Maybe they (the channels) overlap a little

[yubb]

Is there any reason to use channels other than 1, 6 and 11 in an 802.11b network? These are the only non-overlapping channels, right...but is there a case where you'd want to use say channel 5, or 7. I guess my question is, if you have an AP on channel 1, close to an AP on channel 5, there still would be inteference, would there not? Suppose these two AP's are placed slightly farther apart where only the outter reaches of their cells overlap. if you still have the AP's set to use the speed that this range of the cells provides, would there still be interference, even though the cells only overlap slightly?


I ask this because I saw the layout recently of a wireless network and the designer had AP's on all channels all over. Care was taken to keep those on overlapping channels apart from each other, but it just seems that using only 1, 6 and 11 is not only easier to design and implement, but also more efficient.

If what I'm typing doesn't make sense, let me know, I'll draw a picture (seriously).

Thanks,
b3n.

[Aiakos]

if you still have the AP's set to use the speed that this range of the cells provides, would there still be interference, even though the cells only overlap slightly?

Yes. Even though the cells overlap only slightly, there will still be interference. If you only need 2 Aps use 1 & 11.

[yubb]

If you had more than two AP's, say 5 of them. Would you still use only 1, 6 and 11?

[guise]

Ive been instructed that after locating access points, i am to make sure that any access points with overlapping coverage are separated by at least five channels. The cellular-telephone industry uses the "hex pattern" shown bellow to cover large areas.

------11-01-06------
----01-06-11-01----
--06-11-01-06-11--
----01-06-11-01----
------11-01-06------

[yubb]

That's the way I set up my WiFi networks. I just saw that one person used channels other than 1, 6 and 11 and wanted to see what other people thought of that.

I can't see a situation where it would benefit you to use channel 5 instead of 6, or 5 instead of 11, just as an example. But maybe someone else out there can enlighten me.

b3n.

[spiderbite]

You can do it. I like 4 and 8.

I would only do it if your in a small area and you just cant turn the power down any more. There would be some contention but it is not the end of the world.

As a rule I use 1, 6, 11 because it is easy and most of the time I can separate fairly well between floors also.

I am assuming you know why 1,6, 11 are non overlaping so I didnt go into it

[yubb]

I do understand the whole non-overlapping channels thing. That's actually what spurred my question. If those channels are the only ones that don't overlap, why even bother using other channels? Using a channel that's not 1 or 6 or 11 is only going to end up restricting your use of non-overlapping channels elsewhere.

Thanks for the input.

b3n.

[ccrum]

If you only had 2 AP's why not pick any two channels which don't overlap? Or if you only had 1 AP, any channel would suffice. I would think that you would select other channels maybe to mitigate interference from someone nearby using the "Standard" set you mentioned. Even though there is some overlap, there is still some interferece regection associated with going up a channel. or two. Remeber we are talking about a spread spectrum signal here. In short that means that even if you lose part of the signal to interference in a particular part of the band, the rest of the signal will make it through. Statistically speaking, enough bits should make it through to still communitcate unless the interfernce effects enough of the band to kill the whole thing.

[yubb]

Any time I refer to two access points and their channels I'm actually taking them out of the bigger picture of an entire network with many access points. Perhaps I'll draw something up tonight to fully illustrate my questions.

b3n.