A Performance Study of Line-of-Sight Millimeter-Wave Underground Mine Channel

Abstract

This letter studies the performance of the line-ofsight underground mine channel in the millimeter wave band. Using a vector network analyzer (VNA) and three carefully chosen antennas, one omni and two horn antennas, we performed measurements at the 40 and 70 m levels in the CANMET mine located in Val-d'Or, Canada. The performance of the channel is studied in terms of its path loss exponent, shadowing and capacity. Results prove that the path loss exponent in an underground mine is smaller than the free space value. The shadow fading fits very well with the normal distribution. A model of the capacity as a function of the distance between transmitter and receiver is investigated. Channel capacity depends on the multipath characteristics; the capacity found in the narrow environment (70 m) is higher than in the wider environment (40 m). The results also show that it is better to use omnidirectional antennas for a wireless communication system in the millimeter wave band in an underground mine environment.

Improving wireless communications in underground mines using reconfigurable antennas

“…Extending the coverage area required the full mesh wireless network [5] which provided redundant links to improve reliability at the cost of latency. More recently, ultra-wideband (UWB) systems [6,7] and millimeter (MM) wave systems [8,9] were considered in anticipation of the changes in underground mine communication requirements. The main application of the early systems was the transmission of narrowband voice signals.…”

“…The need for video and visual imaging of underground processes in implementing collision avoidance, remote control, robotics, and autonomous systems operations in underground mines will demand more bandwidth. Thus, current research is considering UWB and MM systems [6][7][8][9]. In systems where a wired backbone exists, the last mile-connection is always an antenna [4,5].…”

“…The distribution of the shadowing is also important in characterising the channel with directional antennas. Current research reports shadow fading as being normally distributed [8]. To this effect, the Lilliefors test for goodness of fit was performed on the standard deviation to verify the distribution of each transmit-receive pair.…”

“…When considering each pulse, the effect of fading in the subchannel is assumed to be flat. Following this assumption, the subchannel capacity based on the measured frequency can be determined from [8]:…”

“…Therefore, a simpler option for calculating the channel capacity would be to use the path loss exponent as described in [8]. A path loss channel capacity comparison of the RA and dipole antennas is presented in Figure 5-23.…”