Channels...

[Ruivo]

Hi everybody!

Thank God I´ve found this forum...

I already have learned a lot here.

Well, I´m having some doubts about channels.

I know that when there are AP´s near of each other, the channels that they operate can´t be "adjacents", or they will overlap.

But I´m having some troubles.

There are situations where an AP is working fine, all clients have great taxs, etc... Then, some day, I think the AP awakes with the wrong foot and the clients´ taxs goes really down... If the AP´s channel is changed by a near one, all return to normal...

What can be happening?

What are the characteristics of the channels? Wich one is more efficient to long distances? And short? Or that doesn´t matter?

About the overlap, does this happen only with 2 AP´s, or can happen with a Multi-Link and AP situation?

Can you help me? Or give me some links to where can I research about the channels?

Thank you!

See ya!

[yonah]

Ruivo,

Is it possible that you have other intermittent 2.4 GHz sepctrum devices that might be causing interference? The 2.4 GHz band is also used by a plethora of other devices including Cordless Phones and Microwaves. Is it possible that your network goes haywire when you talk on you 2.4 GHz cordless phone? I worked hard at finding the right channel so that my Wi-Fi wouldn't interfere with my cordless phones or my X-10 Cameras.

HTH,
--Yonah

[beta999]

So can you set your WiFi devices to diffrent channels incase of interferance? How many channels are there?

[nemesis26]

11 channels in the United States.

The US 2.4 Ghz ISM frequency allocation is 2400 Mhz to 2483.5 Mhz.

5 Mhz of channel separation exists.

Channel map of center frequencies are as follows (Mhz):

1: 2412
2: 2417
3: 2422
4: 2427
5: 2432
6: 2437
7: 2442
8: 2447
9: 2452
10: 2457
11: 2462

Generally speaking, 15Mhz of spearation is required to adequately avoid adjacent-channel intersymbol interference. (i.e. must be at least 3 channels apart).

22Mhz of channel separation is required for optimal transmission void of a noise floor. As such, only channels 1, 6, and 11 can simultaneously exist without interference that would decrease signal-to-noise ratios and diminish transmission performance.

In other words... if interference exists on channel 7, one must either adjust up to at least channel 10 or down to channel 4 (channels 2 or 1 being optimal).

Leaky microwave ovens typically create interference between channels 5-7. Cordless telephones, other 802.11 access points, garage door openers, and even flourescent lightbulbs may cause significant interference throught the frequency space; some (such as the cordless telephone) are direct sequence devices that occupy a specific slice of the spectrum.