Critique my RAN (rural area network)

I have an off-grid home. My closest neighbor and I use two-way satellite
(DirecWay). Now we have a third neighbor moving in who was talking about
getting the satellite connection. I said that was nuts :-)

Another neighbor, just about exactly 1km away over open water (foggy at
least 60 days a year, if that matters) has cable access. While she can't
legally share that, I have no problem paying the cable company for a
business connection which we _can_ legally share.

I want to set up an access point where the cable connection is, with a
directional antenna to us. The three houses are within 15 degrees from
that point. Then, at each "client" house, I want to put a directional
antenna pointing back to the base, connected to a repeater, so that the
computers in the client houses have wireless access via the repeater.

The real problem is that I'm confused by much of the terminology used and
I'm not sure what I'm really looking for. Using D-Link as an example, just
because it was easy to find, not because I know enough to want to buy
them :-), it would seem I should be able to use:

- DI-524/624 at the base station, connected to the Cable and external
antenna
- either a DWLG710 range extender or a DWL-G700AP as a repeater. Seems like
they'd both work, but the AP has more capabilities and costs less!

Am I on the right track? And is that fog going to be a problem?
--
derek

Derek,
I don't think you will get 15 degree coverage over 1km, As I learned
the hard way a 15db / 8 degree cantenna goes a lot further than a 20db
/ 30 degree panel antenna. I guess you have to divide the power over
the area covered. I would reccomend several cheap AP's using non
adjacent channels all plugged into a hub or router at the base station
with seperate cantenna's aligned for each client (put it in bridge mode
if client is a network vs an individual machine- you will also need
cantenna on client end to insure hi bandwidth connection. it might be
cheaper to use a pair of dish antenna to bridge the lake and then
redistribute from your side.

frank wrote:

>
> Derek,
> I don't think you will get 15 degree coverage over 1km, As I learned
> the hard way a 15db / 8 degree cantenna goes a lot further than a 20db
> / 30 degree panel antenna.

Well, we'll see that when my test equipment arrives :-) I've got a couple
of 14dBi/20degree antennas to test with. My brother-in-law thinks it'll be
no problem, but that's one of the things I want to be sure of.

> it might be
> cheaper to use a pair of dish antenna to bridge the lake and then
> redistribute from your side.

It might even be necessary. My two neighbors are very close and I'm not
certain the one (who _is_ conveniently line of site to all the buildings)
doesn't block the other from the cross-lake line. If a single antenna at
the internet end could serve all three clients, the centremost house would
probably be in the Fresnel zone of the other house.
--
derek

On Tue, 09 Aug 2005 16:35:13 -0300, Derek Broughton <(E-Mail Removed)> wrote:

>I have an off-grid home.

What does that mean?

>My closest neighbor and I use two-way satellite (DirecWay).

For what?

>Now we have a third neighbor moving in who was talking about
>getting the satellite connection.

For what?

>I said that was nuts :-)
>
>Another neighbor, just about exactly 1km away over open water (foggy at
>least 60 days a year, if that matters) has cable access. While she can't
>legally share that, I have no problem paying the cable company for a
>business connection which we _can_ legally share.
>
>I want to set up an access point where the cable connection is, with a
>directional antenna to us. The three houses are within 15 degrees from
>that point. Then, at each "client" house, I want to put a directional
>antenna pointing back to the base, connected to a repeater, so that the
>computers in the client houses have wireless access via the repeater.
>
>The real problem is that I'm confused by much of the terminology used and
>I'm not sure what I'm really looking for. Using D-Link as an example, just
>because it was easy to find, not because I know enough to want to buy
>them :-), it would seem I should be able to use:
>
>- DI-524/624 at the base station, connected to the Cable and external
>antenna
>- either a DWLG710 range extender or a DWL-G700AP as a repeater. Seems like
>they'd both work, but the AP has more capabilities and costs less!
>
>Am I on the right track? And is that fog going to be a problem?
>--
>derek

Barry
=====
Home page
http://members.iinet.net.au/~barry.og

Barry OGrady wrote:

> On Tue, 09 Aug 2005 16:35:13 -0300, Derek Broughton <(E-Mail Removed)>
> wrote:
>
>>I have an off-grid home.
>
> What does that mean?

