1. IOT Technologies: LoRa
NETW 1010
IOT Technologies:
LoRa
Dr. Eng. Tallal Elshabrawy
Spring 2019

2. Low Power Wide Area Networks (LP-WAN)
LoRa (Long Range)
Low Power Wide Area Networks (LP-WAN)
Battery Lifetime
Years
RFID
Months
BLE
IEEE
Communication Range
Days
Few Meters
Tens-Hundreds of Meters
Kiliometers

3. Low Power Wide Area Networks: Fundamentals
Star/Star-of-Stars
Centralized Control +
Minimal Signaling
Simple Devices
Energy Efficient PHY
ALOHA-Based Medium Access
Reachability
Low Data Rate
Low Receiver Sensitivity
Reliability
Simple FEC
Optional Retransmissions
Any Complexity at Basestation
Data Link Layer
Physical Layer

4. The Growth of LoRa

5. LoRaWAN Characteristics
Long Range
Greater than cellular
Deep indoor coverage
Simple star topology
Max. Lifetime
Low power optimized
Battery lifetime of 10 years
>10x vs cellular M2M
Low Cost
Minimal Infrastructure
Low Cost End Node
Open SW
Multi-Usage
High Capacity
Multi-tenant
Public Network

6. LoRa Use Cases

7. LoRa Network Protocol: Topology

8. Overview of LoRa Technology
𝒇 𝒎𝒂𝒙
Chirp Modulation Spread Spectrum
Multiple Parallel Networks based on Different Spreading Factor (SF)
Different Coverage Ranges based on Different SF
3 different BW:125 kHz, 250KHz and 500 kHz
Multiple Channels per Network (In as many as 8 (sub) frequencies).
ALOHA Medium Access
𝑺𝑭=𝟕
𝑺𝑭=𝟏𝟐
𝒇 𝒎𝒊𝒏
SF12
SF11
SF10
SF9
SF8
SF7
-123 dBm
-126 dBm
-129 dBm
-132 dBm
dBm
-137 dBm

9. LoRa Parameters Transmission Bit Rate: 𝑅 𝑏 =𝑆𝐹 × 𝐵𝑊 2 𝑆𝐹 ×𝐶𝑅 (bps)
BW =125 kHz
CR =4/5 SF
𝑹 𝒃
Ttx
(1 Byte)
(8 Byte)
(20 Byte) 7
5.47 Kb/s
1.463 ms ms
29.26 ms 8
3.12 Kb/s
2.56 ms
20.48 ms
51.2 ms 9
1.76 Kb/s
4.55 ms
36.40 ms
91.02 ms 10
0.98 Kb/s
8.19 ms
65.54 ms ms 11
0.54 Kb/s
14.89 ms ms ms 12
0.29 Kb/s
27.3 ms ms ms
3 parameters influence the BR: BW, SF, CR; BW most important parameter

10. LoRa® Parameters Sensitivity [dBm] 125 kHz 250 kHz 500 kHz SF7 -124
Spreading factor
Sensitivity [dBm]
125 kHz
250 kHz
500 kHz
SF7
-124
-122
-116
SF8
-127
-125
-119
SF9
-130
-128
SF10
-133
SF11
-135
-132
SF12
-137
-129
To obtain a correct demodulation, term sensitivity has to be introduced: minimum i/p signal required to demodulate the i/p signal having a specified SNR
- Sensitivity increases with the decrease in SF ( in return for a longer tx.)
Sensitivity values for a correct demodulation on SX1272/73 transceivers

11. ISM Interference LoRa operates in Europe in 868 MHz ISM Band
License Exempt
Example of Interfering Systems within this band
Short Range
RFID
Remote Control
Baby Monitors
Cordless Phones
Long Range
Smart Meters
Competing LPWAN technologies
Illustrative Example for ISM Interference Measured in the license exempt SRD band in the frequency range between 868 and 870MHz in Erlangen, Germany*.
*J. Robert, S. Rauh, H. Lieske, and A. Heuberger, “Ieee low power wide area network (lpwan) phy interference model,” in 2018 IEEE International Conference on Communications (ICC), May 2018, pp. 1–6.

12. LoRa Modulation frequency (Hz) Bandwidth 𝑩=𝟏𝟐𝟓 𝑲𝑯𝒛
Spreading Factor 𝒔𝒇=𝟕
𝒎=[ 𝟑𝟏 𝟗𝟖 𝟔𝟗 𝟏𝟐𝟕 𝟒𝟒]
𝟔𝟐,𝟓𝟎𝟎 Hz
(𝒎+𝒏=𝟏𝟐𝟕)
frequency (Hz)
−𝟔𝟐,𝟓𝟎𝟎 Hz
(𝒎+𝒏=𝟎)
time (sec.)

