Radio propagation in open-pit mines: A first look at measurements in the 2.6 GHz band

Abstract

In this paper we present the results of an extensive measurement campaign performed at two large iron ore mining centers in Brazil at the 2.6 GHz band. Although several studies focusing on radio propagation in underground mines have been published, measurement data and careful analyses for open-pit mines are still scarce. Our results aim at filling this gap in the literature. The research is motivated by the ongoing mine automation initiatives, where connectivity becomes critical. This paper presents the first set of results comprising measurements under a gamut of propagation conditions. A second paper detailing sub-GHz propagation is also in preparation. The results indicate that conventional wisdom is wrong, in other words, radio-frequency (RF) propagation in surface mines can be far more elaborate than plain free-space line-of-sight conditions. Additionally, the old mining adage "no two mines alike" seems to remain true in the RF domain.

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

“…The path loss exponents are 2.3 and 2.1 respectively, and the intercept points are 36 and 62.7 dB. As in [11], we do not distinguish between LOS and NLOS propagation, because there is no clear breakpoint distance in case of macro cells in open-pit mines. The RMSE in each case is 10.7 and 12 dB.…”

“…Mine 2, Figure 2 Since open-pit mine terrain characteristics differ from those found in urban and suburban scenarios, it is important to redefine terms as macro and small cells. As done in [11], we define a small cell deployment as the one where the transmitter is placed closer to the ground level, below the median altitude of the covered area. A macro cell deployment, on the other hand, is defined as the one in which the transmitter is placed in an elevated position, above the median altitude of the covered area.…”

“…The conclusion is that the increased delay spread limits the performance of orthogonal division multiplexing (OFDM) systems such as LTE and Wi-Fi, with standard values of cyclic prefix. In a previous work [11], we proposed three path loss models based on measurements in the 2.6 GHz band and showed that, also from the radio propagation perspective, there are no two mines alike.…”

An Empirical Study of Propagation Models for Wireless Communications in Open-Pit Mines

“…In our previous contributions, [4], [5], we started to fill in this gap in the literature by analyzing the results of a measurement campaign in two iron-ore open-pit mining complexes located in Minas Gerais, Brazil. In [4] we presented an analysis of the mining scenario, and showed that the altitude differences between transmitters and receivers can go up to 500 m for Macro Cells. We also derived empirical propagation models for the 700 MHz and 2.6 GHz frequency bands, in macro and small cell deployments.…”

“…Second, we derive a simple deterministic model that is able to approximate the results of SPM, while reducing the calibration complexity. The model is derived based on the observations of the efficacy of the models evaluated in this paper and the altitude difference observed in [4]. The proposed model (Vale model) is thus, an extension of the ITU-R 526, which characterizes propagation by diffraction, by the addition of an effective antenna height component, as proposed in [9].…”