mod three computer basics

8/14/2019 Mod Three Computer Basics

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Mod Three

Computer Basics


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What Is A aComputer?

A computer is an electronic device,operating under the control of instructions(software) stored in its own memory unit,

that can accept data (input), manipulatedata (process), and produce information(output) from the processing. Generally, the

term is used to describe a collection ofdevices that function together as a system.


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Devices that comprise a computer system

Printer(output)

Monitor(output)

Speaker(output)

Scanner(input)

Mouse(input)

Keyboard(input)

System unit

(processor,memory)

Storage devices(CD-RW, Floppy,Hard disk, zip,)


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What Does A Computer

Do?Computers can perform four general operations,which comprise the information processing cycle.

Input Process Output

Storage


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Data and Information

All computer processing requires data, which is acollection of raw facts, figures and symbols, such asnumbers, words, images, video and sound, given tothe computer during the input phase.

Computers manipulate data to create information.Information is data that is organized, meaningful,and useful.

During the output Phase, the information that has

been created is put into some form, such as a printedreport.

The information can also be put in computer storagefor future use.


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Why Is A Computer So Powerful?

The ability to perform the information processingcycle with amazing speed.

Reliability (low failure rate). Accuracy. Ability to store huge amounts of data and

information. Ability to communicate with other computers.


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How Does a Computer Knowwhat to do?

It must be given a detailed list of instructions,called a compute program orsoftware, that

tells it exactly what to do. Before processing a specific job, the computer

program corresponding to that job must bestored in memory.

Once the program is stored in memory thecompute can start the operation by executing theprogram instructions one after the other.


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What Are The PrimaryComponents Of A Computer ?

Input devices. Central Processing Unit

(containing the control unit

and the arithmetic/logic unit). Memory.

Output devices.

Storage devices.


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Types of Computer Systems


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Microcomputer Systems

Personal Computer(PC) microcomputer foruse by an individual

Professional Workstation a powerful,networked PC for business professionals

Laptop small, portable PC


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Network Server more powerfulmicrocomputers that coordinatetelecommunications and resource sharing in

small local area networks and Internet andintranet websites

Computer Terminals depend on servers forsoftware, storage and processing power


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Network Computers low-cost, sealedmicrocomputers with no or minimal diskstorage that are linked to the network

Information Appliances hand-heldmicrocomputer devices


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Hardware Organized bySystem Functions Input Devices convert data into electronic form for

direct entry or through a telecommunications networkinto a computer system

Processing Components primarily the CentralProcessing Unit (CPU) Arithmetic-Logic Unit (ALU) - perform arithmetic and logic

functions required to execute software instructions


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Hardware Organized bySystem Functions Output Devices convert electronic information produced

by the computer system into human-intelligible form forpresentation to end users

Storage Devices store data and software instructionsneeded for processing

Control Components primarily the CPUs Control Unit

which interprets software instructions and transmitsdirections that control the activities of the othercomponents of the computer system


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Computer Processing Speeds

Millisecond thousandth of a second

Microsecond millionth of a second

Nanosecond billionth of a second

Picosecond trillionth of a second


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Computer Clock Speeds

MIPS million instructions per second

Megahertz (MHz) millions of cycles persecond

Gigahertz (GHz) billions of cycles persecond


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Input Devices

Keyboard.Mouse.


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The Keyboard

The most commonly used input device is the keyboard

on which data is entered by manually keying in ortyping certain keys. A keyboard typically has 101 or105 keys.


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The Mouse

Is a pointing device which is used to control themovement of a mouse pointer on the screen to makeselections from the screen. A mouse has one to five

buttons. The bottom of the mouse is flat and contains amechanism that detects movement of the mouse.


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The Central processing

UnitThe central processing unit (CPU) contains electroniccircuits that cause processing to occur. The CPU interpretsinstructions to the computer, performs the logical andarithmetic processing operations, and causes the input andoutput operations to occur. It is considered the brain ofthe computer.

Control Unit- ALU


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Memory

Memory also called Random Access Memory or RAM(temporary memory) is the main memory of the computer.It consists of electronic components that store dataincluding numbers, letters of the alphabet, graphics andsound. Any information stored in RAM is lost when thecomputer is turned off.

Read Only Memory orROM is memory that is etched ona chip that has start-up directions for your computer. It ispermanent memory.


