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For the bold among us that have started with 11ac, are you yet running 80 MHz channels? Also, what channels have you made available in 5 GHz? Finally, any issues noted with RRM (or whatever your own WLAN vendor calls autochannel/autopower) with 11ac?
 
Thanks-
 
Lee Badman
 
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Comments

Hi Lee, Bold indeed. Is performance your main rationale for choosing 80 Mhz channels? Are the channels set statically or do the APs fall back to 40 Mhz or 20 Mhz channels if interference is detected? Otherwise, choosing 80 Mhz channels compromises the support of 802.11a and 802.11n clients on the 802.11ac APs. By choosing 80 Mhz, the number of non-overlapping channels reduces to 2, right? Are you using 11ac as an overlay for 11n coverage? Many questions as a response on question, but I wonder about your rationales for choosing 80 Mhz channels. -Frans On Tue Jan 7 17:07:52 2014, Lee H Badman wrote: > For the bold among us that have started with 11ac, are you yet running > 80 MHz channels? Also, what channels have you made available in 5 GHz? > Finally, any issues noted with RRM (or whatever your own WLAN vendor > calls autochannel/autopower) with 11ac? > > Thanks- > > Lee Badman > > ********** Participation and subscription information for this > EDUCAUSE Constituent Group discussion list can be found at > http://www.educause.edu/groups/. > ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
Hi Frans- I haven't chosen 80 MHz at all- but am wondering if anyone has played with it in prod or test to see what RRM etc will do with it- if anyone has slewed the DFS thing to get the extra channels etc. Just seeing who may be doing what- not advocating for it or declaring that I have gone this way. -Lee Lee H. Badman Network Architect/Wireless TME ITS, Syracuse University 315.443.3003 ________________________________________
Lee:

What is the expected performance gain if you do not use 80 MHz channels?

John


Message from me@mpking.com

Cisco has a really nice Whitepaper on this:
http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps11983/white_paper_c11-713103.html

And revolution wifi has a nice one on Channel Planning
http://www.revolutionwifi.net/2013/03/80211ac-channel-planning.html

Some Snippets:

2.3.4 RTS/CTS with Bandwidth Indication

An 802.11ac AP operating on 80 MHz (or 160 MHz and so on) should still be capable of allowing 802.11a or 802.11n clients to associate. Thus beacons are sent on one 20 MHz channel, known as the primary channel, within that 80 MHz. The AP and all clients associated to the AP receive and process every transmission that overlaps this primary channel and extract virtual carrier sense from the frames they can decode.
However, the AP could be nearby other uncoordinated APs. Those APs could be preexisting 802.11a or 802.11n APs, and their primary channels could be any 20 MHz within the 80 MHz of the 802.11ac AP. Then the different APs and their associated clients have a different virtual carrier sense, so can transmit at different times on the different subchannels, including overlapping times. With the wide 802.11ac channel bandwidths, this scenario becomes much more likely than with 802.11n

  • 80 MHz wide channels allow for five (5) non-overlapping channels in the U.S. and five (5) in the UK/EU (channels 149 and higher require light licensing for outdoor use only) when DFS is used, but only two (2) channels in the U.S. and one (1) in UK/EU without DFS.
  • 160 MHz wide channels allow for one (1) non-overlapping channel in the U.S. and two (2) in the UK/EU, with DFS being mandatory for their use in all circumstances.

 There is a saving grace that will allow enterprises to take advantage of these wider channels on a "best-effort" basis. Let's step back for a moment - with 802.11n, 40 MHz channels were an all-or-nothing proposition. The APs channel width was statically set at 20 or 40 MHz.  On the other hand, 802.11ac allows per-frame channel width and bandwidth signaling. Practically, this means that WLAN administrators can allow the use of wider channels by APs and clients when all of the constituent smaller channels are clear. If a portion of the large channel is busy at the point in time when a frame needs to be transmitted, for instance a neighboring AP or WLAN is actively using a 20 or 40 MHz portion, then the AP or client can simply back down and use the primary 20 or 40 MHz portion of the larger channel that is clear. For the next frame transmission, if the entire 80/160 MHz channel is clear then the AP or client can ramp back up and use the full channel width.

From an implementation perspective, most enterprises should plan around non-overlapping 40 MHz channels, or even 20 MHz channels in high-density areas. If the FCC frees up an additional 195 MHz of shared spectrum in late 2014 or early 2015 then designing around non-overlapping 80 MHz channels (or possibly even 160 MHz channels) in the U.S. will become much more practical.

Mike