As an emerging technology, mesh radio (one approach to creating wireless mesh networks) offers end users a self-forming and self-healing reliable network that eliminates single points of failure. Each node in the network recognizes the other nodes and can shift which node is accessed based on availability. The ability for transmission to hop from node to node helps to extend overall range of the network, and the low power usage of nodes provides energy savings.
In a standard mesh architecture, end devices connect to wireless routers, with routers able to serve multiple devices. The routers (nodes) connect to each other and are served by a coordinator unit, which is the device that originally establishes the network and stores data and security keys. Mesh networks of this type are being employed in military applications because of their high degree of reliability. They also serve the largest mobile networks around the world. That technology is now available for industrial control networks.
Full Mesh Topology
We employ a 900 MHz frequency hopping spread spectrum (FHSS) technology for mesh networks. These are typically implemented in closed environments (plants), but such networks may also be used in open environments that need to extend a few miles out. We are also employing a version of the technology that eliminates the need for a coordinator node, making all nodes equal in functionality. This simplifies network setup and allows more flexibility in network expansion. This is known as a full mesh topology.
Each node has a receiver and transmitter, and each node has the ability to sleep when not in use, thus producing the energy savings. Any radio may function as a repeater, with no manual configuration necessary, and that allows the network to be extended over several miles.
Because it is a radio technology, there are standard considerations in play. Radio has a practical line-of-sight limitation of about 1 mile. Antenna height can increase this distance, but issues related to path interference remain in force. These are much less important in a closed environment than in an open environment application.
The platform we use also offers a cellular option, 3G or 4G, for web interfacing, internet access, and achieving longer transmission distances than are practical with radio. Cellular also offers higher speed data communications than achievable with radio. Additionally, the cellular option supports text messaging for alarms and data modes, for web page viewing.
The machine-to-machine networking provided through mesh radio will play a major role as the Industrial Internet of Things gains more traction and the technologies of IT and OT converge. I you want to know more about how mesh radio might fit your particular application, please call 205.999.6472.