O'Reilly logo

CCNA® Wireless Study Guide by Todd Lammle

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Chapter 3. Spread Spectrum Technologies and Modulations

THE CCNA WIRELESS TOPICS COVERED IN THIS CHAPTER ARE:

  • Describe WLAN fundamentals

    • Describe basics of spread spectrum technology (modulation, DSSS, OFDM, MIMO, Channels reuse and overlap, Rate-shifting, CSMA/CA)

Spread Spectrum Technologies and Modulations

A great place to begin is by exploring two general categories of transmission methods commonly used today.

Note

To find dynamic updates to this chapter, please see www.lammle.com.

Transmission Methods: An Overview

As you've probably guessed, you can create RF transmissions a number of different ways. Even though WLANs don't use narrowband transmission, it's still a good thing to go over because it's great to understand for the sake of comparison.

Two important ways that narrowband transmission and transmission methods used by WLANs differ are:

  • The amount of power used to transmit

  • The way interference is dealt with

In narrowband transmission, the signal is sent on a single frequency; a good example of this transmission type is a radio station. In narrowband, very little bandwidth is used. Check out Figure 3.1.

In order to get around that interference issue, the signal is broadcasted at a much higher power level than a spread spectrum transmission would be. The amount of power is regulated by the FCC and has to be licensed so that the frequencies and controls used by each frequency in a given area won't interfere with one another. See ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required