O-RAN-Enabled Adaptive Relaying for Robust V2X Communication in Urban NLOS Scenarios

The Open Radio Access Network (O-RAN) introduces programmability and intelligence into wireless infrastructure, making it a promising enabler of reliable Vehicle-to-Everything (V2X) communication in complex urban environments. Unlike traditional RAN, O-RAN's disaggregated architecture and RAN Intelligent Controller (RIC) allow real-time adaptation to Non-Line-of-Sight (NLOS) challenges, an issue unresolved in many existing V2X systems. This paper proposes an adaptive relaying framework that leverages the near-real-time RIC to dynamically enhance V2X reliability through dynamic relay selection and interference-aware resource coordination. The architecture supports programmable fallback relaying using disaggregated Distributed Unit (O-DU)/Radio Unit (O-RU) at roadside infrastructure, enabling low-latency two-hop paths when direct sidelink communication fails. To evaluate performance, a semi-analytical model based on Moment Matching Approximation (MMA) is developed, capturing the signal-to-interference-plus-noise ratio (SINR) under composite Nakagami-lognormal fading and stochastic co-channel interference. The framework integrates O-RAN with NR-V2X sidelink communication to bridge the gap between centralized and ad-hoc vehicular networks. Simulation results demonstrate that the proposed O-RAN-aided relaying improves Packet Success Probability (PSP) in dense NLOS scenarios, consistently achieving a PSP above 90%. The framework outperforms conventional LOS and NLOS approaches while maintaining compatibility with 3GPP Release 18 and O-RAN Alliance specifications, ensuring practical deployability in future intelligent transportation systems (ITS).