Channelling messages from beyond…

OK, so who owns a BT Home Hub?  I’m sure many tens of you do, as that’s the default solution from BT for home internet connections. And I’m sure its a great product.  However, they seem to cause me nothing but trouble – you see, I don’t use BT as an ISP as they’re comparatively expensive, low on functionality, and reports indicate that its quite slow and unreliable too.   So, I’ve got my own Wifi routers (Linksys WRT54gl’s) in the house which run a custom firmware and allow me to set them up just so.  Three of them ensure that I have total wifi coverage at Very Good or above throughout the house.  Or that’s the theory.

For those that don’t know, here’s a brief technical overview of how wifi works…   Wifi is generally split into 4 types – A, B, G and N, with A & N running at 5 Ghz, and B, G (and N) running at 2.1 Ghz.  5 Ghz offers around 19 channels in Europe with 20 Mhz separation, which is fine.  However,  2.1 Ghz only offers 13 channels spaced 5 Mhz apart, but the wifi protocol requires 25mhz of separation.  This means that in reality, there are only three or four channels that can be used without clashing with other networks.  And that’s assuming that you’ve no other devices on the 2.1Ghz band such as Bluetooth, baby monitors,  TV senders,  wireless video game controllers – even microwaves and fluorescent lights can generate radio noise on this band.

A few minutes spent planning the network can reduce the impact that this has, even for a single access point.  The diagram shows the spectrum coverage of the given wifi channels, and you can use this to work out what the optimal settings for your network is.

File:2.4 GHz Wi-Fi channels (802.11b,g WLAN).png

So what you need to do is find out what channels your neighbours network is on (many wifi drivers and access points will show you).  If for example they’re on channel 11,  you could use 7 downwards.  Where it becomes more complicated is when you have neighbours both sides with wifi – you’ve got to slot in with them and hope that there are free channels available.

But back to my original point – flippin BT HomeHubs!  Most of my neighbours seem to be using them, which is fine, BUT the HomeHubs don’t seem to be able to pick a channel and stick with it – except when manually configured to do so! Every few weeks I find my wireless has gone to hell, and I look, and one of the hubs has changed its channel to the opposite end of the spectrum which means recalibrating my setup to get the best I can with the least overlap.  What’s most annoying is that they seem pretty useless at seeing what’s available and will often arbitrarily pick channel 6 or 7 no matter what is around them!  Which makes it pretty difficult to configure the network without any overlap.  My only hope is 802.11n (N networks) will go someway to improve this, but I don’t currently have any experience on its impact, other than it is supposed to be better in noisy environments.  But for now, I’ll stick with wired ethernet where I require guaranteed service such as to my media server, as its the only way of ensuring a consistent an reliable connection. 

And if you find your wireless experience is awful, check your channel assignment – the chances are you and your neighbours are all shouting at the same time and drowning each other out!

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