Wi fi wireless network

1. Seminar PresentationSeminar Presentation
ONON
Wi-Fi Wireless NetworkWi-Fi Wireless Network
Presented ByPresented By
SYED JAUWADSYED JAUWAD

2. DIPLOMA COMPUTER SEMINARDIPLOMA COMPUTER SEMINAR
OUTLINEOUTLINE
 INTRODUCTIONINTRODUCTION
 WIRELESS NETWORKING COMPONENTSWIRELESS 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

3. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 INTRODUCTIONINTRODUCTION
What 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

4. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
INTRODUCTION(CONTD)INTRODUCTION(CONTD) FeaturesFeatures
 At the physical layer, IEEE 802.11b operates at theAt the physical layer, IEEE 802.11b operates at the
radio frequency of 2.45 gigahertz (GHz) with aradio 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, 802.11bAt the MAC sublayer of the Data Link layer, 802.11b
uses the Carrier Sense Multiple Access withuses the Carrier Sense Multiple Access with
Collision AvoidanceCollision Avoidance
 (CSMA/CA)(CSMA/CA)

5. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 Wireless networking componentsWireless networking components
 StationStation
 Wireless Access PointWireless Access Point
 PortsPorts

6. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 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 withwireless clients communicate directly with
each othereach other
 Infrastructure modeInfrastructure mode
 At least one wireless AP and one wirelessAt least one wireless AP and one wireless
clientsclients

7. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 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 responseAll APs within range reply with a probe response
frameframe
 Roaming node chooses best AP and replies to it withRoaming 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 establishedAP notifies previous AP (if any) of the established
association(handover).association(handover).

8. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 Direct Sequence Spread SpectrumDirect 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 lookstransforms an information signal so that it looks
more like noise.more like noise.
 At receiving end filter converts noise signal intoAt receiving end filter converts noise signal into
original signaloriginal signal
 Implemented for two processesImplemented for two processes
 Frequency HoppingFrequency Hopping
 Direct Sequence.Direct Sequence.

9. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 Direct Sequence Spread Spectrum (contd.)Direct Sequence Spread Spectrum (contd.)
 Direct sequenceDirect sequence
 The carrierThe carrier phasephase of the transmitter abruptlyof the transmitter abruptly
changes in accordance with a pseudo-randomchanges in accordance with a pseudo-random
code sequence.code sequence.

10. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 Wi-Fi SecurityWi-Fi Security
 Authentication through the open system andAuthentication through the open system and
shared keyshared key
 Data confidentiality through WiredData confidentiality through Wired
Equivalent Privacy (WEP)Equivalent Privacy (WEP)

11. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 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 x802.11b 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

12. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 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 scenariosLarge Enterprise & service provider scenarios
require higher capacity systemrequire higher capacity system

13. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 ConclusionConclusion
 wireless networks can make work easier andwireless networks can make work easier and
life more fun , today wi-fi is the good solutionlife more fun , today wi-fi is the good solution
for wireless networkfor wireless network
 802.11b has became the standard wireless802.11b has became the standard wireless
ethernet networking technology for bothethernet networking technology for both
business and homebusiness and home

14. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR
 BibliographyBibliography
 [1].[1]. Sultan Weatherspoon, “Overview of IEEESultan Weatherspoon, “Overview of IEEE
802.11b Security”, Intel technology journal802.11b Security”, Intel technology journal
Q2,2000Q2,2000
 [2]. Martin Heusse, Franck Rousseau,Gilles[2]. Martin Heusse, Franck Rousseau,Gilles
Berger-Sabbatel, Andrzej Duda,“PerformanceBerger-Sabbatel, Andrzej Duda,“Performance
Anomaly of 802.11b”, proceeding of IEEEAnomaly of 802.11b”, proceeding of IEEE
INFOCOM 2003, pp 0-7803-7753-2/03.INFOCOM 2003, pp 0-7803-7753-2/03.

15. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR

16. DIPLOMA COMPUTERDIPLOMA COMPUTER
SEMINARSEMINAR