BANC on Non-Interference

By Gerry Blackwell

February 26, 2004

Bay Area WISPs are putting aside competition to come together and fight their biggest foe: service problems from frequency interference.

Channel interference in outdoor -- and even indoor -- wireless networks, with resulting loss or degradation of service, will be an increasingly common problem for operators as 802.11 technology becomes ubiquitous and the number of service providers grows.

Wi-Fi operators should therefore take special note of the initiative by a group of non-Wi-Fi wireless Internet service providers (WISPs) in the San Francisco Bay/Silicon Valley area.

Led by Fremont, California-based WISP NextWeb, eight network operators in the area -- most nominally competitors -- banded together late last year to form the Broadband Access Network Coordination (BANC) group. Its mandate is to prevent or reduce interference problems among members, and promote frequency management best practices.

BANC members agree to follow a set of best practices and protocols that were in large part developed by NextWeb, one of the largest WISPs in the country. The company is adamant it's not imposing anything on anybody, though, or trying to.

"We don't want to be seen as a big guy pushing everybody to comply or else," says NextWeb president and CEO Graham Barnes. "We want it to be in everybody's interest, so we're doing the whole thing on a neutral basis. That's a very key thing."

The other full members, according to the BANC group's Web site, are Alta Network, ArcWave, Dandin Group, Egation Communications, Etheric Networks, Gatespeed Broadband and Lightwings Communications. Associates include KDWeb, Neopolitan Networks and SkyPilot Networks.

Interference was not a problem a few years ago for pioneering WISPs such as NextWeb. Like most BANC members, NextWeb uses point-to-point and point-to-multipoint technology operating at the upper end of the 5GHz Unlicensed National Information Infrastructure (U-NII) band.

This spectrum was supposed to be relatively free of interference, at least compared to 2.4GHz where most Wi-Fi systems operate.

"These [5.7-5.8GHz] systems are now being used to deliver a lot more payload, though," notes Barnes. "They're serving many more users and there are many more operators. We're now working in a multi-operator environment."

If no precautions are taken, it's very easy to interfere with another operator. It's often the case that a new and inexperienced service provider inadvertently tries to use the same channel as an established operator.

The result can be a temporary loss of service to subscribers on one or both networks or severe degradation -- with data rates sometimes slowing to dial-up levels.

Before BANC, Barnes estimates, there was about one incident a week on average across all of the company's operating territory, which includes 60 cities in California, many of them outside the Bay area.

NextWeb started on its own by developing a set of frequency management best practices and tools for monitoring its networks, and training its engineers and technicians to use them. It often now knows about interference situations long before a customer is aware, Barnes says.

Then it began to contact other service providers in the Bay area about forming a group to help cooperatively manage the interference problems they were all experiencing. The eight current members and three associates account for "all of the most likely potential interferers" in the region, he says.

BANC starts with two guiding principles. Any operator entering a market where other service providers are already doing business will determine what spectrum is already in use and take steps to avoid it. Those who do inadvertently interrupt another's operation will offer to resolve the interference immediately.

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