Network Communications News (NCN) April 2016 | Page 23

wireless networks

the need for additional wiring and allows
a more flexible deployment – either your
LAN switch will need to be PoE capable,
or you will require a POE injector added
to power the AP.
A wireless AP will on average cover
an area of 150m2 in a walled environment
or up to 900m2 outdoors. These are
areas of magnitude that will allow you
to estimate the number of APs that you
will need, although a site survey will
determine precisely how many will be
required. Whether you need to select
APs with internal or external antenna
will in part be determined by the
environment and any physical barriers.
Internal antennas will result in coverage
that is concentric, external antennas are
designed so coverage can be directed,
such as down corridors. ‘Ruggedised’
versions of both variants are available
specifically for outdoor use.

PoE access points draw their power
over the same cable as they use to
transmit data to the corporate LAN.

2: Just what type
of access point?
The access point (AP) is what connects
wireless devices to the corporate LAN
and will allow users to access corporate
resources and the Internet. As such,
making the correct choice here will
enable employees, guests or customers
to enjoy good quality connectivity
anywhere in the building, or on site.
Access points need power, but they
are usually placed higher up for good
coverage and are therefore away from
any electrical point. This is why I would
recommend looking at APs that are
Power over Ethernet (PoE) enabled. PoE
access points draw their power over the
same cable as they use to transmit data
to the corporate LAN. This eliminates

S P E C I A L F E AT U R E

A symphony orchestra needs
a conductor to coordinate all
the instruments, and for the
same reason a Wi-Fi network
needs a radio controller.

3: The numbers game:
How many users?
How much bandwidth?

4: Then there are the
frequencies –
Single or Dual Radio

The ability of an AP to manage a larger
number of users will depend on three key
factors: The power of the processor, the
number of radios and the quality of the
software. On the market you will find a
range of APs, from ones that will struggle
to manage five users, up to professional
APs that can support many dozens of
users. So ensure you choose an AP that is
capable of supporting the right number
of users now and in the future.
An AP will provide an overall
throughput of bandwidth that will be
shared by all the users connected to
the AP, which means the more users
connected to any one single AP, the less
throughput will available to each user
device. High throughput APs will be
required to deliver a reasonable rates of
bandwidth to each user, as will choosing
the latest 802.11ac standard with its
increased bandwidth delivery.

Wi-Fi technology works on two
separate frequencies.
The 2.4Ghz band is the first, and
is shared by other technology such
as remotes, Bluetooth device and
microwaves. Then there is the 5Ghz
band, which is almost exclusively used
for Wi-Fi devices and therefore does
not suffer from the radio pollution from
other sources. The 5Ghz band is a more
recent development the typical business
will need to support a range of devices
which use both 5Ghz and 2.4Ghz bands.
This is why I suggest it is essential that
any business deploys dual radio APs that
can send and receive on both of these
frequency bands at the same time. Single
radio APs, and some dual radio APs that
only work on 2.4Ghz or 5Ghz will only
allow you to support one of these bands
and therefore severely limit the choice of
devices available to the business.

Wi-Fi technology works on two separate frequencies.

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17/03/2016 15:49