topic how to figure out which channel isn't interference with the other ap. in ExtremeWireless (General)

how to figure out which channel isn't interference with the other ap.

zlinuxboy — Wed, 07 Jul 2021 12:06:00 GMT

I deploy an aerohive ap on a public space, and choose 36 channel(width 80Mhz). If the other guy deploy anohter ap(802.11 ac2 ) neaby and choose 44 channle(width 160Mhz), does this two channel interference with each other?

Re: how to figure out which channel isn't interference with the other ap.

Tomasz — Mon, 12 Jul 2021 22:09:59 GMT

Hi,

Yes, they will. The sort of issue you may experience is overlapping BSS, where primary channels are more strict about clear channel assessment than secondary channels from what I remember. That means, you may end up with lots of traffic on wide channel secondary part bursting lot of MCS data not caring much about what’s going on this channel as another AP’s primary. It would be better to keep them off on the spectrum or - if they need to overlap - keep their primary channels the same. You will split your channel capacity in half but it’s better. Is that wide channel really needed? In enterprise I’d aim to remain 20 MHz or go into 40 MHz depending on the radio environment size and density.

https://www.mikealbano.com/2015/10/channelization-obss-impact.html

https://divdyn.com/wi-fi-throughput/

Hope that helps,

Tomasz

Re: how to figure out which channel isn't interference with the other ap.

Tomasz — Mon, 12 Jul 2021 22:32:48 GMT

P.S. According to your question in the topic, please try to avoid reusing same 20 MHz channel or overlapping bonded channels as long as it is possible:

Grabbed the above image from the interwebz.

Cheers,

Tomasz

Re: how to figure out which channel isn't interference with the other ap.

zlinuxboy — Tue, 13 Jul 2021 08:48:26 GMT

base on the image you posted, If choose 40Mhz channel width, then the center point of channel should be 38, 46… 151, 159 etc, but here is the result of `show acsp`

Interface Channel select state  Primary channel  Channel width Power ctrl state      Tx power(dbm) Use Last Selection
--------- --------------------- ---------------- ------------- --------------------- ------------- ---------------------
Wifi0     Disable(Link down)    Down             20            Disable(Link down)    Down          Channel:No  Power:No
Wifi1     Enable                157              40            Enable                14            Channel:No  Power:No

the channel is 157, how to determine if 157 is bonding with 161 or 153?

Re: how to figure out which channel isn't interference with the other ap.

Tomasz — Tue, 13 Jul 2021 20:34:22 GMT

Hi,

It’s always per scheme, 157 can be bonded with 161. Different notion is used sometimes to determine the primary channel. Sometimes bonded channels have their numbers in GUIs/CLIs, sometimes not. Eg. 40 MHz channel might be ‘36+’ or ‘40-’, so it uses 36 or 40 as primary and the next one or previous one (per scheme) is secondary. Or in WiNG we might have 36w, 36ww, 36www for bonded channels of greater width (40/80/160 MHz).

Whether you pick 36, 40, 44 or 48 for your 80 MHz channel, that channel will use all four but the primary channel might be different. But then…

Hope that helps,

Tomasz

Re: how to figure out which channel isn't interference with the other ap.

zlinuxboy — Wed, 14 Jul 2021 22:09:38 GMT

hi, @Tomasz thank you for so detailed info

May I choose 40Mhz as channel width, and set 40+, then the primary channel is 40 and secondary is 44?

Re: how to figure out which channel isn't interference with the other ap.

Tomasz — Thu, 15 Jul 2021 17:27:36 GMT

Hi,

I don’t think so. The scheme only covers possiblity of 36+ or 40- resulting as 40 MHz “CH 38”, 44+ or 48- resulting as “CH 46” and so on.. It comes from the fact that 40 MHz channels are strictly defined with their center frequencies.

Hope that helps,

Tomasz

Re: how to figure out which channel isn't interference with the other ap.

middleton65 — Thu, 16 Sep 2021 14:19:16 GMT

Thanks for the update and quick reply. I'll be sure to keep an eye on this thread. Looking for the same issue. Bumped into your thread. Thanks for creating it. Looking forward for solution.