A clear channel

Originally published in Personal Computer World as part of ‘Your media, anywhere’

A clear channel

A couple of years ago, wifi looked like a great solution for home networking. Now, everyone’s at it, and clashes with other access points are more and more common – especially if you just leave your wireless network at its default settings.

In the 2.4GHz band, where most Wifi equipment operates, there are thirteen ‘channels’ available. You might think the trick is just to find a channel that’s not being used by any other access point in the area, but there’s more to it than that. Channels overlap with each other, covering at least part of the radio spectrum used by two channels on either side, so channel 1 overlaps with 2 and 3, while channel 6 overlaps with 4 and 5 below it, and 7 and 8 above. The upshot is that channels 1, 6 and 11 can be used together with no overlap at all. Put networks adjacent to each other, and they will interfere, slowing performance.

Another problem is the differing standards – an 802.11g network can support 802.11b devices, but all the devices will end up slowing down, as the access point has to mediate between them, at the speed of the slowest.

So, for the best wireless performance, you need to have all your devices using the fastest common standard they support, and use a tool like NetStumbler (or the Mac equivalent, iStumbler) to see what networks are in your area, and ensure there is as little channel overlap as possible.