Networking Explained, 2nd Edition

Chapter 4

Physical Layer Concepts

In this chapter we present an overview of the first layer of the OSI model, namely, the

physical layer. This is the “touch-and-feel” layer. It provides for the physical transmission

of data. As part of our presentation we discuss various transmission media, including

twisted pair, coaxial, and fiber-optic cables. We also examine various forms of wireless

and satellite communications. An outline of the major topics we discuss follows:

• Physical Layer Issues (Questions 1–8)

• Analog vs. Digital Communications (Questions 9–22)

• Bandwidth vs. Throughput and Data Rate vs. Baud Rate (Questions 23–27)

• Noise (Questions 28–30)

• Shannon’s Limit (Questions 31–38)

• Multiplexers and Multiplexing Strategies (Questions 39–43) ...