Be aware of the applications that users may be utilizing
. A user who
performs the occasional file transfer and checks e-mail has very different
needs from someone using a computer-aided design (CAD) application across the
network. Most offices today use a client/server model with frequently used
applications loaded on each terminal. Some companies are moving to thin clients
and may have much greater bandwidth requirements. This type of setup requires a
reliable connection to the network, since an interruption of network service
renders the user helpless.
If the customer intends to use data
collection devices exclusively, this will change the way the site survey is
performed
. Most
data collection devices today operate at 2 Mbps and do not require 11 Mbps. If
the customer is using a 2-Mbps data collection device with no intention of
adding other wireless clients that may operate at 11 Mbps, then perform the
site survey at 2 Mbps.
Make sure that all areas where the data
collection devices will be used have a 2-Mbps link. Some data collection
devices have the ability to rate shift. Discuss the devices that the customer
will be using, what abilities these devices have, and how the customer intends
to use them.
As discussed earlier, retail or warehousing sites may have
areas where large numbers of users will be located. A receiving area may be
this type of an area. As equipment is unloaded off trailers, it is unboxed and
bar codes are scanned in rapid succession. The bandwidth needs are going to be
determined by the application. For example, a screen-scraping emulation sends
large packets containing a lot of data. If there are 20 to 30 users scanning
barcodes and entering keystrokes in rapid succession, a single AP may not be
enough.
For example, if all of the data collection devices are operating at 2 Mbps,
the AP is only operating at 2 Mbps. This does not mean that the AP is limited
to 2 Mbps, but all clients are communicating with the AP at 2 Mbps. While a
55-Mbps or 11-Mbps connection might be sufficient to handle the 20 to 30 users,
the 2-Mbps connection may not be. The packet size of the application and the
number of users must be considered to determine if extra APs are needed in this
area.
Copper versus WLAN
Copper installations can still
provide higher data rates, but price is no longer a factor. A WLAN can be
installed for roughly the same price as a copper-based network, and it provides
many benefits over a wired network. As prices continue to decrease on wireless
products and throughput speeds continue to increase, wireless will continue to
increase in popularity. This may also be a factor in the design. If the
customer wants to start by using a few wireless clients and then increase the
number after ensuring the reliability, the WLAN must be designed to accommodate
future expansion.