dc-lec-1 (intro to data com)

8/3/2019 DC-Lec-1 (Intro to Data Com)

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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


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


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



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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

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