Chapter 18. Introduction to Wireless Networking


SOME OF THE MAIN TOPICS IN THIS CHAPTER ARE

Why Wireless Networks Have Proliferated 281

Access Points and Ad Hoc Networks 283

Physical Transmission Technologies 286

The IEEE 802.11 Wireless Standard 288

Sources of Interference for Wireless Networks 290

Although the installed base of networked computers today is mainly made up of technologies using copper wire and fiber-optic cable, the growing market for wireless technologies should not be underestimated. The popularity and rapid growth of the cellular telephone market, for both personal and business applications, attests to this fact. Just 10 years or so ago, cellular telephones were high-priced items used mainly by business executives. Today, they are sold in shopping mall kiosks. You can even buy a prepaid cell phone now and pay as you go.

Other than the CB (Citizens' Band) radio craze that peaked a few decades ago, it was not until cell phones became inexpensive that wireless networking became a hot issue. And now many kinds of wireless networking devices have worked their way into our everyday life.

Today's wireless phones and other wireless devices now have uses that probably were never envisioned by the creators of this technology. Use your cell phone to report an automobile accident. Put up a wireless camera to monitor a child. Access the Internet through your cell phone. Use a camera phone to capture on-the-spot photos or even video of accidents, crimes, you name it. I could go on and on...

Note

It's hard to write this chapter without discussing the first wireless network: radio! (Hey, we're talking electronic technology here, not the village crier.) Broadcast commercial radio is a one-way technique, but there are many variants of two-way radios, from those used by police and fire departments to the CB radios that were a hot item years ago. However, today we're discussing wireless communications between computers, consumer electronic devicesthe sky is the limit.


Many mobile phones today are already equipped to handle text messaging, Internet email, some limited Web-browsing capabilities, and low-resolution digital photography. This chapter will introduce you to just a few of the many problems that wireless networking can solve, and introduce you to some of the technologies basic to many of the wireless technologies. Other networking solutions are found in Chapter 23, "Security and Other Wireless Technologies," and Bluetooth is covered in Chapter 22, "Bluetooth Wireless Technology." Although Bluetooth is a wireless technology, its original purpose is not as far reaching as the IEEE 802.11b, 802.11g, or 802.11a technologies (covered in Chapters 19, "IEEE 802.11b: Wi-Fi Pioneer;" 20, "Faster Service: IEEE 802.11a;" and 21, "The IEEE 802.11g Standard"). Instead, Bluetooth was initially designed to replace cables that span only a very short distance. Yet new profiles do indeed enable you to create a small LAN using Bluetooth. Because of distance limitations, however, it still is not the wireless LAN technology of choice for anything but a small LAN with minimal bandwidth requirements.

You can now use Bluetooth to exchange data between a mobile phone and a PC. For example, properly configured, a Bluetooth-enabled wireless phone can be used for a modem connection to a PDA or laptop similarly equipped. Or, you can use a Bluetooth keyboard and mouse with a Bluetooth receiver attached to your computer. This short-distance communication capability does not address the much larger distances that the specifications 802.11a, 802.11b, and 801.11g can cover. But it is important to keep in mind that although you can create a small LAN using Bluetooth, it was not developed to create a LAN or WAN. It works best for short-distance transmissions between peripheral devices and consumer electronic devices. Because it uses a radio spectrum, it is possible to create many devices, such as a TV remote, using Bluetooth, because current devices require a line-of-sight. If your cable box is in the living room and you're in the bedroom, you could use a Bluetooth-enabled cable box/remote to change the channel, all while staying in bed! Bluetooth should be seen as a complimentary wireless technology to 802.11-based wireless networks rather than as a direct competitor.

Despite my predictions in previous editions of this book, Bluetooth devices have finally started to make it to the low-cost marketplace, and you can expect to see more of this technology as time marches on. More than a few users like the portability of their keyboard and mouse, as well as the convenience of wireless synchronization with a PDA or downloading from a digital camera.




Upgrading and Repairing Networks
Upgrading and Repairing Networks (5th Edition)
ISBN: 078973530X
EAN: 2147483647
Year: 2006
Pages: 411

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