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Fun with 802.11

I’m constantly fiddling with my home wireless setup. It’s probably because I’m easily amused. I have a Linksys WRT54GS (version 2.0 if you know what I mean).

It’s been around in various incarnations for a couple of years now and there is a fairly active community of 3rd party firmwares for it and it’s older brother the WRT54G. Until quite recently, it was built on a Linux platform. Linksys was forced to release the source code to stay in compliance with the GPL. Lots of talented programmers took the ball and ran from it, adding many new features. Even Earthlink released a customized firmware that add IP6 support to the router.

The latest versions are no longer Linux based, they run a customized VxWorks firmware that provides similiar functionality as the stock WRT line, but requires less ram. This version is not currently compatible with the 3rd party firmwares. There are still Linux based ones out in the retail market, you can tell from the outside of the box. Each version has a slightly different serial number and that will identify the hardware version, based on the list on this page.

These custom firmwares come in many flavors. Some are based off of the current Linksys firmwares and add some new functionality. Others have veered quite a bit from the path and do not look or behave like the original firmware. I’m using the DD-WRT firmware and it works great. I’m only using a fraction of the added functionality, but the stuff it adds is pretty cool.

I use the site survey function on router to see what other routers and/or access points are active near me. I’m in a small residential neighborhood and I can usually see 7 to 10 wireless routers. That’s where the fun begins.

In the US, there are 11 channels reserved for 802.11b and 802.11g. The problem is that the channels overlap each other. Only channels 1, 6, and 11 are distinct channels. For the best reception on your network, you want to be on one of those channels and with the fewest number of neighbors on the same channel. The site survey feature in the DD-WRT firmware will display each router it finds, along with it’s channel and signal strength.

Most of the routers will be at channel 6, that seems to be the default channel that the routers use out of the box. So I’ll use channel 1 or 11, depending on which one has the least amount of traffic. And of course, there’s usually some one using one of the overlap channels like 9 or 2.

Another feature added by DD-WRT (and most of the 3rd party firmwares) is control over the power to the transmitter. I saw a small increase in signal strength with the client PC’s by raising the power setting a bit. I got a bigger boost by using Linksys’s HGA7T High Gain Antennas. You basicly replace the little stubby antennas that come with the WRT with ones that are about twice the size. You can find them on eBay or at Walmarts for around $40. It’s worth the money if you have a weak signal between the router and the PC.