UTD-Based Ray-Tracing MIMO Channel Modeling for the Next-Generation Communications Within Underground Tunnels

Limited work has previously been conducted into deterministic modeling of the fifth generation (5G) millimeter (mm)-wave wireless communications within geometrically nonuniform tunnels. This study predicts and analyzes broadband multiple–input multiple–output (MIMO) propagation in underground mine tunnels for 5G communications and beyond. At extremely short wavelengths, each rugged and uneven surface of the tunnel is modeled as a group of diffracting rectangular prism wedges. A deterministic ray-tracing (RT) MIMO model is developed based on the Uniform Theory of Diffraction (UTD). All predicted MIMO subchannels have been successfully fitted with the experimental measurements. MIMO multipath fading of underground tunnels is found to be lognormally distributed and strongly depends on the tunnel's size and shape.