Optimising wireless LAN for longwall coal mine automation

A significant development in underground longwall coal mining automation has been achieved with the successful implementation of WLAN technology for communication on a longwall shearer. Wi-Fi was selected to meet the bandwidth requirements of the underground data network, and several configurations were installed on operating longwalls to evaluate their performance. Although these efforts demonstrated the feasibility of using WLAN technology in a longwall operation, it was clear that new research and development was required in order to establish optimal, full face coverage. By undertaking an accurate characterisation of the target environment it has been possible to achieve great improvements in WLAN performance over a nominal Wi-Fi installation. The paper discusses the impact of Fresnel zone obstructions and multipath effects on RF propagation, as well as reporting on an optimal antenna and system configuration. Many of the lessons learnt in the longwall case are immediately applicable to other underground mining operations, particularly wherever there is a high degree of obstruction from mining equipment.