News

EarthLink Adds 23 GHz Radios to Muni Plans

The urban backbones for EarthLink's municipal wireless products will get 200 Mbps radios.

by Alex Goldman ISP-Planet Managing Editor [July 25, 2006]

Atlanta, Ga.-based EarthLink announced yesterday that it is adopting Kanata (Ottawa), Ontario, Canada-based DragonWave's AirPair project to provide vital backbone links in tier 1 municipal wireless projects.

"We're pleased to have won the EarthLink contract and are pleased to be able to talk about it," says Alan Solheim, vice president of product development.

One month ago, ISP-Planet published sharp criticism of EarthLink's municipal architecture. The criticism (see Will EarthLink's Muni Architecture Fail?) came from members of our ISP-Wireless list, who were particularly skeptical of the power of Tropos to deliver what EarthLink was ready to demand of it.

EarthLink's head of corporate communications, Jerry Grasso, told us at the time that EarthLink already had the answer, but we publish announcements, not promises. Even though we believed him, we had nothing to publish.

All of this changed with Monday's announcement.

200 Mbps at 23 GHz
Jeb Linton, chief architect of EarthLink's municipal services division, says that DragonWave radios are ideal.

Noting that Motorola recently acquired Orthogon Systems, we ask why not use Orthogon. "We will use Orthogon gear," Linton says, "but it operates in the 5 GHz band. With it, you get 45 Mbps throughput, where spectrum is available. The Orthogon stuff is good, and we like it, but [with Canopy] we're already using that 5 GHz band for other purposes."

DragonWave radios use other bands. "For backhaul, we prefer to mostly use 23 GHz licensed and 24 GHz unlicensed spectrum."

Is 23 GHz spectrum licensed on a point to point basis? "23 GHz spectrum is a per link license. We get a third party provider to check each site, based on FCC guidelines, and ensure that the narrow beamwidth we're using won't interfere with other installs in the area. We like it particularly because these licenses are easy to get. The equipment has a beamwidth of about two degrees. There's a low risk of interference with others or from others. And once you've got the license, that guarantees that there will be no interference."

So Orthogon is out, for backhaul, because there's a lot of interference is the 5 GHz band? "There are probably a few places where we will do backhaul on 5 GHz radios, but you have to be careful about the level of interference. You have to budget in interference when calculating the distance you get from the antenna."

But isn't it true that the shorter the wavelength, the shorter the propagation distance? What are the limits for 23 GHz? "DragonWave has very good, tried and proven models for determining exactly the distance you get. The models take into account the weather (such as haze) over a particular distance in a given band. The tools they provide make it very straightforward to determine the reliability you'll get over a specific link with a specific antenna."

If you've tried 23 GHz, have you tried LED or laser solutions? "Free Space Optics (FSO) has distance limitations. Generally our towers cover two miles, give or take. That places towers a minimum of a mile and a half apart. Many FSO solutions are reliable to a maximum of one mile. They might work if you were in a desert, and there was never any fog."

Was price a consideration? "DragonWave does have very good price point, but its competitors are aggressive too. Their advantage is their Ethernet interfaces. With their products, you do not have to pay the additional cost of SONET interfaces. You can stick with simple Ethernet."

Even better, Linton says he has not pushed the DragonWave AirPair to its limit. "With a two foot (relatively modest) dish, we get better than the 6 miles our backhaul links typically require."

The dragon has landed
He says one DragonWave pair is operating in the EarthLink trial in Minneapolis, and another will be deployed in Anaheim soon. He says the first very large implementation will be in Philadelphia.

The core of the Philadelphia deployment is the local Level 3 data center. "Level 3 is the epicenter of network for Philadelphia," he says. "The rooftop happens to be a good place to get LOS to the other towers around Philadelphia."

In general, the new EarthLink architecture calls for 10 to 40 towers per city, Linton says, and wireless backhaul makes the economics possible. "It would not be cost effective to use leased lines or fiber. Logically, we want wireless backhaul."

The people at DragonWave have a clear idea of what ISPs want from future product. "They want more, and they want it cheaper," says Solheim.

"We're expanding rapidly outside of North America," he adds. "We're now doing customizations for other nations."

DragonWave has always claimed a clear manufacturing process advantage over the competition, allowing it to deliver products cheaper and faster. "Traditional manufacturers," Solheim says, "outsource the production of modules to someone else and then assemble the modules and interconnect them. It's a process that involves a lot of manual labor. It's expensive and it causes long lead times that make it difficult to respond to variations in the market. In contrast, we have a standard surface mount. We've automated the manufacturing and automated the testing. This gives us a better cost point, economies of scale, and a more rapid conversion time from raw materials to finished goods. It takes our competitors 6 to 12 weeks. It takes us 2 to 3 weeks."

—End