Learning Objectives

By the end of this chapter, you will be able to:

  • Differentiate between guided (wired) and unguided (wireless) transmission media.
  • Identify common types of wired media, such as twisted-pair and fiber optic cable.
  • Define bandwidth and its importance in data transmission.

Data Communication Media

Transmission media is the physical path between the sender and receiver in a data communication network. It is the channel through which data is sent from one place to another. Transmission media can be broadly classified into two categories.

1. Guided (Wired) Media

In guided media, the signal is directed along a physical path.

  • Twisted-Pair Cable: Consists of pairs of insulated copper wires twisted together. It is the most common type of media, used in traditional telephone lines and Ethernet networks (LAN cables).
  • Coaxial Cable: Has a single copper conductor at its center, surrounded by a layer of insulation and a metallic shield. It is used for cable television and early computer networks.
  • Fiber Optic Cable: Transmits data as pulses of light through thin strands of glass or plastic. It is much faster than copper cables, has a much higher bandwidth, and is less susceptible to interference. It is the backbone of the modern internet.

2. Unguided (Wireless) Media

In unguided media, the signal is broadcast through the air or space.

  • Radio Waves: Used for a wide range of communication, including Wi-Fi, Bluetooth, and cellular networks.
  • Microwaves: Used for point-to-point communication and satellite communication.

Data Transmission Concepts

  • Signal: Data is transmitted as an electromagnetic signal, which can be either analog (a continuous wave) or digital (a series of discrete pulses).
  • Bandwidth: This refers to the transmission capacity of a network, stated in bits per second (bps). It is the maximum amount of data that can be transmitted over a network connection in a given amount of time.

Summary

Data communication relies on transmission media to carry signals from a sender to a receiver. This media can be guided (wired), such as twisted-pair, coaxial, and high-speed fiber optic cables, or unguided (wireless), such as radio waves. The capacity of these media to transmit data is measured by their bandwidth. Understanding these physical layer components is the first step in understanding computer networking.

Key Takeaways

  • Transmission media can be guided (wired) or unguided (wireless).
  • Fiber optic cable is the fastest type of guided media.
  • Radio waves are the basis for most modern wireless communication.
  • Bandwidth measures the data transmission capacity of a network.

Discussion Questions

  1. What are the main advantages of fiber optic cable over twisted-pair copper cable?
  2. Why is wireless communication more susceptible to interference than wired communication?
  3. What is the difference between bandwidth and the speed of your internet connection?