Wireless connectivity between 2 buildings

I need to get two buildings hooked up through a wireless connection and
have a fair bit of concrete (not real worried about), steel and
insulation.
Now, there is a high amount of security that is needed to be in place,
which is what's making me lean away from a standard omni-directional
802.11G antenna.
I was thinking that a pair of low power directional antennas may do the
trick and for them to just be placed on the out side of the buildings,
or even inside if the signal reaches.

My question is how narrow is the wireless field? The building is about
50ft away, not real far, but I want to be very careful that the
wireless signal is not going right down the block.
My other ocnsideration was using an infrared connection between the two
buildings, but have found little in terms of products that will have an
"ease of use" in terms of connecting to the existing network.

On 12 Jul 2006 07:44:52 -0700, (E-Mail Removed) wrote in
<(E-Mail Removed) .com>:

>I need to get two buildings hooked up through a wireless connection and
>have a fair bit of concrete (not real worried about), steel and
>insulation.

Wi-Fi signals can be greatly attenuated by concrete, depending on
construction. Insulation is a serious problem if foil backed. Steel
can cause problematic reflections. Etc.

>Now, there is a high amount of security that is needed to be in place,
>which is what's making me lean away from a standard omni-directional
>802.11G antenna.

Antennas don't have any real bearing on security -- bad guys have better
antennas than you do. Use WPA with RADUIS or strong passphrases.

>I was thinking that a pair of low power directional antennas may do the
>trick and for them to just be placed on the out side of the buildings,
>or even inside if the signal reaches.

OK.

>My question is how narrow is the wireless field? The building is about
>50ft away, not real far, but I want to be very careful that the
>wireless signal is not going right down the block.

I'd personally use external panel antennas over that distance.

>My other ocnsideration was using an infrared connection between the two
>buildings, but have found little in terms of products that will have an
>"ease of use" in terms of connecting to the existing network.

In addition, infrared can be a problem in bad weather.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

(E-Mail Removed) hath wroth:

>I need to get two buildings hooked up through a wireless connection and
>have a fair bit of concrete (not real worried about), steel and
>insulation.
>Now, there is a high amount of security that is needed to be in place,
>which is what's making me lean away from a standard omni-directional
>802.11G antenna.
>I was thinking that a pair of low power directional antennas may do the
>trick and for them to just be placed on the out side of the buildings,
>or even inside if the signal reaches.
>
>My question is how narrow is the wireless field? The building is about
>50ft away, not real far, but I want to be very careful that the
>wireless signal is not going right down the block.

That's going to be difficult. Most antennas have side lobes that can
be heard from off axis. Even if the side lobes were perhaps 30dB
(1/1000th the power) lower than the main beam, a 30dB direction
antenna in the hands of an evil wireless hack (like me) would bring
the signal back to a usable level. In addition, 2.4Ghz bounces around
and not all the RF that arrives is absorbed by the receive antenna.
Lots of it hits the building and bounces to who knows where. It's a
good idea to limit your beamwidth to reduce interference and enhance
security, but it's not a guarantee.

As a rule of thumb, the antennas -3dB beamwidth is dependent on the
type of antenna and the antenna gain. For example:
Type Gain -3dB BW
dBi degrees
Biquad 10 60
Panel 19 18
Dish 24 8
Yagi 15 30
Dish 15 19
coffeecan 10 60

Using the 19dBi panel as a practical example, with an 18 degree
beamwidth at 50ft, the beam will be 16.2 feet in diameter. That means
that HALF the RF will end up in a 16.2ft diameter circle. Since the
antenna is only about 1 ft square aperture area, something like 1/415
of the transmitted power actually hits the antenna. The rest is
reflected off the target building.

At 50ft, you could probably reduce your transmit power to the absolute
minimum necessary to communicate. However, you're not going to be
able to prevent anyone from hearing the signal.

>My other ocnsideration was using an infrared connection between the two
>buildings, but have found little in terms of products that will have an
>"ease of use" in terms of connecting to the existing network.

For 50ft, I suggest using an FSO (free space optical) bridge. See:
http://www.plaintree.com
However, they're MUCH more expensive the 802.11g wireless.

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

Okay. I think my plan right now is to use approx a 8dbi gain
antenna(DLink Pico) hooked in place of the standard router/AP antenna.
And see what that gets me for signal strength in the other building.
If its not enough, depending on how much is lacking, I will add what I
need there in terms of AP or possibly another directional antenna.

For someone to pick up the wireless signal it would have to travel a
good distance to get out to the street. With the way the directional
would be facing, there is a good 100-150 yards to the closest
street/public lot. And even with the signal bouncing there is not much
in close proximity to the buildings for someone to sit and pick up a
signal.

So a semi powerful signal is not going to get far enough to reach to
the public. I was just concerned about possibly overpowering the signal
needed and allowing the broadcast to reach all the way out to where I
don't want it.
I am not very familiar with how far a directional antenna will reach
with its rated power. DLink claims about 500M for their Pico antenna,
but I don't know if this is really accurate or if its extremely ideal
and I should really expect much less than that. Particullarly with
structures involved.

On 12 Jul 2006 09:55:06 -0700, (E-Mail Removed) wrote in
<(E-Mail Removed) .com>:

>Okay. I think my plan right now is to use approx a 8dbi gain
>antenna(DLink Pico) hooked in place of the standard router/AP antenna.
>And see what that gets me for signal strength in the other building.
>If its not enough, depending on how much is lacking, I will add what I
>need there in terms of AP or possibly another directional antenna.
>
>For someone to pick up the wireless signal it would have to travel a
>good distance to get out to the street. With the way the directional
>would be facing, there is a good 100-150 yards to the closest
>street/public lot. And even with the signal bouncing there is not much
>in close proximity to the buildings for someone to sit and pick up a
>signal.
>
>So a semi powerful signal is not going to get far enough to reach to
>the public. I was just concerned about possibly overpowering the signal
>needed and allowing the broadcast to reach all the way out to where I
>don't want it.

Never make assumptions like that without a careful site survey. I've
shocked clients that had made assumptions like yours by picking up and
cracking into their networks (with their permission) using cheap
equipment.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

John Navas wrote:
> On 12 Jul 2006 09:55:06 -0700, (E-Mail Removed) wrote in
> <(E-Mail Removed) .com>:
>
> >Okay. I think my plan right now is to use approx a 8dbi gain
> >antenna(DLink Pico) hooked in place of the standard router/AP antenna.
> >And see what that gets me for signal strength in the other building.
> >If its not enough, depending on how much is lacking, I will add what I
> >need there in terms of AP or possibly another directional antenna.
> >
> >For someone to pick up the wireless signal it would have to travel a
> >good distance to get out to the street. With the way the directional
> >would be facing, there is a good 100-150 yards to the closest
> >street/public lot. And even with the signal bouncing there is not much
> >in close proximity to the buildings for someone to sit and pick up a
> >signal.
> >
> >So a semi powerful signal is not going to get far enough to reach to
> >the public. I was just concerned about possibly overpowering the signal
> >needed and allowing the broadcast to reach all the way out to where I
> >don't want it.
>
> Never make assumptions like that without a careful site survey. I've
> shocked clients that had made assumptions like yours by picking up and
> cracking into their networks (with their permission) using cheap
> equipment.
>
> --
> Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
> John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
> Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
> Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

As I said, I am unfamiliar with the ranges that I am going to be
dealing with so not much would shock me on how far it is going to go.
And of course full encryption and codes would be in place on the
wireless signal, I am just wanting to avoid broadcasting the network
availability across half the city.

Some of the stuff that we are doing requires an absolute measure of
security, so anything involving that immediately rules out wireless and
even connectivity to the standard network.
The area involved with the wireless I am trying to setup is
confidential, but is not to a degree that is going to be of any
interest to most people. I just want to keep the knowledge of the
network lower key as to not to attract to many unwanted attempts. I
assumed with wireless that there is no sure fire way to protect your
transmissions, but I never assumed that no one would be able to pickup
the signal from out of the compoud.

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
>
> John Navas wrote:
> > On 12 Jul 2006 09:55:06 -0700, (E-Mail Removed) wrote in
> > <(E-Mail Removed) .com>:
> >
> > >Okay. I think my plan right now is to use approx a 8dbi gain
> > >antenna(DLink Pico) hooked in place of the standard router/AP antenna.
> > >And see what that gets me for signal strength in the other building.
> > >If its not enough, depending on how much is lacking, I will add what I
> > >need there in terms of AP or possibly another directional antenna.
> > >
> > >For someone to pick up the wireless signal it would have to travel a
> > >good distance to get out to the street. With the way the directional
> > >would be facing, there is a good 100-150 yards to the closest
> > >street/public lot. And even with the signal bouncing there is not much
> > >in close proximity to the buildings for someone to sit and pick up a
> > >signal.
> > >
> > >So a semi powerful signal is not going to get far enough to reach to
> > >the public. I was just concerned about possibly overpowering the signal
> > >needed and allowing the broadcast to reach all the way out to where I
> > >don't want it.
> >
> > Never make assumptions like that without a careful site survey. I've
> > shocked clients that had made assumptions like yours by picking up and
> > cracking into their networks (with their permission) using cheap
> > equipment.
> >
> > --
> > Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
> > John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
> > Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
> > Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>
>
> As I said, I am unfamiliar with the ranges that I am going to be
> dealing with so not much would shock me on how far it is going to go.
> And of course full encryption and codes would be in place on the
> wireless signal, I am just wanting to avoid broadcasting the network
> availability across half the city.
>
> Some of the stuff that we are doing requires an absolute measure of
> security, so anything involving that immediately rules out wireless and
> even connectivity to the standard network.
> The area involved with the wireless I am trying to setup is
> confidential, but is not to a degree that is going to be of any
> interest to most people. I just want to keep the knowledge of the
> network lower key as to not to attract to many unwanted attempts. I
> assumed with wireless that there is no sure fire way to protect your
> transmissions, but I never assumed that no one would be able to pickup
> the signal from out of the compoud.

you are trying to make a wrench out of a hammer. itdoesnt sound like
wireless fits the application very well, so you should at least look at
alternatives.

if you are paranoid even on different networks, if your security folks are
as paranoid as mine, they will not agree to working wireless even on a
different network in the same building (to be fair, theyare worried about
what happens, when someone comes along and alters the network and joins them
up in some way, or there is access between control networks etc.

So you need to check if your assumptions about wireless and the security
level are acceptable, whether there is a duct inplace, or enough height for
a wire support between buildings.

if possible use fibre or rent a telco Ethernet WAN link -which would also
give you a lot more useful bandwdith, and probably be more reliable.
>
--
Regards

(E-Mail Removed) - replace xyz with ntl

(E-Mail Removed) wrote:

>
> As I said, I am unfamiliar with the ranges that I am going to be
> dealing with so not much would shock me on how far it is going to go.
> And of course full encryption and codes would be in place on the
> wireless signal, I am just wanting to avoid broadcasting the network
> availability across half the city.
>
> Some of the stuff that we are doing requires an absolute measure of
> security, so anything involving that immediately rules out wireless and
> even connectivity to the standard network.
> The area involved with the wireless I am trying to setup is
> confidential, but is not to a degree that is going to be of any
> interest to most people. I just want to keep the knowledge of the
> network lower key as to not to attract to many unwanted attempts. I
> assumed with wireless that there is no sure fire way to protect your
> transmissions, but I never assumed that no one would be able to pickup
> the signal from out of the compoud.
>

Security seems to be your main focus so why have doubt and checkout
running fiber between the two buidings?

Fiber and anything involved installing an underground line isn't
feasible right now. The lot was just redone and the fundage providers
don't want to have to redo it again. And there are no available
conduits that a line can be fed through.

However, one option we are looking at is running fiber to yet another
building from the one we want the connection as we already have the
third building connected to the main building.

I_AM_Rap...@hotmail.com wrote:
> Fiber and anything involved installing an underground line isn't
> feasible right now. The lot was just redone and the fundage providers
> don't want to have to redo it again. And there are no available
> conduits that a line can be fed through.
>
> However, one option we are looking at is running fiber to yet another
> building from the one we want the connection as we already have the
> third building connected to the main building.

Forgot to add that an over head line is out of the question as well.
It would not work with the equipment that needs to get moved around
here.