1. COMPUTER NETWORKS and INTERNETS
Chapter 5
Overview of data communications

2. 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.

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

4. 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

5. 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

6. 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.

7. The end