1. Information Technology
Telecommunications and Networks

2. Learning Objectives When you finish this chapter, you will:
Recognize why successful managers must be familiar with telecommunications concepts and terminology.
Know the principles of communication within a computer system and among computers.
Be able to identify the major media and devices that are used in telecommunications.

3. Learning Objectives
Be able to list and explain the functions of different network layouts and the concept of protocols.
Understand how telecommunications can improve operations in organizations.
Know the latest developments in telecommunications media and transmission speeds.

4. Telecommunications in Business
Transmittal of data from one computer to another over a distance
Telecommunications has improved business in three main ways:
Better communication
Higher efficiency
Better distribution of data

5. What is Data Communications?
Any transfer of data within a computer, between a computer and another device, or between two computers
Two Basic Modes
Parallel transmission
Serial transmission

6. Communication Direction
Three Modes of Communication Between Devices
Simplex
One-way in one direction
Half-Duplex
One-way in two directions
Full-Duplex
Two-way in two directions

7. Communication Direction
Figure 6.2 Simplex, half-duplex, and full-duplex communication

8. Communication Direction
Asynchronous Communication
In asynchronous transmission, the devices are not synchronized by any timing aids.
Advantage of asynchronous transmission
Does not need sophisticated and expensive timing hardware
Disadvantage of asynchronous transmission
Overhead, time spent transmitting bits that are not a part of the primary data

9. Communication Modes Synchronous Communication
In synchronous communication, data are transmitted using timing devices.
Messages are transmitted in packets.
Advantage of synchronous communication
Overhead in synchronous communication is significantly smaller than in asynchronous communication.

10. Communication Modes
Figure 6.4 Synchronous transmission

11. Channels and Media Communication Channel Channel Capacity
Physical medium through which data can be communicated.
Channel Capacity
Narrow band
Broadband

12. Channels and Media
Figure 6.5 Transmission speed measurement unit

13. Channels and Media Media Transmission speed
A medium is any means by which data can be transmitted.
Transmission speed
A medium’s capacity is determined by the range of bits per second at which it can operate.

14. Channels and Media
Figure 6.6 Telecommunications transmission speeds of different media

15. Channels and Media Twisted Pair Coaxial Cable
Telephone line made of a pair of copper wires twisted to reduce electromagnetic interference (EMI)
Coaxial Cable
Commonly used for cable television transmission
More expensive than twisted pair
Greater transmission rate than twisted pair
Much less susceptible to EMI

16. Channels and Media Microwaves Optical Fiber
High-frequency, short radio-frequency (RF) waves
Terrestrial microwave
Satellite microwave
Optical Fiber
Fiber-optic technology uses light instead of electricity to transmit data.

17. Figure 6.7 Characteristics of channel media
Channels and Media
Figure 6.7 Characteristics of channel media

18. Analog vs. Digital Analog signals Digital signals
A continuous series of waves
Digital signals
A series of discrete bits

19. Modulation Modification of a digital signal into an analog signal
Demodulation
Modification of an analog signal into a digital signal

20. Figure 6.8 Signal modulation

21. Modulation Amplitude Modulation (AM) Frequency Modulation (FM)
Phase Modulation

22. Modulation Modems Multiplexers
Devices that modulate and demodulate signals
Multiplexers
Devices that allow several telephones or computers to transmit data through a single line
Frequency division multiplexing
Time-division multiplexing

23. Modulation
Figure 6.9 Multiplexing

24. Figure 6.10 Frequency division
Modulation
Figure 6.10 Frequency division

25. Networks LANs (Local Area Networks) WANs (Wide Area Networks)
Networks within a building, or within a group of adjacent buildings
WANs (Wide Area Networks)
Networks that cross organizational boundaries or reach outside the company
Value-added networks (VANs)
Wireless communication

26. Networks
Figure 6.11 Where wireless LANs are a good choice

27. Networks Network Topology Physical layout of the nodes in a network
Star
Ring
Bus
Tree

28. Figure 6.12 Network topologies
Network Topology
Figure 6.12 Network topologies

29. Protocols Communication protocols Network protocols
Rules governing the communication between computers or between computers and other computer-related devices
Network protocols
Rules governing a network of devices

30. Protocols
Figure 6.13 Some communications software allows a user to establish protocols: bit rate, parity, number of data bits, stop bits, and a handshake procedure.

31. Protocols LAN Protocols WAN Protocols Polling Contention Token passing
OSI (Open Systems Interconnection)
Standard protocol model
Seven layers

32. Figure 6.14 The seven layers of the OSI model
Protocols
Figure 6.14 The seven layers of the OSI model

33. Switching Techniques and Transfer Modes
Circuit Switching
Message is communicated in its entirety from the transmitting computer to the receiving computer
Packet Switching
Message is divided into packets of bytes and transmitted via several nodes

34. The Changing Business Environment
Cellular Phones
Teleconferencing
Voice Mail
Facsimile

35. Ethical and Societal Issues Telecommuting: Pros and Cons
Saves travel cost and time
Decreases pollution
May reduce unemployment.
Productivity higher among telecommuters

36. Ethical and Societal Issues Telecommuting: Pros and Cons
Employers tend to pressure telecommuters to work harder than workers in the office.
No office to foster new social ties and camaraderie.
May negatively impact some segments of the economy
Restaurants
Downtown business and industries