An Open-Source Hybrid Ray-Tracing and 3GPP Channel Simulator for Non-Terrestrial Network

This paper proposes a hybrid channel simulation framework that combines site-specific ray tracing (RT) with 3GPP-compliant statistical channel simulation for non-terrestrial networks (NTNs). The proposed approach uses RT to generate dominant propagation paths and augments them with statistically generated paths and subpaths to provide richer multipath realizations under practical simulation complexity. To provide a complete simulation framework, we integrate Sionna RT, 3GPP, and hybrid RT-3GPP simulators within a unified workflow. Simulation results based on key channel statistics and power delay profiles show that the proposed method preserves site-specific propagation characteristics while providing sufficiently rich multipath components, thereby addressing the complementary limitations of conventional RT-based and purely statistical NTN channel simulators. The developed simulator is also released as an open-source project to support reproducibility and further NTN research.