Wireless Mesh Sensor Networks: When Redundancy is a Good Thing
Mention redundancy in most industries and businesses, and it will usually lead to negative thoughts, i.e. items that can no longer be used, people who lose their job due to their job function no longer being required or relevant, etc.
However, there is an environment in which redundancy is a good thing – underground mines that switch over from a cable-based network to a wireless mesh sensor network to autonomously gather data (or those that simply install a wireless mesh sensor network from the beginning, e.g. new mines or expansion areas within existing underground mines.)
One of the major advantages of a wireless mesh sensor network in an underground mining context, besides the more obvious cost savings and reduced risk of damage (e.g. due to cables being snagged by vehicles and other equipment moving around the mine), is the relative ease with which useful redundancy can be built into these networks.
The foundation of a typical underground mine mesh sensor network is an array of geotechnical, hydrological, and other sensor-based measuring instruments deployed throughout the mine that are connected to wireless nodes that gather data from the instruments and then move it through the network to a central point, usually a LAN/Ethernet gateway, from where it is easily accessible to mine engineers.
Each wireless node also acts as a router, passing along information from other nodes. By positioning wireless nodes in such a way that each one is within range of at least two (or more) other nodes, alternative data pathways are established. Although data will tend to travel via the shortest or easiest route, these alternative or “redundant” routes are what gives a wireless mesh sensor network its reliability.
If a node is unable to pass through information, e.g. due to damage, RF interference, etc., the data from other nodes will simply flow around it via one of the routes, which was redundant up until that point.