Improving MAC Protocols for Wireless Industrial Networks via Packet Prioritization and Cooperation

Stations in Cyber-Physical Systems (CPSs) and especially Industrial Internet of Things applications often work towards a common goal, but not all their tasks may be equally important to reach this goal. Hence, stations need to prioritize traffic because network resources are limited. To increase the service quality by utilizing otherwise unused network resources, stations may also opt to use cooperation instead of contention. Many existing standards and academic approaches focus on implementing either cooperation or Quality of Service (QoS) mechanisms. In this paper, we evaluate how to leverage cooperation to improve QoS. Since stations in wireless industrial applications often communicate locally, we focus on the MAC layer. We identify a set of useful cooperation mechanisms that increase the packet delivery ratio, and then extend them by several packet prioritization strategies and evaluate in multiple simulated industrial scenarios. As a result, we provide a set of guidelines for protocol designers to combine different mechanisms depending on the requirements imposed by industrial applications. Moreover, we provide and evaluate an exemplary combination of mechanisms derived from our results aiming at high reliability and low latency.