When to use channels 3 and 8

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ackray
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PostPosted: Wed Apr 14, 2010 21:42    Post subject: When to use channels 3 and 8 Reply with quote
This is something I do occasionally and I think there may be an advantage to it. Maybe.

I'm bringing this up because I am at a hotel doing a site survey to check the WIFI I have here and the neighborhood is a lot more crowded now. Using inSSIDer I can see that the AP's I moved to 3 and 8 have better 'open' areas on the lobes then the AP's on 1,6,11.

Of course I could just be kidding myself.

Currently i am spending some time checking out connection and throughput and it seems to be better.

Any other thoughts on this?

Thanks!

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phuzi0n
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PostPosted: Thu Apr 15, 2010 2:17    Post subject: Re: When to use channels 3 and 8 Reply with quote
ackray wrote:
Using inSSIDer I can see that the AP's I moved to 3 and 8 have better 'open' areas on the lobes then the AP's on 1,6,11.

Of course I could just be kidding myself.

Don't be fooled by inSSIDer's misleading parabolic representations of the spectrum usage. A/B specs attenuated early for that rounded looking graph, but G/N have pretty solid usage across the entire channel which gives a very flat plateau looking graph. See the Chanalyer pics which show actual spectrum usage by any device.

http://www.metageek.net/products/chanalyzer-3

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ackray
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PostPosted: Thu Apr 15, 2010 13:46    Post subject: Reply with quote
Thanks Phuzion!

Yes these are G and N APs I'm dealing with.

OK, so has anyone else tried this? On CH1 I have an AP radiating on top of six other APs. While I have a +10 DBm margin above the other APs I'm still not sire if it is better to leave it on this channel or move to 3.

Also 6 and 11 are almost as crowded.

I'll try three for another week and see if it makes any difference.

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DaveMcLain
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PostPosted: Thu Apr 15, 2010 17:43    Post subject: Reply with quote
I asked this same question shown in this thread on smallnetbuilder.com 's forum and here's the link:

http://forums.smallnetbuilder.com/showthread.php?t=1837&highlight=oddball+channels

Basically what happens is that when more than one AP are on the same channel they can work to avoid interference. When they are on slightly different channels that overlap they can't do this and only see each other as noise which can reduce throughput more than taking turns/sharing the air with other routers.
ackray
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PostPosted: Fri Apr 16, 2010 1:14    Post subject: Reply with quote
^^^^ Thanks!
Quote:

The problem with using the overlapping channels is that your signal may be seen as noise by the APs and clients on the non-overlapping channels. If it is noise, then the AP and client will just try to communicate as if you were not there.

But if you are operating on an in-use channel, then the DCF mechanism built into 802.11 can operate properly to manage contention for bandwidth. You may not get as much bandwidth on a busy channel. But at least you should not suffer sporadic disconnects, etc.


http://en.wikipedia.org/wiki/Distributed_Coordination_Function > this covers the how it works.

So in my situation where the clients have been complaining about weak signals and disconnects moving the AP to channel 3 or 8 will probably make the situation worse because the WLAN standard already has a mechanism for sharing on similar channels.

So it looks like the best solution will be to replace the very old DI-624 ( Any Takers? ) with a DD-WRT and high gain antenna.

Or low DBi antenna because of all of the background noise.

More practice coming up . . . . . . .

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