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CSC 242 Introduction to Telecommunications Systems

Lecture # 1. CSC 242 Introduction to Telecommunications Systems. Dr. Ehsan Munir Department of Computer Science COMSATS Institute of Information Technology. What is Communication. When we communicate we share information Local Communication Face to face Remote Communication

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CSC 242 Introduction to Telecommunications Systems

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  1. Lecture # 1 CSC 242 Introduction toTelecommunications Systems Dr. Ehsan Munir Department of Computer Science COMSATS Institute of Information Technology

  2. What is Communication • When we communicate we share information • Local Communication • Face to face • Remote Communication • Over distance

  3. DATA COMMUNICATIONS Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. The word data refers to information presented in whatever form is agreed upon by the parties creating and using the data.

  4. Data Communication System • For data communication to occur, communicating devices must be a part of a system made up of some specific kind of hardware and software. This system is known as “DC System”

  5. DC System Components • Message • Sender • Receiver • Transmission Medium • Protocol

  6. Figure Five components of data communication

  7. Factors Effecting DC System • Delivery • Deliver data to correct destination • Accuracy • Deliver data accurately • Timeliness • Deliver data in a timely manner • Jitter • Variation in packet arrival time

  8. Figure Data flow (simplex, half-duplex, and full-duplex)

  9. Data Flow • Simplex • Transmission in one direction. Example Television • Half duplex • Either direction, but only one way at a time. Example Walkie-talkies • Full duplex • Both directions at the same time. Example Phones.

  10. What is Telecommunication • Tele is Greek word, meaning “far off” • Webster calls it communications at a distance • The IEEE Standard Dictionary defines telecommunications as the transmission of signals over long distance, • Science of communicating over distance

  11. Networks • A network is a set of devices (nodes) connected by communication links. • A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. • A link is a communication pathway that transfers data from one device to another • Topology: Arrangement of nodes in a network specify topology.

  12. Figure Types of connections: point-to-point and multipoint

  13. Network Criteria • Performance • Throughput: Number of bits transmitted in one second • Delay: How long it takes a bit of data to travel in network • Reliability • Robustness : ability of the network to perform its function in the face of attack (node failure) • Security • Unauthorized access • viruses

  14. Categories of topology

  15. Figure A bus topology connecting three stations

  16. Bus Topology • Single cable connect all computers • Each computer has connector to shared cable • Cable must end with a terminator • Advantages • Ease of installation • Inexpensive • Works well for small networks • Disadvantages • Cable break, whole network down • Limited number of devices can be attached

  17. Figure A star topology connecting four stations

  18. Star Topology • All computers attach to central point • The devices are not directly linked to one another • Advantages • Ease of installation • Inexpensive (less than mesh) • Robustness • Disadvantages • Hub fails, whole network down • Costly than bus

  19. Figure A fully connected mesh topology (five devices)

  20. Mesh Topology • Each device connected to every other device • Advantages • Robustness • Can carry more data • Disadvantages • Expensive • Difficult to install • Difficult to manage

  21. Figure A ring topology connecting six stations

  22. Ring Topology • Each device connected to two devices (immediate neighbors) • The signal is passed along the ring in one direction • Advantages • Easy to install and reconfigure • Inexpensive (less than mesh) • Disadvantages • Break in a ring disables the whole network • Unidirectional

  23. Figure A hybrid topology: a star backbone with three bus networks

  24. Types of Networks • Local Area Network (LAN) • Links the nodes in a single office, building or campus • Wide Area Network (WAN) • Links the nodes in states, countries or in the whole world • Metropolitan Area Network (MAN) • Between LAN and WAN • Links the nodes in a town or city

  25. Protocols • Protocol defines: • What is communicated • How, it is communicated • When, it is communicated • Elements of a protocol • Syntax • Semantics • Timing

  26. Standards • A standard provides a model for development that makes it possible for a product to work regardless of the individual manufacturer • Standards are essential in: • Creating/Maintaining open and competitive market • Guaranteeing National/International Interoperability

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