Principles of Information Systems

2. Principles of Information Systems Chapter 6 Telecommunications and Networks

3. Why Learn About Telecommunications and Networks? • Need to access data wherever it resides • Fast, reliable communications • Exchange messages • Upload/download data and software • Route business transactions • Connect to remote databases • Send output to printers

4. An Overview Of Telecommunications • Telecommunications: electronic transmission of signals for communications • Telephone, radio, and television • Communications can be synchronous or asynchronous • Synchronous communications: receiver gets message instantaneously • Asynchronous communications: receiver gets message after some delay

5. An Overview Of Telecommunications (continued) Figure 6.1: Elements of a Telecommunications System

6. Basic Communications Channel Characteristics • Communication channels can be classified as: • Simplex channel: transmits data in only one direction • Half-duplex channel: transmits data in either direction, but not simultaneously • Full-duplex channel: permits data transmission in both directions at the same time

7. Channel Bandwidth • Channel bandwidth: rate at which data is exchanged over a communications channel • Usually measured in bits per second (bps) • Broadband communications: telecommunications system in which a very high rate of data exchange is possible • Narrowband communications: telecommunications system that supports a much lower rate of data exchange than broadband

8. Communications Media • Guided transmission media: communications signals guided along a solid medium • Wireless media: communications signal broadcast over airwaves as a form of electromagnetic radiation

9. Guided Transmission Media Types Table 6.1: Guided Transmission Media Types

10. Guided Transmission Media Types Table 6.1: Guided Transmission Media Types

11. Guided Transmission Media Types (continued) Table 6.2: Wireless Technologies

12. Telecommunications Hardware • Typical telephone line only accommodates an analog signal (continuous, curving signal) • Computers generate a digital signal representing bits • Modem: device that translates data from digital to analog and analog to digital

13. Telecommunications Hardware (continued) Figure 6.6: How a Modem Works

14. Telecommunications Hardware (continued) • Multiplexer: device that encodes data from two or more data sources onto a single communications channel • Reduces number of communications channels needed • Lowers telecommunications costs • Front-end processors: special-purpose computers that manage communications serving hundreds or even thousands of users

15. Telecommunications Hardware (continued) • Multiplexer andFront-end processors

16. Services • Telecommunications carriers organize communications channels, networks, hardware, software, people, and business procedures to provide valuable communications services

17. Digital Subscriber Line (DSL) • Telecommunications technology that delivers high-bandwidth information to homes and small businesses over ordinary copper telephone wires • Asymmetric DSL (ADSL): download speed is three to four times faster than upload speed • Symmetric DSL (SDSL): speed of receiving and sending data is the same • Does not allow you to use the phone at the same time

18. Digital Subscriber Line (DSL) (continued) Figure 6.8: Digital Subscriber Line (DSL)

19. Wireless Telecommunications • All major long-distance carriers offer wireless telecommunications services • Phone calls or Internet access • Wireless data communications will be broadly adopted when providers can offer business users enough bandwidth and connectivity so that they use wireless as their sole connection

20. Wireless Telecommunications • All major long-distance carriers offer wireless telecommunications services • Phone calls or Internet access • Wireless data communications will be broadly adopted when providers can offer business users enough bandwidth and connectivity so that they use wireless as their sole connection

21. Networks and Distributed Processing • Computer network: communications media, devices, and software needed to connect two or more computer systems and/or devices • Network nodes: computers and devices on the networks

22. Network Types • Personal area network (PAN) • Local area network (LAN) • Metropolitan area network (MAN) • Wide area network (WAN) • International networks • Mesh (ตาข่าย) networking

23. Network Types (continued) Figure 6.11: Partial Mesh Network

24. Distributed Processing • Centralized processing: all processing occurs at a single location or facility • Decentralized processing: processing devices are placed at various remote locations • Distributed processing: computers are placed at remote locations but are connected to each other via a network

25. Client/Server Systems • Client/server: multiple computer platforms are dedicated to special functions such as database management, printing, communications, and program execution • Each server is accessible by all computers on the network • A client is any computer that sends messages requesting services from servers on the network

26. Client/Server Systems (continued) Figure 6.13: Client/Server Connection

27. Client/Server Systems (continued)

28. Communications Software and Protocols • Communications protocol: set of rules that governs the exchange of information over a communications channel • ATM • Frame relay • IEEE 802.3 (Ethernet) • T-carrier system

29. Communications Software and Protocols (continued) Table 6.4: Common Telecommunications Protocols

30. Wireless Communications Protocols • Wi-Fi • WiMAX • Smart antenna technology • Ultra Wideband (UWB) • 3G wireless communication • 4G wireless communications

