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DATA
COMMUNICATION
Lecture-1
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Course Outline
The course will consist of : 32 lectures 5-10 assignments
4 exams (3 midterm and 1 final)
Grading Criteria: Two Best Midterm:40%
Final Exam: 40% Assignments: 20%
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Textbook
Data Communications and Networking 4thEdition by Behrouz A. Forouzan
Data and Computer Communication 6th
Edition by William Stallings
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Overview of Lecture 1
Data Communication
Brief History of Communication
Data Communication System
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DATA COMMUNICATION
Data Communication is the
exchange ofInformation fromone entityto the other using aTransmission Medium
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History
Telegraph 1837 Samuel Morse This led to building a telecommunication infrastructure of
poles and wires as well as the development ofcommunication hardware and protocols.
Telephone 1876 Alexander Graham Bell Invention of Telephone and wireless communication system
by guglielmo Marconi in 1890s set the stage for today'scommunication industry.
By 1950s By 1950 Telephone and telegraph companies had developed
a network of communication facilities throughout theindustrialized world.
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History (Cont.)
1970S Although development of databases, languages, operating
systems and hardware from 1950 to 1970, large scale datacommunication systems did not emerge until the 1970s. This
was stimulated by three major development Large scaleintegration of circuit reduced cost and size ofterminals and communication system. New softwaresystems that facilitated the development of data
communication networks. Competition amongproviders of transmission facilities reduced the costdata circuits.
Today
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Data Communication Definition
(Modified)
Simply means sharing of data locally or remotely. Exchange of data between two devices via some form of
Transmission medium such as wire. Exchange of data (in form of 0s and 1s) between two
devices (e.g. computers) via some form of the transmissionmedium.
Subset of Telecommunication in which DigitalCommunication Occurs (0s & 1s).
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LOCAL and REMOTE Communication
LOCAL Communicating devices are present in the same
building or a similarly restricted geographical area.
REMOTE Communicating devices are present farther apart.
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Data Communication System
For Data Communication to occur,communicating devices must be apart of a system made up of some
specific kind ofhardware and
software. This system is known asDATA COMMUNICATION SYSTEM
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Effectiveness of Data Comm.
System
Effectiveness depends upon three fundamentalcharacteristics:
Delivery(to the specific destination)
Accuracy(correctly)
TimelinessBetter late than never, Better never than late.
Jitter (uneven delay in the delivery of audio or videopackets)
For example a postal mail.
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Components of a Simple Data
Communication System
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Components of a Data
Communication System
A Data communication system is made up of5 components:
1. Message2. Sender3. Receiver
4. Medium5. Protocol
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Message
The message is the information (data) to becommunicated. A message is transmitted fromsender to receiver.
It can data file an audio or video file or any text message
A message also keeps information like sender anddestination addresses.
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Sender
It is also called source.
It is the device which generates the messageand responsible for its transmission.
It can be a computer Workstation
telephone handset
video camera
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Receiver
It is also called destination/sink.
It is the device that receives the transmittedmessage.
It may be a computer
Workstation telephone handset
Television
or any communication device.
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Medium
The transmission medium is the physical pathby which a message travels from sender toreceiver. It may be a
guided medium coaxial cable
twisted pair cable
fiber optic unguided medium
electro-magnetic waves
micro waves
infrared waves
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Transmission Media
Medium Speed Cost
Twisted Wire 300bps-100Mbps Low
Microwave 256Kbps-100Mbps Low
Coaxial Cable 56Kbps-200Mbps Low
Fiber Optic Cable 500Kbps-10Gbps High
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Protocol
Protocols are also called language of communication. A protocol is a set of rules that governs data
communication.
Both sender & receiver must have the same protocolfor communication.
It represents an agreement between thecommunicating devices.
Without a protocol, two devices may be connected butnot communicating, just as a person speaking Frenchcannot be understood by a person who speaks only
Japanese.
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A Complex Data Comm. System
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Components of a Data
Communication System
Source generates data to be transmitted
Transmitter Converts data into transmittable signals
Transmission System Carries data
Receiver Converts received signal into data
Destination Takes incoming data
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EXAMPLE Electronic Mail
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An Actual Digital Data
Communication System
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Summary
Data Communication
Brief History of Communication Data Communication System
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Suggested Reading
Section 1.1,
Data Communications and Networking 4th Edition by Behrouz A.Forouzan
Sections 1.1,
1.2, Data and Computer Communication 6th Edition by William Stallings