Integration and Validation of 3GPP TR~38.811 Aligned GEO NTN-TDL Channel Models in OpenAirInterface5G

This paper presents the integration of 3GPP TR~38.811-based NTN tapped-delay-line (TDL) channel models into the OpenAirInterface5G (OAI) RF simulator (RFsim) for controlled end-to-end geostationary (GEO) non-terrestrial network (NTN) experimentation. Currently OAI RFsim channel models do not include standardized NTN-specific multipath profiles and elevation-dependent large-scale channel effects. Such effects are important for evaluating frequency selectivity, received signal strength, and their impact on PHY and end-to-end system performance. Our implementation incorporates the NTN-TDL-A/B/C/D profiles, elevation-dependent large-scale attenuation, explicit line-of-sight (LOS) and non-line-of-sight (NLOS) state handling, and initialization-time profile-selection policy. Validation is performed at three levels combining channel-model descriptor checks, PHY-level BLER evaluation, and end-to-end 5G SA trials across multiple channel profiles, elevation angles, and LOS/NLOS conditions. The results confirm the expected channel behavior, profile selection, and successful user-plane establishment. The implementation enables reproducible end-to-end 5G-NTN experiments in OAI under representative TR~38.811-based GEO channel conditions.