Toward 6G Vehicular Connectivity: Industry-Oriented TN–NTN Co-Simulation for Multi-RAT Network Selection

Abstract

G communications solutions can potentially enable a novel generation of ITS, as they would lead to vehicles connected beyond the coverage and capacity limits of Terrestrial Networks (TN), thanks to the seamless integration with Non-Terrestrial Networks (NTN), such as Low-Earth-Orbit (LEO) constellations. However, the full exploitation of TNs and NTNs for ITS raises practical questions on mobility, service continuity, energy use, and validation methodology. This paper presents an industry-oriented co-simulation platform for evaluating multi-radio access technology (multi-RAT) network selection in vehicular TN–NTN scenarios. The platform extends an open OMNeT++ ecosystem by combining road mobility from SUMO/Veins, cellular access from Simu5G, and satellite visibility from OS3/leosatellites-style orbital modeling. It adds hybrid vehicular nodes, coordinate conversion between road and geodetic reference systems, dynamic satellite routing support, and an application-layer interface manager that compares time-based, coverage-based, quality-of-service (QoS)-based, and energy-aware selection strategies. Initial simulation experiments show that adaptive offloading can reduce the extreme delay caused by terrestrial congestion, while also exposing trade-offs among latency, packet delivery, switching frequency, and energy use. The resulting environment supports OEM-facing analysis of service continuity and validation assumptions for connected-vehicle use cases developed in collaboration with Stellantis.