Wi fi wireless network

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Wi-Fi Wireless NetworkWi-Fi Wireless Network

Presented ByPresented By SYED JAUWADSYED JAUWAD

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INTRODUCTIONINTRODUCTION WIRELESS NETWORKING COMPONENTS WIRELESS NETWORKING COMPONENTS WI-FI OPERATING MODESWI-FI OPERATING MODES HOW IT WORKS?HOW IT WORKS? DIRECT SEQUENCE SPREAD SPECTRUMDIRECT SEQUENCE SPREAD SPECTRUM WI-FI SECURITYWI-FI SECURITY ADVANTAGESADVANTAGES OBSTACLES TO WI-FIOBSTACLES TO WI-FI CONCLUSIONCONCLUSION BIBLIOGRAPHYBIBLIOGRAPHY

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INTRODUCTIONINTRODUCTIONWhat is wi-fi ?What is wi-fi ? Abbreviation for Wireless Fidelity General name for wireless technologies Industry standard Services that provide short range, high speed Internet connections Another name for Wi-Fi is 802.11b Other Wi-Fi technologies – 802.11g – 802.11a

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INTRODUCTION(CONTD)INTRODUCTION(CONTD) FeaturesFeatures

At the physical layer, IEEE 802.11b operates at the At the physical layer, IEEE 802.11b operates at the radio frequency of 2.45 gigahertz (GHz) with a radio frequency of 2.45 gigahertz (GHz) with a maximum bit rate of 11 Mbps. maximum bit rate of 11 Mbps.

It uses the direct sequence spread spectrum (DSSS) It uses the direct sequence spread spectrum (DSSS) transmission technique. transmission technique.

At the MAC sublayer of the Data Link layer, 802.11b At the MAC sublayer of the Data Link layer, 802.11b uses the Carrier Sense Multiple Access with uses the Carrier Sense Multiple Access with Collision AvoidanceCollision Avoidance

(CSMA/CA)(CSMA/CA)


Wireless networking componentsWireless networking components StationStation Wireless Access PointWireless Access Point PortsPorts


Wi-Fi operating modesWi-Fi operating modes Ad Hoc Mode (peer-to-peer mode)Ad Hoc Mode (peer-to-peer mode) wireless clients communicate directly with wireless clients communicate directly with

each othereach other Infrastructure modeInfrastructure mode At least one wireless AP and one wireless At least one wireless AP and one wireless

clients clients


How it works ? How it works ? Roaming Node periodically sends probe frameRoaming Node periodically sends probe frame All APs within range reply with a probe response All APs within range reply with a probe response

frameframe Roaming node chooses best AP and replies to it with Roaming node chooses best AP and replies to it with

association requestassociation request AP acknowledges request with association response.AP acknowledges request with association response. AP notifies previous AP (if any) of the established AP notifies previous AP (if any) of the established

association(handover).association(handover).


Direct Sequence Spread Spectrum Direct Sequence Spread Spectrum What is spread spectrum ? What is spread spectrum ? coding technique for digital transmission. coding technique for digital transmission. transforms an information signal so that it looks transforms an information signal so that it looks

more like noise. more like noise. At receiving end filter converts noise signal into At receiving end filter converts noise signal into

original signaloriginal signal Implemented for two processes Implemented for two processes Frequency Hopping Frequency Hopping Direct Sequence.Direct Sequence.


Direct Sequence Spread Spectrum (contd.) Direct Sequence Spread Spectrum (contd.) Direct sequenceDirect sequence The carrier The carrier phasephase of the transmitter abruptly of the transmitter abruptly

changes in accordance with a pseudo-random changes in accordance with a pseudo-random code sequence.code sequence.


Wi-Fi SecurityWi-Fi Security Authentication through the open system and Authentication through the open system and

shared keyshared key Data confidentiality through Wired Data confidentiality through Wired

Equivalent Privacy (WEP)Equivalent Privacy (WEP)


AdvantagesAdvantages No cablesNo cables Typical area of coverage 100 to 500 feetTypical area of coverage 100 to 500 feet Very high speed internet connectionsVery high speed internet connections – – 802.11b downloads at 11Mbps, or 200 x 802.11b downloads at 11Mbps, or 200 x

fasterfaster than dial-up modemsthan dial-up modems – – 802.11g downloads at 54 Mbps802.11g downloads at 54 Mbps


Obstacles to Wi-FiObstacles to Wi-Fi SecuritySecurity WEP was BrokenWEP was Broken Solutions are available nowSolutions are available now Deployment CostDeployment Cost Scaling CoverageScaling Coverage CapacityCapacity Large Enterprise & service provider scenarios Large Enterprise & service provider scenarios

require higher capacity systemrequire higher capacity system


ConclusionConclusion

wireless networks can make work easier and wireless networks can make work easier and life more fun , today wi-fi is the good solution life more fun , today wi-fi is the good solution for wireless network for wireless network

802.11b has became the standard wireless 802.11b has became the standard wireless ethernet networking technology for both ethernet networking technology for both business and homebusiness and home


BibliographyBibliography

[1]. [1]. Sultan Weatherspoon, “Overview of IEEE Sultan Weatherspoon, “Overview of IEEE 802.11b Security”, Intel technology journal 802.11b Security”, Intel technology journal Q2,2000 Q2,2000

[2]. Martin Heusse, Franck Rousseau,Gilles [2]. Martin Heusse, Franck Rousseau,Gilles Berger-Sabbatel, Andrzej Duda,“Performance Berger-Sabbatel, Andrzej Duda,“Performance Anomaly of 802.11b”, proceeding of IEEE Anomaly of 802.11b”, proceeding of IEEE INFOCOM 2003, pp 0-7803-7753-2/03.INFOCOM 2003, pp 0-7803-7753-2/03.

Wi fi wireless network

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