 151 dBm

8. © 2019 Arm Limited 8
Theoretical maximum in free space
2.4 GHz, with 95.5 dBm link budget:
550 meters
915 MHz, with 151 dBm link budget:
850,000 meters

9. © 2019 Arm Limited 9

10. © 2019 Arm Limited 10
Unfortunately... we don't live in free space
Attenuation Reflection and diffraction Fresnel zone

11. © 2019 Arm Limited
Based on Tokyo - model for calculating realistic path loss
Picture by Moyan Brenn: https://commons.wikimedia.org/wiki/File:Tokyo_(16043023330).jpg© 2019 Arm Limited
Hata model
Large city (250 bps)
Large city (1,760 bps)
Suburb (250 bps)
TX height RX height Range
0.1 m 40 m 4 km
0.1 m 40 m 2.5 km
0.1 m 40 m 9 km
Suburb (250 bps) 1 m 100 m 13 km

12. © 2019 Arm Limited
LoRaWAN

13. © 2019 Arm Limited 13
The secret behind low power consumption...
!

14. © 2019 Arm Limited 14
Device classes
Flexibility in power conservation versus fast network initiated transmission
Class A ! Class B ⏰ Class C ⚡
Device initiated communication
Devices are typically in deep
sleep and send messages on
intervals and/or events
Only after uplink transmission,
there is a receive window for
downlink messages
Best for most sensor
applications and battery
conservation
Time synchronized
communication
The network broadcasts beacons
for devices to sync time
In so-called ping slots, devices
wake up and the network may
send downlink messages
Best for most downlink intensive
applications
Network initiated
communication
The devices are continuously
listening, often temporarily or
on power supply
The network can send downlink
message at any given time
Best for downlink intensive
applications that require low
latencies

15. © 2019 Arm Limited 15
Typical LoRaWAN Topology
Network Session Key: Message Integrity
Applicacon Session Key: Join, Encrypcon and Decrypcon
Devices Gateways Network Server User
ApplicaTon
ApplicaTon
Server

16. © 2019 Arm Limited 16

17. © 2019 Arm Limited
Mbed OS 5

18. © 2019 Arm Limited 18
Components required
Bootloader
Asymmetric crypto
Storage driver
Resilient filesystem
Advanced
networking stack
Radio drivers
FlashIAP
Update client

19. © 2019 Arm Limited 18
Components required
Bootloader
Asymmetric crypto
Storage driver
Resilient filesystem
Advanced
networking stack
Radio drivers
FlashIAP
Update client

20. © 2019 Arm Limited 19

21. © 2019 Arm Limited 20
Arm Mbed
A free, open source Platform OS targeting IoT end node devices
Mbed
OS
Cortex-M
RTOS
kernel
Portable
drivers
Integrated
security
IoT
connectivity
Device
management
Development
tools
Developer
community
Partner
ecosystem
150 development boards
LoRa, BLE, Cellular, Wi-Fi, etc.
20

22. © 2019 Arm Limited 21
Open source and community built
325,000 developers
70+ partners
Apache 2.0 licensed
https://os.mbed.com

23. © 2019 Arm Limited 22
Example Mbed OS products
Smart City
Parking sensor
Smart Agriculture
Soil monitoring
Smart Retail
BLE Beacon
Smart Spaces
Air quality monitor
Smart Building
HVAC sensor
Smart Home
AI devices

24. © 2019 Arm Limited 23
Testing
40,000 hours of testing on *real* hardware
Pre-certification testing of LoRaWAN stack

25. © 2019 Arm Limited
Developing for Mbed OS

26. © 2019 Arm Limited 25
Three development environments
Online compiler Mbed CLI Offline IDE
C:> mbed

27. © 2019 Arm Limited 26
Proper online/offline story
C:> mbed
Sync
os.mbed.com
GitHub
Private DVCS

28. © 2019 Arm Limited 27
Getting started - Online Compiler
Import https://github.com/janjongboom/iot-devfest

29. © 2019 Arm Limited 28
Getting started - Mbed CLI
Install Mbed CLI: https://github.com/armmbed/mbed-cli
$ mbed import https://github.com/janjongboom/iot-devfest

30. © 2019 Arm Limited 29
Advanced features
RTOS included (KEIL RTX)
Event scheduler (Mbed Events)
Tickless mode and automatic sleep management
Filesystems included (FAT and LittleFS)
Memory tracing supported
Easy to port!

31. © 2019 Arm Limited
Mbed Labs -
forefront of IoT innovation

32. © 2019 Arm Limited 31

33. © 2019 Arm Limited 32
http://mbed.com/js

34. © 2019 Arm Limited 33

35. © 2019 Arm Limited 34

36. © 2019 Arm Limited 35
Google: "firmware updates lorawan"
https://www.youtube.com/watch?v=0NoshDOqmdM

37. © 2019 Arm Limited
Building something

38. © 2019 Arm Limited 37
Three approaches
Module Radio
Radio + MCU
Easy to integrate in own design
Pre-certified
SX1272 or SX1276
Cheaper
Need to do own RF design
SiP
Integrated silicon
Not certified
Cheap

39. © 2019 Arm Limited 38
Picking a gateway
Kerlink IoT station
Multi-Tech Conduit
IMST iC880A
Lorix One
The Things Gateway
Lorrier LR2
SX1301 + 2x SX1257

40. © 2019 Arm Limited 39
Typical LoRaWAN Topology
Devices Gateways Network Server User
ApplicaTon
ApplicaTon
Server

41. © 2019 Arm Limited 40
Hands-on, building a network
NUCLEO-F411RE
SX1272
Multi-Tech Conduit Network Server

43. © 2019 Arm Limited
https://github.com/janjongboom/iot-devfest

44. Thank You!
Danke!
Merci!
!
!
Gracias!
Kiitos!
감사합니다
धन्यवाद
© 2019 Arm Limited 43
Jan Jongboom
Principal Developer Evangelist
jan.jongboom@arm.com