Nokia goes to the roof

(Telephony) Nokia has completed commercial trials of its fixed broadband wireless rooftop routing system and plans to deliver products in the second quarter of this year, a company executive said at this week’s Broadband Wireless World Forum in San Francisco.

Advanced Telecom Group (ATG) of Santa Rosa, Calif., and meer.net, a regional ISP in Mountain View, Calif., both successfully tested the routing system that uses a “mesh” architecture, the company said. The wireless routers, which were designed to model the wired structure of the Internet, operate in the license-free 2.4 GHz ISM spectrum, eliminating spectrum license costs, line fees and tariffs, but raising questions about signal interference from outside sources.

Nokia’s network, however, overcomes those problems by shortening the distance between receiver points, said Dave Beyer, head of Nokia wireless routers.

“The traditional approach to wireless has been based on point-to-multipoint architecture,” said Beyer. “That means you deploy base stations into the area with enough density to have a certain level of coverage down to the homes.”

In the unlicensed band, these base stations are susceptible to interference, he continued.

“Our solution is to break the network into two pieces. We use a traditional type of approach … to get to a single point in the neighborhood that we call the ‘air head.’ From that point we use a mesh technology and a wireless router technology to distribute the bandwidth around the neighborhood,” he continued.

Nokia’s network defeats interference by transmitting over short rooftop-to-rooftop links.

“We just have to identify a point in the neighborhood that can serve as an air head site. From there, adding a subscriber just means that you don’t need a line-of-sight link back to the base station or air head, you only need a line-of-sight link back to any other subscriber node and the network software will take care of the routing,” he said.

Each air head site can receive and disperse up to 12 Mb/s of bandwidth to six rooftop sites.

“At the initial rollout you want the area to be large. You want to be able to just have one air head site cover a couple mile radius,” Beyer said. “Then, as the network becomes more dense you want more of these air heads inserted. You deploy another point-to-multipoint or point-to-point link into another air head site and then switch over a couple customers that were near that one and add other customers around the first air head site.”

Nokia uses omnidirectional antennas that can receive and transmit signals from and to any direction without having to be adjusted.