Radio access techniques in industrial internet of things networks

The Industrial Internet of Things (IIoT) is a key enabler of the Industry 4.0 paradigm, facilitating the development of efficient, high-performance applications involving industrial assets equipped with wireless connectivity. However, the potential of IIoT is limited by traditional wired communication systems, which have scalability and flexibility issues. In this context, 5th Generation (5G) technology is a substantial improvement over traditional wireless networks and effectively meets many IIoT requirements. Nevertheless, for applications requiring ultra-low latency, high data rates and higher device density, it is evident the need of the next generation of mobile radio networks, the 6th Generation (6G). By leveraging Terahertz (THz) communications, 6G aims to meet the advanced requirements of IIoT. Given these challenges, this thesis provides an in-depth analysis of key IIoT use cases and their demands. It proposes innovative radio access techniques that extend the current state-of-the-art solutions, focusing on enhancing communication performance in industrial environments, where multiple applications with varying demands coexist. In particular, several 5G uplink scheduling algorithms are analyzed, proposing novel solutions to manage traffic correlations and variations in traffic patterns to achieve Ultra-Reliable Low-Latency Communication (URLLC) requirements. The potential of THz communications is then explored through the design of contention-based Medium Access Control (MAC) protocols in both single-hop and multi-hop networks, highlighting the challenges of operating at such high frequencies while also showcasing the benefits that can be achieved. Additionally, this study explores hybrid communication strategies, analyzing the coexistence of pull and push-based communications to optimize performance across multiple devices sharing the same channel. Results are obtained from both mathematical analysis and simulation approaches. Through these contributions, this thesis not only advances the theoretical understanding of wireless communications in IIoT contexts but also demonstrates the feasibility and effectiveness of the proposed solutions in addressing the complex communication needs of Industry 4.0.