Engineering:LoRa

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Short description: Wireless communication technology
LoRa
LoRa Module with antenna and SPI wires attached.jpg
A LoRa module
Developed byCycleo, Semtech
Connector typeSPI/I2C
Compatible hardwareSX1261, SX1262, SX1268, SX1272, SX1276, SX1278
Physical range>10 kilometres (6.2 mi) in perfect conditions

LoRa (from "long range") is a physical proprietary radio communication technique.[1] It is based on spread spectrum modulation techniques derived from chirp spread spectrum (CSS) technology.[2] It was developed by Cycleo, a company of Grenoble, France, and patented in 2014 (patent 9647718-B2. Cycleo was later acquired by Semtech.[3][4]

LoRaWAN (wide area network) defines the communication protocol and system architecture. LoRaWAN is an official standard of the International Telecommunication Union (ITU), ITU-T Y.4480.[5] The continued development of the LoRaWAN protocol is managed by the open, non-profit LoRa Alliance, of which SemTech is a founding member.

Together, LoRa and LoRaWAN define a low-power, wide-area (LPWA) networking protocol designed to wirelessly connect battery operated devices to the internet in regional, national or global networks, and targets key Internet of things (IoT) requirements such as bi-directional communication, end-to-end security, mobility and localization services. The low power, low bit rate, and IoT use distinguish this type of network from a wireless WAN that is designed to connect users or businesses, and carry more data, using more power. The LoRaWAN data rate ranges from 0.3 kbit/s to 50 kbit/s per channel.[6]

Features

LoRa uses license-free sub-gigahertz radio frequency bands EU868 (863–870/873 MHz) in Europe; AU915/AS923-1 (915–928 MHz) in South America; US915 (902–928 MHz) in North America; IN865 (865–867 MHz) in India ; and AS923 (915–928 MHz) in Asia;[7] LoRa enables long-range transmissions with low power consumption.[8] 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.[9]

LoRa devices have geolocation capabilities used for trilaterating positions of devices via timestamps from gateways.[10]

LoRa PHY

LoRa uses a proprietary spread spectrum modulation that is similar to and a derivative of chirp spread spectrum (CSS) modulation. Each symbol is represented by a cyclic shifted chirp over the frequency interval ([math]\displaystyle{ f_0-B/2,f_0+B/2 }[/math]) where [math]\displaystyle{ f_0 }[/math] is the center frequency and [math]\displaystyle{ B }[/math] the bandwidth of the signal (in Hertz). The spreading factor (SF) is a selectable radio parameter from 5 to 12 [11] and represents the number of bits sent per symbol and in addition determines how much the information is spread over time.[2] There are [math]\displaystyle{ M=2^{\mathrm{SF}} }[/math] different initial frequencies of the cyclic shifted chirp (the instantaneous frequency is linearly increased and wrapped to [math]\displaystyle{ f_0-B/2 }[/math] when it reaches the maximum frequency [math]\displaystyle{ f_0+B/2 }[/math]).[12] The symbol rate is determined by [math]\displaystyle{ R_s = B/2^{\mathrm{SF}} }[/math]. LoRa can trade off data rate for sensitivity (assuming a fixed channel bandwidth [math]\displaystyle{ B }[/math]) by selecting the SF, i.e. the amount of spread used. A lower SF corresponds to a higher data rate but a worse sensitivity, a higher SF implies a better sensitivity but a lower data rate.[13] Compared to lower SF, sending the same amount of data with higher SF needs more transmission time, known as time-on-air. More time-on-air means that the modem is transmitting for a longer time and consuming more energy. Typical LoRa modems support transmit powers up to +22 dBm.[11] However, the regulations of the respective country may additionally limit the allowed transmit power. Higher transmit power results in higher signal power at the receiver and hence a higher link budget, but at the cost of consuming more energy. There are measurement studies of LoRa performance with regard to energy consumption, communication distances, and medium access efficiency.[14] According to the LoRa Development Portal, the range provided by LoRa can be up to 3 miles (4.8 km) in urban areas, and up to 10 miles (16 km) or more in rural areas (line of sight).[15]

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.[16] Range extenders for LoRa are called LoRaX.

