Cross-layer inter-UE coordination: A facilities layer approach to NR-V2X mode 2 scheduling

This paper proposes a cross-layer Inter-UE Coordination (IUC) mechanism for 5G New Radio (NR)-Vehicleto-Everything (V2X) Mode 2 communications to mitigate the hidden-node problem in decentralized sidelink scheduling. Unlike standard 3GPP Release 17 IUC, our approach piggybacks midterm resource reservations onto standard Cooperative Awareness Messages (CAMs). By extracting scheduling information from Sidelink Control Information (SCI) and disseminating it via CAMs, we enable cooperative spectral awareness on Release 16-compliant hardware. We implement the framework in the high-fidelity MSVAN3T simulator and evaluate it within a virtual train coupling scenario. Results demonstrate significant improvements in Packet Reception Ratio (PRR) and reveal a critical trade-off between the look-ahead reservation window and protocol overhead.