5GHz channel selection

[Pooneil]

All the mobile devices at home now can use 5 GHz wifi and I've stopped using 2.4 GHz on some to force them onto the faster 5 GHz connection. So it is time to extend the system to cover weak spots that now only reliably get a 2.4 GHz signal.

I am familiar with the selection of 1, 6 &11 as non-overlapping channels on 2.4GHz wifi. But is there a similar rule of thumb to minimize interference from overlapping 5GHz channels?

 

[bill001g]

5g channels are 20mhz wide where the 2.4g ones are only 5mhz. You have to look at the channel width you intend to use. Used to be easy when all things used only 20mhz now you get 40mhz and even 80mhz for 802.11ac so now you have to worry about overlap on 5g also. It is way to complex to come up with a easy answer. They are working very hard on getting 802.11ac to use 2 blocks of 80mhz which eat 8 of the 9 channels so you will only really have 1 option anyway.....and it will work really good

 

[Pooneil]

Thanks for the info Bill. I know this is more complicated so I am trying to limit it to a few reasonable scenarios that I can experiment with and select from to find which works for me. So if I set my router to use only 20mhz bandwidth, what would the channel selection be to avoid overlap? What about at 40mhz width? I doubt I'll need to go the full monty with AC any time soon.

 

[bill001g]

If you use 20mhz there is no overlap on the 5g channels they are all 20mhz wide already. There are 9 (i think) you can pick from. If you use 40mhz it gets more complex because now you must use 2 consecutive ones. If you search for 802.11 channels you will find some graphical examples of how they are laid out.

 

[Unkk]

There is a free android app called WiFi analyzer that shows you all wifi channels and what the signal strength is on that channel. If a neighbor is using channel 7, then your channel 6 may be impacted.

 

[Pooneil]

On My ASUS router with 20MHz selected, I have 9 channels 36, 40, 44, 48, 149, 153, 157, 161, & 165.
With 40MHZ or 80 selected there are 8. As above except missing 165. The page adds a box called extension channel, but the only selection is "Auto."

Thanks again for your help Bill, it gives me a framework to start on. It sounds like there is enough space that setting the APs to 80 MHz and auto channel selection they should take care of it. Particularly give the quick fall off that is prompting me to put in a few more access 5 GHz points anyway. I'll play around with the variables to see what works well enough for us.

 

[Pooneil]

So with a sample of 1, here are my results.

MHz Setting ------ Speedtest.net
20/40/80 --------- 43.77 Mb/s
20 ----------------- 44.02 Mb/s
40 ----------------- 53.26 Mb/s
80 ----------------- 50.85 Mb/s

It would seem at the first take that 20MHz channel width is adequate for iDevice connections and streaming and that 40 MHz is noticeably better and still practical to implement. I'll have to test this out later to better understand how the settings affect steaming MKV files between computers.

 

[bill001g]

The main issue with the wireless is you have way too many people competing. Many times it is impossible to even get 1 20mhz block to yourself.

All those fancy tri band router that claim 3200 or whatever are using almost every possible radio channel available. That means he will interfere with almost every other person living nearby......and they will interfere with him.

It works well when you live far away from other people, those that live in dense living arrangements like apartment wireless does not work so well

 

[Pooneil]

Yes, but we can only control our own networks. Thankfully I live in a house with only two homes next to me and one a low tech neighbor. It's just a good time to build my skills a bit by learning more about 5GHz wifi. If for no other reason than I can out geek a good friend who insists on talking computers when we get together.