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From what I can tell, best practice for setting up WLANs in the 2.4GHz spectrum has been to limit channel selection to 1, 6, and 11.

Channelfly does away with that meaning any channel can be used if the algorithm thinks it is less congested.

Has anyone had experience with this in practice? I have seen a few reports that it is not very effective.

In my opinion, it also makes it harder for other techs such as 802.15.4 to co-exist in a friendly way.

How effective is channelfly in reality?

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    This sound like market-speak for a functionality as simple as iw wlan0 survey dump on a linux laptop. – BatchyX Mar 20 '14 at 11:42
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    I think you're misinterpreting what Channelfly does. It will not pick "any" channel -- it will choose among 1, 6 and 11. To choose anything else will almost guarantee interference from other adjacent channels. The problem with this technology (or other mfrs have similar capability) is that when the AP system decides to change frequencies, there often isn't a better choice. The 2.4G band is very crowded, so in a office bldg for example, all channels are already in use. Switching to another might be just as bad. – Ron Trunk Mar 20 '14 at 12:22
  • Also consider that when one AP changes, its neighbors have to change too to avoid co-channel interference. That may result in reduced performance somewhere else in the building. – Ron Trunk Mar 20 '14 at 12:24
  • @Ron The information from Ruckus states it uses all channels: [c541678.r78.cf2.rackcdn.com/feature-sheets/fs-channelfly.pdf] This is why I am skeptical about it's effectiveness. – Dwev Mar 20 '14 at 12:37
  • @Dwev Yes, I see that, and IMO, that's the marketing department taking liberties. For example, imagine that channel 6 very is busy. That means that channels 4-8 will also be busy because of the bandwidth required for users on 6. If Channelfly chooses channel 3, the side bands will interfere with users on 1 and 6, and they will interfere with ch 3 users. The only safe choices are 1 and 11, and as I said above, those often won't be any better. – Ron Trunk Mar 20 '14 at 12:49
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Channelfly, and similar features from other manufacturers (e.g., Cisco Clean Air) attempt to improve wifi performance by directing an AP to change to a different channel when it detects interference. The idea is that the AP can switch to another channel to avoid the interference, for example, from a microwave oven or even an overly crowded channel.

While this sounds good in theory, there are a couple of factors that limit its effectiveness. First, there are only 3 usable channels in the 2.4GHz band. Because the entire band is often crowded and shares the spectrum with non-wifi devices (microwave ovens, garage door openers, wireless video cameras, etc.), its is often the case that if one channel is being interfered with, so are the other two. Microwave ovens operate approximately on channel 9, where they interfere with both 6 an 11. That leaves just channel 1 as a possible substitute. There is no guarantee that it has less interference or lower channel utilization.

Second, in a large wireless system, there is usually a central controller that controls and coordinates the channel of every access point. The controller tries to adjust each APs channel so that no two adjacent APs are on the same channel (reducing co-channel interference). If one AP has to change channels to avoid interference, then its surrounding APs also have to change channels to avoid co-channel interference. That in turn causes other APs to change, cascading the channel change throughout the network. You might end up reducing interference in one location, only to increase it somewhere else.

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  • This is not only about channel interference, it's also about channel utilization. If there is another wifi network that is heavily used on the same channel as yours, you will have zero interference but heavy media access contention. This is common in crowded cities. – BatchyX Mar 22 '14 at 18:29
  • @BatchyX you are correct. But in crowded cities, as you point out, the other two channels are likely to be just as crowded. – Ron Trunk Mar 22 '14 at 19:31
  • Depends, i've seen particularly braindamaged configurations where channel 1 is unusable, but 6 is almost clear. – BatchyX Mar 22 '14 at 19:59
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From my experience ,channelfly proves to be a great feature in environment where the RF presence and interference level is potentially unpredictable and requires constant scanning for better channels.The ISP for which I used to work deployed RUCKUS APs and the channel fly proved to be a boon for us in areas where assigning channels manually proved to be cumbersome.We are now looking forward to also use the feature of beamflex as we have not yet employed 5 GHz band.Looking forward for the results....

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