Wireless LAN performance is a moving target for enterprises since Wi-Fi relies on unlicensed, shared radio frequency...
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(RF) spectrum.. So vendors have taken to battling it out for the best RF management and optimization solution. The latest punch thrown in that fight is automated wireless channel selection.
Wireless LAN vendor Ruckus Wireless, which is known for its beamforming technology that performs real-time analysis of the wireless environment to choose the best path for transmitting signals between wireless access points and clients, has added ChannelFly to its offerings. ChannelFly is an automated wireless channel selection technique that uses real-time analysis of channel capacity to choose the best Wi-Fi channel to serve wireless clients.
Ruckus joins a crowded field of vendors offering various forms of wireless LAN channel selection, and the company has a ways to go in proving the significance of this release.
“All these vendors have their various techniques for choosing the right [Wi-Fi] channel [and] for transmitting the signal to get to a destination at the highest signal-to-noise ratio, but the fact of the matter is that there is no one vendor that is clearly superior to everybody else,” said Paul DeBeasi, research vice president at Gartner.
Ruckus says the difference is that many vendors make wireless channel selection decisions by passively listening to other Wi-Fi channels for a few milliseconds at a time while not actively communicating with clients. But Ruckus access points enabled with ChannelFly use the dynamic frequency selection [DFS] feature of the 802.11h IEEE standard to bring wireless clients with them as they migrate from one Wi-Fi channel to another to perform real-time wireless channel selection analysis.
“By listening to the packets that are out there, we can understand how many megabits per second a channel can have,” said David Stiff, Ruckus director of product management. “We get a view of how the capacity should be for each channel and then we pick the channel with the best capacity.”
Real-time wireless channel selection can open up channels in the 2.4 GHz band that enterprises typically avoid due to signal overlap. Today, most wireless LAN networks operate only on channels 1, 6 and 11 in the 2.4 GHz band, but ChannelFly can analyze other channels to see if they offer better capacity in a particular environment.
Opening up those extra channels was important to Ruckus customer Towerstream Corp., a 4G and Wi-Fi wireless Internet service provider that was an early beta tester of ChannelFly. It activated the technology on the 1,250 Ruckus access points it had deployed on its New York City-based public Wi-Fi network that it wholesales to service providers.
“There are 11 channels of Wi-Fi spectrum [in the 2.4 GHz band] to select from. The legacy approach is to look at channels 1, 6 and 11 decide on which is the best channel,” said Arthur Giftakis, vice president of engineering and operations at Towerstream. “You leave a lot of other channels on the table, and when you have as many access points as we do and with so many other access points in the environment, we wanted something more robust.”
ChannelFly doesn’t just look at noise on every channel, it looks at how much capacity would be available on each channel every 15 seconds. It also checks modulation rates, the number of clients and neighboring access points in order to make intelligent decisions, said Giftakis.
That means ChannelFly’s wireless channel selection capabilities might identify that channels 1, 6 and 11 offer 20 Mbps capacity, but the little-used channel 8 offers 80 Mbps.
“Some existing techniques out there would not do that, so it’s almost tripled my available [wireless] channel selection,” Giftakis said.
Towerstream hasn’t done a comprehensive analysis of how this wireless channel selection has improved its network performance, but Giftakis does have anecdotal evidence of improvement from his early testing of ChannelFly.
“We were originally getting 5 or 6 Mbps on an iPhone with 18 milliseconds of latency,” Giftakis said. “That was great, but when we started rolling out ChannelFly, we started seeing much higher throughput and lower latency --12 to 15 milliseconds of latency and 8 to 10 and even 20 Mbps on an iPhone. Our testing is up 3 to 5 Mbps per smartphone device.”
Giftakis described an initial “learning curve” for access points performing wireless channel selection with ChannelFly.
“It moves channels a little more rapidly in the beginning until it settles down and gets a good benchmark of all the channels, and then it gets to a point where it rarely moves around unless there is a big gain to be had,” he said.
This rapid transition from one channel to another might affect performance initially, a process that could take a couple hours, according to Giftakis. But it didn’t impact Towerstream’s network.
“We burn a site in for a week to two weeks before we put it into production, so there’s no consequence,” he said.
Every vendor has a wireless channel selection story to tell
Ultimately the decision as to which RF optimization solution works boils down to the individual needs of the user.
“The radio environment can change from moment to moment. Sometimes there is saturation and a millisecond later there is not. So channel allocation strategies and radio optimization strategies need to take into account what the organization is trying to do, whether it is increase capacity or some other metric, and determine whether [a technology] contributes anything,” said Craig Mathias, principal at the consultancy Farpoint Group.
Gartner's DeBeasi would like to see some third-party testing of Ruckus’ wireless channel selection feature, and metrics on what kinds of results customers can expect to have with ChannelFly.
“Ruckus should have had a third-party do a standard configuration against Cisco, Aruba and Ruckus, and demonstrated that under certain test conditions you get [certain] throughput,” he said. “But they didn’t do that. This is just throwing technology out there and giving it a cool name.”
Advanced wireless channel selection is cool, but most enterprises need to get down to basics
Technologies like ChannelFly might offer enhancements to wireless LAN performance, but most enterprises have plenty of other things to worry about before that, said DeBeasi.
“Most enterprises have done a terrible job of designing their networks,” he said. “Many are still using 802.11g, or if they are using 802.11, they never did a site survey and they never did a design. They just threw things in there. Even without Ruckus’s ChannelFly, customers can get a boost in performance just by using best practices. Many aren’t following best practices because they just don’t have the money to rip out stuff they put in three or four years ago.”
Let us know what you think about the story; email: Shamus McGillicuddy, News Director.
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