Measurements and Models of 915 MHz LoRa Radio Propagation in an Underground Gold Mine

Abstract

Underground mining increasingly relies on wireless communications for its operations. The move to automating many underground mining processes makes an understanding of the propagation characteristics of key wireless technologies underground a topic of considerable importance. LoRa has great potential for communications in underground mines, but data on its propagation are quite scarce. In this paper, we describe our measurements of LoRa radio propagation in an underground gold mine. We took measurements in an extraction tunnel with line of sight and in extraction and access tunnels without line of sight. We observed excellent propagation, both with and without line of sight. Our observations support claims by others that the steel-lined tunnels act as a waveguide. As well as reporting measurements, we also developed models of propagation. For line of sight, we show that pathloss is well modelled by a power law with pathloss index of 1.25 and that variability of signal strength is well modelled by a lognormal distribution. We also successfully modelled propagation without line of sight over short distances using a Fresnel Diffraction and Free Space model.

Lora Communication Maintenance and Signal Propagation Evaluation in Obstacle-Dense Industrial Environments: A Wood Processing Application

“…5), which is utilised for higher frequency use cases. Because of the obstacles and the fact that LoRa has a restricted bandwidth at higher spreading factor values, the client or node only had a limited amount of time to deliver the data packet to the gateway [23][24][25]. The customers were positioned in the midst of the wood pallets (Fig.…”

Development of LoRa Communication System for Effective Transmission of Data from Underground Coal Mines

“…It i worth to mention that information on LoRa propagation underground is extremely scarce There have been a very few investigations of LoRa for various industries and only one fo the underground mining industry. It is not unexpected that there is only a few research i carriedout using LoRa in underground mining in India because it needs permission from the Directorate General of Mines Safety (DGMS) to take the developed system into mine to carry out investigation and seeking such permission is a lengthy process [43].…”