Efficient Radio Wave Propagation Modeling in Tunnels With a Sparse Fourier Transform-Based Split-Step Parabolic Equation Method

With the emergence of fifth-generation (5G) and beyond wireless systems deployed along the railway, there is an increasing need for efficient propagation models in tunnels. The parabolic equation method has been widely used for radio wave propagation modeling for long guiding structures such as tunnels. However, carrying out simulations with such a method at high-frequency bands is still computationally expensive. This letter proposes an efficient split-step parabolic equation-based model utilizing sparse Fourier transform techniques. The proposed model can significantly accelerate the modeling of wave propagation in tunnels. The accuracy and efficiency of the proposed model are demonstrated through comparison with experimental measurements and simulation models in actual tunnel cases.