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Amount of RAM In

ComputersThe amount of memory in computers is typicallymeasured in kilobytes or megabytes. One kilobyte(K or KB) equals approximately 1,000 memorylocations and one megabyte (M or MB) equals

approximately one million locations A memorylocation, or byte, usually stores one character.

Therefore, a computer with 8 MB of memory canstore approximately 8 million characters. One

megabyte can hold approximately 500 pages oftext information.


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Output Devices

Output devices make the information resulting fromthe processing available for use. The two outputdevices more commonly used are the printer and

the computerscreen.

The printer produces a hard copy of your output,and the computer screen produces a soft copy of

your output.


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Storage Devices

Auxiliary storage devices are used tostore data when they are not being used

in memory. The most common types ofauxiliary storage used on personalcomputers are floppy disks, hard disks

and CD-ROM drives.


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Floppy Disks

A floppy disk is a portable,inexpensive storage medium that

consists of a thin, circular, flexibleplastic disk with a magnetic coatingenclosed in a square-shaped plastic

shell.


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Compact Discs

A compact disk (CD), also called an opticaldisc, is a flat round, portable storage mediumthat is usually 4.75 inch in diameter.

A CD-ROM (read only memory), is a compactdisc that used the same laser technology asaudio CDs for recording music. In addition itcan contain other types of data such as text,

graphics, and video. The capacity of a CD-ROM is 650 MB of data.


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Peripherals Advice


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RAM vs. ROM

Random Access Memory (RAM) eachmemory position can be both sensed andchanged

Read Only Memory (ROM) can be read butnot erased or overwritten


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ASCII Codes


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What is Software?

Definition:

Various kinds of programs used to operatecomputers and related devices


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Types of Software


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Types of Software

Application Software - performs informationprocessing tasks for end users

System Software manages and supportsoperations of computer systems andnetworks


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Application Software

General-Purpose programs that performcommon information processing jobs for endusers

Application-Specific support specificapplications of end users in business and

other fields


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General-Purpose ApplicationSoftware Software Suites Web Browsers Electronic Mail

Word Processing Spreadsheets Database Managers

Presentation Graphics Personal Information Managers Groupware


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Software Suites


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The Early Period: Up to1940 3,000 years ago: Mathematics, logic, and

numerical computation

Important contributions made by the Greeks,

Egyptians, Babylonians, Indians, Chinese, andPersians

1614: Logarithms

Invented by John Napier to simplify difficultmathematical computations

Around 1622: First slide rule created


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The Early Period: Up to 1940(continued)

1672: The Pascaline Designed and built by Blaise Pascal One of the first mechanical calculators Could do addition and subtraction

1674: Leibnitzs Wheel Constructed by Gottfried Leibnitz Mechanical calculator Could do addition, subtraction, multiplication, and

division


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The Pascaline: One of the Earliest Mechanical Calculators


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1801: The Jacquard loom Developed by Joseph Jacquard Automated loom

Used punched cards to create desired pattern 1823: The Difference Engine

Developed by Charles Babbage Did addition, subtraction, multiplication, and

division to 6 significant digits Solved polynomial equations and other

complex mathematical problems


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Drawing of the Jacquard Loom


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1830s: The Analytic Engine Designed by Charles Babbage More powerful and general-purpose

computational machine Components were functionally similar to the four

major components of todays computers Mill (modern terminology: arithmetic/logic unit) Store (modern terminology: memory) Operator (modern terminology: processor) Output (modern terminology: input/output)


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1890: U.S. census carried out withprogrammable card processing machines

Built by Herman Hollerith

These machines could automatically read, tally,and sort data entered on punched cards


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The Birth of Computers:19401950 Development of electronic, general-purpose

computers Did not begin until after 1940

Was fueled in large part by needs of World War II Early computers

Mark I ENIAC

ABC system Colossus Z1


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Photograph of the ENIAC Computer


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The Birth of Computers:19401950 Stored program computer model

Proposed by John Von Neumann in 1946 Stored binary algorithm in the computers memory

along with the data Is known as the Von Neumann architecture Modern computers remain, fundamentally, Von

Neumann machines First stored program computers

EDVAC EDSAC


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The Modern Era: 1950 to thePresent (continued)

Second generation of computing (1959-1965) Replaced vacuum tubes by transistors and

magnetic cores Dramatic reduction in size

Computer could fit into a single room Increase in reliability of computers

Reduced costs of computers High-level programming languages

The programmer occupation was born


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Third generation of computing (1965-1975)

Used integrated circuits rather than individual

electronic components

Further reduction in size and cost of computers

Computers became desk-sized

First minicomputer developed

Software industry formed


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Fourth generation of computing (1975-1985) Reduced to the size of a typewriter

First microcomputer developed Desktop and personal computers common Appearance of

Computer networks

Electronic mail User-friendly systems (Graphical user interfaces) Embedded systems


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The Altair 8800, the Worlds First Microcomputer


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Fifth generation of computing (1985-?)

