6E APs and Non PSC channels

[FlyingFrames]

Does the radio management algorithm assign non PSC channels e.g. 1, 5, 9, 13, 17, 25 etc or limit channel assignment to PSC channels?

Since 5 & 21 are PSC channels as explained in this blog:

https://www.extremenetworks.com/resources/blogs/the-road-to-ap-discovery-in-6-ghz

[alemabrahao]

Hi, the radio management algorithm for Meraki 6E APs does consider both PSC and non-PSC channels. However, the use of non-PSC channels may lead to longer connection times for client devices.

Wi-Fi 6E Frequently Asked Questions - Cisco Meraki Documentation

[KarstenI]

Luckily, the client base seems to use the RNR quite efficiently. With that, even 40 MHz without PSC is possible:

https://www.youtube.com/watch?v=lAG5jXZCd_8

[FlyingFrames]

So will a Meraki AP assign or not assign a non psc channel with RRM? Sorry but its still unclear.

[alemabrahao]

Will the additional channels in Wi-Fi 6E result in longer connection times?

It depends on what modes of scanning the client device are using to discover the Wi-Fi 6E networks. There are currently two modes available:

a. Active scanning: In this mode, client devices will scan a list of PSC (Preferred Scanning Channels) These channels are essentially 4 x 20MHz channels apart from each other. With Wi-Fi 6E using 80MHz channels is going to be the new standard and hence client devices will be actively scanning PSC channels first in order to discover the SSID available in 6GHz. It is expected that APs in 6GHz will be using PSC channels. This is the reason in the Radio Settings page in Dashboard a user can select channels in increment of 4 channels at a time in Dashboard for 6GHz configuration.

b. Passive scanning: Some clients will be performing passive scanning in which they will not be probing the network actively, instead configure their radio to a specific channel in 6GHz and passively listen on that channel. Wi-Fi 6E standard allows the APs to transmit mini-beacons at even 20ms intervals. This will reduce wireless airtime and will also save some battery on the client devices.

In some scenarios where the Wi-Fi 6E APs is configured to a non-PSC channel, it may take client devices a really long time to discover the Wi-Fi networks from such APs. As mentioned above, clients will be performing a scan of the PSC channel first and then scanning individual channels, hence it may take a long time for the client to discover the Wi-Fi network on 6GHz. However, in the real-world, majority of the clients will be performing an out-of-band scan using a reduced neighbor report which will provide all the required information of SSIDs on the 6GHz network. This will reduce the wireless network discovery time on the 6GHz spectrum significantly on the client-side.

[KarstenI · Accepted solution]

I don't have a definitive answer. However, while testing, the first 40 MHz APs were always placed on channels that included the PSC. The question is what happens when more APs are deployed than 40MHz channels with PSC are available. Sadly I don't have a system to test it.

[yantisj]

RNR is required for Wifi-6E, and PSC is only supposed to be used for pure 6Ghz client AP discovery. IIRC, scanning isn't even supported by Apple devices, they must rely on RNR. Given that, in my testing, PSC's don't really matter. That said, if you are using 80Mhz channels, may as well use a PSC ones.

One more tip with 6ghz, if you are using 40Mhz channels on 5Ghz, and 80Mhz channels on 6Ghz, all of our clients immediately goto 6Ghz without an issue since there's more bandwidth from the client perspective. When we synced the channel width, we didn't always see clients switch to 6Ghz.

[TBHPTL]

What a client connects to is based solely on it's proprietary client  wireless chipset/driver algorithms.  Apple lists theirs plainly enough . They don't really list anything for channel width in 6GHz but they do mention  it  for 5 GHz...

https://support.apple.com/en-us/102169#:~:text=When%20auto%2Djoining%20networks%2C%20macOS,private%2....