LoRa

LoRa uses license-free sub-gigahertz radio frequency bands like 433 MHz, 868 MHz (Europe), 915 MHz (Australia and North America), 865 MHz to 867 MHz (India) and 923 MHz (Asia). LoRa enables long-range transmissions with low power consumption.[4] The technology covers the physical layer, while other technologies and protocols such as LoRaWAN (Long Range Wide Area Network) cover the upper layers. It can achieve data rates between 0.3 kbit/s and 27 kbit/s depending upon the spreading factor.[5]

LoRa devices have geolocation capabilities used for trilaterating positions of devices via timestamps from gateways.[6]

LoRa uses a proprietary spread spectrum modulation that is similar to and a derivative of chirp spread spectrum (CSS) modulation. The spread spectrum LoRa modulation is performed by representing each bit of payload information by multiple chirps of information. The rate at which the spread information is sent is referred to as the symbol rate, the ratio between the nominal symbol rate and chirp rate is the spreading factor (SF) and represents the number of symbols sent per bit of information.[2] The result is an M-ary digital modulation, where the ${\displaystyle M=2^{SF}}$ possible waveforms at the output of the modulator are chirp modulated signals over the frequency interval (${\displaystyle f_{0}-B/2,f_{0}+B/2}$) with M different initial frequencies: the instantaneous frequency is linearly increased, and then wrapped to ${\displaystyle f_{0}-B/2}$ when it reaches the maximum frequency ${\displaystyle f_{0}+B/2}$. [7]

LoRa can trade off data rate for sensitivity with a fixed channel bandwidth by selecting the amount of spread used (a selectable radio parameter from 7 to 12). Lower SF means more chirps are sent per second; hence, you can encode more data per second. Higher SF implies fewer chirps per second; hence, there are fewer data to encode per second. Compared to lower SF, sending the same amount of data with higher SF needs more transmission time, known as airtime. More airtime means that the modem is up and running longer and consuming more energy. The benefit of high SF is that more extended airtime gives the receiver more opportunities to sample the signal power which results in better sensitivity.[8]

In addition, LoRa uses forward error correction coding to improve resilience against interference. LoRa's high range is characterized by high wireless link budgets of around 155 dB to 170 dB.[9]

Since LoRa defines the lower physical layer, the upper networking layers were lacking. LoRaWAN is one of several protocols that were developed to define the upper layers of the network. LoRaWAN is a cloud-based medium access control (MAC) layer protocol but acts mainly as a network layer protocol for managing communication between LPWAN gateways and end-node devices as a routing protocol, maintained by the LoRa Alliance.

LoRaWAN defines the communication protocol and system architecture for the network, while the LoRa physical layer enables the long-range communication link. LoRaWAN is also responsible for managing the communication frequencies, data rate, and power for all devices.[10] Devices in the network are asynchronous and transmit when they have data available to send. Data transmitted by an end-node device is received by multiple gateways, which forward the data packets to a centralized network server.[11] Data is then forwarded to application servers.[12] The technology shows high reliability for the moderate load, however, it has some performance issues related to sending acknowledgements.[13]

• Amazon Sidewalk, IoT network for Ring home cameras, Amazon Alexa assistant and other consumer devices[26]
• Reindeer tracking in Finland[27]
• Glasgow IoT network[28]
• IoT networks in Argentina, Brazil and Estonia[29][30][31]
• Smart fire alarms and fire detection[32][33]
• Smart Parking[34]
• Black rhino poaching protection in Tanzania[35] and endangered sea turtle monitoring in Peru[36]
• Natural disaster prediction[37]
• Cotton farming in Australia[38]
• Utility metering in India[39]
• Autonomous irrigation[40] and soil health monitoring[41]
• Smart water monitoring[42] and water monitoring for commercial farms[43]
• City-wide network in Calgary, Alberta, Canada[44]
• IoT Network in Alba Iulia, Romania[45]

• IoT Network in Gold Coast, Australia as part of required upgrades for the 2018 Commonwealth Games[46]
• Country-wide LoRa network in Switzerland, operated by Swisscom.

• DASH7 - a popular open alternative to LoRa
• IEEE 802.11ah – non-proprietary low-power long-range standard
• CC430 - an MCU & sub-1 Ghz RF transceiver SoC
• NB-IoT
• LTE Cat M1
• Helium Systems - a proprietary protocol system based on similar technology
• MIoTy - Sub-GHz LPWAN technology for sensor networks.

• Lee, Chang-Jae, Ki-Seon Ryu, and Beum-Joon Kim. "Periodic ranging in a wireless access system for mobile station in sleep mode." U.S. Patent No. 7,194,288. 20 March 2007.
• Ghoslya, Sakshama (2019-04-17). "How to generate LoRa Symbols". All About LoRa and LoRaWAN.
• Quigley, Thomas J., and Ted Rabenko. "Latency reduction in a communications system." U.S. Patent No. 7,930,000. 19 April 2011.
• Bankov, D.; Khorov, E.; Lyakhov, A. "On the Limits of LoRaWAN Channel Access". 2016 International Conference on Engineering and Telecommunication (EnT): 10–14.
• Seneviratne, Pradeeka. "Beginning LoRa Radio Networks with Arduino - Build Long Range, Low Power Wireless IoT Networks." Apress, 2019, eBook ISBN 978-1-4842-4357-2, Softcover ISBN 978-1-4842-4356-5, Ed: 1

• LoRa Alliance