How much non-802.11 interference is too much?

[DRNeale]

So, I was reviewing utilization on an MR26 today and noticed that the non-802.11 interference was running about 8% on channel 1 of the 2.4 GHz band.  Curiously, at the same time, the utilization was 26% with no current clients connected.

Anyway, is 8% too much non-802.11 interference to be tolerated?  If not, what is too much?

Thanks,

Dan Neale

[GIdenJoe]

You can't really put a number on it.

It depends if you have reduced quality of experience at that spot.

8% can be low enough if you only have a typical usage of 20% airtime as a baseline.

Does the interference stick to one channel?

[DRNeale]

Thanks for the reply. 

Out of 41 various MRs on this site, I could only find 2 that were showing this much non-802.11 interference and only on the 2.4 GHz channels.  However, almost all real usage is on 5 GHz channels so we've not had any usage complaints recently.

It's not practical to change the channel assignment right now due to adjacent usage.

I'm going to do some serious investigation for 2.4 GHz interference sources to see if I can locate a cause.

[Bruce · Accepted solution]

@DRNeale, there is a lot of interference in the 2.4GHz spectrum in comparison to 5GHz. It could be poorly insulated microwave ovens, Bluetooth devices (although this is unusual to be just on one channel as it frequency hops), AV equipment (e.g. wireless microphones), the list goes on. Then you just have general RF interference from plant equipment or the like. If its not causing you problems I wouldn't worry about it. Since its the 2.4GHz band you've got limited non-overlapping channels so it will be difficult to avoid, and you're probably better off just trying to move towards 5GHz wherever possible. 

[DRNeale]

@Bruce, thanks for the reply. 

This is actually a large church site with no one present on the day in question but it's OK, I suppose.  We have a few legacy non-5G users and some legacy IoT devices using 2.4GHz on active days, but almost all serious WiFi connections are in the 5GHz range. 

We only have 2.4GHz running for backward compatibility for a very few connections.  I have identified a large inside utility transformer on the radio coverage periphery of the first AP so that's probably the culprit for the interference I found but, nevertheless, I am not seeing any significant interference on the 5GHz band anywhere on the campus.