IEEE 802.11 and Bluetooth

Wireless LANs: IEEE 802.11 and Bluetooth

1. Wireless
➢WirelessLANs:IEEE802.11andBluetooth.
➢ConnectingDevices:
➢PassiveHub
➢Repeater
➢ActiveHub
➢Bridge
➢TwolayersSwitch
➢Router
➢ThreelayersSwitch
➢Gateway
© Hitesh Mohapatra

2. Wireless LANs: IEEE 802.11 and Bluetooth.
IEEEhasdefinedthespecificationsfora
wirelessLAN,calledIEEE802.11,which
coversthephysicalanddatalinklayers.

3. IEEE 802.11 -WLAN/Wi-Fi
WirelessLAN(WLAN,alsoknownasWi-Fi)isasetoflowtier,terrestrial,
networktechnologiesfordatacommunication.
TheWLANstandardsoperatesonthe2.4GHzand5GHzIndustrial,Science
andMedical(ISM)frequencybands.
ItisspecifiedbytheIEEE802.11standard[2]anditcomesinmanydifferent
variationslikeIEEE802.11a/b/g/n.
TheapplicationofWLANhasbeenmostvisibleintheconsumermarket
wheremostportablecomputerssupportatleastoneofthevariations.
Standard Ad hoc Infrastructure
802.11a/b/g/n Yes Yes
802.15.1 Yes No
802.15.4 Yes No
802.15.6 Unknown Unknown

4. History of Wi-Fi
WirelessFidelity,moreknownbyitsshortformWi-Fi,isadigital
communicationsprotocol,throughwhichgadgetscancommunicatewith
eachotherinaunicastorabroadcastingmannerwithoutusinganywires.
TheideaoffastspeedwirelessLANoriginatedwhentheUnitedStates
FederalCommunicationsCouncil,acommunicationagencyoftheUS
government,decidedintheyear1985toutilizeafewbandsofwireless
spectrumwithoutsubjectingthemtoalicensefee.Followingthis,theIEEE
committeefor802standardswhichmanagesnetworkingprotocolsamong
electronicdevices,formedanextension802.11whichwouldworkonthe
wirelessmode.Thiscommitteewasfoundedintheyear1990andwas
headedbyVictorHayes,FatherofWi-Fi.Takingonthelicensefreebands
(nowbeingtermedasISMbands)andcollaboratingwithnetworkinggiants
suchasNokia,Motorolaetc,thecommitteeintroducedWLANlegacyof
Wi-Fiintheyear1997.

5. Block Diagram Explaining Data
Communication in Wi-Fi Network

6. Overview of How MAC Layer uses Distributed
and Point Coordinated Function

7. MAC layers in IEEE 802.11 standard

8. Medium access
Inordertoconducttwo-waywirelesscommunicationaprotocoldetailinghowthewireless
terminalsaretoaccessthismediummustbeestablished.
The802.11standardspecifiesamethodcalledCarrierSenseMultipleAccesswithCollision
Avoidance(CSMA/CA).
CarrierSenseMultipleAccesswithCollisionDetection(CSMA/CD)usedbyEthernetisthe
wiredcounterparttoCSMA/CA.TheCSMA/CAtechniqueallowswirelesstransmissionsto
becompletedwithoutinterferencefromotherterminals.WhenCSMA/CAisusedapartof
thepotentialdatarateislosttotheoverheadofthisprotocol.
Ifthecommunicationwasone-wayonlythecommunicationchannelscouldbebetter
utilizedbecausethesourceterminalwouldnothavetotakeintoconsideration
transmissionsbeingsentfromotherterminals.
Inordertodealwiththehiddenterminalproblem802.11canalsousearequesttosend,
cleartosend(RTS/CTS)schemeinordertoreservethechannelforcommunication.

9. CSMA/CA

10. CSMA/CA and NAV

11. Example of Repetition Interval

12. Basic Service Sets (BSSs)
A BSS without an AP is called an adhocnetwork; a BSS with an AP is called
aninfrastructurenetwork.

13. Architecture
Whentwoormoregadgets(stationsorSTA)are
connectedtoeachotherthroughWi-Fi,theyforma
basicserviceset(BSS)andtheareathatdevices
connectedinaBSSarecoveringistermedasBasic
ServiceArea(BSA).ABSAcanextendup-totensof
metersinsidewithBSSunitscancommunicateinafully
fledgedmanner.Interestingly,twoormoreBSScanbe
collocatedwiththesameBSAandwillstillnotinterfere
intoeachother’sworking.Thisispossiblethroughad-hoc
networking.Underad-hocnetworking,thestationsare
specificallyconnected totheonetheywantto
communicate with.Ad-hocmodeofnetworkingis
temporaryandstationsconnectedunderitcanbe
disbandedwhenevertheuserwants.
WhenoneBSShastocommunicatewiththeother,aservicecalledAccessPointisaddedtotheBSS.
ThroughAccessPoint,awirelessdistributionsystem(WDS)getscreatedwhichconnectstwoormore
BSS.InterconnectionofmultipleBSS’sistermedasExtendedServiceSet(ESS).ItisthroughanESSthat
usersofthewirelesssystemcanconnecttoawiredsystemlikeinternetoranEthernetnetwork.Aiding
ESSinthisconnectionisportalwhichisplacedonthebordersofthedistributionsystem.

14. Extended Service Sets (ESSs)

15. Frame Format

16. Subfields in FC Field

17. Control Frames

18. Addressing Mechanisms

19. Hidden Station Problem

20. Exposed Station Problem

21. Use of handshaking in exposed station
problem

22. IEEE 802.15.1 -Bluetooth
TheIEEE802.15.1standard[3]isthebasisfortheBluetoothwireless
communicationtechnology.
Bluetoothisalowtier,adhoc,terrestrial,wirelessstandardforshortrange
communication.
Itisdesignedforsmallandlowcostdeviceswithlowpowerconsumption.
Thetechnologyoperateswiththreedifferentclassesofdevices:Class1,
class2andclass3wheretherangeisabout100meters,10metersand1
meterrespectively.
WirelessLANoperatesinthesame2.4GHzfrequencybandasBluetooth,
butthetwotechnologiesusedifferentsignallingmethodswhichshould
preventinterference.

23. Definition of Bluetooth
Bluetooth is a wireless LAN technology designed to connect devices of
different functions such as telephones, notebooks, computers, cameras,
printers, coffee makers, and so on. A Bluetooth LAN is an ad hoc network,
which means that the network is formed spontaneously.
•Architecture
•Bluetooth Layer
•Baseband Layer
•L2CAP

24. Piconet

25. Scatter net

26. Bluetooth Layers

27. Frame Format Types

28. Reference
Author:Behrouz A. Forouzan
Publication:· Book
Data Communications and Networking (McGraw -Hill ForouzanNetworking)
McGraw-Hill Higher Education ©2007
ISBN:0072967757

29. AsK
AnyQuestion
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