LoRaWAN

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.[17] Devices in the network are asynchronous and transmit when they have data available to send. Data transmitted by an end-node device are received by multiple gateways, which forward the data packets to a centralized network server.[18] Data are then forwarded to application servers.[19][20] The technology shows high reliability for the moderate load. However, it has some performance issues related to sending acknowledgements.[21]

CSMA for LoRaWAN

In wireless communication, particularly within the IoT domain, effective channel utilization and collision avoidance are essential for network reliability and spectral efficiency. Previously, LoRaWAN has relied upon ALOHA as the medium access control (MAC) layer protocol. To improve this, the LoRa Alliance's Technical Recommendation TR013[22] introduces CSMA-CA, tailored to account for LoRa's distinctive modulation characteristics, including Spreading Factor orthogonality[14] and the capability for below noise-floor communication.[14] This adaptation overcomes the limitations of simple received signal strength (RSS)-based sensing, which can disrupt these unique properties. Implementing TR013 enhances LoRaWAN's spectrum efficiency and ensures more reliable device communication, even in congested environments.[22]

Version history

  • January 2015: 1.0[23][24]
  • February 2016: 1.0.1[25]
  • July 2016: 1.0.2[26]
  • October 2017: 1.1, adds Class B[27]
  • July 2018: 1.0.3[28]
  • October 2020: 1.0.4[29]

LoRa Alliance

The LoRa Alliance is an open, non-profit association whose stated mission is to support and promote the global adoption of the LoRaWAN standard for massively scaled IoT deployments, as well as deployments in remote or hard-to-reach locations.

Members collaborate in a vibrant ecosystem of device makers, solution providers, system integrators and network operators, delivering interoperability needed to scale IoT across the globe, using  public, private, hybrid, and community networks. Key areas of focus within the Alliance are Smart Agriculture, Smart Buildings, Smart Cities, Smart Industry, Smart Logistics, and Smart Utilities.

Key contributing members of the LoRa Alliance include Actility; Amazon Web Services (AWS); Cisco; Everynet; Helium; Kerlink; MachineQ, a Comcast Company; Microsoft; Minol Zenner; Netze BW; Semtech; Senet; ST Microelectronics; TEKTELIC; and The Things Industries [30] In 2018, the LoRa Alliance had over 100 LoRaWAN network operators in over 100 countries; in 2023, there are nearly 200, providing coverage in nearly every country in the world. [31]

See also

  • 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 - Narrowband Internet of Things
  • LTE Cat M1
  • MIoTy – sub-GHz LPWAN technology for sensor networks
  • SCHC – static context header compression
  • Short-range device
  • Helium (cryptocurrency) - LoRaWAN protocol paired with blockchain technology
  • Amazon Sidewalk - community-based network based on LoRa, BLE, and FSK (USA only)