Recent developments

Massively parallel processors Handheld devices and other types of personal digital

assistants (PDAs)

High-resolution graphics

Powerful multimedia user interfaces incorporatingsound, voice recognition, touch, photography, video,and television


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Recent developments (continued)

Integrated global telecommunications

incorporating data, television, telephone, FAX, theInternet, and the World Wide Web

Wireless data communications

Massive storage devices

Ubiquitous computing


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Some of the MajorAdvancements in

Computing


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Some of the MajorAdvancements in

Computing


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Operating System

SoftwareOperating system software tells the computer how toperform the functions of loading, storing andexecuting an application and how to transfer data.

Today, many computers use an operating system

that has a graphical user interface (GUI) thatprovides visual clues such as icon symbols to helpthe user. Microsoft Windows 98 is a widely usedgraphical operating system. DOS (Disk OperatingSystem) is an older but still widely used operatingsystem that is text-based.


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Application Software

Application Software consists of programs thattell a computer how to produce information.Some of the more commonly used packages are:

Word processing

Electronic spreadsheet

Database

Presentation graphics

C t d ft


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Computers and software Application software is designed to solve a

specific problem System software provides a general programming

environment

Operating system is a subset of the system software Provide functions used by the application software Provides the mechanisms for application software to

share the hardware in an orderly fashion Sharing increases the overall performance by allowing different

application software to use different parts of the computer at thesame time, decreasing the time to execute a collection ofprograms and increase overall system performance

S t S ft


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System Software Runtime system for a programming language C libraries runtime Standard input/output (I/O) library procedures to perform

buffered input/output on a stream of data The math library functions to perform various

mathematical functions Graphics libraries functions to render images on a

bitmapped display

Window system software that provides a virtualterminal to an application program

Introduction to Computer Networks


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INTRODUCTION TO COMPUTERNETWORKS



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Computer Networks

Computer networkconnects two or moreautonomous computers.

The computers can begeographically locatedanywhere.



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LAN, MAN & WAN

Network in small geographical Area (Room,Building or a Campus) is called LAN (Local AreaNetwork)

Network in a City is call MAN (Metropolitan AreaNetwork)

Network spread geographically (Country or acrossGlobe) is called WAN (Wide Area Network)



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Applications of Networks

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information Sharing

Easy accessibility from anywhere (files,databases)Search Capability (WWW)

Communication

EmailMessage broadcast

Remote computing


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Bus Topology

Commonly referred to asa linear bus, all thedevices on a bus

topology are connectedby one single cable.



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Star & Tree TopologyThe star topology is the mostcommonly used architecture inEthernet LANs.

When installed, the star topologyresembles spokes in a bicycle

wheel.Larger networks use the extendedstar topology also called treetopology. When used with networkdevices that filter frames orpackets, like bridges, switches, and

routers, this topology significantlyreduces the traffic on the wires bysending packets only to the wires ofthe destination host.


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Mesh Topology

The mesh topology connects alldevices (nodes) to each otherfor redundancy and faulttolerance.

It is used in WANs tointerconnect LANs and formission critical networks likethose used by banks andfinancial institutions.

Implementing the meshtopology is expensive anddifficult.



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Network Components

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications



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Networking Media

Networking media can bedefined simply as themeans by which signals(data) are sent from one

computer to another(either by cable orwireless means).



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Networking Devices

HUB, Switches, Routers,Wireless Access Points,Modems etc.



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Computers: Clients and

ServersIn a client/server networkarrangement, networkservices are located in adedicated computerwhose only function is torespond to the requests

of clients.

The server contains thefile, print, application,security, and other

services in a centralcomputer that iscontinuously available torespond to clientrequests.



