LoRa - LoRaWAN

Introduction
LoRa® (standing for Long Range) is a LPWAN technology, characterized by a long range associated to a low power consumption. It is a technology that can be parametrized to change its range and data rate, influencing its power consumption. It is usually provided with its integrated MAC layer called LoRaWAN, offering IoT-oriented devices management. It is relatively easy to set up thanks to the public network coverage provided by the TTN.

LoRa®
Developed by Semtech, is a spread spectrum modulation technique derived from chirp spread spectrum (CSS) technology. It allows high noise robustness, and so provides a rather long range (up to 10km) even with small power. However, it has low data rate of up to 50kbps because it uses Sub-GHz ISM bands. It has different parameters that can be determined to fix properties such as range, data rate, noise robustness. These parameters are the bandwidth used, the spread factor and the code rate. All three influence the power consumption, as a higher bandwidth or range implies higher consumption.

LoRaWAN™
The LoRaWAN open specification is a low power, wide area networking (LPWAN) protocol based on LoRa Technology. It is developed by the LoRa Alliance, an open association working on LoRa devices and networks (see their site for more detailed protocol reference). This technology adds several useful features to the communication mean:
 * automatic frequency switching is implemented to avoid collisions and interferences
 * both confirmable and non confirmable messages can be sent, thanks to an optional ACK mechanism
 * AES encryption is provided for data security, along with device authentification
 * over-the-air setup to connect to gateways is available, to ease infrastructure flexibility
 * devices battery management is divided into three classes:
 * Class A : extremely low battery, class A devices will stay asleep unless they have information to send, after what they will remain listening for a fixed period before going to sleep again. This mechanism allows to spare as much battery as possible, but a fast responsive bidirectional communication is impossible.
 * Class B : mean battery, class B devices will act like class A but will also wake up to listen at scheduled time slots. This uses a little more battery but allows easier downlink interaction.
 * Class C : constant power source, class C devices will never go to sleep. This is the most reactive communication scheme but it uses the most power.

Sources and further information
https://www.semtech.com/company/brand-resources

https://www.lora-alliance.org/