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Americas Issue: December 2005
Cognio’s Spectrum Expert:
Helping Wi-Fi Find Its Place
by Telecommunications Magazine
Wi-Fi is an intrinsically courteous protocol. It won’t hog bandwidth in the 2.4 GHz spectrum. In fact, it’s designed to step aside and let other devices take priority. While Emily Post might find this behavior praiseworthy, network engineers find it annoying — at the least — and that’s why Cognio developed the Spectrum Expert product spectrum analysis solution.
“Wi-Fi is a very polite protocol. It will listen to the air and determine if there’s anything transmitting before trying to transmit. The net of that is that Wi-Fi isn’t really in a good position to compete, but it competes for spectrum with a bunch of other types of consumer devices,” said William Flanigan, vice president of marketing at Cognio.
The problem with Wi-Fi, added Joel Conover, principal analyst for enterprise infrastructure at Current Analysis, is that it will “take a backseat to whatever else is going on and that can negatively impact the performance of your network.”
There is a lot going on in a wireless enterprise network, with cordless phones competing with Bluetooth headsets competing with microwave ovens, and even fax machines running around within the unlicensed 2.4 GHz spectrum.
Despite the best efforts of regulators, network managers and vendors to eliminate interference, that’s a crowded space where, when elbows start to be thrown, Wi-Fi steps back and lets others take center stage, to the despair of those hoping to get broadband connectivity via their Wi-Fi networks.
“We took these really common complaints about wireless technology, and we looked at what tools you could use to solve the problem,” Flanigan said.
The result was the Spectrum Expert, a product that in its smallest iteration fits into a laptop computer and can be carted around a network sniffing out interference and pointing a finger at the offending party.
“It can tell you where it is ... and then we can use location technology to actually take you to the source of that interference,” Flanigan said.
A spectrum analyzer could, under some circumstances, accomplish that as well, but it would cost a lot more, weigh a lot more, be more difficult to operate and lack some focus.
“They weigh about 60 pounds. They’re the size of a tower computer or a small briefcase and a lot heavier,” Conover said. “They’ve shrunk this down into something that’s very portable. It’s focused on the wireless bands whereas a full spectrum analyzer is specifically targeted where the Wi-Fi signals live.”
Most self-respecting network engineers probably have some kind of spectrum analyzer to check on network interference issues with both wireline and wireless devices. Besides being big and expensive, they’re also hard to use.
“People don’t like the form factor of a spectrum analyzer. It requires an expertise in RF that most people who are IP people don’t have,” Flanigan said. “Where a traditional spectrum analyzer will show you squiggly lines, our Spectrum Expert will show you squiggly lines but also tell you there’s a cordless phone, there’s a microwave causing the problem.”
That targeting capability, along with the size and ease of use, make the Spectrum Expert “a fairly cost-effective piece in an arsenal for dealing with pinpointing problems. It’s a walk-around style tool,” Conover said.
It’s not, he emphasized, something that everyone is going to need, “It’s something that is relevant if you’re having problems.”
A lot of wireless networks are having problems that can’t be readily identified, Flanigan said.
“If the network’s slow, it can be any number of things. You could have some sort of rogue on your network that has some denial of service happening; it could be a network configuration or client configuration issue or it could be a physical layer issue,” he said. “On top of that we came to the realization that a lot of the problems with Wi-Fi really have their roots in the physical layer.”
The Cognio equipment can sniff out those problems.
“This thing runs at Layer 1. It’s as low as you can go and the fact that it’s got expert analysis of that Layer 1 area makes the tool easier to use,” Conover said.
Most importantly, it identifies the problem so it can be solved.
“Knowing what the problem is solves about 90 percent of the problems,” Flanigan said. “Naming devices is something that nobody else does. Because we can name them, we can locate them.”
And to locate them is to eliminate them.
“It can tell you if you have a Bluetooth interfering source or a microwave or a fax machine. Anything can generate interference that can dilute a Wi-Fi signal,” Conover said.
The product comes in two form factors: the laptop version used for roaming analysis and an enterprise version that’s built as an overlay for a typical access point network.
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