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Applications

E-mail

Searchable Data (Web Sites)

E-Commerce

News Groups

Internet Telephony (VoIP)Video Conferencing

Chat Groups

Instant Messengers

Internet Radio

LAN Technologies


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Ethernet BUS Topology

Repeater

LAN Technologies


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Ethernet STAR Topology

Hub


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Classification of computers based on the


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Classification of computers based on theprinciples of operation

Analog computers

Analog computers operates by measuringphysical units such as voltage, pressure,

temperature, speed etc. These computers donot deal directly with numbers.

Analog computers are used for scientific and

engineering purposes.

Di it l t


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Digital computers

Digital computer: computer that operates with numerical information

or non-numerical information, represented in adigital form is known as digital computer.

These computers operate on binary values 0 and 1.

Analog quantities must be converted into digitalquantity before processing it.

The output will also be in digital.

H b id t


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Hybrid computers

The hybrid computers combines analog and digitalcapabilities.

The user can process both analog and digital data. These computers can take either analog or digital data

and gives the result as per requirement throughspecial devices.

A converter is used to convert analog data into digitaldata and vice-versa.e.g., ROBOT is the best exampleof hybrid computer.

These computers are used for scientific applications,various field of engineering and in industrial controlprocess.

Classification of computers


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Classification of computersbased on size and speed

Based on size and speed, we can dividecomputers into four major categories.

1. Micro computers

2. Mini computers3. Main frame computers

4. Super computers

Layered System View


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Layered System View

Clients, partners, customers

Intranet

Extranet

Internet

Corporate members

Global society: competitors

Internets and Extranets


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Internets and Extranets

Intranets Private network within an organization

Provides information to employees

Extranets Private network that connects organizations Used to allow suppliers and others access

Firewalls Security system

Protects against external threats

age 257

Internet Introduction


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Internet Introduction Internet: The internet is a global network of

interconnected networks, connecting private,public and university networks in one cohesiveunit.

Intranet: An intranet is a private enterprise

network that uses internet and webtechnologies for information gathering anddistribution within an organization.

Extranet: An extranet is a community ofinterest created by extending an intranet toselected entities external to an organization.

The Internet


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The Internet

The internet A network of networks The internet transmits data from one computer

(called a host) to another

Internet networks Linked networks that work much the same way --

they pass data around in packets, each of whichcarries the addresses of its sender and receiver

Have a


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Have anice day

Encryption

software

running onsending

computer

Decryption

software

running on

Receiving

computer

E%$&:}{|

Have anice day

What is the Internet


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What is the Internet

The Internet connects millions of servers.

Intranets and Extranets


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Intranet An internal corporate network built using Internet and

World Wide Web standards and products that allowsemployees of an organization to gain access to

corporate information Extranet

A network based on Web technologies that linksselected resources of the intranet of a company with its

customers, suppliers, or other business partners



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Intranet A within-organization computer network that

uses Internet technologies to communicate

Extranet Uses Internet technologies to facilitate

communication and trade between anorganization and its business partners, such assuppliers



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Internet, intranet, and extranet potential for productivity enhancement

The Internet


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The Internet

The internet A network of networks The internet transmits data from one

computer (called a host) to another Internet networks Linked networks that work much the same

way -- they pass data around in packets,each of which carries the addresses of itssender and receiver


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How the Internet Works


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How the Internet Works Transport control protocol (TCP)

A protocol that operates at the transport layer andis used in combination with IP by most Internetapplications

Backbone

An Internet high-speed, long distancecommunications links (like a bus; wire thatconnects nodes)

Uniform resource locator (URL)

An assigned address on the Internet for eachcomputer E.g., http://www.yorku.ca/

Domain Affiliations


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Domain Affiliations

arts cultural and entertainment activitiescom business organizationsedu educational sitesfirm businesses and firmsgov government sites

info information service providersmil military sitesnom individualsnet networking organizations

org organizationsrec recreational activitiesstore businesses offering goods for purchaseweb entities related to World Wide Web activities

net networking organizations

Access to the Internet


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Access to the Internet

LAN servers Local servers can provide access to the Internet through

normal connections (e.g., Ethernet)

Serial line internet protocol (SLIP) and

Point-to-point protocol (PPP) Communications protocol software that transmits packets over

telephone lines, allowing dial-up access to the Internet

Connection via an on-line service

Examples are America Online and Microsoft Network. Theseservices usually require sign-up procedures

Three Ways to Access the


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Three Ways to Access theInternet

Schematic


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Internet Service Providers


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Internet Service Providers

Internet service provider (ISP) Any company that provides individuals or

companies with access to the Internet

Thousands of providers including largecommunications companies Need an account with the ISP and software that

links with TCP/IP

The World Wide Web


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e o d de eb

World Wide Web A collection of tens of thousands of independently-

owned computers that work together as one in anInternet service

WWW Terminology


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gy

Home page The cover page for a Web site that has graphics, titles,

coloured text, etc.

