You just got Comcast or U-verse – fast multi-megabit connection – and then you started using your laptop or another wireless device with it. The speed is great if you are connected with a wire, but the speed sucks if you are connected through wireless. You wonder – what the hell?

Chances are that you are experiencing a lot of wireless interference. And interference is the main cause for slow wireless network speeds.

Many people buy their wireless at the store, they plug it in, configure its security settings and they start using it. Well, most of the Wireless Access Points default to channel 6, so that part of the spectrum becomes very heavily used, since no common folk would ever think about changing the default Wireless Access Point channel.

Here is a reference for the frequency of each channel from the North American frequency range:

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

The frequencies above are separated by 5 Mhz and they are the central frequencies of the channel, however the channels also have lower and upper frequencies due to their 22Mhz width:

Lower Center Upper
1 2.401 2.412 2.423
2 2.406 2.417 2.428
3 2.411 2.422 2.433
4 2.416 2.427 2.438
5 2.421 2.432 2.443
6 2.426 2.437 2.448
7 2.431 2.442 2.453
8 2.436 2.447 2.458
9 2.441 2.452 2.463
10 2.446 2.457 2.468
11 2.451 2.462 2.473

The 802.11b protocol channel width is 22 Mhz, 802.11g uses 20 Mhz channel width and 802.11n uses 20 or 20/40 Mhz channel width.

Here is an example – when you have a Wireless Access Point on channel 6 and another one on channel 7, channels being so wide, causes them to overlap with each other, which produces interference in the channel you use and the ones next to it.

If you are looking for channels that do not overlap each other you have to choose 1, 6 and 11. However, chances are that you will have other Access Points in the vicinity that would overlap their channels with any of the ones you use.

To wrap it, the key is to find the least used channel around you and configure your Wireless Access Point to use it.

To scan the channels around your Wireless Access Point, you can use inSSIDer. It will give you an excellent idea what is being used and where you can position your Wireless Access Point in the spectrum.

To test your speed before and after your channel adjustment, use either Speedtest.net or SpeakEasy Speedtest.