MultiChannel SSID 802.11AC are coChannel

Installing and Using OpenWrt
1

I was surprised to discover 2 wifi routers, set to auto-channel, persisting on the same 5GHz channel. It's my understanding 5GHz wifi router will detect co-channel interference and move to another channel. Both signals are strong >-60dBm. It was brought to my attention when a Roku TV could not connect, I discovered 2 wifi routers co-channel setup.

How sensitive or robust is this roaming algorithm? From experience, is it best to use fixed channels?

Using Linksys WRT3200ACM 802.11AC (2 Ch) and WRT1900ACS 802.11AC (1Ch). Irrelevant but the completion, the WRT3200ACM also set to 802.11N auto-channel.

2

There is no auto channel algorithm in OpenWrt. The setting "auto" merely chooses the lowest number channel that is allowed by regulations.

Two or more APs can and often do operate on the same channel. This should not prevent clients from connecting. Better speed results from operating on independent channels where possible.

1 Like
3

Why is that my 5GHz radio takes forever to start up? The radar check is just that, for radar only?

4

If you've selected a DFS channel, the kernel must scan the channel for at least 60s for DFS patterns, before it is allowed to start transmitting.

1 Like
5

I know, my question is: no additional checks for other APs?
edit: channel is set to auto

6

No scanning for other APs (on 5ghz). Just radar.
2.4 does scan for 20/40mhz transmission rules

2 Likes
7

Again, the "auto" setting is reserved for some time in the future when some sort of automatic selection might be implemented. Presently it does nothing other than select the first channel.

Best practice is to run a scan, identify neighbor's networks, and select a channel manually to best avoid them.

2 Likes
8

When the Openwrt 802.11AC radio scans channel for SSIDs is it performed in any particular order, e.g. low ch number to high ch number, or vice versa, and/or does it sort strongest signals strength hi to lo etc?

Is there any logic in the radio code to go to a quote “better” channel? Or does it sit and waits till the signal drops then initiates change channel or find another ssid?

(I’m thinking as in cellular communication mobiles have a neighbor list n roam to the strongest after a scan.) WiFi radios it appears shows you a list of channels sorted by signal strength.

I want to set n space the channels out so clients can easily find the identical ssid. I’m thinking if I use alternate channels, non-interfering, where the client would quickly choose to roam onto.

I’m forced to avoid co-channel due to a RokuTV connection failure.

9

Ah, thanks for the explanation, I didn't know that.
Does it apply to both bands or is it a peculiarity of 5GHz?
edit: right now I have channel 8 and 52 (and both are set to auto)