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.