Windows Vista Security: Praxisorientierte Sicherheit für Profis

Wireless Networking

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Try again

The wizard attempts to make the dial-up connection again, using the same set-

tings as your previous attempts.

Try a different connection

The wizard takes you back to the “Select a network to connect to” page, allow-

ing you to choose a different connection.

Wireless Networking

If you travel frequently, chances are you are quite familiar with the existence of wire-

less networks. Most hotels, coffee shops, airports, and libraries offer WiFi or 802.11

networks. Many cities are beginning to offer WiFi connections also, offering low-cost

Internet access to residents. Eventually wireless networks may become so prevalent

that we’ll be able to connect to the Internet from just about anywhere. With this in

mind, Windows Vista makes creating and connecting to wireless networks very easy.

With Windows Vista, Microsoft has taken the time to revamp the wireless network-

ing interface, making it considerably easy to create and connect to wireless networks.

The beauty of wireless networking correlates directly to the word wireless. Wireless

networks allow you the freedom to move about, whether in your home or on the

road, which can make your life considerably easier when you need to connect to a

network. With wireless networking, you gain the complete functionality of a stan-

dard network without the need for any cables to connect the computers or devices.

This eases the requirements and restrictions of regular networks, but it adds some

complexity and additional pitfalls to the networking process.

Wireless Network Technologies

The most common wireless network technologies fall under the Institute of Electrical

and Electronics Engineers (IEEE) 802.11 specification. Although other wireless tech-

nologies exist, they are not as prevalent as 802.11 (WiFi) networks. WiFi networks

transmit radio waves between devices to allow network communications. WiFi uses

the 2.4 GHz and 5 GHz spectrums. There are three major standards within the WiFi

designation. See Table 17-4 for a listing of the major standards and their specifications.

Table 17-4. Common wireless networking technologies

Version Transmission frequency Transmission rate

802.11a 5 GHz Up to 54 Mbps

802.11b 2.4 GHz Up to 11 Mbps

802.11g 2.4 GHz Up to 54 Mbps

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Chapter 17: Mastering Dial-Up, Broadband, and On-the-Go Networking

The 802.11b specification was the first WiFi technology introduced to the market. It

uses the 2.4 GHz spectrum to transmit data at 11 Mbps. The 802.11b specification

uses Complimentary Code Keying (CCK) coding to transmit data. While 802.11b

has enjoyed the most widespread use, the lowering costs of faster technologies are

rapidly replacing it with newer technologies.

The 802.11a specification transmits in the 5 GHz spectrum at a transmission rate of

54 Mbps. This specification uses Orthogonal Frequency-Division Multiplexing

(OFDM) to transmit data, which is considerably better than the CCK coding stan-

dard. This gives 802.11a a considerably faster transmission rate.

The 802.11g specification transmits in the 2.4 GHz spectrum at a transmission rate

of 54 Mbps. This specification also uses OFDM to transmit data, and it enjoys the

most widespread use of the newer technologies.

These technologies fall under the WiFi designation, since they transmit in the 2.4

GHz and 5 GHz spectrums. Windows Vista supports each of these wireless technolo-

gies and the devices used to make connections to these types of networks.

New networking standards are also in the marketplace today. It bears noting that

early adoption of new technologies does not always favor the consumer, because

some products in the market may support early adoption of a standard that is not yet

finalized. Therefore, if you purchase products too early you may have to purchase

additional hardware to support the additional features defined in the final version of

the standard. While this is not always true, be wary of purchasing the latest and

greatest wireless products. Take some time to research the technology before buying

equipment on impulse.

Newer 802.11 transmission specifications include 802.11n, which offers up to 540

Mbps while using Multiple-Input-Multiple-Output (MIMO) technology. Essentially

this means that the client computer and the wireless access point will use multiple

receivers and multiple transmitters to achieve improved performance.

Not all 802.11 specifications are about transmission speed and rate, however. The

802.11i specification offers enhanced security. The 802.11h specification offers fre-

quency and power control management. The 802.11e specification offers quality of

service enhancements. The 802.11x specification provides a framework for authenti-

cating users and controlling their access to a protected network.

Another emerging wireless technology is Worldwide Interoperability for Microwave

Access (WiMax). WiMax is not really a technology, but a stamp of approval for use

with the 802.16 specification in broadband wireless deployments in metropolitan

areas. WiMax-certified equipment usually uses the 2.5 GHz spectrum, but the 3.5

GHz, 2.3 GHz, and 5 GHz spectrums are available in other countries. Currently, a

movement exists to use the 700 MHz spectrum for future WiMax deployments.