We’re running a 20MHz channel plan due to our AP density (one per classroom), 
over summer I’m going to look at enabling 40MHz in the less-dense non-teaching 
areas. Whenever I try out DFS channels they always get radared out within a day.

While troubleshooting a performance issue recently I was trying out a 40MHz 
channel width and noticed it was a lot noisier outside the channel bands:

[cid:[email protected]]

Picture from Chanalzyer Pro with a Wi-Spy DBx. So that’s another reason to 
avoid 40MHz channels unless you actually get out there and check the RF to 
confirm your channel plan works in practice.

As for dual-radio 5GHz APs, I still think they’re stupid and vendors should be 
making single-radio 5GHz APs. OK, some already do, but they’re low-performance 
(2x2), not high-end (4x4). A single-radio 5GHz AP will fit within 802.3af even 
at 4x4, won’t have internal interference, and will allow better AP positioning. 
Yes, you do need to run an extra cable (although not if you’re already using 
dual-radio APs with 2.4GHz turned off), and it’ll still use a full AP license, 
but at least give us that option *gets off hobby horse*.

--
James Andrewartha
Network & Projects Engineer
Christ Church Grammar School
Claremont, Western Australia
Ph. (08) 9442 1757
Mob. 0424 160 877

From: The EDUCAUSE Wireless Issues Constituent Group Listserv 
<[email protected]> on behalf of "Trinklein, Jason R" 
<[email protected]>
Reply-To: The EDUCAUSE Wireless Issues Constituent Group Listserv 
<[email protected]>
Date: Wednesday, 30 November 2016 at 5:35 am
To: "[email protected]" <[email protected]>
Subject: [WIRELESS-LAN] 5GHz Channel Width

Hi All,

I was just reading a blog article that heavily recommends not to use 40Mhz 
channel width in multi-floor environments, particularly where many 5GHz radios 
are used (particularly in our case with Xirrus multi-radio APs). Our campus 
presently uses 20MHz channel width in all buildings. We are testing and 
considering 40MHz width because of the bandwidth benefits for clients. What do 
you use on your campus? Have you found that setting a 40MHz channel width on 
your 5GHz radios has caused too much interference?

Here is the article:
http://divdyn.com/dual-5ghz-radio-aps/

Your thoughts are appreciated.
--
Jason Trinklein
Wireless Engineering Manager
College of Charleston
81 St. Philip Street | Office 311D | Charleston, SC 29403
[email protected]<mailto:[email protected]> | (843) 300–8009
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