## 6 Conclusions  
Localization of miners, objects, and trucks, among others, is one of the most important applications in underground mining, especially for security and safety. The traditional GPS is not useful in underground mining for indoor positioning; therefore, other short range wireless technologies such as RFID, Wi-Fi, Zigbee, and VLC have been preferred to meet this purpose. Hence, in this manuscript a novel visible light communication system (VLC) for localization in under ground mining was proposed. A novel 3D VLC-based localization system was introduced by placing at least three LEDs in each sector of the mine, and using photodetectors in the objects to localize. The LEDs transmit information in different carrier tones and the photodetector receives the superposition of these signals. The distance between the photodetector and each LED is calculated by filtering and comparing the transmitted and received power. Three spheres are plotted by centering the LEDs locations and these distances are used  
Figure 5: Intersections between the three spheres for the (**a**) first scenario, (**b**) second scenario, and (**c**) third scenario.  
Figure 6: Performance comparison of the proposed system and traditional radio frequency technologies in terms of the localization estimation error. Radio Frequency IDentification (RFID), Wireless Fidelity (Wi-Fi).  
as as diam. The source location is estimated by the intersection between these spheres. Based on the simulation results, the proposed algorithm localizes the source with an average localization estimation error of less than (16.4 cm) based on the source location. The average error is (3.5 cm) for subjects that are very close to the LEDs. In addition, the results show the superiority of the proposed method in comparison with other short range wireless technologies such as RFID, Wi-Fi, Zigbee.  
Conceptualization, A.D.F. and C.A.-M.; Formal Analysis, A.D.F., C.A.-M., and I.S.; Funding acquisition, I.S.; Experiments, A.D.F.; Project administration, C.A.-M., D.I., F.S., and N.K.; Writing--original draft preparation, A.D.F, C.A.-M., and F.S.; Writing--review and editing, A.D.F., C.A.-M., I.S., F.S., N.K., D.I., P.C., and D.Z.-B.  
This research was funded by Project STIC-AMSUD 19-STIC-08, FONDECYT No. 3190147, FONDEF IT17M10012, and FONDECYT No. 1160517.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} AWGN & Additive White Gaussian noise \\ DTM & Dynamic Triangular Measurement \\ GPS & Global Positioning Systems \\ FIR & Finite Impulse Response \\ IM-DD & Intensity-Modulation and Direct-Detection \\ ILO & International Labour Organization \\ LED & Light Emitting Diode \\ MINER & Mine Improvement and New Emergency Response act \\ NNSS & Nearest Neighbor in Signal Space \\ OWC & Optical Wireless Communication \\ OwIPS & Owl Positioning Systems \\ RF & Radio Frequency \\ RFID & Radio Frequency IDentification \\ RSSI & Received Signal Strength Indicator \\ SLAM & Simultaneous Location And Mapping \\ RSS & Strength of the Received Signal \\ VLC & Visible Light Communication \\ Wi-Fi & Wireless Fidelity \\ \end{tabular}