Wireless bridge

Thu Jun 18 15:54:58 UTC 2009

> From: Michael Dillon [mailto:wavetossed at googlemail.com]
> > (for example, after a good thunderstorm, the wireless link will be
> down for
> > at least 12 hours, but will fix itself eventually.
> 
> Sounds like there are trees in the line of sight, and maybe they are
> getting
> leafier over the years. The only solution to that is to change the path
> if
> it is possible.

The line of sight is all clear, no trees. Only one building along the way
has a rooftop of similar height, but the antennas are extended far above the
roofline. We have used a rifle scope to confirm line of sight is all clear
at all angles.

> From: Tim Huffman [mailto:Tim at bobbroadband.com]
> We're a WISP, so I have lots of experience with this kind of thing. The
> problem with using 2.4GHz equipment is that there's a whole lot of
> noise out there (run Network Stumbler sometime on a laptop with a
> wireless card, and you'll be shocked by just how many wi-fi APs are
> floating around).
> 

Oh I know. Luckily it's located in an industrial area just on the outskirts
of the city. There isn't a lot of other WiFi (in my opinion); 3-5 total
SSIDs spread across 2 of the 3 physical channels (1,6,11) depending on which
rooftop you measure from. 

> You didn't mention your bandwidth requirements, but I'm assuming that
> you're trying to get more (and spend less), so I'll only recommend
> unlicensed gear. For that distance, you might want to consider using a
> 5.2GHz radio. The FCC limits their transmit power, so they only work
> well in short-range applications (>2 miles or so), and 5.2GHz doesn't
> propagate the way that 2.4GHz does, so there tends to be much less
> noise in that band.
> 

Bandwidth requirements aren't too picky. If it can handle minimum 9 Mbps
full-duplex everyone will be happy. Of course, the faster the better.
I don't know if it makes a difference or not but this is all taking place in
Canada. I don't know of any regulations drastically different from the U.S's
regarding frequency use here. The biggest problem I've ever had though has
just been payment/shipping depending on the supplier (some don't ship to
Canada or are very specific about payment methods!).

Just to answer a few more questions I've been getting, the access points are
located inside, connected to a small UPS. The antenna wire is a very thick
coax up to the roof, BNC connectors to the access point and I'm fairly
certain BNC connectors on the antenna end as well. I'll double check
grounding on the poles but I'm somewhat afraid to turn it into a lightning
rod. I'm fairly certain that the ground in the antenna wire is clean but
again, something to double check.

Rain/moisture doesn't seem to cause problems. In fact the connection is more
reliable through the winter. The last 2 months here have been cold/warm,
dry/wet and there's been no pattern to the stability issues. The only
correlation between weather and stability that they have noticed there is
lightning related.

> From: Jason Gurtz [mailto:jasongurtz at npumail.com]
> Are you sure there's not a moisture problem in the antennae cabling?

I hope I just answered most of your questions Jason. Good tips to check for
too. I'll answer more of your specific questions ASAP.

Thanks everyone for the responses so far on and off list. I've been getting
lots of product suggestions as well as ideas for troubleshooting the current
implementation for the short term. I'm working on another project for today
so I've just been skimming through the responses. Later tonight I'll go
through all the options in more detail and report back/answer more
questions.

Keep 'em coming and thanks again,

Peter