Original URL: http://www.theregister.co.uk/2008/04/21/mesh_networks/
Ruckus and Terranet rewire Mesh Wi-Fi dream
No longer just for socialist dreamers
Despite various attempts to change the world using mesh networks, real deployments are thin on the ground and the technology has not proved the panacea that some had hoped.
But two companies, at least, still reckon mesh networking can change the wireless world.
In a mesh network each wireless point of presence can use surrounding points as a route to somewhere more useful. In a Wi-Fi mesh, for example, an access point might not be connected to the office Ethernet at all, but simply pass traffic on to another access point which might itself just be a hop on the way to a wired connection.
Ruckus Wireless's 802.11n access point does exactly that. Ruckus reckons the speed of 802.11n makes it ideal as a backbone connection, and its access points can manage such connections thanks to their ability to become directional - each access point has 12 directional antennas and switches between them to improve the signal.
The hardest part of running a mesh is the routing, working out which packet should be directed where, and the user-management, sorting out users and security. Ruckus solves the latter problem with Zone Director, and even with 802.11n its networks are limited to three hops (before getting to a wired access point) so routing isn't too complicated.
Much more complicated is the mesh proposed by Swedish outfit TerraNet. It can cope with seven hops, and the firm expects to be able to carry voice over the connection - which is a good thing as its access points are mobile phone handsets. TerraNet does not expect routing to just connect them to the nearest wired point. Once they're deployed into a village, the firm reckons the majority of calls will originate and terminate within its mesh, without touching any servers or gateways anywhere.
With no central infrastructure the cost of deployment is very low, and the company has developed a robust pre-payment mechanism to ensure that minutes are deducted even when the connection is only local, so a profit can still be made.
One of the examples TerraNet gives is of a hiker atop a mountain trying to communicate with a helicopter hovering nearby: using traditional mobile technology the call would have to be routed to the nearest base station, if coverage was available at all, but with their system the call goes direct from the summit to the air.
TerraNet's plans are impressive, though for the moment its technology is limited to a few demonstration circuit boards and lots of PowerPoint slides. But the availability of kit from Ruckus demonstrates the practicality and utility of mesh networking when it's done properly.
Both companies are using 2.4GHz, the industrial, scientific and medical (ISM) frequency that is reserved world-wide for unlicensed use. In Western countries 2.4GHz is pretty packed, though TerraNet points out its technology isn't aimed so close to home.
Mesh networks were envisioned as the ultimate disruptive technology, replacing cellular, and even fixed, networks with thousands of volunteer nodes. That hasn't happened yet, but meshes are popping up around the place and could yet prove to be an important technology. ®