All of this comes with the obvious statement, “It depends on your environment.”
Speaking only to our residential, the construction is such that with life/safety and occupant comfort high on the list, our residential building, including those constructed in the mid-late 1920’s (with renovations), tend to use materials that have high attenuation properties. Fire-rated doors, walls, and ceilings. Concrete, concrete block, metal studs, metal lath/plaster, rock or mineral wool, and high-performance window glazing. Our residential construction means that those APs, with few exceptions, can use the wider channels with no consequences. It also means we’re installing nearly one AP per room. It’s not a terrible place to be, as it leads to WiFi nirvana where we have few devices per AP, excellent signal quality, and little CCI. Coupled with our 80% Apple population, and those 3SS 11ac clients are pretty happy. Jeff From: "[email protected]" <[email protected]> on behalf of Chuck Enfield <[email protected]> Reply-To: Chuck Enfield <[email protected]> Date: Tuesday, September 26, 2017 at 9:37 AM To: "[email protected]" <[email protected]> Subject: Re: [WIRELESS-LAN] Two RF Questions Your experience is consistent with ours Jeff. We get good use of 40MHz channels in most areas. That said, complaints about basic connectivity greatly outnumber complaints about speed, so I recommend that when in doubt people should use 20MHz. However, we currently have locations where speed is an issue, and I’m expecting those to increase with time. Once your APs are close enough together to provide an SNR of 30dB or more (See GT’s contributions for reasons why this is important), adding 20MHz APs is more costly and less effective effective than enabling 40 MHz. From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[email protected]] On Behalf Of Jeffrey D. Sessler Sent: Tuesday, September 26, 2017 11:43 AM To: [email protected] Subject: Re: [WIRELESS-LAN] Two RF Questions For your residential, is that concern rooted in belief/assumption or proven by testing in production? I remember channel-width discussions with the advent of 11n, and people here advocated sticking to 20 MHz for the same reasons, only our in-field testing said it was a bad assumption, reaffirmed by our vendor and SEs. We’re been using 40 MHz-wide channels since 2008, and adopted DBS with the deployment of 11ac. Unless our campus and/or residential is unique in some way, shape, or fashion – our dense deployments overwhelmingly prefer 80 MHz wide channels, and data on both sides (client and infrastructure) reaffirms the software is making the right decision. Jeff From: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> on behalf of Rob Harris <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Tuesday, September 26, 2017 at 7:33 AM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: [WIRELESS-LAN] Two RF Questions While there are performance gains to be sure (by going to 40, or 80), there are other concerns as well. We use 20 in our dorms because of the density of APs and users, we need those additional channels (even with dfs in use). We use 40 in our public spaces when there’s adequate capacity for it, and 80 in our theater area since we designed for it. [e Culinary Institute of America] Robert Harris Manager of Network Services Culinary Institute of America 1946 Campus Drive Hyde Park, NY 845-451-1681 www.ciachef.edu<http://www.ciachef.edu/> Food is Life Create and Savor Yours.™ Please consider the environment before printing this e-mail. From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[email protected]] On Behalf Of Jeffrey D. Sessler Sent: Tuesday, September 26, 2017 10:20 AM To: [email protected]<mailto:[email protected]> Subject: Re: [WIRELESS-LAN] Two RF Questions It’s surprising to me that anyone would purchase a Lamborghini, then disconnect ten of the twelve cylinders and drive it at 25 mph on the autobahn. When I see static 20 MHz channels, or using 40 MHz in only limited areas, I wonder what’s behind the purposeful neutering of the system. If you are a Cisco customer running 8.1 or above, and not using DBS (Dynamic Bandwidth Selection), then it’s the equivalent of the Lamborghini above running on only two cylinders. Don’t miss out on the significant advancements in bandwidth management. Free those resources spent doing point-in-time simulation and surveys for something the software doesn’t already do far better at. I promise, DBS won’t hurt a bit and your users will thank you a hundred times over. Jeff From: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> on behalf of "Street, Chad A" <[email protected]<mailto:[email protected]>> Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Tuesday, September 26, 2017 at 6:59 AM To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: [WIRELESS-LAN] Two RF Questions What is your reasoning behind not wanting 40 megahertz channels if you have plenty of overhead with your channel utilization? People saying you should or should not do something without Gathering any type of metric worry me. On Sep 25, 2017 3:28 PM, Chuck Enfield <[email protected]<mailto:[email protected]>> wrote: 1. Enable it in places to check for radar events. If you get few, then yes. Client devices are almost fully capable now. Hidden SSID’s are the only issue. Some clients don’t probe on DFS channels, and will only respond to beacons. Make sure 2.4 is usable for the small number of incompatible devices. 2. No. Don’t even consider 40MHz unless you’re using almost all the DFS channels, but even then you’ll probably have to disable it in some high density areas. From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:[email protected]] On Behalf Of David Blahut Sent: Monday, September 25, 2017 3:17 PM To: [email protected]<mailto:[email protected]> Subject: [WIRELESS-LAN] Two RF Questions Greetings, I have two hopefully simple RF related questions: 1. Should I enable the extended UNII-2 channels campus wide? 2. Should I enable 40Mhz channel width campus wide? In other words what are you doing on your campus and what is the "best practice? Our wireless infrastructure: 3 Cisco 5508s running 8.2.141.0 20 - 3800 APs 368 - 3700 APs 414 - 3600 APs 8 - 3500 APs 7 - 1810 APs 32 - 1142 APs Prime 3.1.0 Thanks for your input. David ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/discuss. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/discuss. ________________________________ This e-mail message (including any attachments) is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this message (including any attachments) is strictly prohibited. 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