Advanced Traffic Differentiation in LoRaWAN IIoT Networks Through Contention Window Strategies

The Industrial Internet of Things (IIoT) has emerged as a factory paradigm in Industry 4.0, and aims for transmitting and receiving information from sensors and actuators. The information collected by the IIoT End Nodes (ENs) is processed to detect patterns that optimize the associated processes. In addition, in some factories, there are thousands of sensors, making wired transmissions impractical and expensive. Thus, Wireless Sensor Networks (WSNs) have become cost- and time-effective technologies to replace traditional wired transmitters. Long Range Wide Area Network (LoRaWAN) is a cutting-edge communication protocol currently applied to IIoT since it can cover large areas and operate for years with low energy consumption requirements. However, since LoRaWAN uses a Pure-ALOHA Medium Access Control (MAC), it does not include a mechanism to assign higher priorities to mission-critical sensors such that they have a higher probability of accessing the channel and a lower probability of experiencing collisions. In this paper, we propose a novel mechanism to reduce the probability of collisions and include a traffic differentiation scheme using an enhanced version of the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) strategy. Besides, we use a Contention Window (CW) approach to assign higher priorities to mission-critical ENs. Numerical studies showed that the use of the CW approach increases the probability of accessing the channel by 74.6%.