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PC Cards
When you want to add wireless networking capability to a laptop computer,
your first choice for a wireless network interface should probably be a
Personal Computer Memory Card International Association (PCMIA) card
(also called a PC Card; shown in Figure 2-4). Nearly all Windows and some
Mac notebook/laptops have PCMCIA ports that are compatible with these
cards. (An AirPort card is a special type of PC Card. In Chapter 8, we tell you
more about the AirPort card and how to set up a wireless Mac network.)




Figure 2-4:
A PC Card
wireless
network
adapter.



All wireless PC Cards must have an antenna so that the built-in radio can
communicate with an access point. Most have a built-in patch antenna that™s
enclosed in a plastic casing that protrudes from the PC while the card is fully
inserted. At least one manufacturer offers a retractable antenna that™s less
likely to get damaged when not in use.
33
Chapter 2: From a to g and b-yond

PCI adapters
Nearly all desktop PCs have at least one Peripheral Component Interconnect
(PCI) slot. This PCI slot is used to install all sorts of add-in cards, including
network connectivity. Most wireless NIC manufacturers offer a wireless PCI
adapter ” a version of their product that can be installed in a PCI slot (see
Figure 2-5).




Figure 2-5:
A wireless
PCI adapter.



Some wireless PCI adapters are cards that adapt a PC Card for use in a PCI
slot. The newest designs, however, use a mini-PCI Card that™s mounted on a
full-size PCI Card with a removable dipole antenna attached to the back of the
card.

USB adapters
The USB standard has over the last several years become the most widely
used method of connecting peripherals to a personal computer. First popu-
larized in the Apple iMac, USB supports a data transfer rate many times
faster than a typical network connection and is, therefore, a good candidate
for connecting an external wireless network adapter to either a laptop or a
desktop computer. Several wireless networking hardware vendors offer USB
wireless network adapters. They are easy to connect, transport, and reposi-
tion in order to get better reception.
34 Part I: Wireless Networking Fundamentals

Most computers built in the last two or three years have at least one (and
usually two) USB port(s). If your computer has a USB port and you pur-
chased a wireless USB network interface adapter, see Chapter 7 for more on
setting up that adapter.

USB wireless NICs are sometimes a better choice than PC Cards or PCI cards
because you can more easily move the device around to get a better signal,
kinda like adjusting the rabbit ears on an old TV. If a computer doesn™t have a
PC Card slot but does have a USB port, you either need to install a PCI
adapter or select a USB wireless network adapter.

Note that there are two forms of USB adapters: ones that have cables and
ones that don™t. The cabled USB adapters allow for positioning of the
antenna; the non-cabled ones directly connect in a fixed way into the back of
your computer, and are designed for economy of size. You might hear either
of these form factors referred to as dongles. (See Chapter 5 for more about
form factors.)

CF cards
With the growing popularity of handheld personal digital assistant (PDA)
computers, the newest category of wireless network adapters uses a
Compact Flash (CF) interface to enable connection to PDAs. With a Compact
Flash card, such as that from SMC shown in Figure 2-6, you can connect a
Pocket PC to a wireless home network. (For more about PDAs and how they
can enhance your wireless home network experience, check out Chapter 1.)




Figure 2-6:
A Compact
Flash card
wireless
network
interface
card.



CF cards are small, 11„2"-wide electronic modules that you insert into a CF card
slot. The CF card slot where you insert the card is an 11„2" slot in the top edge
of the Pocket PC. Compact Flash refers to the technology used to store soft-
ware or other data on the device. Many users employ CF cards to expand the
memory in their Pocket PCs and for many other PDA add-ons.
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Chapter 2: From a to g and b-yond

Most Pocket PC manufacturers provide either standard or optional support
for add-on cards built to the Compact Flash form factor. D-Link, for example,
makes the DCF-660W model (www.dlink.com/products/wireless/
dcf660w; $99.99) that works with Compaq, HP, Casio, Sharp, and other PDAs.
As times goes by, more and more PDAs will have wireless natively onboard;
the top-of-the-line HP Pocket PC h5400 series includes integrated support for
IEEE 802.11b wireless networking, as well as for Bluetooth, for instance.

Although Pocket PCs are typically more expensive than Palm PDAs (see the
nearby sidebar, “Wi-Fi network adapters and the Palm OS”), they boast com-
puting power more akin to a full-sized PC, and they are perfect candidates for
wireless network connectivity. You can use them for data synchronization,
Internet access, and connecting with other Pocket PCs.




Get the (Access) Point?
Let™s talk some more about the central pivot point in your wireless network:
the access point. Somewhat similar in function to a network hub, an access
point in a wireless network is a special type of wireless station that receives
radio transmissions from other stations on the wireless and forwards them to
the rest of the network. An access point can be a standalone device or a com-
puter that contains a wireless network adapter along with special access
point management software. Most home networks use a standalone AP, such
as shown in Figure 2-7.