Hypermedia Tools that connect the data on Web pages, allowing

users to access topics in whatever order they wish

Hypertext markup language (HTML) The standard page description language for Web pages



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Intranet An internal corporate network built using Internet

and World Wide Web standards and productsthat allows employees of an organization to gainaccess to corporate information

Extranet A network based on Web technologies that links

selected resources of the intranet of a company

with its customers, suppliers, or other businesspartners


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Extranet


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A new buzzword that refers to an intranet that is partiallyaccessible to authorized outsiders.

Whereas an intranet resides behind a firewall and isaccessible only to people who are members of the samecompany or organization, an extranet provides variouslevels of accessibility to outsiders. You can access an

extranet onlyif you have a valid username and password, and your identity

determines which parts of the extranet you can view.

Extranets are becoming a very popular means for businesspartners to exchange information.

Firewall


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Firewall A device that sits between your internal

network and the outside Internet and

limits access into and out of your networkbased on your organizations accesspolicy

What is Wireless


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Now the term is used to describe modern

wireless connections such as those in cellularnetworks and wireless broadband Internet. Inmodern usage, wireless is a method of

communication that uses low-powered radiowaves to transmit data between devices. Wireless refers to communication without

cables or cords, chiefly using radio frequency

and infrared waves.


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Internet


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Internet

The internet is a worldwideinterconnection of many differentcomputers and networks.

The internet allows users toefficiently share information,programs and equipments and to

communicate with each other.


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Disadvantages of extranet


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Disadvantages of extranet

Extranets can be expensive to implement and maintain withinan organization (e.g.: hardware, software, employee trainingcosts)

Security of extranets can be a big concern when dealing with

valuable information. System access needs to be carefullycontrolled to avoid sensitive information falling into the wronghands.

Extranets can reduce personal contact (face-to-face meetings)with customers and business partners. This could cause a lack

of connections made between people and a company, whichhurts the business when it comes to loyalty of its businesspartners and customers.

Wireless technologies


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Wireless technologies

Bluetooth, WiFi and WiMAX are wirelesstechnologies which allow devices to inter-connect and communicate with each

other. Radio waves are electro magneticwaves and have different frequencies.These technologies are radio frequencies.

Similar to the analogue radio, or FM radio.


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Blue tooth


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Blue tooth

Named after the Danish king, HaroldBlue tooth, was the first to emerge,several devices like mobile phones,pdas, headsets, keyboards, mice,medical equipment and even carsnow come with this feature.

D t it l t f t


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Due to its low cost, manufacturers

are willing to implement thistechnology in most devices. It isdesigned for short range

communications with a range ofabout 10m. As a result, it consumes

less power and are suited for verysmall battery powered devices andportable devices.


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Problems associated when devicescommunicate via infrared or cables

are removed. Infrared requires a lineof sight, blue tooth only needs to bein reasonable vicinity.


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As cables are not required, it would

be less cumbersome carrying apersonal blue tooth device andspace would be less cluttered.


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As blue tooth devices

automatically communicate witheach other, it requires very littlefrom the user.Bluetooth allows for a wirelessPersonal Area Network (PAN) with

it's short range.

Wi - fi


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Wi fi

WiFi or Wireless Fidelity, has a range ofabout 100m and allows for faster datatransfer rate between 10 - 54Mbps. Thereare three different wireless standards

under WiFi, 802.11a, 802.11b and802.11g. 802.11 being the wirelessstandard set by The Institue of Electricaland Electronic Engineers (IEEE). WiFi is

used to create wireless Local AreaNetworks (WLAN).

The most widely used standard is 802.11band 802 11g is expexcted to grow rapidly
http://standards.ieee.org/wireless/index.htmlhttp://standards.ieee.org/wireless/index.html


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and 802.11g is expexcted to grow rapidly.These two standards are relatively

inexpensive and can be found providingwireless connectivity in airports, railwaystations, cafes, bars, restaurants and otherpublic areas.

