At the Intel Developer Forum in San Jose this week, wireless networking has been a major theme. Yet while the success of Wi-Fi as a replacement for wired networks is not in doubt, there may be more to wireless than just an alternative to cables.
Intel's Network Architecture Lab has unveiled some of its ideas about a wireless system called mesh networking, which could massively increase bandwidth and reliability. They also demonstrated a prototype network using the technology. Researchers Mike Witteman and Lakshman Krishnamurthy described the current state of the art, and outlined why Intel thinks mesh could be a major technology in the near future. "It's like a minature version of the Internet," said Witteman, "and with many of the same advantages."
Each device on a mesh network not only receives and transmits its own traffic, it acts as a router that forwards messages destined for other stations. Although mesh isn't a new concept, the sudden ubiquity of 802.11b networks — Intel predicts 90 percent of laptops will have 802.11b as standard by 2004 — has focused attention on the evolution of wireless. Because each node on a mesh network only has to make contact with its immediate neighbour and not a distant base station, it can transmit at a very low power; frequencies used by one node can be reused by another only a short distance away. "The physics of wireless networks means that nodes close to each other can operate at much higher speeds, all else being equal," said Witteman.
Mesh networks are also inherently robust, as new routes can be found if any one node goes down. There isn't normally just one point of failure. Witteman identified four main areas where mesh wireless may be useful. In the enterprise, mesh can be used to quickly extend the reach of a wireless LAN without having to wire up new base stations, and it can also be used to balance network traffic load as the nodes can automatically choose to use their more underemployed neighbours and avoid congestion.
Wireless ISPs can use the technology to provide service in areas out of range of their main transmitters, by relaying connectivity through their users — the new standard for last-mile broadband wireless, 802.15, will include some mesh ideas. Industrial users can quickly deploy networks of sensors and controllers in factories and laboratories. Home users will be one of the major areas for mesh, according to Intel, especially when the entire household starts to want to watch high quality video streamed from the home server. Each link from the server to the viewer will route to avoid the others, resulting in lots of reliable high bandwidth connections.
Witteman foresees the availability of domestic wireless routing nodes "that plug into a power socket like a room freshener": if you need more bandwidth or want to extend the network further afield, you just buy some more blocks and plug them in. Although the researchers didn't mention it, the military are also very interested in mesh networks and have funded much of the original and continuing research into the more difficult areas — routing packets across a network that can be constantly changing is challenging, and maintaining high quality links in real time with nodes in motion is also what engineers call a non-trivial task.
But the military see a good correlation between mesh networks and battlefield communication: they also see it working well with the new breed of silicon radios that can rapidly reconfigure themselves to new frequency bands and transmission methods to avoid interference and jamming. The same technologies, including security and robustness, may well be applicable to high density urban environments: Krishnamurthy said that security and management were areas where work was being done; installation, coexistance and quality of service were also under active investigation.