Thank you for the highly intelligent response to my question. Look it up.
I have no connections to cables of any kind.
>
>>My closest neighbor and I use two-way satellite (DirecWay).

<plonk>
--
derek

On Tue, 09 Aug 2005 16:35:13 -0300, Derek Broughton
<(E-Mail Removed)> wrote:

>I have an off-grid home.

Nice. Do you read Home Power Magazine?
http://www.homepower.com

Look into the Linksys WRT54G. It has some big advantages for what
you're trying to do. It can run on anything between about 4VDC and
18VDC (negative ground). Using altenative firmware from Sveasoft, you
can configure it as a router, access point, or client device. It will
do WDS repeater bridging.
http://www.sveasoft.com/content/view/3/1/

>My closest neighbor and I use two-way satellite
>(DirecWay). Now we have a third neighbor moving in who was talking about
>getting the satellite connection. I said that was nuts :-)

DirecWay isn't all that fast. There really isn't that much bandwidth
to share. Two of my customers have these with about 3 simultaneous
coputers. It's a battle when everyone is on at once. The headache is
the upstream bandwidth which averages about 40Kbits/sec and is easily
saturated.

>Another neighbor, just about exactly 1km away over open water (foggy at
>least 60 days a year, if that matters) has cable access. While she can't
>legally share that, I have no problem paying the cable company for a
>business connection which we _can_ legally share.

Cable is far better bandwidth suitable for sharing.

>I want to set up an access point where the cable connection is, with a
>directional antenna to us. The three houses are within 15 degrees from
>that point. Then, at each "client" house, I want to put a directional
>antenna pointing back to the base, connected to a repeater, so that the
>computers in the client houses have wireless access via the repeater.

15 degrees is not impossible but difficult. A 14dBi panel antenna
will have about 30 degree -3dB beamwidth which should work. You don't
want to get a 15 degree wide antenna as the stations at the edge will
probably be marginal. Instead of a repeater, I suggest either of the
following approaches.

1. Use WDS (wireless dispribution service) to build to store and
forward network system. I has all the advantages of a repeater, plus
you can plug computahs into the WDS radio to "tap" off a connection.
WRT54G is perfect for such a system. Essentially, each house forwards
to the next house. The problem is that every time you store and
forward repeat the data, the maximum bandwidth gets cut in half. See
guesswork on bandwidth below.

2. Install the WRT54 in an outdoor box on top of a pole and run CAT5
to the computers. No need for power over ethernet at the WRT54G will
run on just about any DC voltage from 4.0 to 18VDC. Just connect
12VDC, accept the copper losses, and it will work. This is generally
simpler, easier, and probably more reliable.

>The real problem is that I'm confused by much of the terminology used and
>I'm not sure what I'm really looking for. Using D-Link as an example, just
>because it was easy to find, not because I know enough to want to buy
>them :-), it would seem I should be able to use:
>
>- DI-524/624 at the base station, connected to the Cable and external
>antenna
>- either a DWLG710 range extender or a DWL-G700AP as a repeater. Seems like
>they'd both work, but the AP has more capabilities and costs less!

No comment on range extenders and repeaters. Well, maybe a small
comment. I think they suck, work only in about half the systems, are
incompatible with much of the available hardware, and chop the
available bandwidth in half.

>Am I on the right track? And is that fog going to be a problem?

Fog will not be a problem at 1km. However condensation on any outdoor
electronics will be. I've had to coat my boards with various Humiseal
products to keep them water tolerant. Perhaps a heater inside the box
to raise the dew point will be necessary.