References

  1. ↑ "What is LoRa?" (in en). https://www.semtech.com/lora/what-is-lora. 
  2. ↑ 2.0 2.1 "LoRa Modulation Basics". https://www.semtech.com/uploads/documents/an1200.22.pdf. 
  3. ↑ "Semtech Acquires Wireless Long Range IP Provider Cycleo" (in en). https://www.design-reuse.com/news/28706/semtech-cycleo-acquisition.html. 
  4. ↑ "Wireless communication method" US patent 9647718, issued 2017-05-09
  5. ↑ "LoRaWAN® recognized as ITU International LPWAN standard" (in en). 8 December 2021. https://www.eenewswireless.com/en/lorawan-recognized-as-itu-international-lpwan-standard/. 
  6. ↑ Ferran Adelantado, Xavier Vilajosana, Pere Tuset-Peiro, Borja Martinez, Joan Melià-Seguí and Thomas Watteyne. Understanding the Limits of LoRaWAN (January 2017).
  7. ↑ "RP002-1.0.3 LoRaWAN Regional Parameters". lora-alliance.org. https://lora-alliance.org/wp-content/uploads/2021/05/RP-2-1.0.3.pdf. 
  8. ↑ Ramon Sanchez-Iborra; Jesus Sanchez-Gomez; Juan Ballesta-Viñas; Maria-Dolores Cano; Antonio F. Skarmeta (2018). "Performance Evaluation of LoRa Considering Scenario Conditions". Sensors 18 (3): 772. doi:10.3390/s18030772. PMID 29510524. Bibcode: 2018Senso..18..772S. 
  9. ↑ Adelantado, Ferran; Vilajosana, Xavier; Tuset-Peiro, Pere; Martinez, Borja; Melia-Segui, Joan; Watteyne, Thomas (2017). "Understanding the Limits of LoRaWAN". IEEE Communications Magazine 55 (9): 34–40. doi:10.1109/mcom.2017.1600613. ISSN 0163-6804. 
  10. ↑ "GPS-free Geolocation using LoRa in Low-Power WANs". http://orbit.dtu.dk/files/130478296/paper_final_2.pdf. 
  11. ↑ 11.0 11.1 "SX1261/2 Datasheet". Semtech. https://www.semtech.com/products/wireless-rf/lora-core/sx1262#download-resources. 
  12. ↑ M. Chiani; A. Elzanaty (2019). "On the LoRa Modulation for IoT: Waveform Properties and Spectral Analysis". IEEE Internet of Things Journal 6 (5): 772. doi:10.1109/JIOT.2019.2919151. 
  13. ↑ Qoitech. "How Spreading Factor affects LoRaWAN device battery life" (in en). https://www.thethingsnetwork.org/article/how-spreading-factor-affects-lorawan-device-battery-life. 
  14. ↑ 14.0 14.1 14.2 J.C. Liando; A. Gamage; A.W. Tengourtius; M. Li (2019). "Known and Unknown Facts of LoRa: Experiences from a Large-Scale Measurement Study". ACM Transactions on Sensor Networks 15 (2): Article No. 16, pp 1–35. doi:10.1145/3293534. ISSN 1550-4859. 
  15. ↑ "What are LoRa® and LoRaWAN®?". https://lora-developers.semtech.com/library/tech-papers-and-guides/lora-and-lorawan/. 
  16. ↑ Mohan, Vivek. "10 Things About LoRaWAN & NB-IoT" (in en-us). https://blog.semtech.com/title-10-things-about-lorawan-nb-iot. 
  17. ↑ "LoRaWAN For Developers" (in en-US). https://lora-alliance.org/lorawan-for-developers. 
  18. ↑ "A Comprehensive Look At LPWAN For IoT Engineers & Decision Makers". https://www.link-labs.com/lpwan. 
  19. ↑ LoRa Alliance (2015). "LoRaWAN: What is it?". https://lora-alliance.org/sites/default/files/2018-04/what-is-lorawan.pdf. 
  20. ↑ Example of LoRaWan IoT end device transmitting data. Cloud Studio platform used: https://gear.cloud.studio/gear/monitor/shared-dashboard/88c96030a42c4a1fa2669286a6bde321
  21. ↑ Bankov, D.; Khorov, E.; Lyakhov, A. (November 2016). "On the Limits of LoRaWAN Channel Access". 2016 International Conference on Engineering and Telecommunication (EnT). pp. 10–14. doi:10.1109/ent.2016.011. ISBN 978-1-5090-4553-2. 
  22. ↑ 22.0 22.1 "Enabling CSMA for LoRaWAN TR013-1.0.0". LoRa Alliance. https://resources.lora-alliance.org/home/tr013-1-0-0-csma. 
  23. ↑ "LoRaWAN Specification". lora-alliance.org. https://lora-alliance.org/sites/default/files/2018-05/2015_-_lorawan_specification_1r0_611_1.pdf. 
  24. ↑ Version 1.0 of the LoRaWAN specification released.
  25. ↑ "LoRaWAN Specification". lora-alliance.org. https://lora-alliance.org/resource_hub/lorawan-104-specification-package/. 
  26. ↑ "LoRaWAN Specification". lora-alliance.org. https://lora-alliance.org/sites/default/files/2018-05/lorawan1_0_2-20161012_1398_1.pdf. 
  27. ↑ "LoRaWAN™ 1.1 Specification". lora-alliance.org. https://lora-alliance.org/sites/default/files/2018-04/lorawantm_specification_-v1.1.pdf. 
  28. ↑ "LoRaWAN 1.0.3 Specification". lora-alliance.org. https://lora-alliance.org/sites/default/files/2018-07/lorawan1.0.3.pdf. 
  29. ↑ "LoRaWAN 1.0.4 Specification". lora-alliance.org. https://lora-alliance.org/resource-hub/lorawan-104-specification-package. 
  30. ↑ "Member Directory | LoRa Alliance". https://lora-alliance.org/member-directory. 
  31. ↑ "LoRa Alliance passes 100 LoRaWAN network operator milestone" (in en-US). 2019-01-25. https://lora-alliance.org/lora-alliance-press-release/lora-alliance-registra-una-crescita-del-66-delle-reti-pubbliche-lorawan-negli-ultimi-3-anni/. 

Further reading

External links

de:Long Range Wide Area Network



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