A swath of radio frequencies recently approved by the Federal Communications Commission (FCC) as unlicensed spectrum has come into play in the growth of wireless broadband networks.

A 250MHz patch of the 24GHz band is now available unlicensed for point-to-point links between radios on towers or roofs with a clear line of sight between them. In addition to letting an enterprise or service provider span an environment where cables can't be laid, such as a creek, point-to-point wireless gives competitive carriers a way to quickly deliver high-speed data services without paying -- and waiting -- to use another carrier's lines, according to industry analysts. That could mean more options and lower bandwidth costs for many businesses.

Radio maker DragonWave said Monday it has added 24GHz capability to its AirPair-100 fixed wireless systems, which have been on the market since 2001 for use with licensed frequencies between 18GHz and 38GHz.

AirPair is designed for use by both enterprises and service providers for access and backbone links, according to Erik Boch,CTO and vice president of engineering at DragonWave, in Ottawa, Ontario.

AirPair can provide a link as fast as 100M bit/sec that plugs directly into a Fast Ethernet port on a carrier's or enterprise's router, Boch said. With the new unlicensed-band capability, enterprises can save the cost and complexity of getting a radio license and carriers can quickly set up a link to a new customer or a new coverage area when the opportunity arises.

This is especially good for competitive carriers that want to enter new markets quickly and without having to lease fiber capacity, Boch said.

"It allows you to sneak into the next guy's territory under the radar," Boch said.

The longest link created so far with AirPair is about 38 kilometers (24 miles), but some customers plan to deploy the technology over distances of more than 70 kilometers, he said.

The strength of a signal isn't degraded over a long distance but very heavy rain over a long distance can cut it off, so DragonWave provides software with local rainfall information that helps customers in different locations find the right balance of distance and reliability, he added.

Looking beyond its 100M bit/sec technology, DragonWave is developing a system that would provide 1G bit/sec of capacity, Boch said.

The radios are designed for easy installation and setup by employees who have never worked with radio equipment, Boch said. To position and test the radio units, the deployer can use a PalmOS PDA with a DragonWave application, plugged into the PDA via its cradle port. The software tests the network connection and gives graphical instructions on how to position the antenna.

Boch, a cofounder of DragonWave in 2000, is confident the company has a head start on potential competitors. Its products can be manufactured without hand-tuning by radio specialists, unlike those of most competitors, which allows for high-volume production and low prices, he said.

TowerStream, a wireless broadband provider in Waltham, Mass., has begun using the DragonWave 24GHz technology for access links to corporate customers with high bandwidth requirements. Provisioning this type of connection is much easier than setting up one with a licensed frequency, said Jeff Thompson, COO and founder of TowerStream.

The provider has rolled out service to a Boston-area customer using DragonWave, he said, and the process took only hours. By contrast, provisioning a point-to-point link using licensed frequencies requires a study of possible interference, an application to the FCC and a waiting period for potential protests from other local users of the frequency, Thompson said.

Some companies are embracing wireless broadband because it provides a truly redundant backup connection to the Internet, according to Thompson. With wired leased connections such as T-1 lines, both the primary and the backup connection could be on the same set of fibers.

"If someone takes out the fiber going into your building, it's going to take out all the T-1s you've got. Meanwhile, we're going off the roof," Thompson said.

Unlicensed fixed wireless can help competitive service providers grab business customers, according to Patti Reali and Bettina Tratz-Ryan, analysts at Gartner.

"If you want to be a competitive service provider and you want to get up and operating quickly, you don't have to get a license and you don't have to lay fiber, so the economics seem to be ... more compelling," Reali said.

Competitive providers that need to use wired capacity from the incumbent carrier typically have to factor in a delay of four to six weeks when they roll out a leased line to a customer, Tratz-Ryan said.

The 24GHz range should be good spectrum for high-capacity fixed wireless, the Gartner analysts said.

"There's not going to be a whole lot of people who are going to be interfering with it ... given that it's a pretty wide swath," with relatively little activity on the portions of spectrum above and below it, Reali said. It also helps that the high frequency results in very narrow beams that are less likely to run into each other, said Yankee Group analyst Lindsay Schroth.

Point-to-point wireless devices that use lower frequencies don't have to be aligned as precisely as do the 24GHz gear, but the trade-off is generally lower maximum capacity, she said.

The move to IP-based radios such as DragonWave's from traditional circuit-based systems is driving down the cost of point-to-point wireless systems, according to Emmy Johnson, principal analyst at Sky Light Research, a wireless last-mile research company in Scottsdale, Ariz. Wireless may be a key technology for competitive service providers to bring high-speed business services to suburban and rural areas out of reach of cable and DSL broadband, she added.

DragonWave's AirPair-100 with the 24GHz capability has a list price of about $20,000 per link, including two radios and all the hardware and software needed to set them up. It is available now in the U.S. and undergoing approvals in Europe. Regulatory changes will probably happen soon in Canada that will allow the product to be sold there, Bloch said