Cross-Channel/Adjacent Channel Interference Mitigration

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We have a high-density deployment of APs serving 200-300 clients/day. From my surveys, we have a lot of ccci and aci. What are some best practices for mitigating interference? 
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JasonD

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Posted 1 year ago

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Michael Brado, Official Rep

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Use the fewest SSIDs as needed, don't locate APs too close.
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JasonD

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What would be considered too close? ...AP proximity seems to be very subjective. We're running tx power -8 for 5ghz and -3 for 2.4 (only corner APs) to mitigate the ap proximity issue.
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Dionis, AlphaDog

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JasonD,

Well, you started well by using Ruckus, assuming that's the case.  With 2-300 clients density, you shouldn't have too much of a problem with Ruckus APs.  As stated by Michael, positioning the APs with a bit of distance in between and ensuring that structures are well defined, as in making sure there are no metal walls, elevators or things of that nature that could cause you issues AND utilizing as few SSIDs as possible is a great way to start. 

Ruckus APs are very effective at mitigating interference and are used in some of the highest density environments in the world today.  You will be pleasantly surprised as to how well they operate once deployed.

Have fun. 
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JasonD

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Thanks, Dionis. They're deployed and in production, I'm working on optimizing our deployment. I've been using a netscout aircheck g2 for quick testing and it keeps throwing errors for cci and aci. I want to make sure I'm not overlooking anything.
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Dionis, AlphaDog

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Sounds good.. 

Remember that we use proprietary technology that permits us to use overlapping channels such as 2,3,4,5,7,8,9,10, etc on the 2.4Ghz spectrum.  Your testing equipment may see this as an error and cause your reports to show cci and aci.  Our APs use channelfly and beamflex to mitigate this interference and work around those issues by ensuring that signal is sent directly to the client and not necessarily to the nearby APs.  So, while your tools may see co-channel interference, that may not necessarily be the case with the APs themselves.  At least not to the same level that the test equipment may see it.  Take a look a this short video https://www.youtube.com/watch?v=BvIu_g3nN4g.

The best way to test and verify that your network is operating as expected is by using real clients with real data.  Grab your devices and run some high quality videos such as 4k or HD from real sites on the internet.  Make sure those sites have good quality streaming services.  See if you detect any issues on a few of those devices.

Things you may want to consider are data rates allowed at the moment.  May want to lock in min BSS rates of 12Mbps or higher if no 802.11b clients are being used in the environment or they are at a very minimal use.  This will help improve your network performance and prevent slow clients from causing issues later on.  Again, only do this if you are sure you don't have a lot of b clients or devices that rely on these data rates to operate running in your network. Most devices today don't, but just to be sure.   
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JasonD

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Thanks, Dionis! Our consulting Ruckus engineer recommended  a three channel 1,6,11 2.4ghz model, which we're using alongside background scanning. Would you agree with that? Another engineer suggested a 4-channel model utilizing  1, 4, 8, and 11.

We've enabled ofdm-only, bss-minrate 12, and a few other things.
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Dionis, AlphaDog

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I personally tend to stay away from making too  many customization to the network and let the APs do their thing when dealing with Ruckus APs.  I've deployed many other vendor networks before as well as Ruckus and for them I surely have had to make several changes like those that you described. 

With that said, I'm sure that the Ruckus engineer's recommendations are justified and he knows what the best approach is for your specific case.  WiFi is one of those things, can't really recommend much without looking in details the design and implementation as well as environment.  In many cases, limiting channels to those non-overlapping ones is the best way to approach things, sometimes, leaving things alone and the APs to do their discovery and avoidance as design is the best path.  It really all comes down to your environment and use case. 

How many APs in total are you utilizing here and are they using a Ruckus controller? 
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JasonD

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Fair enough, I agree with that. We're running redundant ZD1200s with 10 R710s (we added two more this weekend to address dead spots) @ -3 2.4 and -8 5ghz tx power.
(Edited)
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Dionis, AlphaDog

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In your case, may want to leave tx power on 5Hgz on auto/full. Just a suggestion. You won't have interference problems on 5Ghz even if they were all relatively close. I usually run about 12 APs stacked on top of each other in a live trial and training platform with upwards of 25 people using them and don't ever see an issue
(Edited)
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JasonD

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Very, very interesting! During our first survey it was recommended to bring 5ghz all the way down to -8, but I've been toying with increasing tx power upwards. I think I'll take the plunge now :)

What type of negative repercussions might I see if 5ghz is too powerful? Constant client roaming?
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Dionis, AlphaDog

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Doubt you will find any negative impact in your case.