5G in Open-Pit Mines: Considerations on Large-Scale Propagation in Sub-6 GHz Bands

5G will play a pivotal role in the digitization of the industrial sector and is expected to make the best use of every bit of spectrum available. In this light, this paper presents the results of an extensive measurement campaign in two iron-ore open-pit mining complexes, at the 700 MHz and 2.6 GHz bands, considering macro and small cell deployments. The study is further motivated by the rise of unmanned machinery in the mining industry. We present values of path loss exponents, shadow fading standard deviations, autocorrelation distances and inter-frequency cross-correlation, which are all useful for the future wireless network design, simulation and performance evaluation. The results show that, in order to comply with ultra-reliable communications (URC) availability requirements, larger shadowing margins will have to be considered in the network planning in open-pit mines, when compared to traditional industrial environments. Furthermore, large cross-correlation between the shadowing in both frequency bands limits the gains when using multi-connectivity in order to enhance overall network availability.