The main difference between the two is thespeed. 802.11b has data transfer rate ofupto 11Mbps and 802.11g has a rate ofupto 54Mbps. 802.11g is a relatively new

and has yet to be adopted widely. 802.11ais more expensive and as a result it notavailable for public access.

Wi -max


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Wi max

Wi MAX is Worldwide Interoperability for Microwave Access.The IEEE standard for WiMAX is 802.16 and falls under the

category of wireless Metropolitan Area Network (WMAN).WiMAX operates on two frequency bands, 2 - 11GHz and 10 -66GHz and has a range of about 50km with speeds of up to

80Mbps.

This enables smaller wireless LANs to be interconnected by WiMAXcreating a large wireless MAN. Networking between cities can beachieved without the need for expensive cabling.

It is also able to provide high speed wireless broadband access tousers. As it can operate in two frequency bands WiMAX canwork by line-of-sight and non-line-of-sight.

WiMAX, More Than Internet?


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WiMAX has the potential toreplace a number of existingtelecommunicationsinfrastructures. In a fixedwireless configuration it canreplace the telephonecompany's copper wirenetworks, the cable TV'scoaxial cable infrastructurewhile offering Internet ServiceProvider (ISP) services. In itsmobile variant, WiMAX hasthe potential to replace

cellular networks.

Bluetooth Technology


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Bluetooth is an industrialspecification for wirelesspersonal area networks(PANs), also known as IEEE802.15.1. Bluetooth providesa way to connect andexchange informationbetween devices such aspersonal digital assistants(PDAs), mobile phones,laptops, PCs, printers, digitalcameras and video gameconsoles via a secure,

globally unlicensed short-range radio frequency.

Bluetooth Contd.
http://en.wikipedia.org/wiki/Image:Bluetooth-logo.svg


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Bluetooth is a radio standard and communications protocolprimarily designed for low power consumption, with a short range(power class dependent: 1 meter, 10 meters, 100 meters) basedaround low-cost transceiver microchips in each device.

Bluetooth lets these devices communicate with each other whenthey are in range. The devices use a radio communicationssystem, so they do not have to be in line of sight of each other,and can even be in other rooms, so long as the receivedtransmission is powerful enough.

How it all started


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The Bluetooth specification was first developed in 1994 by JaapHaartsen, who was working for Ericsson Radio Systems locatedin Emmen in The Netherlands. The specifications wereformalized by the Bluetooth Special Interest Group (SIG). TheSIG was formally announced on May 20, 1998.

Today it has over 1800 companies worldwide. It was established

by Ericsson, Sony Ericsson, IBM, Intel, Toshiba and Nokia, andlater joined by many other companies as Associate or Adoptermembers. Bluetooth is also known as IEEE 802.15.1.

http://en.wikipedia.org/wiki/Bluetooth

Introduction


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WiMAX stands forWorldwide Interoperability

forMicrowave Access IEEE 802.16 standards-based wireless

Metropolitan Area Network technology

Extends upto 50 km (31 miles) & connectsIEEE 802.11( Wi-Fi Hotspots) to the internetand provides a wireless extension to Cableand DSL (Digital Subscriber Line) broadband

connections over long distances.

IEEE 802.16, specifies WiMAX in the 10 to66 GH


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66 GHz range.

WiMAX technology also provides data ratesupto 70 mbps.

Wi Fi


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Wi-Fi is an acronym for Wireless Fidelity

IEEE 802.11 standard forwireless local areanetworks (WLAN)

Wi-Fi was intended to be used for mobile

devices and LANs, but is now often used forInternet access. Other wi fi standards are 802.11a, 802.11b

and 802.11g

Wi Fi: How it works


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Setup requires Wi Fi hotspots composed of many

access points(AP). AP broadcasts its SSID(service set identifier) via

packets called beacons every 100 ms at 1 mbps.

Based on settings of SSID, the client decideswhether to connect to an AP.

Based on the signal strength, the firmware on theclient wi fi card decides to which AP it will connect.

Wifi standard allows the connection criteria


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and roaming totally open to the client.

Feature called Zero Configuration available inWindows XP shows any N/W available to theuser & lets the user connect to it on the fly i.e.

it controls the roaming criteria. Wi Fi has the same properties as an Ethernet

N/W.

