The
following guidelines are meant to serve as a checklist overview
to be reviewed prior to beginning a wireless network installation.
Neatness counts: Before
beginning installation of the network, make sure that
everyone working on the network commits to completing
the work in a tidy fashion. Careful work will ensure
that the network will last longer, and it will be much
easier to troubleshoot if future problems occur! If
leaving the site before the job is complete, make sure
that the site is left neat, and safe!
Towers and poles:
Activities 5, 6, and 7 in this module
explain several types of tower installation. If mounting equipment
onto poles, ensure first that the proper permissions have
been obtained if they do not belong to the organization putting
up the wireless equipment. If poles are to be installed, have
professional installers do the work, as there is liability
associated both with pole installation, and with work done
on poles after they are installed. For more information on
installation of poles, visit the BICSI (Building Industry
Consulting Service International, Inc.) website: http://www.bicsi.org/Index.aspx
BICSI also publishes educational
material such as the "Customer Owned Outside Plant Design
Manual. This manual is "written for individuals who design
and maintain the outside plant infrastructure in a campus
environment. It provides a comprehensive overview of the components
of outside plant design and acts as a refresher course for
those with previous outside plant design experience."
This is an excellent manual which explains many aspects of
designing outdoor networking infrastructure. BICSI also covers
regulatory aspects of pole and tower construction, including
covenants and other specific ordinances which may need to
be overcome or complied to in order to build a tower.
Trees?In addition to "standard" towers and poles,
the Open Network Craft audience may require that antennas
be placed in "non-standard" locations, such as trees.
Antennas CAN be mounted in trees, but this solution may not
be optimal for several reasons. Mounting antennas in trees
has several disadvantages:
Tree growth means that the antennas
may not line up properly after some time
Trees are subject to lightning strikes,
and aren't as easy to ground and protect from this hazard
as constructed towers
Trees are more subject to wind movement
than towers are, which may cause the antennas to not line
up, and therefore to not work
Trees can be easier to climb than towers
(if properly fenced and protected) and can be more subject
to vandalism (depending upon the location)
If the antenna is mounted in a tree
in the wintertime, foliage growth in spring and summer could
render the antenna useless
Other trees growing up around the antenna-mount
tree could eliminate line of sight.
TIP:
BE CREATIVE in the environment when placing antennas -
church belfry towers or existing lamp standards may provide
perfect opportunities!
Placement:
Line
of Sight: Antennas need
to be place so that they will have line-of-sight, or
in other words, that the antennas can "see"
each other. The best way to ensure this is to use binoculars
or a telescope while at one antenna mounting site, to
see that you can see the antenna mounting site at the
other end.
If binoculars or a telescope
aren't handy, prop up a length of pipe on one end and
look through it towards the other site to ensure that
you can see the site from where the first antenna is
to be installed.
Polarity:
Antennas also need to be installed so that their polarity
is correct. For example, directional
yagi antennas need to be pointed towards one another, and
in the same plane, i.e. both vertical, or both horizontal.
The diagram below shows this concept more clearly.
Because directional antennas
are able to receive signals within a certain pattern area,
it is also possible to use the polarity of antennas to go
around obstacles. For example, in the diagram below, although
the two antennas mounted do not have line of sight, their
polarity is matched in such a way that their signals are able
to pass around an obstacle.
In addition to these overview
guidelines, the activities in this module will describe how
to properly install the towers and equipment required for
wireless installations.
The network equipment, in addition
to being well placed must be:
well supported (see tower construction
activities)
protected from weather (see enclosures
- make sure that all connections are wrapped, sealed,