31. Wireless Communications Protocols (continued) Table 6.14: Wi-Fi Network

32. Wireless Communications Protocols (continued) • Switch: uses physical device address in each incoming message to forward message to another device on the same network • Bridge: connects one LAN to another LAN that uses the same telecommunications protocol • Router: forwards data packets across two or more distinct networks toward their destinations through routing • Gateway: serves as an entrance to another network

33. Wireless Communications Protocols (continued) • Switch: • Bridge: • Router: • Gateway:

34. Communications Software • Network operating system (NOS): systems software that controls computer systems and devices on a network and allows them to communicate with each other • Network-management software • Monitors the use of individual computers and shared hardware • Scans for viruses • Ensures compliance with software licenses

35. Telecommunications and Network Applications • Telecommunications and networks are a vital part of today’s information systems • In some industries, telecommunications is virtually a requirement for doing business

36. Linking Personal Computers to Mainframes and Networks • Personal computers can be connected to mainframe computers so that data can be downloaded or uploaded • Example: user can download a file from a database to a personal computer • Unattended systems: communications software programs that instruct the computer to connect to another computer on the network, download or send information, and then disconnect from the telecommunications line

37. Voice Mail • Users can send, receive, and store verbal messages for and from other people around the world • Call management systems can be linked to corporate e-mail and instant messaging systems

38. Home and Small Business Networks • Simple networks can be used to share printers or an Internet connection, access files on different machines, etc. • Wireless network • 802.11n access point • Combined router, firewall, Ethernet hub, and wireless hub • Configure computers to share printers and files

39. Electronic Document Distribution • Send and receive documents in a digital form without printing them (although printing is possible) • Much faster • Saves paper • Saves document storage space

40. Call Centers • Call center: physical location where an organization handles customer and other telephone calls • Usually with some computer automation • Automatic call distributor (ACD): telephone facility that manages incoming calls • Handles calls based on the called number and an associated database of instructions • National Do Not Call Registry • Offshore call centers

41. Telecommuting and Virtual Workers and Workgroups • Telecommuting: employees work away from the office using computing devices and networks • More effective workers • Saves money on office and parking space and office equipment • Reduces traffic congestion and air pollution • Some types of jobs are better suited for telecommuting than others • Telecommuters must work independently, manage time well, and balance work and home life

42. Videoconferencing • Enables people to hold a conference by combining voice, video, and audio transmission • Reduces travel expenses and time • Increases managerial effectiveness through faster response to problems, access to more people, and less duplication of effort in multiple sites • Systems usually combine video and phone call capabilities with data or document conferencing

43. Electronic Data Interchange • Intercompany, application-to-application communication of data in a standard format • Permits recipient to perform a standard business transaction, such as processing purchase orders • Follows standards and procedures that can process output from one system directly as input to other systems without human intervention

44. Electronic Data Interchange (continued) Table 6.17: Two Approaches to Electronic Data Interchange

45. Public Network Services • Give personal computer users access to vast databases, the Internet, and other services • Usually an initial fee plus usage fees • Fees are based on services used; can range from under $15 to over $500 per month • Providers of public network services include Microsoft, America Online, and Prodigy

46. Electronic Funds Transfer • Electronic funds transfer (EFT) • Transfers money from one bank account directly to another without the use of paper money • Wire transfer • Fast, reliable means to move funds from one account to another using one of three major wire-transfer networks • Automated clearing house (ACH) • Secure private network connecting all U.S. financial institutions to each other through the Federal Reserve Board or other ACH operators

47. Distance Learning • Use of telecommunications to extend the classroom • Instructors create course home pages on the Internet • Students access the course syllabus and instructor notes on the Web page • Student e-mail mailing lists allow students and the instructor to e-mail one another • Chat groups allow students to form “virtual teams”

48. Team Collaboration Systems • Microsoft Office Groove: example of software designed to enable collaboration and communication within small teams • Allows you to set up shared workspaces among employees and others outside your organization

49. Specialized Systems and Services • Increased interest in specialized and regional information services • Electronic bulletin board: message center that displays messages in electronic form • Regional, national, and international bulletin boards • Global positioning systems (GPSs) provide specialized telecommunications services • Virtual workers: conduct business at any time and place

50. Summary • Telecommunications: electronic transmission of signals for communications, by such means as telephone, radio, and television • Guided transmission media types: twisted-pair wire, coaxial cable, fiber-optic cable, and broadband over power lines • Wireless transmission types: microwave, radio, and infrared • Computer network: communications media, devices, and software needed to connect two or more computer systems and/or devices