Studies on Propagation Characteristics of Radio Waves for Wireless Networks in Underground Coal Mines

Communication systems relying on wireless technology can significantly improve the safety and production in underground mines; however, their unreliable operation in such high-stress environments is a significant obstacle to achieving this. Underground mine tunnels offers several distinctive features that are quite different from regular rail/road tunnels. While several studies have been performed on electromagnetic (EM) wave propagation in tunnel environments, there is limited understanding of the inter-working of tunnel dimension with long range tilt variations (a typically feature of coal mines) on the propagation characteristics of wireless radio waves. In this paper, we study and describe a new hybrid multimode model for wireless communication applications in underground coal mines; and analyze it with respect to significant parameters such as operating frequency, mine tunnel size, transmitter-receiver position, electrical parameters and antenna gain. The characterization results suggest that the mine tunnel size and transmitter-receiver position affects the signal behavior significantly. However, the electrical parameters have almost negligible effects on the propagation.