Presentation on theme: "CSC 242 Introduction to Telecommunications Systems"— Presentation transcript:
1 CSC 242 Introduction to Telecommunications Systems Lecture # 1Dr. Ehsan MunirDepartment of Computer ScienceCOMSATS Institute of Information Technology
2 What is Communication When we communicate we share information Local CommunicationFace to faceRemote CommunicationOver distance
3 DATA COMMUNICATIONSData 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
7 Factors Effecting DC System DeliveryDeliver data to correct destinationAccuracyDeliver data accuratelyTimelinessDeliver data in a timely mannerJitterVariation in packet arrival time
8 Figure Data flow (simplex, half-duplex, and full-duplex)
9 Data Flow Simplex Half duplex Full duplex Transmission in one direction. Example TelevisionHalf duplexEither direction, but only one way at a time. Example Walkie-talkiesFull duplexBoth directions at the same time. Example Phones.
10 What is Telecommunication Tele is Greek word, meaning “far off”Webster calls it communications at a distanceThe IEEE Standard Dictionary defines telecommunications as the transmission of signals over long distance,Science of communicating over distance
11 NetworksA 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 anotherTopology: Arrangement of nodes in a network specify topology.
12 Figure Types of connections: point-to-point and multipoint
13 Network Criteria Performance Reliability Security Throughput: Number of bits transmitted in one secondDelay: How long it takes a bit of data to travel in networkReliabilityRobustness : ability of the network to perform its function in the face of attack (node failure)SecurityUnauthorized accessviruses
15 Figure A bus topology connecting three stations
16 Bus Topology Single cable connect all computers Each computer has connector to shared cableCable must end with a terminatorAdvantagesEase of installationInexpensiveWorks well for small networksDisadvantagesCable break, whole network downLimited 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 anotherAdvantagesEase of installationInexpensive (less than mesh)RobustnessDisadvantagesHub fails, whole network downCostly than bus
19 Figure A fully connected mesh topology (five devices)
20 Mesh Topology Each device connected to every other device Advantages RobustnessCan carry more dataDisadvantagesExpensiveDifficult to installDifficult to manage
22 Ring TopologyEach device connected to two devices (immediate neighbors)The signal is passed along the ring in one directionAdvantagesEasy to install and reconfigureInexpensive (less than mesh)DisadvantagesBreak in a ring disables the whole networkUnidirectional
23 Figure A hybrid topology: a star backbone with three bus networks
24 Types of Networks Local Area Network (LAN) Wide Area Network (WAN) Links the nodes in a single office, building or campusWide Area Network (WAN)Links the nodes in states, countries or in the whole worldMetropolitan Area Network (MAN)Between LAN and WANLinks the nodes in a town or city
25 Protocols Protocol defines: Elements of a protocol What is communicatedHow, it is communicatedWhen, it is communicatedElements of a protocolSyntaxSemanticsTiming
26 StandardsA standard provides a model for development that makes it possible for a product to work regardless of the individual manufacturerStandards are essential in:Creating/Maintaining open and competitive marketGuaranteeing National/International Interoperability
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