A Multi-Hop Industrial IoT Network at THz Bands Using Contention-Based Access

This paper addresses the problem of enabling intra-machine communication in an Industrial Internet of Things (IIoT) scenario using Terahertz (THz) frequencies. To mitigate the path loss of such high frequencies, a tree-based topology is built: each automation machine of the factory is controlled by a Router that collects data measured by wireless sensor devices located on the machine and forwards them to a final Gateway (GW) for elaboration purposes. Routers are equipped with multiple antenna elements, while sensor devices have only a single antenna element. In this scenario, we study the applicability of a contention-based access protocol, based on Carrier Sense Multiple Access, and we demonstrate its effectiveness when compared to Aloha. The performance of an uplink communication is evaluated in terms of Packet Success Probability and Network Throughput. Results demonstrate the impact of different parameters, like the sensing range of devices, the number of radiating elements at the Routers, the size and number of machines, and demonstrate that propagation delays cannot be neglected at THz frequencies.