Modeling and analysis of 5G-A channel characteristics in underground environments using a novel CRCB-FDTD method

The advancement of intelligent mining and industrial digital transformation relies heavily on robust wireless communication systems in underground mines. To enable scientifically sound network planning, this study proposes a finite difference time domain (FDTD) approach with a conformal grid for roadway curved boundaries (CRCB-FDTD) method for high-precision wireless channel modeling in complex mine environments. The model addresses the critical challenge of accurately simulating wave propagation in curved roadway structures through an optimized conformal grid approach. Field measurements collected from operational coal mines validate the model's performance, demonstrating a mean error reduction of 1.2 dB compared to the conventional FDTD and 0.5 dB compared to the equivalent cross-sectional area-based FDTD (ECSA-FDTD), while maintaining computational efficiency. A key finding reveals asymmetric channel characteristics in branch roadways, where path loss significantly increases when transmitters are placed in the main roadways. This phenomenon arises from the wave-guide effect in the main roadways and variations in directional energy coupling. The results deliver significant practical contributions, providing a computationally efficient modeling framework for precise path loss prediction in curved mine roadways, along with fundamental insights for optimizing base station placement and antenna configurations to mitigate coverage asymmetry.