My guess(tm) is that at 1km (0.62miles), you'll end up with a 19dBi
dish antenna at the client end and a 14dBi panel at the cable modem
end. With +15dBm tx power output, about -85dBm rx sensitivity, and
4dB cable losses at each end, you'll get a fade margin of about 25dB,
which is more than adequate for the link. My guess(tm) is that you'll
end up with a fixed connection rate of about 12Mbits/sec OFDM. That
will give you about half that in thruput. The first WDS bridge will
get the full 6Mbit/sec thruput. However, the 2nd wireless hop will
only get about half that, and so on. Methinks that's adequate. If
you want more bandwidth, get a 24dBi dish instead of the 19dBi, and
increase the connection rate.
http://www.terabeam.com/support/calculations/som.php


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558

On Wed, 10 Aug 2005 10:26:36 -0300, Derek Broughton
<(E-Mail Removed)> wrote:

>frank wrote:
>
>>
>> Derek,
>> I don't think you will get 15 degree coverage over 1km, As I learned
>> the hard way a 15db / 8 degree cantenna goes a lot further than a 20db
>> / 30 degree panel antenna.
>
>Well, we'll see that when my test equipment arrives :-) I've got a couple
>of 14dBi/20degree antennas to test with. My brother-in-law thinks it'll be
>no problem, but that's one of the things I want to be sure of.

Fire your brother in law. A 14dBi antenna with a 20 degree -3dB
beamwidth would be a yagi. In my never humble opinion, this is a
terrible choice. The signal strength falls over VERY rapidly at the
-3dB points. Even though you allegedly lose only -3dB at the end
points, the slope is so steep that even the slightest misalignment
will be fatal.

Here's some sample beamwidths extracted from random datasheets.

Type gain -3dB Beamwidth
dBI degress
patch 13 38
yagi 14 30
planar 13 25
dish 15 19

This chart for a yagi may also be of interest:
gain -3db beamwidth
dBi degrees
8 60
10 40
14 30
16 25

>> it might be
>> cheaper to use a pair of dish antenna to bridge the lake and then
>> redistribute from your side.

See my previous posting. Methinks that would be best. A solid dish
to dish link across the lake, and then redistribute using WDS
repeaters.

You may have one potential problem with the cross lake link that's
unique to microwave over water. There will be two paths. The direct
path between antennas and the bounce path off the lake. They will
arrive at slightly differnet times at the destination resulting in
self-interference also known as multipath. OFDM is very good at
eliminating these effects but is not perfect. There will be times
when the RF signal cancels and there's no signal to work with. The
ugly solution is to setup one end of the link so that the antenna can
be raised or lowered. I use cast aluminium hand rail connectors for
the purpose over a pole/pipe to raise and lower the antenna assembly.
After a bit of tinkering, the optimium, or least disgusting location
can easily be found.

>It might even be necessary. My two neighbors are very close and I'm not
>certain the one (who _is_ conveniently line of site to all the buildings)
>doesn't block the other from the cross-lake line. If a single antenna at
>the internet end could serve all three clients, the centremost house would
>probably be in the Fresnel zone of the other house.

Ok, time to get irate.... Would you kindly replace "very close" with
some real numbers? I'm a big fan of calculating before I build and
find it difficult to insert "very close" into my spreadsheet.

It might be possible to run CAT5 or coax between houses. I've broken
the cable length rules many times and know most of the tricks. You
can go about 1000ft of CAT5 or RG-6/u (yeah, I know it's 75 ohms) at
10BaseT-HDX speeds without any difficulty. You'll get about
6Mbits/sec thruput. I've posted details previously. Please advise if
interested.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558

Jeff Liebermann wrote:

> On Tue, 09 Aug 2005 16:35:13 -0300, Derek Broughton
> <(E-Mail Removed)> wrote:
>
>>I have an off-grid home.
>
> Nice. Do you read Home Power Magazine?
> http://www.homepower.com

On and off. I wish I'd read it _at all_ before I went off-grid :-)

> Look into the Linksys WRT54G. It has some big advantages for what
> you're trying to do. It can run on anything between about 4VDC and
> 18VDC (negative ground).

