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Non-overlapping channels - 802.11a/n - need clarification

There seems to conflicting or inconclusive information the topics below. I have just been readying various docs using google searches. I am hoping to get some solid answers.

1) What channels for 802.11a are really non-overlapping? 8 or 12?  I have read in some sources that it is 12 but the last 4 are for outdoor use(?).

2) in regards to 802.11a, channels 149 - 165 are considered for outdoor use so indoor availability is only 8 channels, correct?

3) What would be the non-overlapping channels for 802.11n? Indoor use only.

4) What happens when an 802.11n/a device and a traditional 802.11a device connect to the same network?

Thank you,

4 REPLIES

Non-overlapping channels - 802.11a/n - need clarification

It's the same channel structure with .11n.  The channels you have are dependent on the country you are in an what they allow.

Generally you want to not use the UNI-II extended as they are subject to the DFS/Radar detection rules.

http://en.wikipedia.org/wiki/List_of_WLAN_channels#5.C2.A0GHz_.28802.11a.2Fh.2Fj.2Fn.2Fac.29.5B16.5D

But basically you do have 8 channels that are non-overlapping.

With 802.11n and channel bonding, there are mechanisms in place for the legay clients.  With channel bonding there is a primary channel the AP is on, and a legacy client will only see that part of teh spectrum.

HTH,
Steve

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HTH, Steve ------------------------------------------------------------------------------------------------ Please remember to rate useful posts, and mark questions as answered
Community Member

Non-overlapping channels - 802.11a/n - need clarification

Ok. That does help clarify things a bit. Let me go just a bit further to be clear. If I have 8 non-overlapping channels with 802.1a then I would have four with 802.11n due to the wider 40mhz channels, correct? If so, what channels would those be?

Thank you,

VIP Purple

Re: Non-overlapping channels - 802.11a/n - need clarification

Hi Jacob,

Following diagram should helps you (Ref source )

Referencing this & if you look at your 4 queries you can find the proper answer. Here is my response

1) What channels for 802.11a are really non-overlapping? 8 or 12?  I have read in some sources that it is 12 but the last 4 are for outdoor use(?).

As you can see, excluding UNII-2 extended there are 12 non overlapping channels (13 including CH165), depends on the different country regulations you can use those for indoor/outdoor deployments.

2) in regards to 802.11a, channels 149 - 165 are considered for outdoor use so indoor availability is only 8 channels, correct?

It depend on the courntry regulation. I think in US you can use that band(UNII-3) for both indoor/outdoor deployments. So in that case 12 CH availabel excluding UNII-2 extend band.

3) What would be the non-overlapping channels for 802.11n? Indoor use only.

802.11n in this band, you can aggregate two 20MHz channel, (effective 40MHz bandwidth). You can see 6 non-overlapping channels available with 40MHz width in those bands (80MHz & 160MHz option shown in the above diagram applicable to 802.11ac standard)

4) What happens when an 802.11n/a device and a traditional 802.11a device connect to the same network

802.11n device will communicate with 40MHz (if configured on you wireless network & client support channel bonding) & normal 802.11a client will connect using 20MHz channel without any CH bonding or aggregation

If that answers to your query pls mark this thread as "Answered"

HTH

Rasika

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Re: Non-overlapping channels - 802.11a/n - need clarification

Don't forget... 802.11ac and 80mhz channel width:)

Sent from Cisco Technical Support iPhone App

-Scott
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