1. 1 January 2011wichai@buu.ac.th1

2. 1 January 2011wichai@buu.ac.th2 2 NetworksNetworks

3. 321450 Management of Information Technology Chapter 8 Chapter 8 Telecommunication Technology Asst. Prof. Wichai Bunchua E-mail : wichai@buu.ac.th http://www.informatics.buu.ac.th/~wichai

4. 1 January 2011wichai@buu.ac.th4 4 Telecommunications Electronic transmission of signals for communications Telecommunications medium Any material substance that carries an electronic signal to support communications between a sending and receiving device Telecommunications protocol Defines set of rules that governs the exchange of information over a communications medium An Overview of Telecommunications

5. 1 January 2011wichai@buu.ac.th5 5 An Overview of Telecommunications (cont.)

6. 1 January 2011wichai@buu.ac.th6 6 Synchronous communications Receiver gets message instantaneously Asynchronous communications Receiver gets message after some delay An Overview of Telecommunications (cont.)

7. 1 January 2011wichai@buu.ac.th7 7 Basic Telecommunications Channel Characteristics 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

8. 1 January 2011wichai@buu.ac.th8 8 Basic Telecommunications Channel Characteristics (continued) Channel bandwidth Rate at which data is exchanged Telecommunications media Categories: guided transmission media and wireless Guided transmission media types Available in many types Twisted-pair wire Classified by category: Category 1, 2, 3, 4, 5, 5E, and 6

9. 1 January 2011wichai@buu.ac.th9 9 Basic Telecommunications Channel Characteristics (continued) Coaxial cable Offers cleaner and crisper data transmission (less noise) than twisted-pair wire Fiber-optic cable Transmits signals with light beams Broadband over power lines Potential problem: transmitting data over unshielded power lines can interfere with both amateur (ham) radio broadcasts and police and fire radios

10. 1 January 2011wichai@buu.ac.th10 Basic Telecommunications Channel Characteristics (continued)

11. 1 January 2011wichai@buu.ac.th11 Guided transmission media types

12. 1 January 2011wichai@buu.ac.th12 Basic Telecommunications Channel Characteristics (continued) Wireless communications options Wireless transmission involves the broadcast of communications in one of three frequency ranges Radio, microwave, or infrared frequencies

13. 1 January 2011wichai@buu.ac.th13 Frequency Ranges Used for Wireless Communications

14. 1 January 2011wichai@buu.ac.th14 Short Range Wireless Options Near Field Communication (NFC) Short-range wireless connectivity technology designed for cell phones and credit cards Bluetooth Wireless communications specification that describes how cell phones, computers, personal digital assistants, etc., can be interconnected Ultra wideband (UWB) Transmits large amounts of digital data over short distances of up to 30 feet

15. 1 January 2011wichai@buu.ac.th15 Short Range Wireless Options (continued) Infrared transmission Sends signals at a frequency of 300 GHz and above Zigbee Form of wireless communications frequently used in security systems and heating and cooling control systems

16. 1 January 2011wichai@buu.ac.th16 Medium Range Wireless Options Wi-Fi Wireless telecommunications technology brand owned by the Wi-Fi Alliance Wireless access point Consists of a transmitter with an antenna, receives the signal, and decodes it Wi-Fi access points Have maximum range of about 300 feet outdoors and 100 feet within a dry-walled building

17. 1 January 2011wichai@buu.ac.th17 Wi-Fi Network

18. 1 January 2011wichai@buu.ac.th18 Wide Area Wireless Network Options Microwave transmission High-frequency (300 MHz - 300 GHz) signal sent through the air Common forms of satellite communications Geostationary satellite Low earth orbit (LEO) satellite Very small aperture terminal (VSAT) Wireless mesh Uses multiple Wi-Fi access points to link a series of interconnected local area networks

19. 1 January 2011wichai@buu.ac.th19 Wide Area Wireless Network Options (continued) 3G wireless communications Useful for business travelers, people on the go, and people who need to get or stay connected. Rate 2 Mbps. Normally 384 Kbps 4G wireless communications Will provide increased data transmission rates in the 22-40 Mbps range Worldwide Interoperability for Microwave Access (WiMAX) Set of IEEE 802.16 wireless metropolitan area network standards

20. 1 January 2011wichai@buu.ac.th20 Future Wireless Communications Developments Digital signal Represents bits Analog signal Variable signal, continuous in both time and amplitude so that any small fluctuations in the signal are meaningful

