Wireless technology provides convenience for users and makes
it far easier to network computers that move around (notebooks and handhelds)
and those located in places where cable hasn’t been run. It also creates some
extra administrative and security headaches. If you’ve weighed the pros and
cons and decided to implement a wireless LAN (WLAN) for your organization, one
consideration in choosing the right wireless technology and topology is how
well it will scale to meet your future needs.

Here are some factors to keep in mind when you plan your
wireless infrastructure.

Wireless options

Most wireless networks today use one of three variations of
wi-fi technology:

  • 802.11b
  • 802.11a
  • 802.11g

We’ve listed them in chronological order of their
introduction/adoption, rather than alphabetical order. The most common, least
expensive and first to become widespread is 802.11b, which provides data
transfer rates of 11 Mbps (or, in an “enhanced” version, 22 Mbps) and
a typical distance range of approximately 300 feet. It operates at the 2.4 GHz
radio frequency (as do many cordless phones, microwave ovens and other
devices).

802.11a was developed to provide higher speed
communications, up to 54 Mbps. Unfortunately, you sacrifice range to get that
speed because the signal typically only reaches about half as far. However, it
has another advantage in that it suffers less from interference. That’s because
it operates at the 5.8 GHz frequency, which is used by fewer common household
and office devices.

802.11g in some ways gives you the “best of both
worlds.” You get the high speed of a 54 Mbps, with “enhanced”
versions available that claim double that speed and a distance range closer
to that of b. Since 802.11g is really an extension to its 802.11b cousin, it
operates at the same frequency, 2.4 GHz.

Note that the speeds given are “stated maximum
throughput.” In practice, you will probably get transfer rates somewhat
lower than these. But keep in mind that even the slowest (about 5 Mbps
effective throughput on most 802.11b networks) is still faster than the typical
broadband Internet connection.

There are other wireless networking technologies, such as
BlueTooth (used for short range communications between devices in close
proximity) and Wi-Max (being developed as a long-distance wireless solution to
connect computers over distances greater than the scope of the typical LAN),
not to mention satellite-based networking. In this article, we’ll stick to the
802.11 variants that are commonly used to give wireless connectivity to a local
network. (For more information, download TechRepublic’s
Wireless Technologies Scorecard.)

Speed and distance

Speed and distance can be important factors in scalability
of a WLAN. As your organization grows, you will add more users. In addition,
you’ll most likely need more bandwidth for the transfer of larger files and for
higher bandwidth technologies such as streaming audio/video, real-time
conferencing, etc. That means the more bandwidth, the better.

802.11a and 802.11g provide more scalability in this regard
than 802.11b, and with 802.11a you can combine channels to get even higher
throughput.

Distance range can also be a factor in the scalability of
your WLAN. As your office expands physically, you’ll have to deploy more access
points to reach the areas you need to reach with 802.11a than you would need
with 802.11b or g.

Compatibility

Another factor that affects scalability is compatibility,
and this is a two-pronged consideration: compatibility of wireless technologies
with one another and compatibility with wireless devices, especially the
network adapters built into many of today’s notebook computers.

A big advantage of 802.11g over a is its backward
compatibility with 802.11b. This means you can “start small” with an
inexpensive 802.11b WAP and then later replace it with a WAP that supports both
b and g. Computers that have 802.11b network adapters will still work, but at
the lower 802.11b speeds. You can replace the NICs gradually, making for a
smooth transition. If you switch to 802.11a, everything will have to be
replaced immediately because it is not backwardly compatible with your old
802.11b equipment.

Another problem with 802.11a is that the built-in wireless
equipment in notebooks is almost always of the more common 802.11b or g
varieties. These will be useless with an 802.11a infrastructure; you’ll have to
turn off the built-in wireless and add 802.11a NICs via the PCMCIA (PC card)
slot.

Finally, employees who connect to your wireless network may
also want to connect to other wireless networks at their homes or at public
access points (“hot spots”) in hotels, airports and restaurants. Most
home and public wireless networks use 802.11b technology, so they’ll need to
swap out two different NICs (or use built-in wireless for home/public networks
and a separate NIC for the corporate wireless network).

(For a set of checklists to help you select, install,
configure, and manager your network, download TechRepublic’s Support
and Configuration Checklists for Small/Midsize Networks.)

Reliability

Up to this point, it may seem that 802.11b/g is the clear
choice, but there is one more important factor to consider. In order to scale
to meet your networking needs, your WLAN must be reliable. An unreliable
technology isn’t scalable because it doesn’t make sense to expand its
deployment if you can’t count on it to work properly.

This is where 802.11a has the home-court advantage. By
virtue of its incompatibility — that is, because it operates on an entirely
different frequency from other popular wireless networking and consumer
communications technologies — it’s far less prone to interference that can
bring the network down or disrupt transmissions. Another aspect of reliability
is security, and 802.11a enjoys a form of “security through
obscurity.” Simply because it’s not as widely deployed and the equipment
costs more, fewer hackers target networks based on 802.11a. (For more on
wireless security, see Manage
your company wireless network hardware to prevent security breaches.)

Weigh your options

Before you take the plunge into wireless, or upgrade your
existing 802.11b network, be sure to consider the scalability factors for each
of the available technologies. There is no “one size fits all”
solution; the best choice for your organization depends in large part on which
is more important to you: compatibility and distance range or reliability. Most
organizations will probably opt for the 802.11b/g combination because of the
ease of transition, but those who use wireless communications for mission
critical tasks and who need more security may find 802.11a to be a better
option.