Chapter 19. Introduction to Wireless Networking


SOME OF THE MAIN TOPICS IN THIS CHAPTER ARE

Why Wireless Networks Are Inevitable

Access Points and Ad Hoc Networks

Physical Transmission Technologies

The IEEE 802.11 Wireless Standard

Sources of Interference for Wireless Networks

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 malls, and it is common to see teenagers walking around with them stuck to their heads (no offense intended!). You can even rent a prepaid cell phone now and pay as you go. The fact that several states have passed laws that prevent use of a cell phone (unless it's "hands free") by the driver of a car can attest to the wide acceptance, and use ”or misuse ”of the cell phone.

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 wireless networking of many kinds of devices is working its way into 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. I could go 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 devices ”the sky is the limit.

Many mobile phones today are already equipped to handle text messaging, Internet email, and some limited Web-browsing capabilities. 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 24, "Other Wireless Technologies," and Bluetooth is covered in Chapter 23, "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 20, 21, and 22). Instead, Bluetooth was initially designed to replace cables that span only a very short distance. Yet new profiles, which are discussed in Chapter 23, 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 that requires a small bandwidth.

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!

Despite my predictions in previous versions of this book, Bluetooth devices have started finally to make it to the low-cost marketplace , and you can expect to see more of this technology.

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. Bluetooth has a few major competitors in the consumer market though ”IEEE 802.11b, 802.11a, and, more especially , 802.11g (see Chapter 22, "The IEEE 802.11g Standard").

In Chapter 24, you'll find that myriad other devices, such as PDAs and tablet PCs, can also be used with wireless technologies, enabling you to "carry it with you" yet still be able to communicate with consumer devices, or your desktop/laptop computer.




Upgrading and Repairing Networks
Upgrading and Repairing Networks (5th Edition)
ISBN: 078973530X
EAN: 2147483647
Year: 2003
Pages: 434

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