LoRaWAN Link Layer
The LoRaWAN Link Layer specification  is a communication protocol for the Internet of Things. It targets low power, long range, low cost communication using unlicensed spectrum. Network topology is collaborative, which reduces a lot protocol signalling compared to a cellular network. The device is connected to a network server, and protocol overhead is limited to 13 bytes for any data frame. There are three classes of operation. Class A is optimized for low power operation of end-devices, while class B and class C offer reduced downlink latency. The protocol specification offers several mechanisms to adjust the link layer parameters: adaptive data rate, adaptive power control, variable repetition rate, and channel selection.
TS001-1.0.4, LoRaWAN Link Layer Specification, LoRa Alliance Technical Committee, October 2020
B. Martinez, F. Adelantado, A. Bartoli, X. Vilajosana, ‘Exploring the Performance Boundaries of NB-IoT’, IEEE Internet of Things Journal, Volume 6, Issue 3, June 2019.
RP002-1.0.2 LoRaWAN Regional Parameters, LoRa Alliance Technical Committee, November 2020