Mission-Critical Connectivity Enhanced by IAB in Beyond 5G: Interplay of Sidelink, Directional Unicasting, and Multicasting.

Guaranteeing operational connectivity in emergency situations by means of prompt on-demand network re-configuration is crucial to carry out effective public protection and disaster relief actions. This article analyzes network configuration options enhanced by the integrated access backhaul (IAB) feature for 5G-Advanced and beyond mission-critical services. We specifically aim to investigate the possible interplay of sidelink communications, directional unicast transmissions, and multicasting. To this end, we offer a practical methodology based on a fluid model approximation to capture the time dynamics of mission-critical services in their transient phase. Simulation results show that the interplay of multicasting, unicasting, and sidelink is a highly effective solution for mission-critical communications. In contrast, standalone unicast, multicast, and sidelink transmissions are unable to support such services. A further emerging aspect is that, in a mixed unicast-multicast-sidelink configuration, optimal results are obtained when multicast exploits most of the available resources, specifically more than 70%.