High channel utilisation and interference on AIR-2602I WAP

[Mark Hamilton]

WLC is reporting extremely high channel utilisation and interference on 5GHz for one of our older 2602i WAPs. There are no connected clients on the 5GHz radio and there are no interferers being reported by CleanAir.

The channel utilisation and interference on 5GHz radios for neighbouring WAPs, and all other WAPs on our network, is usually between 0% - 5% at most.

I have tried rebooting the WAP but the utilisation and interference remains high.

Any ideas on how I can find the cause, or determine if it is a hardware/software fault?

[Scott Fella]

Swap the ap out with another ap and see if the issue follows the ap or if the utilization stays in the same area.

[Mark Hamilton]

Thanks Scott, I'll try that tomorrow.

[Leo Laohoo]

I know the reason why: 160 Mhz channel width.
Look at the number of channels the AP is operating on -- 52, 56, 60 & 64. Yup, that'll kill it.
Change the settings from 160 Mhz channel width to 40 Mhz channel width and things should get better.

[Mark Hamilton]

Hi Leo,

The 5 GHz channel width is set to 80 MHz, is that what you meant? I'll try changing it to 40 MHz anyway.

[Mark Hamilton · Accepted solution]

Reducing the channel width to 40 MHz has resolved the issue. I wonder why this was the only AP affected by 80 MHz channels?

[Scott Fella]

That is something you need to investigate more in order to figure that one out. I think many here won’t go past 40mhz channel width in production.

[Mikey Boy]

What type of enviroment is this? It looks like you could have a lot of AP's. 2.4Ghz is transmitting at 1dBm and Channel utilisation is over 50% on that band.

I was recently in an office where they had lots of AP's (too many) and only 20Mhz channels were appropriate. I would probably drop it to 20Mhz and see how much of an improvement you get.

[Mark Hamilton]

We have approximately 220 APs spread across four buildings in the CBD (which are in close physical proximity), and we see a lot of noise and interference on 2.4 GHz from neighbouring buildings.

[Scott Fella]

That is sort of normal on the 2.4ghz. With so many wireless networks out there and only three channels, that is to be expected. You see this in malls and in buildings with shared tenant space.