1. Information Technology in Business: Telecommunications and Networks

2. Learning Objectives
Explain why successful managers must be familiar with telecommunications concepts and terminology
Describe the principles of communication within a computer system and among computers
Identify the major media and devices used in telecommunications

3. Learning Objectives (Cont.)
List and explain the functions of different network layouts and the concept of protocols
Explain how telecommunications can improve operations in organizations
Cite the latest developments in telecommunications media and transmission speed

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. Telecommunications in Daily Use
Cellular Phones
Videoconferences
Voice Mail
Facsimile
Information Kiosks
Pay at the Pump

6. Telecommunications in Daily Use (Cont.)
Easy Passing
Web-Based Electronic Commerce
Worldwide Peer-to-Peer File Sharing
Napster, Gnutella, BearShare, Morpheus
With directory
Without directory

7. Telecommunications in Daily Use (Cont.)

8. Data Communications
Any transfer of data within a computer, between a computer and another device, or between two computers
Parallel and Serial Data Communications
Serial data transfer refers to transmitting data one bit at a time.
Parallel means the device is capable of receiving more than one bit at a time (that is, it receives several bits in parallel). Most modern printers are parallel.

9. Data Communications (Cont.)

10. Communication Direction
Simplex
One-way in one direction
Half-Duplex
One-way in two directions
Full-Duplex
Two-way in two directions

11. Communication Direction (Cont.)

12. Error Detection Parity Check Error detection method
Checks that no bits are added or deleted during transmission

13. Bandwidth and Media Communications medium Capacity
Physical medium through which data can be communicated
Telephone lines, television cables
Capacity
Speed at which data are communicated
Also called the transmission rate
It is often called “bandwidth”
Bandwidth is measured in bits per second (bps)
The greater the capacity, the faster the transmission

14. Bandwidth and Media (Cont.)

15. Bandwidth and Media (Cont.)
Narrowband is low speed
Broadband has greater capacity
Media
A medium is any means by which data can be transmitted

16. Transmission speed
A medium’s capacity is determined by the range of bits per second at which it can operate
Baud is the number of signals per minute
e.g. 300 bits per second = 300 baud
Repeater receives and strengthens signals before sending them on

17. Transmission Speed (Cont.)

18. Twisted Pair
Telephone line made of a pair of copper wires twisted to reduce electromagnetic interference (EMI)

19. Coaxial Cable Commonly used for cable television transmission
More expensive than twisted pair
Greater transmission rate than twisted pair
Much less susceptible to EMI

20. Microwaves High-frequency, short radio-frequency (RF) waves
Terrestrial microwave
Satellite microwave

21. Optical Fiber
Fiber-optic technology uses light instead of electricity to transmit data
SUPER CLEAR GLASS STRANDS
FAST, LIGHT, DURABLE
TRILLIONS OF BITS PER SECOND, FULL DUPLEX
EXPENSIVE, HARDER TO INSTALL
OFTEN USED AS BACKBONE OF NETWORKS
SIGNAL
LASER
CABLE
PHOTO
DETECTOR

22. Characteristics of Media

23. Modulation
Modification of a digital signal into an analog signal
Demodulation
Modification of an analog signal into a digital signal
Modems
Devices that modulate and demodulate signals
Multiplexor - device that transmits multiple signals over single medium

24. Modulation (Cont.) Analog vs. Digital
Analog: A continuous series of waves
Digital: A series of discrete bits

25. Modulation (Cont.)

26. Modulation (Cont.)
Figure 6.9 Multiplexing

27. 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

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

29. Network Topology

30. Star Topology
HOST
USER
Star topology: a central host computer receives all messages and then forwards the message to the appropriate computer or device (e.g. printer) on the network. In a star topology, all communications must go through the main computer, and this topology is one of the oldest types.
Advantage: easy to expand the network by adding more computers. This set-up is ideal when some information has to be centralized on the host computer, and other computers on the network can download that information from the host computer.

31. Bus Topology
A bus topology connects all computers on the network through a single circuit such as fiber optics, twisted pair etc to a central channel. Signals transmitted over the channel are called messages. This topology transmits each message to all computers on the network, although only the targeted device will respond to the message. Each device has an address and each device forwards messages to the address of a given device.
Advantages:
easy to add or remove devices from the network without affecting network performance.
if one of the devices on the network fails, the network is not affected.
Disadvantage: network performance decreases as the number of messages increases, because each device checks to see if the message is for it, or for some other device. This topology is ideal for LAN’s and for applications such as and file transfers.

32. Ring Topology
Ring Topology: network devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it (closed ring). This topology transmits a message to all devices between the sending node and the receiving node. Each computer communicates directly with any other computer by specifying the address of the device; the topology distributes processing and control functions among all devices on the network. If a computer on the network fails, the message is rerouted around it.

33. Networking Hardware
Network Interface Card
Hub
Switch
Bridge
Router

34. Virtual Private Network
A combination of private and public lines
A link between a private network and the Internet
“Virtual” refers to the illusion that the use is accessing a private network directly

35. 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

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

37. Protocols (Cont.)

38. Switching Techniques Circuit Switching Packet 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
TCP/IP

39. Switching Techniques (Cont.)

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

41. A Variety of Services Cable Digital Subscriber Line (DSL)
T1 and T3 Lines
Satellite
Fixed Wireless
Gigabit Ethernet
Optical Carrier

42. A Variety of Services (Cont.)

43. A Wireless Revolution Popular Wireless Technologies
Would You Like Wi-Fi With That?
Combining Technologies

44. Wireless Technologies (Cont.)

45. Wireless Technologies (Cont.)

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

47. 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

48. Summary Telecommunications concepts and terminology
Communication within a computer system and among computers
Telecommunications media and devices
Network layouts and protocols
Telecommunications impact on operations
Telecommunications developments and speed