Proximity of Unifi Access Points?

[maxrebo]

Just wondering how close to each other can you\do you put your Unifi Access points in your school?

 

I've spaced ours out going off the signal but due to them being so cheap and the signal strength being around 50/60% in some areas, I might need to install a few more.

 

Thanks

[Michael]

One per class/area is usually suffice.

[Primus]

One per class and you can adjust the power on the 2.4 and 5ghz bands - 5ghz tends to not travel well through walls so you can leave that set higher than 2.4Ghz.

[maxrebo]

One per class and you can adjust the power on the 2.4 and 5ghz bands - 5ghz tends to not travel well through walls so you can leave that set higher than 2.4Ghz.

 

Thanks, I will look to get a few more installed.

 

How do you adjust the power on the bands?

[Primus]

It's in the admin console. You can adjust per AP or adjust on multiple APs in one go.

[robyholmes]

We have them 1 per two classrooms (Or there abouts) but we don't have a bank of laptops, just odd ones and phones etc. If we did have that I'd go one per classroom.

[psydii]

"For voice deployments, it is recommended that the cell edge should be at -67 dBm with 20 percent overlap"

 

We built for voice several years ago, because Teams seemed like it might be important in the future. Turns out we were right . Go for 4x4 APs (I think all ax APs are?). They allow for higher density of devices. Depending on the vendor implementation of channel management, you, at school-grade densities, can also have 80Mhz channels as the channel stacking allows fall-back to 40 or 20Mhz if the rest of the channel is busy. If you have too-high a density of APs you are less likely to feel the benefit of 80Mhz, but you get more power per channel, which in turn increases the chances of achieving 256+ QAM

 

You do need higher power to hit 256+QAM, so there is a delicate balance between density and bandwidth.

 

In practice for us this roughly means one AP in every other classroom. Most offices are near classrooms so are covered. But for blocks of offices in some areas, one AP per two rooms also is a good 'guestimate'. Don't forget to think in 3D - if the floor is relatively transparent, try not to put APs directly above/below each other.

 

I really would recommend getting an independent wireless survey and design done, they save a lot of stress and give you something to fall back on with certainty when a random problem occurs ("the RF design is good - it has to be something else - look I have the paperwork to prove it")

 

EDIT: You also need -20db clearance between devices on the same channel but different APs - otherwise you get co-channel interference. So if you pack APs at too higher a density you risk some stations shouting over the top of neighbours on other APs - producing errors and actually reducing your operational throughput.

Edited December 4, 2020 by psydii

[RobD]

Have a read of this:

https://wlanprofessionals.com/why-one-access-point-per-classroom-approach-is-wrong/

 

Its a good read but it doesn't take into account the fact that a lot of Schools don't have the funds to either buy the equipment to survey or pay for someone to do it for them.

[TwistedHelixis]

I use a WiFi app on my phone and walk around testing the signal strength

[Davit2005]

A true site survey and/or using a specific adapter that can also pick up interference etc. We had a bit of software at a previous place and used during a Ruckus deployment that used a specific WiFi dongle in a laptop which gives more info. This was about 10 years ago and cannot remember the name. I don't think it was that expensive, didn't have phone based apps back then I don't think.

 

Also consider that phones could have weaker WiFi chips than a dongle with a decent antenna. But still a good idea to use a phone or similar to get likely signal strength and experience from user perspective.

 

The app we used picked up interference in the area where the AP was covering.

Edited December 4, 2020 by Davit2005

[RobD]

I do predictive and ap on stick surveys with work. It's a difficult task given sites we have to look after.

 

Use Ekahau pro and a sidekick. It's a lot of fun but difficult to get right.

[RobD]

I need to practice my predictive designs so if anyone has any floor plans and a scale then send me a message (I dont work for any support companies etc so this won't end up in a sales pitch)

[Sonic007]

One Unify AP Pro every 2 classrooms here.

[maxrebo]

One per class and you can adjust the power on the 2.4 and 5ghz bands - 5ghz tends to not travel well through walls so you can leave that set higher than 2.4Ghz.

Having another look at this after a few issues with Teams call quality - I see both Radios are set to "Auto" - Would you set the 5ghz on to "High" and leave the 2.4ghz on Auto?

Have you done this for all your APs?

 

Thanks

[Primus]

Having another look at this after a few issues with Teams call quality - I see both Radios are set to "Auto" - Would you set the 5ghz on to "High" and leave the 2.4ghz on Auto?

Have you done this for all your APs?

 

Thanks

 

On Unifi auto is just high power mode.

 

We back the 2.4 off to low and set the 5 to medium.

 

But we have an AP in every classroom.

[RobD]

It can be difficult working with power, if you set it too high the SSID may broadcast further but the device might not have a sufficient antenna to broadcast back. Another issue is if the power is too high then you're at risk of CCI and ACI which can have a negative affect on your devices.

 

I'm not familiar with the power levels on unifi but I'd set them to half and check the farthest classroom, use something CloudCheck on a mobile or iperf or jperf on laptop to test speed from client to server.

Edited March 17, 2021 by RobD