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

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Presentation on theme: "CSC 242 Introduction to Telecommunications Systems Dr. Ehsan Munir Department of Computer Science COMSATS Institute of Information Technology Lecture #"— Presentation transcript:

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

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

3 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 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 5 DC System Components Message Sender Receiver Transmission Medium Protocol

6 6 Figure Five components of data communication

7 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 8 Figure Data flow (simplex, half-duplex, and full-duplex)

9 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 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 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 12 Figure Types of connections: point-to-point and multipoint

13 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 14 Categories of topology

15 15 Figure A bus topology connecting three stations

16 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 17 Figure A star topology connecting four stations

18 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 19 Figure A fully connected mesh topology (five devices)

20 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 21 Figure A ring topology connecting six stations

22 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 23 Figure A hybrid topology: a star backbone with three bus networks

24 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 25 Protocols Protocol defines: What is communicated How, it is communicated When, it is communicated Elements of a protocol Syntax Semantics Timing

26 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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