Wireless paging system for underground mines

Underground working in different horizons with intricate haulage and traveling roadways is very complex in nature. Wired communication is presently the most adopted technology in Indian underground mines. Also, the cellular network cannot be used for communication due to the non- availability of the coverage link. So, addressing of key-personnel to pass on the information and assign task becomes a challenge for mine management. Implementation of wireless paging systems with routers and/or repeaters at strategic locations can instruct manpower for the jobs as well as obviate the impending mishap, if any, at remote locations of the mine. This paper presents a design of a wireless paging system for underground mines which consists of a two-way alphanumeric paging system operating on a ZigBee based wireless network and a paging terminal software. This paging system can be used to unicast or broadcast messages to all the pagers working in the RF network. A successful field trial of the same is also conducted to devise a node placement strategy for the routing units with prototype pagers in the shaft and traveling roadways at 400 and 500 m horizon of a deep underground coal mine.