Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
PATRI, A. and NIMAJE, D. S.. Radio frequency propagation model and fading of wireless signal at 2.4 GHz in an underground coal mine. J. S. Afr. Inst. Min. Metall. [online]. 2015, vol.115, n.7, pp. 629-636. ISSN 2411-9717. http://dx.doi.org/10.17159/2411-9717/2015/V115N7A9.
Wireless sensor networks and wireless communication systems have become indispensable in underground mines. Wireless sensor networks are being used for better real-time data acquisition from ground monitoring devices, gas sensors, and mining equipment, whereas wireless communication systems are needed for locating and communicating with workers. Conventional methods like wireline communication have proved to be ineffective in the event of mine hazards such as roof falls, fires etc. Before implementation of any wireless system, the variable path loss indices for different workplaces should be determined. This helps in better signal reception and sensor node localization, and also improves the method by which miners carrying the wireless devices are tracked. This paper proposes a novel method for determining the parameters of a suitable radio propagation model, which is illustrated with the results of a practical experiment carried out in an underground coal mine in southern India. The path loss indices, along with other essential parameters for accurate localization, have been determined using the XBee modules and ZigBee protocol at 2.4 GHz frequency.
Keywords : WSN; RSSI; path loss index; miner localization; underground coal mining; ZigBee.