Design Criteria for Wireless Mesh Communications in Underground Coal Mines

The Mine Improvement and New Emergency Response (MINER) Act of 2006 was enacted in response to several coal mining accidents that occurred in the beginning of 2006. The MINER Act does not just require underground mines to integrate wireless communication and tracking systems, but aims to overall enhance health and safety in mining at both surface and underground operations. In 2006, the underground communication technologies available to the mining industry had inherent problems that limited communication capabilities. Since the passage of the MINER Act, there have been several developing applications for underground wireless communications. Underground wireless communications allow signals to propagate and take multiple paths to destinations providing a survivable, redundant, and adaptable means of communication and tracking. An underground wireless communications allow underground and surface personnel to directly correspond to one another without being as restricted as hardwired systems. Communication systems also allow miners to be tracked underground to provide a real-time or last known post-accident position, and ensure a more efficient rescue operation.

In order to increase the overall efficiency of developing communication systems there is a need for modeling of wireless signal propagation in underground mines. Research, modeling, and analysis of wireless signal propagation in underground mines ongoing and developing with underground communications systems as the systems progress. The work on this project is based upon the Accolade system from L-3 Communications Global Security and Engineering Solutions but applies to all underground wireless mesh systems currently available. A general approach is taken to solving underground wireless communications networks to allow the design criteria to be adaptable to other communication systems belong the Accolade system.

The data is based upon measurements and field work that took place July 2007 through December 2008 in International Coal Group's Sentinel Mine in Philippi, West Virginia. Comms, a computer method developed at the Virginia Center for Coal and Energy Research at Virginia Tech, allows underground mine communication networks to be solved and analyzed. Comms was developed to solve and analyze underground wireless communication networks. The method which Comms solves communication networks is not mine specific and may be adapted to predict the performance of a system(s) in another mine.

The developed model discussed in Chapters 3 and 4 highlights the general signal loss parameters that are encountered by wireless signals in a mine. The model predicted the signal strength observed when encountering those categorized signal losses within 16 percent of the data measured during a mine survey. The model has been developed in a general manner to allow future investigation and pinpointing of additional interferences that occur within the underground environment.

Wireless communications have proven to be the way of the future and will continue to be integrated into underground coal mines as mandated by the MINER Act. Wireless communications systems are a redundant and survivable means of communication that will be utilized in not only emergency and rescue efforts but daily operational communication as well.