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

Unanswered Question
Jan 17th, 2014
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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,

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Stephen Rodriguez Fri, 01/17/2014 - 11:09
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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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jacob6000 Fri, 01/17/2014 - 11:11
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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,

Rasika Nayanajith Fri, 01/17/2014 - 13:54
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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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Scott Fella Fri, 01/17/2014 - 14:15
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Don't forget... 802.11ac and 80mhz channel width:)

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