Interference from the neighbor: how much RSSI is worth considering?

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Interference from the neighbor: how much RSSI is worth considering?

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Interference from the neighbor: how much RSSI is worth considering?
Interference from the neighbor: how much RSSI is worth considering?
2022-05-10 20:01:58
Model: EAP245  
Hardware Version:
Firmware Version:

Hello! I am about to configure a bunch of EAP 245's in the next weeks. (They aren't mounted yet: I'm waiting for it) There are signals from neighbors, I wanted to ask you, how much RSSI is big enough that I should consider avoiding using the same channel ?

I am thinking that I will look at the places where the signal from my AP is weak, then look at signals from elsewhere, look at the strongest one (strong enough to use the internet with that signal), I should avoid the channel. Would that be enough ?

 

There are a lot more channels on 5G, and 5G signals don't reach that far anyway. I am inclined to just let the channel auto. Would that be OK?

 

I would appreciate your advice!

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Re:Interference from the neighbor: how much RSSI is worth considering?
2022-05-10 21:30:46

  @doremifajb 

 

Hey

 

Im guessing you are using a controller to manage these APs?   something like the OC200 or a software controller?   If so then YES I would recommend just letting the controller handle the channel selection, it appears to do a good enough job from my experience.   The problem with manually setting channels is that other WiFi in the area don't stick to their channels and may hop about, therefore undoing your manual selection.   The only way to combat this is to hop yourself!

 

In answer to your question, as a rule of thumb -40dbm is an awesome signal, -50 to -65dbm is the normal good range.   At -70dbm its only really email and surfing and should be considered the minimum strength.   -80dbm its dead air, you will connect but it wont be usable

With that in mind, anything over -70dbm coming from your neighbour you can pretty much ignore as it won't cause you any real issues. 

 

Its not uncommon to share channels with other WiFi, its almost unavoidable if honest.

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Re:Interference from the neighbor: how much RSSI is worth considering?
2022-05-11 04:16:20

  @doremifajb 

The one thing I would suggest is to hard limit your 2.4G channels to 20Mhz instead of 'Auto' unless you like to be the source of your own problems.  There are only 3 non-overlapping channels in NA and a surprising amount has been written on how to optimize them.  Let me just give you one example...let's say you do a standard 1,6,11 deployment...but your AP on CH1 switches to 40Mhz BW to service users...well, it is now stomping all over your CH6 APs and users...and everybody has a bad time.  20Mhz is good to 80-90Mbps even with just 802.11ac tech, and if you need more, the idea is to add more APs and dial back everyone's power so you can crowd your 1,6,11 cells closer together.  This is becoming every more important in congested areas where everybody is stomping all over each other...I was horrified to discover that internet modems from the big providers here are spewing RF on many channels, even when not being used.  The 'Fibe' product around here has 2 x 2.4G radios, 2 x 5.8G radios and a Zigbee radio.  You can turn off 2 of the 5 radios, but the others are hidden, full power, on whatever channel they find convenient (even if you don't subscribe to the TV package...shame I say!)

 

and an example of good frequency planning for APs (2.4 on the left, 5.8 channels on the right)

 

My threshold is -80dB for foreign signals at my point of use.  Meaning...if my neighbour's Fibe box is blasting my office at -70dB...I'd better pick a different channel if my AP is across the house and also in the -70dB range in the office...that's just a lose-lose situation.

 

 

 

<< Paying it forward, one juicy problem at a time... >>
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Re:Interference from the neighbor: how much RSSI is worth considering?
2022-05-11 20:11:08

  @d0ugmac1 and @ Philbert

Thank you very much for your replies! Actually the signals from neighbors are around -85db at most, so I suppose I can just ignore them :) I would still prefer to fix the channel to avoid disturbing another system I'm running (unifi) in the next building. I have Omada Controller on Raspberry pi 4. I don't trust it that much, so I would prefer to run the system so that it's not dependent on the connectivity to the controller, even though I will have it connected all the time. (For example, captive portal on the router, not on the controller.)

 

The APs got mounted today:) The cables are going to come next week:)

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