Re: wireless specs

"William Andersen" <wgander@xxxxxxx> hath wroth:

What's the difference in range?

Probably none. Minor changes in router design offer some minor
variations in range. What really makes a *BIG* difference is the gain
of the antenna system. However, there's no free lunch. If you want
to increase the range in one direction, you do it by redirecting the
power that would normally be lost going in the wrong direction, thus
trading coverage area for range.

I see wireless routers for as little as $19; most of them are $49; and some
are pretty expensive.

Many of the differences are tied up in router features, not wireless
features. Some have dual band radios (2.4GHz and 5.7GHz). Some have
security features (VPN termination). Some have enhanced *SPEED*
features (Pre-802.11n, Turbo-G, Afterburner, etc) none of which offer
more range.

I'm happy with my ZyXEL P-330W 802.11g (I think it was less than $50), but I
only use it to access the internet from within my house.

I'll be temporarily
working at a different location and I'll be 100' from it, in a workshop in
the backyard. The router will be on the second floor, and can be located in
the attic, if necessary.

100ft through what appears to be 2 walls is going to be difficult. If
the walls are made of concrete and steel, or you have foil backed
insulation in the walls, it will be impossible. Range is really a
function of the environment. Also, when you're setting up in a new
location, there's also the possibility of interefrence from existing
systems. Having the local municipal network installed outside your
window will essentially trash your home network.

Is there a spec that provides a clue about range?

No. It's a combination of ingredients with no single number or
parameter. Everything can be traded for range.
1. Wireless router TX power
2. Wireless router RX sensitivity
3. Wireless client TX power
4. Wireless client RX sensitivity
5. Wireless router antenna gain
6. Wireless client antenna gain.
7. Wireless connection speed.
8. Interference susceptibility.
9. Signal loss in obstructions along the path.
10. Fresnel Zone losses.
11. Environmental issues (fog and rain attenuation).
12. Whatever else I forgot.

If you don't mind, I don't want to get into how each of these affects
range in detail. Basically, the bottom line if the fade margin, which
establishes how reliable the connection will be and at what speed the
connection will run. If you increase drop the path loss by 6dB (such
as by increasing the antenna gain(s) by 6dB), the range doubles. If
you increase the transmit power by 6dB, the range doubles.

Or, you can trade speed for range. At a given fade margin, if you
drop the speed 4 times, the range will be double.

It is possible to calculate the range if all the aformentioned are
known. This is normally used for microwave point to point links,
where moving obstructions, moving wireless clients, and interference
are uncommon. It can also be calculated using terrain models, as in
cellular coverage calculations, but you would need to have an accurate
architectual map of your workshop and backyard to do this.

If it won't work at that
distance I'll buy a different one to take with me.
My HP laptop has wireless builtin.

If your coverage requirements are all in one direction, then any
wireless router with an external antenna connector, plus a moderately
directional gain antenna will help. Putting the antenna in a window
will be a huge help (to avoid going through at least one wall).

However, there's no way to predict or guarantee that it will work. For
example, if your workshop is a metal building, it won't work. The
easiest way is to take what you have, and just try it. If it works,
an external gain antenna will be a big help. Try different locations
and positions.

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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