Software Access Point sharingone Internet connection


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o e e e co ec o

Photo Courtesy Data communication and Networking by Behrouz

A.Forouzan.

Wi Fi vs. Cellular Obstacles to Wi Fi are missing roaming


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Obstacles to Wi Fi are missing roaming,

authentication features(SIM cards, RADIUS)& the limited range of Wi-Fi.

Wi-Fi is ideal forVoIP applications in acorporate LAN.

Wi-Fi only phones have limited range upto300 ft & setting up a covering N/W would bevery expensive.

Companies: Zyxell, UT Starcomm, Samsung,Hitachi, etc. are offering VoIP Wi-Fi Phonesfor reasonable prices.


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Bluetooth devices are embedded with a small,inexpensive radio transmitter/receiver module


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inexpensive radio transmitter/receiver modulewhereas Wifi products have an inbuilt wi fi

chip/adapter/wi fi card which access theAP/hotspot within its proximity (300 ft radius) for afee.

Commercial Wi Fi Commercial Wi Fi services are available in


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Commercial Wi Fi services are available inplaces such as Internet cafes, coffee housesand airports around the world.

WiSE Technologies provides commercialhotspots for airports, universities &

independent cafes in the U.S. In sept.2003,Ozoneparis in France, started

deploying ozoneparis N/W across the city

with the aim to construct a wirelessmetropolitan network with full wi fi coverageof Paris.

Sify, an Indian Internet service provider, hasset up 120 wireless access points in


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set up 120 wireless access points inBangalore, India in hotels, malls and govt.offices.

FON, a Spanish start-up created inNov.2005, aims to become the largest N/W of

hotspots in the world by the end of 2006 with30,000 access points financially supported bycompanies like Google & Skype.

Advantages of Wi Fi Wi Fi uses unlicensed radio spectrum &


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Wi Fi uses unlicensed radio spectrum &doesnt require regulatory approval for

individual deployers. Reduces the cost of N/W deployment and

Expansion.

Wi Fi products support roaming. Many access points & N/W interfaces support

various degrees of encryption to protect

traffic from interception. Wi-Fi is a global set of standards.

Disadvantages of Wi Fi Wi Fi uses the unlicensed 2 4 GHz spectrum


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Wi Fi uses the unlicensed 2.4 GHz spectrum,which is also used by other technologies likeBluetooth, microwave ovens, cordlessphones. Thus causes degradation inperformance.

Power consumption is fairly high compared tosome other standards.

Wi Fi N/Ws have limited range. A typical wi fi

home router using 802.11b/802.11g mighthave a range of45 m(150 ft) indoors & 90m(300ft) outdoors.

Technical Advantages of WiMAXover Wi Fi


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WiMAX uses the LLClayer(standardised by

IEEE 802.2) used by other LANs & WANs, itcan be both bridged & routed to them.

IEEE 802.16 defines a MAC layer thatsupports multiple physical layer(PHY)specifications.

In wi fi the MAC uses contention accesscausing interruption which reduces their

throughput whereas WiMAX has ascheduling MAC which works in time slots bythe base station.


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WiMAX actually can provide two forms of wireless service:1.non-line-of-sight service


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2. line-of-sight service

Through the stronger line-of-sight antennas, the WiMAXtransmitting station would send data to WiMAX-enabledcomputers or routers set up within the transmitter's 30-mileradius (2,800 square miles or 9,300 square km of coverage).This is what allows WiMAX to achieve its maximum range.


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Uses of WiMAX Provides up to 50 km (31 miles) of linear


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Provides up to 50 km (31 miles) of linearservice area range and allows connectivitybetween users without a direct line of sight.

Claims to provide shared data rates up to 70mbps which according to WiMAX proponents,

is enough bandwidth to simultaneouslysupport more than 60 businesses with T1-type connectivity and well over a thousand

homes at 1Mbit/s DSL-level connectivity.


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Conclusion WiMAX outdistances WiFi by miles WiFi's


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WiMAX outdistances WiFi by miles. WiFi srange is about 100 feet (30 m). WiMAX willblanket a radius of30 miles (50 km) withwireless access. The increased range is dueto the frequencies used and the power of the

transmitter. This outstanding efficiency along with speed

of transmission (upto 70 mbps) makes

WiMAX a sort out technology in the field ofwireless networking.

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