AP121 300mbit in 2.4GHz Range - no 40MHz channelbandwidth?

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My Problem is that the AP121 doesn ́t switch to 40MHz channel bandwidth in 2.4GHz n Mode.

Radio Profile settings are Channel Width -> 40-MHz below, Preamble -> Auto and "enable Short Guard Interval" is set.

Any Ideas?
What will the sentence in Hivemanager mean: "Note: Only AP120/110/170/320/340 11ng mode support Channel Width 40-MHz above, 40-MHz below, other platform just support 20 MHz." ???

Will it tell me, that the AP121 does only support 20MHz channelbandwidth in 2,4GHz-n-Mode?
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BenjaminKessler

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  • confused

Posted 3 years ago

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ATSUSHI ASAMI

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Hello,

Unfortunately as you noticed AP121 doesn't support HT40 in 2.4GHz.

Cheers,
Asami
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BenjaminKessler

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Thanks Asami,

i ́ve not found that in the Datasheet and in no other documentation of Areohive. Can anyone tell me where i can find that info direct from Areohive?

cheers

Ben
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Nick Lowe, Official Rep

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As you've found, it's clearly stated within HiveManager so it would show up in a trial/evaluation while configuring.

I cannot find it stated elsewhere explicitly though. That's likely to be because it's well known that HT40 at 2.4 GHz is nearly always a bad idea.

Nick
(Edited)
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Nick Lowe, Official Rep

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Hi Benjamin,

It is a generally bad idea to use a 40 MHz channel width at 2.4 GHz.

It is, on balance, a good thing that it cannot be configured on the AP121. It is certainly not unfortunate! :)

There are only three non-overlapping 20 MHz channels that are realistically available at 2.4 GHZ: 1, 6 and 11.

It would be detrimental to many business or enterprise deployments to use a 40 MHz channel width at 2.4 GHz.

Think about neighbouring APs that are likely to be using a channel plan on 1, 6 and 11 with a 20 MHz channel width and the need, within a business/enterprise, to have intersecting cell coverage on non-overlapping channels to maximum overall coverage and capacity, and reliability.

You should instead look to 5 GHz to get the higher data rates with a 40 MHz channel width.

Also see the following thread where this has been discussed before:

https://community.aerohive.com/aerohive/topics/how_do_i_improve_802_11n_connection_speeds

Nick
(Edited)
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BenjaminKessler

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Nick,

i ́m fully aware if that, with all the Problems.
It was not a question of "is it a good idea", it ́s a question of "is it possible"!
Customer is king...you know ;-)

Sometimes you can discuss that hours long and the management want ́s it anyway.
So what to do? Activate it and show them that it ends in slow shit....lesson learned...switch back to 20MHz and problem is solved ;-)

But thanks anyway

Ben
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Nick Lowe, Official Rep

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Hi Benjamin,

It was just the vibe that I got with your question and Atsushi's reply that it was being suggested that it was a limitation/weakness of the product when actually it's a strength.

You said it was a problem, he said it was unfortunate. Neither are true! :)

I wanted to explain why that is the case therefore.

If you are a reseller or in a position of support, yes, you ought to try to correct the customers misconceptions or misunderstanding.

The salient point here is: Use 5 GHz!

Cheers,

Nick
(Edited)
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BenjaminKessler

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Sorry, but it is a limitation and a weakness of the product!
I can ́t find it in the Datasheet that the AP121 does HT40 ONLY in 5GHz band.
I read that it does 2.4 and 5GHz in 802.11n and HT40.

If you are able to use it or if you realy activate it is another question and not part of the problem.
Don ́t get me wrong, i ́m absolute on your side that you should not use it in 2.4GHz mode. :-)

cheers
Ben
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Nick Lowe, Official Rep

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Hi Ben,

I agree that the datasheet should be clear on this point, it's always worth avoiding ambiguity. It's sensible that somebody considers adding that extra detail in for the APs.

Because it's well known that HT40 at 2.4 GHz is nearly always a bad idea, expecting an Enterprise-class product to support it in the first place, and then wondering where it is explicitly stated that it does not, is not, in my opinion, a sensible line of reasoning: It's upside down.

Cheers,

Nick
(Edited)
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Crowdie, Champ

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Benjamin I would strongly recommend you look into why utilising 40 MHz channels in the 2.4 GHz spectrum is, as Nick says, an extremely bad idea.  Once you have the answer you will will heading down a path of discovery as you suddenly realise that there is a whole lot more to deploying wireless then most people think.  All the champs here will have gone down that path at some point and it is the beginning of a very interesting journey.
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BenjaminKessler

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Nick and Asami -> thanks for your help