[TriLUG] WLAN Research

[Greg Brown]

I've used Ciscos before too, and if money is not an object I would go with
these units if at all possible (running IOS, not that other OS.. whatever it
is).

Anyway, if money is an object I would go with WRT54G linksys boxes, NOT
running Linksys code.  Why?  For distances this great I would highly
reccomend amplification.  In order to run amps without rediculious noise you
need to drop the input power on your AP going into the amp.  I've found 20
mw of power works best.

Being as this is a point-to-point link you can raise the gain on the
antennas and the amps a bit to.  Here are your limits:

Total    Amp                         Max gain           EIRP in watts
*30dBm 1W                            6dBi                 3.98
29dBm 800mW                      9dBi                 6.35
28dBm 630mW                    12dBi                10.14
27dBm 500mW                    15dBi                15.81
26dBm 398mW                    18dBi                25.23
25dBm 316mW                    21dBi                40.28
24dBm 250mW                    24dBi                62.79
23dBm 200mW                    27dBi                100.2

So, looking at this we have a couple options.  I'd go with Yagi antennas or
dishes.  Personally I would only mess with 500 mw or 1 watt amps, too much
freakiness on the adjustable amps.

Use LMR400 antenna cables.  The other stuff has too high loss.  And mount
the amp as close to the antenna as possible.

Personally I'd go with Antennex Yagis, they are weatherproof and sealed.
Nice.  At 14.6 dBi gain you can still go with a 500 mw amp and you'll be
just under max power.  Anything more then 100 yards I'd consider going with
dishes, but at this power level you should be ok.

Use WPA between the devices too (keep the prying eyes out).  If you get
adventerous try afterburner mode on the wrts.  I've never tried it, but I
can't see why not.

Anyway, those are my suggestions.

Greg

*
On 5/22/06, Matt Dinsmore <matt at centrix.net> wrote:
>
> I've done this before, not locally though. We used Cisco 350 bridges.
> Worked great, except for when it got snowy/icey which I don't think will
> be a problem here. We had multiple sites with yagi antennas. At the
> center we had an omni. We had a 3 mile radius. The extreme edges got
> kinda sketchy, but 100 yards should work fine and be stable.
>
> I would recommend the Cisco stuff, or even the Linksys ( which is now
> owned by Cisco ) stuff if this is tmp / on a budget.
>
> How is your line of site ? This is VERY important for long distance hauls.
>
> Matt Dinsmore
> matt at centrix.net
>
> Carl Crider wrote:
> > I am currently researching parts/designs for a wireless LAN here at my
> > office.
> > We need to connect a building that is 100 yards away from our main
> > switch.
> > This building houses only 5 PC's. Does anyone have suggestions on both
> > design and local shops to buy the parts?
> >
> > This will be a permanent installation replacing the current underground
> > fiber patching these 2 buildings. The fiber has to come up due to
> > construction.
> >
> > Thanks in advance for any input.
> >
>
>
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