UNII-2 extended 5GHz channels usage (Europe)?

[milos_p]

Hi guys,

My deployment consists of WLC 5520, 8.5.171 software, running 20MHz channel width with mix of 2700i/2800i APs.

Right now I am using UNII-1 and UNII-2 channels, having totally available 8 channels for approx. 70 access points in 7-floor building.

Is there any pros/cons of adding UNII-2 extended channels to the DCA channel list?

I know it will give me potentially 11 more 20MHz channels, but is there any real benefit or disadvantage of doing it?

Thanks a lot in advance!

Regards,

Milos

[Flavio Miranda]

Hi

 The main problem of Wi-Fi is exactly the lack of channels. When you use less channel, you will saturate those channels by increasing the channel utilization. This way, the more channel we have, the better the Wi-Fi connection. 

 If you use all the available channel, you can also think about use wider channel like 40Mhz instead 20. Which will give more throughput capacity per channel. 

[milos_p]

Hi,

I am fine with throughput, I don't need 40MHz channels for now.

Just trying to understand if I can have some benefit of extra channels or not, or I can loose something.

As clean as it was 5GHz few months ago, now I am noticing more and more foreign APs around being on 5GHz, mostly on UNII-1 and few on UNII-2 channels.

Regards,

Milos

[Flavio Miranda]

 If you are OK with throughput, then, you can benefit from more channel.  The WLC will ask the AP to jump to a less crowded channel when it realise that the current channel is loaded.

[milos_p]

@Flavio MirandaThanks!

Any issue with using UNII-2 extended channels generally?

[Flavio Miranda]

 We have some discussions here in the community that you might take a look. But, if I were to worry about something, I´d worry about clients compatibility.

https://community.cisco.com/t5/wireless/dca-5-ghz-channel-list-and-unii-2-channels/td-p/2591170 

[milos_p]

Hi,

I found some discussions, but I am trying to see if someone has some fresh update/feedback of using UNII-2 extended and if there are some issues.

Regards,

Milos

[Flavio Miranda]

I am in a different location as your but here I´ve been using with no problem.

[ammahend]

If you want really clean channel with no Cochannel and adjacent channel interference then you should design for each AP being 40MHz apart, having Extra channel, gives you ability to do that. 

[milos_p]

So let me ask the question again, as I was hoping for more practical answers :-).

What you guys are using for 5GHz, channel width and channel list?

Thanks,

Milos

[patoberli]

I'm using 40 or even 80 MHz channels (if the walls between the rooms are thick).

Essentially you need to check AP 5 GHz interface load on a general day and time plus co-channel interference. If both is well below 15% you will probably not gain much by adding those channels. If many of your AP have more than 30% of interface usage, you might gain a lot of additional free airtime and lower latency by adding the additional channels.

[milos_p]

Hi,

This sounds very reasonable, to see usage of APs.

Generally, I didn't have much, and maybe just on few had more than 20% utilization, mostly being interference.

I will check again, great tip!

[JPavonM]

I'm using all channels from RLAN bands 1 sub-bands I and II (UNII-I and UNII-2a) plus RLAN band 2 (UNII-2e) where I'm removing channels 120, 124 and 128 to avoid any inherence from RADARs, but this is not mandatory in ETSI domain nor in EMEA. Then I'm using 40MHz channels width.

With this setup I have not found any issue with RADARs so far today, but some with DDoS attacks from adminstrators playing around with wIPS features an a huge lack of knowledge of what can and can't be done.

Then I'm using different RF profiles to account for different maximum TX powers and enabled data rates in order to minimize propagation and effective cells.

With this been said, you need to take into account that using a maximum width of 40 MHz is the best practice for metropolitan areas due to congestion. Notice that nearby APs would be using almost all channels, so it is likely that your APs should have an adjacent neighbour operating in the same channel, so it doesn't matter if you selected 20 or 40 MHz as the devices would adapt the transmission to the "interference" to the maximum channel width that would be available in order to avoid collisions.

This, in theory, would be improved when using dot11ax.

HTH

Jesus

[milos_p]

Hi,

This is so useful post, thank you so much!