21. 1 January 2011wichai@buu.ac.th21 Networks and Distributed Processing Computer network Consists of communications media, devices, and software needed to connect two or more computer systems or devices Can transmit and receive information to improve organizational effectiveness and efficiency

22. 1 January 2011wichai@buu.ac.th22 Network Types Network Types Personal area networks Supports interconnection of information technology within a range of about 33 feet Local area networks Connects computer systems and devices within a small area (e.g., office or home) Metropolitan area networks Connects users and their devices in a geographical area that spans a campus or city Wide area networks Ties together large geographic regions

23. 1 January 2011wichai@buu.ac.th23 A Typical LAN

24. 1 January 2011wichai@buu.ac.th24 A Wide Area Network

25. 1 January 2011wichai@buu.ac.th25 Client/Server Systems Client/server architecture Multiple computer platforms are dedicated to special functions Client Any computer that sends messages requesting services from the servers on the network Database server Sends only the data that satisfies a specific query, not the entire file

26. 1 January 2011wichai@buu.ac.th26 Client/Server Systems

27. 1 January 2011wichai@buu.ac.th27 The Client/Server Networks

28. 1 January 2011wichai@buu.ac.th28 Client/Server Systems (cont.)

29. 1 January 2011wichai@buu.ac.th29 Telecommunications Hardware Modems Modulation/demodulation devices Multiplexers Combines data from multiple data sources into a single output signal that carries multiple channels Front-end processors Special-purpose computers that manage communications to and from a computer system

30. 1 January 2011wichai@buu.ac.th30 Telecommunications Hardware (cont.) 30

31. 1 January 2011wichai@buu.ac.th31 Telecommunications Hardware (continued) Private branch exchange (PBX) Telephone switching exchange that serves a single organization Switches, bridges, routers, and gateways Switch: Uses the physical device address in each incoming message on the 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 Gateway: Serves as an entrance to another network 31

32. 1 January 2011wichai@buu.ac.th32 Telecommunications Hardware (cont.) 32 Switch:

33. 1 January 2011wichai@buu.ac.th33 Telecommunications Hardware (cont.) 33 Bridge: Router: Gatewa y:

34. 1 January 2011wichai@buu.ac.th34 Telecommunications Software Network operating system (NOS) Systems software that controls the computer systems and devices on a network Network management software Protects software from being copied, modified, or downloaded illegally Performs error control to locate telecommunications errors and potential network problems

35. 1 January 2011wichai@buu.ac.th35 Securing Data Transmission Encryption Converting an original message into a form that can only be understood by the intended receiver Key Variable value that is applied (using an algorithm) to a set of unencrypted text to produce encrypted text or to decrypt encrypted text

36. 1 January 2011wichai@buu.ac.th36 The Encryption Process

37. 1 January 2011wichai@buu.ac.th37 Securing Data Transmission (continued) Securing wireless networks Wired equivalent privacy (WEP) Used encryption based on 64-bit key, which has been upgraded to a 128-bit key Wi-Fi Protected Access (WPA) Security protocol that offers significantly improved protection over WEP War driving Involves hackers driving around with a laptop and antenna trying to detect insecure wireless access points

38. 1 January 2011wichai@buu.ac.th38 Other Encryption Methods Data Encryption Standard (DES) Early data encryption standard developed in the 1970s that uses a 56-bit private key algorithm Advanced Encryption Standard (AES) Extremely strong data encryption standard based on a key size of 128 bits, 192 bits, or 256 bits

39. 1 January 2011wichai@buu.ac.th39 Virtual Private Network (VPN) Private network that uses a public network (usually the Internet) to connect multiple remote locations Supports secure, encrypted connections between a company’s private network and remote users

40. 1 January 2011wichai@buu.ac.th40 Telecommunications Services and Network Applications Cellular phone services Operate using radio waves to provide two- way communications Picocell Miniature cellular base station designed to serve a very small area such as part of a floor inside a building

41. 1 January 2011wichai@buu.ac.th41 Cellular Phone Services Digital subscriber line (DSL) Service Telecommunications service that delivers high-speed Internet access Voice over Internet Protocol (VoIP) Services Enables voice conversations to be converted into packets of data that can be sent over a data network

42. 1 January 2011wichai@buu.ac.th42 DSLDSL

43. 1 January 2011wichai@buu.ac.th43 VoIP Options

44. 1 January 2011wichai@buu.ac.th44 Linking Personal Computers to Mainframes and Networks Basic way that telecommunications connect users to information systems Connecting personal computers to mainframe computers so that data can be downloaded or uploaded

