Radio-wave propagation into an underground mine environment at 2.4 GHz, 5.8 GHz and 60 GHz

In this paper, an overview of the overall channel characterizations for wireless communication systems in underground mines is presented. Such environments, because of the very nature of the mining operation, the complexity of the systems, and the procedures and extraction methods of the minerals are considered to be dangerous, hazardous and aggressive. Radio signals suffer from strong attenuations due to reflection, diffractions and scatterings in this complex transmission medium. The transmitted radio signals are therefore subject to different impairments and distortions. Moreover, for the deployment of a wireless network, the choice of the operation frequency band, which has a major impact on the planning and the dimensioning, is as important as the deploying environment. Propagation measurements were carried out at 2.4 GHz, 5.8 GHz and 60 GHz. These frequencies were targeted because they are commonly used for different wireless communication applications. This paper summarizes different findings on the propagation characteristic parameters such as the path loss, outage probability, delay spread and the coherence bandwidth. This the first time, to our knowledge, that a comparison of the operating frequency effects in an underground mine is reported.