Introduction to the LPWAN options for Long Range Low Power communications ideal for Internet of Things devices (IoT) with a particular focus on LoRa

1. LPWan for IoT
Presented at the Sept 2016 Austin IoT Hardware Focus Group Meeting
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2. LPWan for IoT By Peter R. Egli 2015 @indigoo.com

3. LPWan in ISM bands
● ISM is Industrial, Science, and Medicine
● Open use with limits
○ USA : 915MHz
○ Europe : 868Mhz (HAMs can use this in USA)
○ Everywhere : 2.4GHz (WiFi)
● Used by LoRa, Ingenu, Sigfox and others
● Cellular Industry has other frequencies

4. LPWan for IoT - Tiny Data - Low Power
● Data dribblers
● 2MB/Month
● Low update rate
● Rarely transmitting
● Low output power, long battery life
● Long range

5. $Cost
● Radio Module: $10
● Connection: $1.50/Month 2MB
● Some modules will allow for application code
saving the cost of adding an application
processor. But this is a kind of lock in.

6. LoRa
● Low Power - NB-IoT and Sigfox are lower
● Bandwidth - Good for IoT (small)
● Network is open
● Radio chip is proprietary (SemTech)
● Long range, limited by terrain, miles
● Easy to use, with our without network
● Lots of deployment locations, Europe etc.
● Senet is deploying in the US

7. ● Higher bandwidth gives shorter range
● Higher bit rate gives shorter TX on times,
less power
● Wider Spreading give redundancy
increasing range margins
● Effective rate is about 0.25KBPS to about
11KBPS (low duty cycle)
● Adaptive Data Rate (ADR). Server
manages power output and data rates
● Payload size: 11 to 242 bytes
● Payload size a function of spreading
Code Spreading Bandwidth Bitrate
0 SF10 125KHz 980 BPS
1 SF9 125KHz 1760 BPS
2 SF8 125KHz 3125 BPS
3 SF7 125KHz 5470 BPS
4 SF8 500KHz 12500 BPS
Security
○ Several layers of encryption
○ Unique Network Key (16 bytes)
○ Unique Application Key (8 bytes)
○ Device specific key (8 bytes)
Range
● 22km 13.5miles Line of sight
● 2km 1.2miles in urban environment

8. Device Classes
● Class A Bi-directional end-devices
○ ALOHA-type protocol
○ Transmit at random times
○ Receive only after transmit
● Class B Bi-directional with scheduled RX slots
○ Receives a sync beacon from the server
○ Beacon assigns a time slot for communications
● Class C Bi-directional with maximal receive slots
○ Always able to receive from server (!TX)

9. Example Packet receive via MQTT
{ "EUI":"008000000000A322",
"PDU":"01080120000200160303E0",
"GW":"00250C0001000099",
"RSSI":-24,
"SNR":10,
"DataRate":3,
"TXPower":30,
"FREQ":902.9,
"SeqNo":535,
"Port":1,
"TXTime":"2016-09-13T20:28:53.544Z"
}

10. Star Network - typical
● System Parts
○ Nodes - Modules with Semtech chips
○ Gateways - Senet or other provider
■ MultiTech Conduit
■ Do your own with Raspberry Pi
■ Skip the gateway and do point to point

11. Sigfox
● Super low power
● Very low data rates
● Protocol open, lots of radio suppliers
● Lots of coverage in Europe
● Planned coverage in the USA

12. NB-IoT
Coming soon
Extreme low power, more bw than sigfox
Open standard, 3GPP standard in development
Lots of suppliers
Some small deployments now.
Wide deployment less than 2 Years away.

13. LTE-M
Little brother of LTE
Not as power efficient
Wide bandwidth
Lots of device suppliers
High security
No deployments, less than 2 Years away.

14. Playing with LoRa
● Ideal for getting started
● Modules all have SemTech chips
● Adafruit has a nice M0 Feather with LoRa
● SemTech has MDot modules with embed
● Can use for point to point data
● Easy to set up base for internet gateway
● Show and tell...

15. Playing with LoRa
● Just did a LoRa bootcamp.
● Using Senet as a central server
● Data piped to MQTT
● Using LoRa for IoT devices
● Range question