13. LoRa Demodulation LoRa Demoulation = Dechirping + FFT
𝒎=[ 𝟑𝟏 𝟗𝟖 𝟔𝟗 𝟏𝟐𝟕 𝟒𝟒]
Dechirping  𝑟 𝑛 =𝑟 𝑛 × 𝜔 0 ∗ 𝑛 𝟒𝟒 𝟑𝟏
𝟏𝟐𝟕 𝟗𝟖 𝟔𝟗

14. LoRa Modulation & Demodulation
LoRa Symbol (𝒎=𝟑𝟏)
Dechirping
FFT

15. LoRaWAN™ Mac Layer ALOHA protocol
Define the communication protocol and network architecture.
Have the most influence in determining the network capacity.
- LoRaWAN refers to a network protocol using LoRa chips for communication.
So you can use LoRa modulation without LoRaWAN and you can use LoRaWAN like network without the LoRa Radio ->not practical though

16. LoRaWAN End Device Classes
LoRa End Nodes
Before an ED join a LoRaWAN, it must be activated:
Over the Air Activation (OTAA)
Activation By Personalization (ABP)
Battery Lifetime
Downlink Communication Latency C
Main power actuators
ED afford to listen continuously
No link for downlink communication B
Battery powered actuators
Energy efficient with latency controlled downlink
Slotted communication synchronized with a beacon A
Battery powered sensors
Most energy efficient
Supported by all devices
Downlink available only after ED tx.
LoRaWAN End Device Classes
Differ only with regards to downlink scheduling
Class’s behavior depending on choice of optimization
ABP: shared keys at production time locked to a specific network[no additional procedure, device ready to communicate ]

17. Battery Powered - Class A
pkt_tx
Rx_Slot 1
Rx_Slot 2
TOA
RECEIVE_DELAY1
RECEIVE_DELAY2
Base Station
End Device
Rx_Slot1 uses same frequency channel as uplink and data rate function of the uplink tx. data rate
Rx_Slot2 uses fixed frequency and data rate
RECEVIE_DELAY1 & RECEIVE_DELAY2 are constants
Rx_Slot length ≥ downlink frame preamble
Application Ex. : Metering, mobile asset tracking.
- If a preamble if detected during one of the receive slots, radio receiver stays active until downlink frame is demodulated.
If frame was detected, demodulated and and intended for this ED, ED doesn’t open 2nd receive window.
If a net intends to tx a downlink msg to an ED, it will always intiate the tx precisely at the beginning of one of those 2 receive windows.
An ED shall not tx another uplink msg before either receving a downlink msg or 2nd receive slot has expired.
NB: ED may listen or tx to other protocols bet lorawan tx and rx windows
The interval between the end of RX2 and next transmission should be random (ALOHA)but for different sequence for every device.
(example using a pseudo random generator seeded with the device’s address)

18. LoRaWAN MAC Message Format
LoRaWAN Message Type
Confirmed Message
Un-Confirmed Message 
NbTrans
PHYPayload
5+M
Size (bytes)
PHDR
PHDR_CRC
Preamble
CRC
Radio PHY layer
FHDR
FPort
FRMPayload
FCtrl
FCnt
DevAddr
FOpts
Bit#
7..5 | | 1..0
MType | RFU | Major
MHDR
MACPayload
MIC
1 ..M* 4 1
LoRaWAN MAC Message Format

19. LoRaWAN MAC Message 6 different MAC message types MType Description
000
Join Request
001
Join Accept
010
Unconfirmed Data Up
011
Unconfirmed Data Down
100
Confirmed Data Up
101
Confirmed Data Down
110
RFU
111
Proprietary

20. LoRaWAN™ Regional Summary
License free regulated Sub-GHz Frequencies
Europe: 868 – 870 ISM Band channel frequencie
EU gateways are typically using 8 channels
End-devices must be capable of at least 16 channels
Modulation
Bandwidth [kHz]
Channel Frequency [MHz]
FSK Bitrate or LoRa DR / Bitrate
Nb Channels
LoRa
125
868.10
868.30
868.50
DR0 to DR5 / kbps 3
These frequencies are unlicensed, yet they are regulated and have duty cycles
The LoRaWAN™ specification varies slightly from region to region based on the different regional spectrum allocations and regulatory requirements.
LoRaWAN™ defines ten channels, eight of which are multi data rate from 250bps to 5.5 kbps, a single high data rate LoRa® channel at 11kbps, and a single FSK channel at 50kbps. The maximum output power allowed by ETSI in Europe is +14dBM, with the exception of the G3 band which allows +27dBm. There are duty cycle restrictions under ETSI but no max transmission or channel dwell time limitations.
EU default gateways

21. LoRaWAN™ Regional Summary
Duty Cycle <1%
same sub band can not be used again during the next 𝑇𝑜𝑓𝑓 seconds where:
𝑇𝑜𝑓𝑓= 𝑇𝑂𝐴 𝐷𝑢𝑡𝑦𝐶𝑦𝑐𝑙𝑒𝑠𝑢𝑏𝑏𝑎𝑛𝑑 −𝑇𝑂𝐴
Default radiated transmit output power: 14 dBm
RECEIVE_DELAY1 = 1s
RECEIVE_DELAY2 = 2s
ACK_TIMEOUT = 2+/-1s (random delay between 1 and 3 seconds)
NbTrans = 1 (single transmission of each frame)