Random access protocols for industrial internet of things: Enablers, challenges, and research directions

Industrial Internet of Things (IIoT) comprises a variety of sensing and actuation applications deployed in automation scenarios. With their stringent latency and reliability requirements and, on the same time, sporadic traffic patterns, IIoT challenges the way radio resources will be managed beyond 5G networks. Conventional grant-based scheduling is inefficient and introduces additional latency due to control plane procedure. In this chapter, we revisit random access protocols as an alternative to provide low-latency and low-overhead IIoT communications. We present main enabling techniques to improve random access performance and enhance its resistance to collisions. Furthermore, we break random access protocols down into typical building blocks and introduce the design challenges, which need to be addressed to make these building blocks IIoT-ready.