Figure 2-7:
A stand-
alone
access
point.
36 Part I: Wireless Networking Fundamentals




Wi-Fi network adapters and the Palm OS
Wi-Fi network adapters for handhelds using Only time and the marketplace will determine
the Palm operating system (OS) are less whether 802.11-based technology, Bluetooth, or
widely available today than are those for some yet unidentified technology will become
Pocket PCs. The one module that we see the dominant method of connecting PDAs and
most often used is the Xircom Wireless other small devices to local area networks. The
LAN Module for Palm (www.intel.com/ list of potential applications of wireless tech-
nology to handheld electronic devices is virtu-
network/connectivity/products/
xirpwe1130.htm). Unlike the CF cards that ally limitless.
we talk about in this chapter, this module is a
sled. That is, you slide the Palm handheld into it,
much like how you might slide it into its cradle
for syncing with your PC or Mac.



Because many homes and businesses use wireless networking, a method is
needed to distinguish one wireless network from another. Otherwise, your
neighbor might accidentally send a page to the printer on your network.
(That could be fun, or that could be a little scary.) Three parameters that can
be used to uniquely identify each segment of a wireless network:

Network name: When you set up your wireless network, you should
assign a unique name to the network. Some manufacturers refer to the
network name by one of its technical monikers ” Service Set Identifier
(SSID) or perhaps Extended Service Set Identifier (ESSID). This can be
confusing and comes up most often if you™re using equipment from dif-
ferent manufacturers. Rest assured, however, that network name, SSID,
and ESSID all mean the same thing.
If the AP manufacturer assigns a network name at the factory, it will
assign the same name to every AP that it manufactures. Consequently,
you should assign a different network name to avoid confusion with
other APs that might be nearby (like your neighbor™s). Note: All stations
and the AP on a given wireless network must have the same network
name to ensure that they can communicate.
Assigning a unique network name is good practice but don™t think of the
network name as a security feature. Most APs broadcast their network
name, so it™s easy for a hacker to change the network name on his com-
puter to match yours. Changing the network name from the factory set-
ting to a new name just reduces the chance that you and your neighbor
accidentally have wireless networks with the same network name.
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Chapter 2: From a to g and b-yond

Channel: When you set up your wireless network, you have the option
of selecting a radio channel. All stations and the access point must
broadcast on the same radio channel in order to communicate. Multiple
radio channels are available for use by wireless networks. The number
of channels available varies according to the type of wireless network
that you™re using and the country in which you install the wireless net-
work. Wireless stations normally scan all available channels looking for a
signal from an AP. When a station detects an AP signal, the station nego-
tiates a connection to the AP.
Encryption key: Because it™s relatively easy for a hacker to determine a
wireless network™s name and the channel on which it™s broadcasting,
every wireless network should be protected by a secret encryption key
unless the network is intended for use by the general public. Only some-
one who knows the secret key code will be able to connect to the wire-
less network.

The most popular wireless network technology, Wi-Fi, uses the Wired
Equivalent Privacy (WEP) encryption protocol. This technology uses the RC4
encryption algorithm and a private key phrase or series of characters to
encrypt all data transmitted over the wireless network. For this type of secu-
rity to work, all stations must have the private key. Any station without this
key cannot get on the network. A new encryption protocol that will replace
WEP has recently been announced. This new protocol, Wi-Fi Protected
Access (WPA), will soon be available built in to all new Wi-Fi equipment and
as a free upgrade from most Wi-Fi equipment manufacturers . . . probably by
the time you™re reading this book.

You™ll commonly find AP functionality bundled into the same device as sev-
eral separate but related functions. For instance, some APs perform the func-
tions of a router, a switched hub, and a DHCP server as well as normal AP
functions. Similar devices might even throw in a print server. This Swiss
Army knife-like approach is often a real bargain for use in a home wireless
network.

Wireless networking devices can operate in one of two modes: infrastructure
mode or ad hoc mode. The next two sections describe the difference between
these two modes.

Infrastructure mode
When a wireless station (such as a PC or a Mac) communicates with other
computers or devices through an AP, the wireless station is operating in infra-
structure mode. The station uses the network infrastructure to reach another
computer or a device rather than communicate directly with the other com-
puter or device. Figure 2-8 shows a network that consists of a wireless net-
work segment with two wireless personal computers, and a wired network
segment with three computers. These five computers communicate through
the AP and the network infrastructure. The wireless computers in this net-
work are communicating in infrastructure mode.
38 Part I: Wireless Networking Fundamentals


Wired
network



Wireless PC
PC
PC


Figure 2-8: Ethernet cable
The two
Access
wireless
point
computers PC
in this
network
Wireless
commun-
PC
icate
through the
AP in

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