Determining WLAN Hardware Costs

As with any project, you need to carefully consider all costs of a wireless
LAN before moving forward with deployment. You may use your resulting numbers
to compare a wireless LAN with an Ethernet alternative, perform a feasibility
study for a specific mobile application, or provide the basis for a budget you’re
proposing to upper management or a customer. In all of these cases, you need
to take into account the hardware, software, and services necessary to install
and support the system.

Let’s take a look at what hardware to consider.

First things first

Before determining the costs of a wireless LAN, you need a preliminary sketch
of the requirements
and design in order to know what components form the basis of the solution.
Requirements at this point should at least describe the overall application.
A network that only provides Internet access for a group of three users and
another solution that implements desktop conferencing will have much different
cost structures. The reason is that a system for video conferencing requires
diverse requirements and design than one only supporting common office applications.
This results in different costs.

To help you prepare a foundation for assessing the financials, here are some
questions related to the requirements and design:

  • What applications will the wireless LAN support? What performance levels
    do these applications require? Will the wireless LAN support subscription-based
  • Which 802.11 standard should you deploy: 802.11a
    or 802.11b?
  • How many users, printers, and other end devices will the wireless LAN serve
    directly? How many of these devices are already equipped with radio NICs?
  • How many access points do you need to cover the facility?
  • Do you have an existing Ethernet network? If yes, how many ports are available
    for access points?

Answer these questions, and then start the financial exercise.

Radio NICs

You need a wireless client ability of some sort for each user device, such
as PDAs, laptops, PCs, printers, etc. More and more users are choosing wireless
options when ordering laptops. So, you may not need to purchase a NIC for each
user device.

Plan on paying on the average about $125 each for 802.11b radio NICs, and figure
another 25 to 50 percent more for 802.11a NICs. I’ve seen 802.11b radio NIC
prices as low as $49, however, and prices will fall more throughout 2002 and
2003. Unless you have unique application requirements, the user devices will
not require any additional components that incur costs other than radio NICs.

Access Points

If you’re planning to use ad
hoc mode (an 802.11 option), then you don’t need any access points. In most
cases, however, you’ll be implementing an infrastructure network, which requires
the use of access points. An access point links the wireless users to the wired
network of file servers and Internet access. Multiple access points also provide
roaming throughout a larger facility.

Access points vary in price, ranging from $300 to $2,000 depending on the features.
For smaller office and home networks, you can get by with the lower-end, less
costly access points under $200, but consider using the higher-end access points
for enterprise solutions. The benefits you’ll receive from the advanced features
will likely make the difference cost effective. We have a pervious
tutorial that helps you choose an access point vendor.

An access point has limited range, and you’ll need more than one to cover most
facilities. An accurate method to determine the number of access points is to
perform an RF
site survey. You can employ an installation company or consultant to perform
the site survey at a cost of approximately $1,000 per day, with a couple days
necessary for a two or three story office building. Figure up to a week or so
for larger facilities, such as hospitals and larger airports.

As a basis for determining preliminary costs before performing a site survey,
plan on approximately one access point per 70,000 square feet of coverage area.
This assumes a range of about 150 feet, but forms of attenuation and specific
performance requirements may affect this value. You need to perform a RF site
survey to obtain an accurate number of access points.

When installing a WLAN, include the costs for mounting the access points and
running network cabling to each access point from an Ethernet switch or hub.
For larger enterprise solutions, hiring a company specializing in wireless LAN
installation will be well worth the expense. Each cable run will cost approximately
$100 for each access point, depending on the scope of your network. Include
another $150 or so per access point for installation and mounting hardware.
You may also need to include some additional costs for installing radio NICs
in user devices and making applicable configuration settings if needed.

A wireless LAN installation may require the addition of electrical wiring and
outlets to power the access points. If you don’t have an outlet within a couple
yards from an access point, then include the cost of using an extension cord
or running a new outlet to that access point location. The installation of each
new outlet costs approximately $250. Extension cords are much cheaper ($15),
but a professionally installed outlet looks better and offers a higher degree
of safety. Of course you may be able to save the costs of adding electrical
wiring by using power-over-Ethernet
(PoE) technology.

In addition to the minimum hardware necessary, plan on having some spare hardware
on site for replacing components that may become defective. With any system,
it makes sense to have spares for elements that offer a single point of failure.
For WLANs, the access point will cause the most havoc if it fails, at least
for the users it serves.

With a spare, you can replace an access point within an hour or less. It may
take 24 hours to replace one if you need to purchase a replacement. You need
to make an assessment of the importance of availability and how long the network
can be down, but it doesn’t hurt to have at least one spare access point. Factor
in the costs of these extras into your budget.

Wired Network Components

If you’re implementing a public
wireless LAN (i.e., hotspot), then include the cost of access
controllers that regulate user access to the services that require subscriptions.
You’ll probably need one access controller per facility, unless you decide to
have an additional one for automatic fail-over backup purposes. Access controllers
vary in price depending on features, but plan on spending approximately $6,000
per access controller. Some access point vendors have the access control function
built into the access point, which might be the best route to go if the network
has very few access points.

Don’t forget that with public wireless LANs, you’ll also need to include costs
for Internet connections as well.

If you’re extending an existing Ethernet network to include wireless users,
then there may be enough ports open on the existing Ethernet switches to connect
the access points. If not, then include costs for some switches or hubs to interconnect
access points. In general, each switch/hub can support up to eight access points
and costs from $50 to several hundred dollars each depending on features. Similar
to the access points, the more expensive Ethernet switches are needed for enterprise
solutions in order to reduce support costs.

That pretty much sums up the hardware costs to consider. For the larger deployments,
also include costs associated with project management and user training if applicable.
And, don’t forget the operational support element, such as network monitoring
and problem resolution.

Jim Geier provides independent consulting services to companies
developing and deploying wireless network solutions. He is the author of the
Wireless LANs
(SAMs, 2001), and regularly instructs workshops on wireless LANs.

Join him for discussions as he answers questions in the 802.11 Planet Forums.