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Telecommunication Technology & Networks: An Overview

This chapter provides an overview of telecommunications, including the types of channels, guided transmission media, wireless options, and future developments. It also covers networks and distributed processing.

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Telecommunication Technology & Networks: An Overview

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  1. wichai@buu.ac.th

  2. Networks wichai@buu.ac.th 2

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

  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 wichai@buu.ac.th 4

  5. An Overview of Telecommunications (cont.) wichai@buu.ac.th 5

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

  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 wichai@buu.ac.th 7

  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 wichai@buu.ac.th 8

  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 wichai@buu.ac.th 9

  10. Basic Telecommunications Channel Characteristics (continued) wichai@buu.ac.th 10

  11. Guided transmission media types wichai@buu.ac.th 11

  12. 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 wichai@buu.ac.th 12

  13. Frequency Ranges Used for Wireless Communications wichai@buu.ac.th 13

  14. 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 wichai@buu.ac.th 14

  15. 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 wichai@buu.ac.th 15

  16. 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 wichai@buu.ac.th 16

  17. Wi-Fi Network wichai@buu.ac.th 17

  18. 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 wichai@buu.ac.th 18

  19. 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 wichai@buu.ac.th 19

  20. 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 wichai@buu.ac.th 20

  21. 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 wichai@buu.ac.th 21

  22. 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 wichai@buu.ac.th 22

  23. A Typical LAN wichai@buu.ac.th 23

  24. A Wide Area Network wichai@buu.ac.th 24

  25. 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 wichai@buu.ac.th 25

  26. Client/Server Systems wichai@buu.ac.th 26

  27. The Client/Server Networks wichai@buu.ac.th

  28. Client/Server Systems (cont.) wichai@buu.ac.th 28

  29. 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 wichai@buu.ac.th 29

  30. Telecommunications Hardware (cont.) wichai@buu.ac.th 30

  31. 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 wichai@buu.ac.th 31

  32. Telecommunications Hardware (cont.) • Switch: wichai@buu.ac.th 32

  33. Telecommunications Hardware (cont.) • Bridge: • Router: • Gateway: wichai@buu.ac.th 33

  34. 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 wichai@buu.ac.th 34

  35. 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 wichai@buu.ac.th 35

  36. The Encryption Process wichai@buu.ac.th 36

  37. 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 wichai@buu.ac.th 37

  38. 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 wichai@buu.ac.th 38

  39. 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 wichai@buu.ac.th 39

  40. 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 wichai@buu.ac.th 40

  41. 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 wichai@buu.ac.th 41

  42. DSL wichai@buu.ac.th 42

  43. VoIP Options wichai@buu.ac.th 43

  44. 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 wichai@buu.ac.th 44

  45. 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 wichai@buu.ac.th 45

  46. Asynchronous Digital Subscriber Line(ADSL) wichai@buu.ac.th

  47. 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 wichai@buu.ac.th 47

  48. 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 wichai@buu.ac.th 48

  49. 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 wichai@buu.ac.th 49

  50. 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 wichai@buu.ac.th 50

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