COMPUTER NETWORKS and INTERNETS Chapter 5 Overview of data communications

introduction Transmission of information across media such as wires, optical fibers, and radio waves. Overview of data communications and explains how the conceptual pieces from a complete communications system.

The essence of data communication The subject involves concepts from mathematics, physics, and electrical engineering

Motivation and scope of the subject Sources of info can be of arbitrary types Transmission uses a physical system Multiple sources of information may be able to share a medium Real physical systems have limitations

The conceptual pieces of a communication system Transmitting multiple sources of information across a shared medium is not as simple as it may seem. It doesn't "just work" if a bunch of people shout at each other in a hallway. Issues: encoding information (e.g. digitizing) encrypting information error detection and correction multiplexing/demultiplexing

The subtopics of data communications Sources of information can be analog or digital. There are reasons to transform one digital form into another, for example to achieve compression. Security considerations may require the addition of encryption. Channel coding for detection and correction of errors in bit values Mulitplexing/Demultiplexing - ways to combine different streams of information for transmission and separate them out at the destination. Modulation/Demodulation - e.g digitizing for transmission and then translating back into analog at the destination. Properties of Physical Channels - e.g. bandwidth, noise, interference, channel capacity, and transmission modes: serial and parallel.

The end