OpenWrt GUI doesn’t follow 5GHz bandplan

Installing and Using OpenWrt Network and Wireless Configuration
1

Why does OpenWRT not use the 5g bandplan?

The correct channel assignments is this.
Available channels

  • 20mhz channels = 36,40,44,48,52,56,60,64,100,104,108,112,116,120,124,128,132,136,140,144,149,153,157,161,165

  • 40Mhz channels = 38,46,54,62,102,110,118,126,134,142,151,159

  • 80Mhz channels = 42,58,106,122,138,155

  • 160Mhz channels = 50,114

You will notice that the same number does not show up in more than one list. This is how the bandplan was designed. If you select a channel it automatically corresponds to its bandwidth.

This is based on the available bandplan for 5ghz

image
image2000×1093 309 KB

There is never any reason to be able to select the channel width. Channel width is decided by the channel you pick. The entire point of having "center" channels in the bandplan it to allow channel selection to decide channel width.

To be completely clear, the above chart and and "Available channels" section is how the bandplan for 5ghz is designed. Channels are tied directly to their widths.

I would be happy to answer any questions you may have but the question I have is:

Why does OpenWRT not apply the correct bandplan once a location has been selected?

If you are in the US the above bandplan is what is allowed, period.

Extensive discussion regarding the topic here
https://forum.openwrt.org/t/channels-not-available-for-40mhz-80mhz-and-160mhz-5ghz/

2

The wifi drivers are taken from mainstream Linux, and they look at the situation differently. Passing "Channel = 42" to the kernel wifi driver is an error. However if width 80 and any channel 36, 40, 44, or 48 is set, the on air result is the same 80 MHz range in compliance with the band plan and interoperable with other equipment set to "channel 42". It would be additional OpenWrt- specific work to have the user interface use different channel numbers.

5 Likes
3

What do you think is simpler for a layperson?
Remembering 4 channels lists (or patterns)
OR
Having a simple channel list (that grows and shrinks) and a width parameter?

And what about being able to select a primary channel at larger widths? Because that changed based on my initial channel choice right? (I don’t have time right now to go capture packets)

Also this new channel naming only came into effect with 802.11ac. OpenWrt supports devices that are N only, should they have to code an entirely different interface scheme?

It’s a pretty practical solution.

2 Likes
4

even your chart is missing 20Mhz 68 & 96 witch openwrt is not using

5

Isn't this information in another thread?

For others: https://forum.openwrt.org/t/channels-not-available-for-40mhz-80mhz-and-160mhz-5ghz/

I do have a reason and multiple use cases...

but again and I think as @lantis1008 is pointing out...they'd have to actually know the bandplan to pick the correct channel if it wasn't selectable.

And layperson here == does not know Wireless Band segmentation schemes

6

when i said "There is never any reason to be able to select the channel width." i meant that channel width would be tied to channel number.