Does the AP230 support dynamic channel bandwidth now?

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Before I set some of our AP230's to 80MHz channels, I'd like to know that they'll be good neighbors and only transmit 80 MHz wide frames when the spectrum is clear. Thanks.
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Jim Vajda

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Posted 4 years ago

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Krishna, Employee

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Hi Jim,

This is Krishna from the AP PLM team. We do support this feature, but not on a per frame basis. We are looking to add some enhancements to this feature later this year. Hope this answers your question.

Krishna

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Jim Vajda

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Thanks Krishna. How is dynamic channel width managed now if not on a per-frame basis?
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Krishna, Employee

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Jim - I stand corrected. We do channel width adjustment on a per frame basis. If the channel width is set to 80 MHz and is 80 MHz is not available, the AP will scale down to 40 MHz automatically. 
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Andrew MacTaggart, Champ

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Howdy

The AP will send out a RTS/CTS on each channel and only use what is available.



here I had a AP350 using 40MHz channels 157 and 161

and an AP 230 using 80 MHz channels 149,153,157 and 161

I sent a constant stream of traffic through the AP350 and then a constant stream through the AP230, so basically when the AP won contention on channels 157 and 161 it would send data on those channels. Packet captures shows as much.

It's all in Matthew's book 
802.11ac: A Survival Guide
http://chimera.labs.oreilly.com/books/1234000001739

Chapter 3 Media Access procedures
Dynamic Bandwidth Operation (RTS/CTS)



(Edited)
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Andrew MacTaggart, Champ

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I have done a packet capture with same scenario

I see RTS/CTS frames and block ACKs 

I do see data frames from the AP350 and a Intel n client when monitoring channel 108 +1, and I see data frames when monitoring channel 100 +80MHz


would love to see what others are finding.

I think I was trying to find something that wouldn't exist.

channelyzer shows me an increase in energy across the 80MHz band but captured packets on channel 108 only shows control frames from AP230 and I do have a lot of these unrecognized frames which I assume are pieces of data frames as the information is distributed across the OFDM subchannels.



Cheers
A
(Edited)
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Jim Vajda

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Thank you Krishna and Andrew. This is very helpful. I knew this was a feature of 802.11ac but I was unsure if it was part of Wave 1 hardware and if HiveOS supported it yet. Matthew's book is an excellent resource and a surprisingly quick read.

A couple follow-up questions: Will an AP230 using 80 MHz channel width also fall back to 20 MHz if the other 60 MHz is unavailable? (I assume the answer is yes as that is what the spec calls for)

And, do AP230's using auto channel selection in 80 MHz mode pick unique primary 20 MHz channels to use in the event of channel contention (e.g. two neighboring AP230's use channels 149-161 for 80 MHz, but each picks a different primary channel to prevent CCI when 80 MHz is unavailable), or does that configuration require a manual channel plan?
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Andrew MacTaggart, Champ

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I am not sure it's falling back, it appears to use the channels if they are available.

I can tell you that with 80MHz width that you can manually select adjacent channels if you wished to, although I think you would want the greatest separation as possible. Anyway channel planning would be critical.

As far as the ACSP
quoted from
http://blogs.aerohive.com/blog/wi-fi-that-wont-die/cooperative-control-part-3

"ACSP (Aerohive Channel Selection Protocol) – Used by HiveAPs to analyze the RF environment on each channel within a regulatory domain and to work in conjunction with each other to determine the best channel and power settings for wireless access and mesh.  ACSP minimizes co-channel and adjacent channel interference in order to provide optimized application performance."




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Javier Rodriguez

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So based on the comments above it looks like this will work on the Uni 1 and Uni3 bands.  Does the 230AP support (today) uni 2 and uni 2 ext bands?
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Andrew MacTaggart, Champ

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depends on the country regulations and certification status of the Aerohive AP.
(Edited)