All these agencies use a variety of different radio systems which usually can't communicate. But this time they were equipped with a new type of data link allowing them to coordinate on laptops, PDAs and tablet PCs with video links, real-time resource maps and multimedia messaging, among other applications.
The three-hour session was a simulation by the Golden Gate Safety Network, comprised of 11 California emergency bodies, trialling an emerging wireless networking technique known as mesh. In this case, technology from PacketHop, a Silicon Valley start-up, set up an ad-hoc broadband wireless network linking workers with different varieties of off-the-shelf equipment on the bridge, on land and on the water. There was no central server, no single point of failure, and the nodes were able to maintain their network connections without being in range of an access point -- each node acted as a repeater and router for the nodes around it.
The next step for wireless
Tech industry heavyweights such as Cisco and Intel believe mesh techniques are the logical next step for the wireless networks that are increasingly ubiquitous in offices, homes and public places. Enterprises could use mesh to quickly create new wireless networks or extend existing WLANs without needing a wired connection to each base station. Mesh-enabled base stations are good at load balancing because they can choose the most efficient path for data. Industrial users can quickly deploy networks of sensors and controllers with embedded wireless mesh radios.
Start-ups and established vendors are selling modified wireless local-area network (WLAN) kit incorporating mesh ideas. Standards groups are working on building mesh into the families of standards in use today, such as 802.11, and those coming down the line, such as 802.16 (also known as WiMax). On the embedded side, mesh technologies are feeding into nascent standards like ZigBee.
A fine mesh
In essence mesh is something very familiar -- wireless mesh networks are really just applying the basic principles of the wired Internet to the wireless world, says Scott Burke, vice president of engineering for PacketHop: "The fixed Internet we have today can be thought of as a large fixed mesh network."
Each device on a mesh network receives and transmits its own traffic, while acting as a router for other devices; intelligence in each device allows it to automatically configure an efficient network, and to adjust if, for example, a node becomes overloaded or unavailable. The advantages include ease of setup, the ability to spread wireless access over a wide area from a single central wired connection, and the inherent toughness of such networks.
Perhaps not surprisingly, wireless mesh got an initial kick-start from the Defense Advanced Research Projects Agency (DARPA), the central research and development organisation for the US' Department of Defense, the same agency that helped develop the Internet in the first place. Early work on PacketHop's technology, for example, was carried out for DARPA at the Stanford Research Institute, and focused on creating on-the-fly wireless data networks for soldiers going into the field. The technology of Florida-based start-up MeshNetworks was originally developed under DARPA-directed programmes.
The military and security agencies are still seen as the most immediate markets for mesh products. "That's a market that is happening right now," says Burke.
Mesh in the enterprise
Enterprises may have a lot to gain from mesh-enabled WLANs, according to Nortel and a handful of start-ups targeting corporate networks. Nortel is launching a Wi-Fi mesh product in the first half of this year, the Wireless 7200 Series, although a planned London trial with BT has been put off.
"Whereas in a traditional WLAN solution every access point is connected to the backbone, in our solution we have eliminated the need for a wired backbone," says Peter Zwinkels, EMEA business development manager for wireless mesh networks. "This will make it possible to deploy wireless in areas where it was difficult or not cost-effective in the past."
These areas include large areas, either indoor or outdoor, such as a warehouse or a golf course. The catch with Nortel's solution is that a power source has to be present, although this could be a traffic light or streetlamp; but Nortel admits that customers in situations where traditional wired networks are available or could be easily installed would be better off with traditional power-over-Ethernet access points.
One of Intel's planned mesh trials at Dartmouth College, New Hampshire, will link students living in areas around the campus to the university network. The campus itself is already wired up, but many in the surrounding area have had to rely on dial-up connections; the trial, scheduled to go live this spring or summer, will give them broadband connections with no need for expensive telco or cable company infrastructure.
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