MineSense: sensing the radio signal behavior in metal and non-metal underground mines

The requirement for consistent well-being upgrades of mine personnel and improved mine productivity is encouraging the underground mining industry through a move from manual to automated mine operations. From a communication point of view, this move introduces a new set of challenges and design goals of business driven and emergency response applications that need to be addressed by wireless technology. Solution based on wireless technology has a wide scope of deployment in underground mines supporting applications such as environmental monitoring, ventilation on demand, tracking of miners and remote asset monitoring, etc. However, the reliable operation of such networks is restricted in real time due to the unique characteristics of underground mines such as gallery dimension, humidity, curves and bends, support systems, noise etc. In addition, the lack of experimental understandings of electromagnetic wave propagation in such high stress environment affect the features offered by these technologies. In this work, we have focused on empirical understandings of radio signal behavior in different underground mines. The contribution of this work is three fold. First, it outlines the impact of depth on the signal propagation characteristics and then identifies the major propagation factor contributing to significant losses at the receiver in the mine tunnel space. Second, based on the propagation data collected at different metal and non-metal mines, discusses the role of mining methods on radio signal behavior. Third, it critically presents the need for modifications in formulations of the theoretical channel model which have been characterized by extensive data measurements in operational underground mines. The observations reported in this work may significantly help the wireless design community to achieve reliable and optimized performance of communication devices to be deployed in such high stress work environments.