Underground wireless networking: A performance evaluation of communication standards for tunnelling and mining

• We test a range of wireless technologies including the very latest IEEE802.11ac.
• We use three different underground tunnel locations.
• Significantly enhanced wireless performance underground is demonstrated.
• A comparison with a modal theoretical analysis is presented.
• We discuss generalising the results and method for practitioners and other tunnels.

Tests on both commonly-used and new wireless communication standards operating in the 2.4 GHz and 5 GHz bands (IEEE 802.15.1 Bluetooth, and IEEE 802.11g, 802.11n and 802.11ac Wi-Fi) were carried out in a variety of underground tunnels. In general, it was shown that wireless data communication in tunnels shows significantly increased throughput vs. range characteristics compared to open space or office environments, however, transmission is largely restricted to line-of-sight paths. Particular attention has been given to the effect of tunnel cross-sectional area, the presence of cross-cuts, a comparison between 2.4 GHz and 5 GHz, and the relative effectiveness of those standards that employ MIMO. Tests also investigated tolerance to loss of line-of-sight. It is anticipated that the results presented here will provide guidance for planning wireless networks for use in mining and transport tunnels, or for temporary use in drains, sewers or service tunnels such as those carrying cables and pipework.