John,
At Emory University, we've just completed upgrading our ResHalls to 802.11n and
are now working on our academic buildings as part of a system-wide upgrade to
802.11n. We've moved from single radio b/g APs to dual radio a/b/g/n APs. We
are running 802.11n (backwards compatible to b/g) on our 2.4GHz radios, but
without the 40MHz (high-throughput) channel plan. In fact I (and most wireless
engineers) would advise against running 40MHz channels at 2.4GHz. We do run
the 40MHz channels in the 5GHz band, however.
That said, 802.11n with standard 20MHz channels does give marked improvement
over 802.11b/g because of other dot11n technologies - multiple special streams,
frame aggregation, etc.
>>-> Stan Brooks - CWNA/CWSP
Emory University
University Technology Services
404.727.0226
AIM/Y!/Twitter: WLANstan
MSN: wlans...@hotmail.com<mailto:wlans...@hotmail.com>
GoogleTalk: wlans...@gmail.com<mailto:wlans...@gmail.com>
From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:wireless-...@listserv.educause.edu] On Behalf Of j...@nww.com
Sent: Tuesday, August 24, 2010 10:08 AM
To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU
Subject: Re: [WIRELESS-LAN] Any issues with iPhone 4 and 2.4GHz 802.11n?
Chris,
Thanks. Your observation on 40Mhz limiting the channel options in 2.4 band fits
with what I've learned also.
As I mentioned in my direct reply, your email reminded me -- and I should have
thought of this -- that of course the same 3-channel "limitation" exists for
11b/g iPhones.
But...what I'm wondering is if the iPhone 4's demand or preference for 11n
makes the situation more problematic, especially in a mixed-client environment
-- when b/g iPhones are associating to the same 11n access point?
Regards,
John Cox
Senior Editor
Network World
From: Chris Murphy [mailto:ch...@mit.edu]
Sent: Monday, August 23, 2010 7:28 PM
To: The EDUCAUSE Wireless Issues Constituent Group Listserv
Cc: John Cox
Subject: Re: [WIRELESS-LAN] Any issues with iPhone 4 and 2.4GHz 802.11n?
John,
I don't think there is much of an issue here, unless there is a requirement
that the iPhone 4's need the bandwidth possible using 40Mhz channels. Just
about every design guideline I've seen, and every conversation I've had with
engineers at various networking companies, considers using 40Mhz channels at
2.4Ghz to be a bad idea, due to the loss of what little flexibility one has
with channel layout as well as with adverse effects on neighboring networks in
crowded areas (the "anti-social" effect), so here at least we never considered
it.
-Chris
On Aug 23, 2010, at 9:12 AM, <j...@nww.com<mailto:j...@nww.com>>
<j...@nww.com<mailto:j...@nww.com>> wrote:
Folks,
I was talking to a higher education IT guy last week; they have a lot of
iPhones, and are rollling out iPhone 4's to new freshman and to faculty. As
part of this, they upgraded the campus WLAN to 802.11n.
BUT, after iPhone 4 was announced, they realized its 11n support was ONLY for
the 2.4 GHz band (with of course only 3 non-overlapping channels, and tradeoffs
if you merge two of them into one 40MHz channel).
In SOME locations, they're having to do some fancy juggling of access points,
channel and power settings.
Juggling 3 channels in a crowded location clearly is NOT new. But the fact that
this is occurring in 11n with a popular client device that often relies on WLAN
access, seems noteworthy.
I was wondering if anyone else is running into similar issues with iPhone 4 and
11n?
I'm going to be writing this up as a "Network World" story today or early
Tuesday. If you're interested in emailing/talking briefly with me about this,
please just copy any listserv response to (or email me directly at) my NW
email: john_...@nww.com<mailto:john_...@nww.com>.
Thanks!
Regards,
John Cox
______________________________________________________
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Chris Murphy
Network Engineer
MIT Information Services & Technology
Room W92-191
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ch...@mit.edu<mailto:ch...@mit.edu>
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