Cool, but not necessary. I'm off-grid, but I do have AC - and plenty to
handle a wireless device.

> Using altenative firmware from Sveasoft, you
> can configure it as a router, access point, or client device. It will
> do WDS repeater bridging.
> http://www.sveasoft.com/content/view/3/1/

However, that's nice.

> DirecWay isn't all that fast.

Tell me about it (oh, you did :-) ). I tell everyone who asks that it's
only a solution for people who have _no_ other solutions. At the time I
installed it, I didn't

> 15 degrees is not impossible but difficult. A 14dBi panel antenna
> will have about 30 degree -3dB beamwidth which should work. You don't
> want to get a 15 degree wide antenna as the stations at the edge will
> probably be marginal. Instead of a repeater, I suggest either of the
> following approaches.
>
> 1. Use WDS (wireless dispribution service) to build to store and
> forward network system.

The difference is what? That's my problem. I don't have a clue what the
wireless manufacturers are selling when they say "repeater". Can you point
me to some links? It's especially difficult when I go to sveasoft.com and
they tell me their firmware has "WDS/Repeater mode"!

> I has all the advantages of a repeater, plus
> you can plug computahs into the WDS radio to "tap" off a connection.

I thought that's what the repeater was supposed to do.

> WRT54G is perfect for such a system. Essentially, each house forwards
> to the next house. The problem is that every time you store and
> forward repeat the data, the maximum bandwidth gets cut in half. See
> guesswork on bandwidth below.

That's not a huge issue. I want to be able to promise better speed for less
cost than Direcway for each of three sites. I don't think that's hard :-)
(for those who don't know DirecWay, it's usually considered to be
approximately ISDN speed once everything's taken into account - it can be
much faster for large downloads, but latency kills www access).
>
> No comment on range extenders and repeaters. Well, maybe a small
> comment. I think they suck, work only in about half the systems, are
> incompatible with much of the available hardware, and chop the
> available bandwidth in half.

As would the WDS, right? Half the bandwidth is just fine :-)

Thanks for all your help.
--
derek

Jeff Liebermann <(E-Mail Removed)> wrote:
>It might be possible to run CAT5 or coax between houses. I've broken
>the cable length rules many times and know most of the tricks. You
>can go about 1000ft of CAT5 or RG-6/u (yeah, I know it's 75 ohms) at
>10BaseT-HDX speeds without any difficulty. You'll get about
>6Mbits/sec thruput. I've posted details previously. Please advise if
>interested.

Very interested, though I don't remember the discussions, please fill
us in!

On Thu, 11 Aug 2005 17:02:23 -0400, William P. N. Smith <> wrote:

>Jeff Liebermann <(E-Mail Removed)> wrote:
>>It might be possible to run CAT5 or coax between houses. I've broken
>>the cable length rules many times and know most of the tricks. You
>>can go about 1000ft of CAT5 or RG-6/u (yeah, I know it's 75 ohms) at
>>10BaseT-HDX speeds without any difficulty. You'll get about
>>6Mbits/sec thruput. I've posted details previously. Please advise if
>>interested.

>Very interested, though I don't remember the discussions, please fill
>us in!

Surely Google Groups is searchable:

http://groups-beta.google.com/group/...40b8ec03d59cfe

Basically, I've gone about 900ft with CAT5 and 1200ft with RG-6/u.
The article above explains some of the tricks and calcas involved.

The rules and limitations for coax are:
1. Must be 10baseT-HDX (half duplex)
2. No "Tee" connector in the middle of the coax run.
3. To short a run with RG-6/u are a problem.
4. Ground only one end of the coax or you will have a ground loop.
5. 50 ohm terminators, not 75 ohms.
6. Squirrels and mice love to eat coax cable. Conduit is nice.

Any questions? Gotta run.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# http://802.11junk.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS