For architectural and building management reasons we cannot mount our
antennas in a rooftop or outdoor location at either end. The distance
between two buildings is 1.5 km, and the fresnel zone is clear. Antennas
need to be located indoors at both ends and will be placed on small speaker
stand tripod pointing at windows. This has been done successfully before
with 2.4 GHz 802.11g equipment and a link from an office in the Westin to a
nearby apartment building, but I am unsure of what effect glass will have on
5 GHz. Has anyone tried this?
The goal of this link is to achieve a 10 Mbps+ full duple bridge to a
building which is only serviced by ADSL2+ Telus service in a Western
Canadian city. Telus' upstream speed offering do not exceed 1 Mbps.
Equipment. These have been used successfully for MCS13/MCS14 50 Mbps+
bridges at 11 km distance between towers.
A lot depends on the windows themselves. Windows in some modern buildings have a thin metallic coating that can have a big impact on the ability to pass an RF signal.
For architectural and building management reasons we cannot mount our
antennas in a rooftop or outdoor location at either end. The distance
between two buildings is 1.5 km, and the fresnel zone is clear. Antennas
need to be located indoors at both ends and will be placed on small speaker
stand tripod pointing at windows. This has been done successfully before
with 2.4 GHz 802.11g equipment and a link from an office in the Westin to a
nearby apartment building, but I am unsure of what effect glass will have on
5 GHz. Has anyone tried this?
The goal of this link is to achieve a 10 Mbps+ full duple bridge to a
building which is only serviced by ADSL2+ Telus service in a Western
Canadian city. Telus' upstream speed offering do not exceed 1 Mbps.
Equipment. These have been used successfully for MCS13/MCS14 50 Mbps+
bridges at 11 km distance between towers.
Imo, Ubiquiti stuff is so cheap ($95 for the 25dBi version), it's probably more cost effective to just buy it and try it rather than spending the time analyzing the glass (on both ends).
For architectural and building management reasons we cannot mount our
antennas in a rooftop or outdoor location at either end. The distance
between two buildings is 1.5 km, and the fresnel zone is clear. Antennas
need to be located indoors at both ends and will be placed on small speaker
stand tripod pointing at windows. This has been done successfully before
with 2.4 GHz 802.11g equipment and a link from an office in the Westin to a
nearby apartment building, but I am unsure of what effect glass will have on
5 GHz. Has anyone tried this?
glazed windows (which is tin in general) are a problem... when most of
your radiation as being thrown right back at you that is a challange.
Codes are usually defined in one of two ways... Either "cannot be
above the building parapet" or "cannot be visible from the street
below" (which allows you to position a stant at the center of the roof
so you can clear the parapet) but when talking to building management,
it can very easily be, "can't put anything on the roof"
So to be certain we're not missing an opportunity, do you know that
you don't actually have the second of those definitions as an option?
In my area, neighboring jurisdictions adopt either the first or the
second with building management usually adopting the first and making
my life difficult. (IE, can do it in one place but not on the
companion building.)
Codes are usually defined in one of two ways... Either "cannot be
above the building parapet" or "cannot be visible from the street
below" (which allows you to position a stant at the center of the roof
so you can clear the parapet) but when talking to building management,
it can very easily be, "can't put anything on the roof"
So to be certain we're not missing an opportunity, do you know that
you don't actually have the second of those definitions as an option?
In my area, neighboring jurisdictions adopt either the first or the
second with building management usually adopting the first and making
my life difficult. (IE, can do it in one place but not on the
companion building.)
The third consideration is "someone notices and cares".
The Nanostation Loco (again from Ubiquiti) is easily capable of the
distances that you're talking about and is an all-in-out unit (antenna
plus radio, fed with POE) about twice the size of a pack of cigarettes
(does anyone use that as a point of reference anymore or have enough
of us quit smoking that it's irrelevant?). It has a built-in mount on
the back and is intended to be zip tied to an existing vent pipe or
mast. They even include a zip tie in the packaging.
As someone else noted, it is cheaper to buy Ubiquiti equipment and see
if it works than it is to do the engineering. In this case, it may
well be worth the investment to buy the Ubiquiti equipment and bring
it to a meeting with the building management folks to do some *social
engineering*.
Most of these regulations are centered on the concern that your
building not look like a tower site. An antenna that is sufficiently
small that it can not be seen from the ground without resorting to
optics may be on their "oh, that's fine" list once they see one
sitting on the table in front of them.
Low-E glass is brutal on radio waves. If the windows are tinted, multi-layer, or have metalic particles success may be difficult. You may want to test with some 802.11a network cards in ad-hoc mode to see if you can actually communicate over the 1500m path. We have had to deal with a condo association to get approval to mount some panels outside at one site. It can usually be discussed when presented with the facts and some photo-shop edits to show what visual impact it will have. However, be prepared for a significant delay in some cases and success is never a sure thing.
Another item of concern is you are looking at IC/FCC unlicensed bands. Ten years ago 5.8 was fairly clean, but more recently we have found a lot more consumer devices invading the spectrum. We had a 1km path with a $15K microwave system knocked out by a consumer $50 cordless phone that was 1/2 block away. (We purchased a DECT6 phone for them and 'solved' the immediate issue... until we could obtain a license/path and the equipment to install something that wouldn't be interfered with.)
Don't forget about OTARD, where so long as you control the space in your
lease, no local government regulations can prevent installation of a internet
reception radio.
Also, the Ubiquiti is crap from a build/reliability standpoint. If you're
doing anything serious, it would be worth it to buy a better product. I'm
partial to the Alvarion and Motorola PtP links.
While certainly not the best stuff made I've found the ubiquiti
equipment to be very nice for the price and have a few of their AP's
which have been in service 24x7 for a couple of years now.
Thanks,
-- Josh Smith
KD8HRX
email/jabber: juicewvu@gmail.com
phone: 304.237.9369(c)
