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Networking & Communications

High-Performance Mesh Networking Makes Its Mark on M2M

June 1, 2005 By: Rick Rotondo Sensors


Recent attention to wireless machine-to-machine (M2M) communications may portend the next big revolution for the wireless industry. Automatic and ad ho c communications between machines, particularly in industrial settings, will provide new ways of remotely monitoring, measuring, and tracking both fixed and mobile systems. Self-forming, self-healing wireless mesh networks make it simple and cost effective to poll, monitor, adjust, and control systems that once required either laborious and expensive manual processes or expensive cabling or wiring. Until recently wireless alternatives to these networks were limited to point-to-point, low-bandwidth, stationary sensors. However, the crossover of high-performance (i.e., mobile broadband) meshing technology into the wireless sensor space is opening up a whole new set of applications and capabilities that were beyond the reach of traditional wireless sensor solutions.

Sensors are a vital part of modern manufacturing process control. An M2M communications system enables sensors to provide critical data for real-time process control applications. By automatically collecting and analyzing process data, these systems lessen the burden on plant technicians and operators.

Early attempts to wirelessly network sensors and controllers with cellular or 802.11 technologies have met with mixed results. Smaller-scale and light industrial deployments have generally been successful since traditional wireless technologies can manage both the physical scope and radio interference in these settings. However, large-scale and heavy industrial settings have proven far more problematic for wireless solutions; long distances, thick concrete walls, extensive metal structures, and machines that generate radio frequency noise create interference and "non-line-of-sight" issues that thwart reliable end-to-end radio communications. It is in these types of facilities that high-performance wireless mesh networking is gaining acceptance.

Mesh Networking

A wireless mesh is different from the typical point-to-point and centralized radio solutions used for networking sensors today. In a mesh network, each node (in this case, the sensor and its mesh-enabled radio) can send and receive its own information and can also function as a router/repeater to relay messages for neighboring nodes. This ability to "hop" signals through neighboring nodes offers several critical benefits. Peer-to-peer connectivity and hopping between nodes means signals can automatically be routed around obstructions, interference, congestion, and node failures. The ability of nodes to create multi-hop non-line-of-sight connections simplifies deployment and engineering of the network. Since each node regenerates and strengthens the signal as it is passed along, wireless coverage and reliability are enhanced. Multi-hop systems also allow the mesh network to offer very high bandwidth at lower radio power levels. Finally, meshing enables these wireless networks to support end-to-end broadband data rates to more than just sensors; video, imaging, and other bandwidth-intensive applications can be wirelessly networked to infield and remote users. Since the mesh network communication protocol is IP based, mesh networks can extend existing wired network applications to field personnel laptops and PDAs, giving field technicians real-time seamless access to their existing networks and applications.

Some mesh networks also offer self-forming, self-healing features. In these networks, each node maintains a continuously updated dynamic routing table. This enables the network to adapt to changing electromagnetic noise and environmental conditions by dynamically changing network connections. Meshing also creates redundant communication paths throughout the network, so if a node or link fails, the network automatically switches to new routes via alternate paths. This intelligent routing allows for automatic network capacity balancing because the signals will automatically hop away from congested routes. This ensures continued connectivity, increased network utilization, and enhanced end-to-end reliability. Self-forming and self-healing routing also means that additional mesh-enabled devices will automatically join the network when they are powered up. 

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