Ray Tracing-Based Wireless Channel Modeling in Room-and-Pillar Mines

To establish reliable wireless communication systems in underground mines, accurate channel modeling plays an indispensable role in the design phase. In this paper, we propose ray tracing-based channel modeling in room-and-pillar mines. Specifically, the propagation paths of signals are firstly determined in the horizontal plane of a room-and-pillar mine using the ray tracing method. Then, the two-dimensional (2D) propagation paths are converted into their corresponding three-dimensional (3D) counterparts by deriving the heights of intersection points at obstacles and the locations of reflection points on mine ceilings and floors. Since the roughness of mine surfaces has a non-negligible influence on radio propagation properties, it is also taken into account when the electric fields of propagation paths are calculated. To validate the accuracy of the proposed ray tracing-based room-and-pillar channel model, we compare simulation results with experimental measurements conducted in an actual mine in terms of mean excess delay and root mean square (RMS) delay spread. The comparisons show simulation results have a good consistency with measurement data.