45. 1 January 2011wichai@buu.ac.th45 Voice Mail Users can send, receive, and store verbal messages for and from other people around the world Reverse 911 service Delivers emergency notifications to users in a selected geographical area Voice-to-text services Convert speech to text so that you can manage voice mails more effectively

46. 1 January 2011wichai@buu.ac.th46 Asynchronous Digital Subscriber Line (ADSL)

47. 1 January 2011wichai@buu.ac.th47 Home and Small Business Networks DSL modem Enables each computer in the network to access the Internet Firewall Filters the information coming from the Internet into your network

48. 1 January 2011wichai@buu.ac.th48 Electronic Document Distribution Lets you send and receive documents in a digital form without printing them Much faster to distribute electronic documents via networks than to mail printed forms Viewing documents on screen instead of printing Saves paper and document storage space

49. 1 January 2011wichai@buu.ac.th49 Call Centers Physical location where an organization handles customer and other telephone calls Used by: Customer service organizations Telemarketing companies Computer product help desks Charitable and political campaign organizations

50. 1 January 2011wichai@buu.ac.th50 Telecommuting and Virtual Workers and Workgroups Telecommuters Need to be strongly self-motivated, organized, focused on their tasks with minimal supervision Jobs unsuitable for telecommuting Those that require frequent face-to-face interaction, need much supervision, and have many short-term deadlines

51. 1 January 2011wichai@buu.ac.th51 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

52. 1 January 2011wichai@buu.ac.th52 Electronic Data Interchange Idea behind EDI Connecting corporate computers among organizations EDI Can link the computers of customers, manufacturers, and suppliers Eliminates the need for paper documents and substantially cuts down on costly errors

53. 1 January 2011wichai@buu.ac.th53 Two Approaches to EDI

54. 1 January 2011wichai@buu.ac.th54 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

55. 1 January 2011wichai@buu.ac.th55 เครือข่ายผู้ให้บริการ บริษัท กสท. โทรคมนาคม จำกัด ( มหาชน ) http://www.cat.net.th/ บริษัท อินเทอร์เน็ตประเทศไทย จำกัด ( มหาชน ) http://www.inet.co.th/ บริษัท สามารถอินโฟเนต จำกัด http://www.samarts.com/ บริษัท ทีทีแอนด์ที จำกัด ( มหาชน ) http://www.ttt.co.th/ บริษัท ทีโอที จำกัด ( มหาชน ) http://www.tot.co.th/ บริษัท ซีเอส ล็อกซอินโฟ จำกัด ( มหาชน ) http://www.csloxinfo.com/ บริษัท ทรู อินเทอร์เน็ต จำกัด http://www.trueinternet.co.th/ Public Network Services

56. 1 January 2011wichai@buu.ac.th56 Electronic Funds Transfer Transfers money from one bank account directly to another without the use of paper money Used for both credit and debit transfers

57. 1 January 2011wichai@buu.ac.th57 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”

58. 1 January 2011wichai@buu.ac.th58 Shared Workspace Shared Workspace Common work area where: Colleagues can share documents, issues, models, schedules, spreadsheets, and all forms of information

59. 1 January 2011wichai@buu.ac.th59 Summary Telecommunications and networks Creating profound changes in business because they remove the barriers of time and distance Communications Can be classified as synchronous or asynchronous Telecommunications media can physically connect data communications devices Guided transmission media and wireless media

60. 1 January 2011wichai@buu.ac.th60 Summary (continued) Wireless communications solutions for very short distances include: Near field communications, Bluetooth, ultra wideband, infrared transmission, and Zigbee Transborder data flow Electronic flow of data across international and global boundaries Client/server system Network that connects a user’s computer (a client) to one or more host computers (servers)

61. 1 January 2011wichai@buu.ac.th61 Questions?Questions?

62. 1 January 2011wichai@buu.ac.th62 Assignment#8Assignment#8 8a. การสื่อสารทางไกล (Telecommunication) สัมพันธ์กับระบบ สารสนเทศอย่างไร จงยกตัวอย่างประกอบ 8b. จงบอกองค์ประกอบ 6 อย่างของระบบการ สื่อสารทางไกล (Telecommunication) พร้อมอธิบายหลักการทำงานพื้นฐานของ ระบบ

63. 1 January 2011wichai@buu.ac.th63 ส วั ส ดี