Characterization and modeling of a wireless channel at 2.4 and 5.8 GHz in underground tunnels

Underground tunnels, such as caverns and mine galleries, are indoor environments far more hostile, in terms of wireless communication, than conventional ones like road tunnels, offices or factories. Wireless propagation behavior in these areas is found to be fairly peculiar, mainly due to the extreme roughness of wall surfaces. This paper presents comprehensive broadband measurement and modeling results of electromagnetic wave propagation in real underground mine tunnels at 2.4 and 5.8 GHz. Broadband radio propagation in these environments is observed to exhibit behavior that is quite different from conventional indoor environments with smooth surfaces. Notably, signal variation can be highly locally specific and site-specific, rms delay spread varies randomly with transmitter-receiver distance and no path arrival clustering effect is observed. These path time arrivals tend to follow a Modified Poisson distribution and amplitude tends to follow Rice and Rayleigh distributions for line-of-sight and non-line-of-sight cases, respectively. Extensive simulations have shown the models to be very close to reality.