LoRa (Long Range) is a low-power wide-area network (LPWAN) technology. It is based on spread spectrum modulation techniques derived from chirp spread spectrum (CSS) technology.[1][2] It was developed by Cycleo of Grenoble, France and acquired by Semtech the founding member of the LoRa Alliance.[3]
LoRa uses license-free sub-gigahertz radio frequency bands like 433 MHz, 868 MHz (Europe), 915 MHz (Australia and North America) and 923 MHz (Asia). LoRa enables long-range transmissions (more than 10 km in rural areas) 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.
In January 2018, new LoRa chipsets were announced, with reduced power consumption, increased transmission power, and reduced size compared to older generation.[5]
LoRa devices have geolocation capabilities used for triangulating positions of devices via timestamps from gateways.[6]
LoRa and LoRaWAN permit long-range connectivity for Internet of Things (IoT) devices in different types of industries.[7]
The LoRa physical layer protocol is proprietary; therefore, there is no freely available official documentation, though Semtech has provided an overview of the modulation and other relevant technical specifications.[1] However, several independent researchers have analyzed it and documented their findings.[8][9]
LoRa uses a proprietary spread spectrum modulation that is similar to and a derivative of Chirp spread spectrum (CSS) modulation. This allows LoRa to 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). This spreading factor determines the data rate and dictates the sensitivity of a radio. In addition, LoRa uses Forward Error Correction coding to improve resilience against interference. LoRa's high range is characterized by extremely high wireless link budgets, around 155 dB to 170 dB.[10]
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 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.[11]
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.[12] 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.[13] The network server filters duplicate packets, performs security checks, and manages the network.[citation needed] Data is then forwarded to application servers.[14] The technology shows high reliability for the moderate load, however, it has some performance issues related to sending acknowledgements.[15]
The LoRa Alliance is an association created in 2015 to support LoRaWAN (long range wide-area network) protocol as well as ensure interoperability of all LoRaWAN products and technologies. This open, nonprofit association has over 500 members.[16] Some members of the LoRa Alliance are IBM, Actility, MicroChip, Orange, Cisco, KPN, Swisscom, Semtech, Bouygues Telecom, Singtel, Proximus and Cavagna Group.[17] In 2018, the LoRa Alliance had over 100 LoRaWAN network operators in over 100 countries.[18]
^Jesus Sanchez-Gomez; Ramon Sanchez-Iborra (2017). "Experimental comparison of LoRa and FSK as IoT-communication-enabling modulations". IEEE Global Communications Conference (Globecom'17): 1–6. doi:10.1109/GLOCOM.2017.8254530. ISBN978-1-5090-5019-2.
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.
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