Nortel Networks is preparing to launch a Wi-Fi mesh product next year, following trials with BT and MIT's Media Lab. The system could cut the cost of some Wi-Fi network installations by as much as 70 percent by eliminating network connections from many of the access points, Nortel claims.

"BT has proposed this trial to a large enterprise customer in London," said Etchieson -- no details yet as to who or where. MIT, meanwhile, has six access points in a network which reaches from the Media Lab to a hotel outside the MIT campus, and will expand to twenty access points by the end of the year. "They will stretch this tech and see how it could be used in future," said Etchieson.

The architecture uses specially built dual-radio access points; the trick being to use the 802.1b/g radio for access, and the 802.11a radio for "backhaul" connections to the wired network. Each access point includes a router, so the traffic can take multiple hops across a mesh of access points, before hitting a wire.

"This has big advantages in a place where you don't have existing Ethernet," according to Todd Etchieson, director of business and technology strategy, in Nortel's wireless networks division. "You don't have to pull cable, you just have to provide AC power." Suitable sites might be large open convention areas, parks or campuses. The network sets itself up by autodiscovery, so each new access point is brought into the network. If one node fails, the others route around it, so it is also "self-healing". Smart antennas ensure that the range of the 802.11a is enough to span to the next access point, with a directional boost, said Etchieson.

Nortel is "looking at having [a mesh product] available in the first half of next year," said Etchieson. The access points will be more expensive than conventional (thin or fat) access points, but for some situations it could represent a big saving, he said. The eventual product will be aimed at service providers and enterprise customers, said Etchieson: "This technology crosses a lot of boundaries. We are getting interest from all segments."

Service providers wanting to give blanket coverage to a large part of a city could do so with cheaper backhaul, said Etchieson: "If you are covering a large downtown area with a hundred access points, in the current model you would need a hundred different ADSL or E1 lines for backhaul. With a wireless mesh network you could reduce that to five E3s. The recurring charge for that would be much less."

Enterprises with a large campus might be interested too, although Etchieson concedes that inside most corporate buildings, the problem is not Ethernet access but power cables: "If you have Ethernet, I would say go out and get our usual access point. It has power over Ethernet."

The announcement will complement, not replace Nortel's efforts to make campus wireless networks, based on the centralised switch model, designed for areas where Ethernet is widely available.