[sclug] Long distance Wifi

[ed]

On Mon, 27 Feb 2006 18:16:40 +0000
Peter Brewer <p.w.brewer at reading.ac.uk> wrote:

> We have a place on a hill in the depths of Wales and would like to get
> 
> broadband.  Unfortunately we are too far from the exchange to get it 
> directly although some friends have it in the village down in the 
> 'valley'.  I was wondering about the possibility of using
> point-to-point  antenna to do wifi from our friends.  I've seen loads
> of commercial and  'pringles can' antenna on the web but nobody seems
> willing to put a  distance on their performance.

By pringles can, are you referring to 'yagi-uda'? These have better
performance on ptp networks, you will need one at each end of course.

> First, is this actually possible?  How far can these antenna work? 
> Our  closest friends are about 1km away in direct line of sight.
> Second, is it legal?  How do people like BT view sharing a broadband 
> line like this?

It's possible to go over 1km, I used to work at a wifi ISP, you can get
the performance, but it's all dependent on the conditions, the amount of
coax you're using and the quality of the direct line of sight. If you
have anything other than pure, clean, direct LOS then you may as well
stick to dial up.

Speaking of dialup, you can do some tricks where you get a bunch of
dialup links and with a few lines in OpenBSD/pf you can round robin your
outbound connections.

On the subject of what's legal, you can go to 19dbi, if you attach an
amplifier you can get more, but you'd not be letting anyone else
communicate. So, try and get ethernet bridges that have 14 channels,
then you can use the highest channel and hopefully your Yagi will not be
pointing at any households that use wifi.

If you can get external bridges (such as smartbridges) you can attach
the bridge to the antenna mast and keep coax short, the shorter the less
loss incurred.

-- 
Regards, Ed                      :: http://www.usenix.org.uk
:%s/\t/  /g                      :: proud unix system person
:%s/Open Source/Free Software/g