LoRa (Long Range) is a patented[1] digital wireless data communication technology developed by Cycleo of Grenoble, France, and acquired by Semtech in 2012.[2] LoRa is a long-range wireless communication protocol that competes against other low-power wide-area network (LPWAN) wireless such as NB-IoT or LTE Cat M1. Compared to those, LoRa achieves its extremely long range connectivity, possible 100km+, by trading off data rate. Because its data rates are below 50kbps and because LoRa is limited by duty cycle and other restrictions, it is suitable in practice for non-real time applications in which one can tolerate.[3]
LoRa uses license-free sub-gigahertz radio frequency bands like 169 MHz, 433 MHz, 868 MHz (Europe) and 915 MHz (North America). LoRa enables long-range transmissions (more than 10 km in rural areas) with low power consumption.[4] The technology is presented in two parts: LoRa, the physical layer and LoRaWAN (Long Range Wide Area Network), the upper layers.
LoRa is a spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology, and is the first low-cost implementation of chirp spread spectrum for commercial usage.[5] In January 2018, new LoRa chipsets were announced, with reduced power consumption, increased transmission power, and reduced size compared to older generation.[6]
LoRa devices have geolocation capabilities used for triangulating positions of devices via timestamps from gateways.[7]
LoRa and LoRaWAN permit long-range connectivity for Internet of Things (IoT) devices in different types of industries.[8]
The LoRa physical layer protocol is proprietary; therefore, there is no freely available official documentation. However, several people have analyzed it and documented their findings and Semtech has provided an overview of the modulation and other relevant technical specifications.[9][10]
LoRa uses a proprietary spread spectrum modulation that is similar to and a derivative of Chirp Spread Spectrum modulation (CSS).[11] This allows LoRa to trade off data rate for sensitivity with a fixed channel bandwidth by selecting the amount of spread used (a selectable parameter radio parameter from 7 to 12). This spreading factor determines the data rate and dictates the sensitivity of a radio. In addition, LoRa uses Forward Error Correction coding to improve reselience against interference.
LoRa's high range is characterized by extremely high wireless link budgets, around 155 dB to 170 dB.[12]
Since LoRa defines the lower physical layer, the upper networking layers were lacking. LoRaWAN was developed to define the upper layers of the network. LoRaWAN is a media access control (MAC) layer protocol but acts mainly as a network layer protocol for managing communication between LPWANgateways and end-node devices as a routing protocol, maintained by the LoRa Alliance. Version 1.0 of the LoRaWAN specification was released in June 2015.[13]
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.[14] 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.[15] The network server filters duplicate packets, performs security checks, and manages the network. Data is then forwarded to application servers.[16] The technology shows high reliability for the moderate load, however, it has some performance issues related to sending acknowledgements.[17]
The LoRa Alliance is an association created in 2015 to support LoRaWAN protocol as well as ensure interoperability of all LoRaWAN products and technologies. This open, nonprofit association has over 500 members.[18] Some members of the LoRa Alliance are IBM, MicroChip, Orange, Cisco, KPN, Swisscom, Semtech, Bouygues Telecom, Singtel and Belgacom.[19] In 2018, the LoRa Alliance had over 100 LoRaWAN network operators in over 100 countries.[20]
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.
Quigley, Thomas J., and Ted Rabenko. "Latency reduction in a communications system." U.S. Patent No. 7,930,000. 19 April 2011.
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