Ray-tracing model calibration for underground mines propagation prediction at high UHF frequencies

In a mining environment, due to the electromagnetic waves propagation complexity, one of the major problems is the radio coverage definition. At frequencies lower than 300 MHz, signals are most of the time transmitted using leaky feeders. At higher frequencies, wireless propagation [1–3] in underground confined area is essential because this mode of propagation undergoes less attenuation than with leaky feeders. Also, wireless propagation has the advantages of being less expensive, easier to install and can be adapted according to the topology of a given environment. In mining installations, the variability [3] in the geometry associated with the work progression makes wireless network configuration an ideal prospect for these installations. Wireless network operators are dealing with complex problems when planning network operations, particularly in an underground environment. To permit an acceptable level of automation in the planning process, simulation and optimization tools are being developed on a large scale basis. In this paper, the genetic algorithm is combined with the fingerprinting technique to calibrate an efficient ray-tracing model based on experimental narrow band wave propagation in a confined area.