necessarilysinglehop

MobileandWirelessNetworkingLecture3Dr.
XinbingWangOutlineWirelesscommunicationsystemsFlexibilitytosupportroamingLimitations:Geographicalcoverage,transmissionrate,andtransmissionerrorsArchitecturesofwirelessnetworksCellularnetworkarchitectureWirelessLAN/PANSatellitesystemsAdhocnetworksSensornetworkBackgroundFDMA/TDMA/CDMAConnectionsetupTraditionalApplicationsWeathersatelliteRadioandTVbroadcastingMilitarysatellitesTelecommunicationApplicationsGlobaltelephoneconnectionsBackboneforglobalnetworkGPSSatelliteSystemsWLAN--InfrastructureNetworkStation(STA)terminalwithaccessmechanismstothewirelessmediumandradiocontacttotheaccesspointBasicServiceSet(BSS)groupofstationsusingthesameradiofrequencyAccessPointstationintegratedintothewirelessLANandthedistributionsystemPortalbridgetoother(wired)networksDistributionSysteminterconnectionnetworktoformonelogicalnetwork(EES:ExtendedServiceSet)basedonseveralBSSDistributionSystemPortal802.
xLANAccessPoint802.
11LANBSS2802.
11LANBSS1AccessPointSTA1STA2STA3ESSWLAN--802.
11Advantagesveryflexiblewithinthereceptionarea(almost)nowiringdifficulties(e.
g.
historicbuildings,firewalls)morerobustagainstdisasterslike,e.
g.
,earthquakes,fire-oruserspullingaplug.
.
.
Ad-hocnetworkswithoutpreviousplanningpossibleDisadvantagestypicallylowerbandwidthcomparedtowirednetworks(1-54Mbit/s)manyproprietarysolutions,especiallyforhigherbit-rates,standardstaketheirtime(e.
g.
IEEE802.
11)productshavetofollowmanynationalrestrictionsifworkingwireless,ittakesaverylongtimetoestablishglobalsolutions.
AdhocNetwork--802.
11DirectcommunicationwithinalimitedrangeStation(STA):terminalwithaccessmechanismstothewirelessmediumBasicServiceSet(BSS):groupofstationsusingthesameradiofrequency.
SometimescalledIndependentBSS(IBSS)mode802.
11LANBSS2802.
11LANBSS1STA1STA4STA5STA2STA3WhatisMobileAdhocNetwork(MANET)Mobileuserswith(compatible)wirelesscommunicationdevicestosetupapossibleshort-livednetworks--foraspecificneed/purpose!
Without(necessarily)usingapre-existinginfrastructureRoutesbetweennodesmaypotentiallycontainmultiplehopsModelofOperationAssumption:thenodesareusingIP,andtheyhaveIPaddressesthatareassignedbysomemeans.
MANET--RouteChangesMobilitycauseroutechangesChallengesinMANETLimitedwirelesstransmissionrangeBroadcastnatureofthewirelessmediumHiddenterminalproblemPacketlossesduetotransmissionerrorsMobility-inducedroutechangesMobility-inducedpacketlossesBatteryconstraintsPotentiallyfrequentnetworkpartitionsEaseofsnoopingonwirelesstransmissions(securityhazard)ComparisonofAdHocandInfrastructureNetworkScalabilityExpansionislimitedtothecoverageoftheradiotransmitterandreceiverforsingle-hopnetworks;Nosimplewaytoscaleupthenetworkcoverageorcapacity;Thepotentialcoverageofthenetworkisincreased,butthetraffichandlingcapacityremainsthesame;Useproxyserverswithawirelessconnectiontothebackbonewirednetworks.
Infrastructurenetwork:byincreasingthenumberofbasestationsoraccesspoints,thecoverageandthecapacitywillbeincreased.
Itisusedforwideareacoverageandforvariabletrafficloads.
ComparisonofAdHocandInfrastructureNetwork(2)FlexibilityAdHocnetwork:flexibleandcanbeseupinstantly,itisusedfortemporaryapplications.
Infrastructurenetwork:time-consumingandexpensiveforgooddesign.
Controllability:timesynchronization,powercontrol,authenticationandsoon.
Adhoc:requirescomplicatedstructuresdemandingchangesinallterminals.
Infrastructure:allfeaturesareimplementedinBSsorAPs.
RoutingcomplexityAdhoc:requireseachterminaltomonitortheexistenceofothersandbeabletoconnectandroutemessages,needscomplicatedalgorithms.
Infrastructure:theproblemdoesnotexist.
ComparisonofAdHocandInfrastructureNetwork(3)CoverageAdhoc:themaximumdistancebetweentwoterminalsistherangeofcoverage.
Infrastructure:themaximumdistancebetweentwoterminalsistwicetherangeofasinglewirelessterminalbecausetheycommunicatethroughBSsorAPs.
ReliabilityAdhoc(s.
s.
WLANformilitary):singlefailurepointdoesnotexist.
Infrastructure:singlefailurepointnetworks.
StoreandforwarddelayandmediausageefficiencyAdhoc:informationtransmittedonlyonce,thereisnostoreandforwardprocedureforsingle-hopnetworks.
However,multi-hopnetworksdependonthetopologyandnumberofhops.
Infrastructure:informationistransmittedtwice,firsttoBS/AP,thenfromBS/APtoterminals.
BasestationAntennaSensorTargetWirelessSensorNetworksOutlineWirelesscommunicationsystemsFlexibilitytosupportroamingLimitations:Geographicalcoverage,transmissionrate,andtransmissionerrorsArchitecturesofwirelessnetworksCellularnetworkarchitectureWirelessLAN/PANSatellitesystemsAdhocnetworksSensornetworkBackgroundFDMA/TDMA/CDMAConnectionsetupUser1User2Usern…TimeFrequencyFDMA(FrequencyDivisionMultipleAccess)123…nFrequencyTotalbandwidth4FDMABandwidthStructureFrequency1User1Frequency2User2FrequencynUsernBaseStation……MobileStationsFDMAChannelAllocationUser1User2Usern…TimeFrequencyTDMA(TimeDivisionMultipleAccess)123…nTimeFrame4TDMAFrameStructureTime1Time2Timen……BaseStationUser1User2Usern…MobileStationsTDMAFrameAllocationUser1TimeFrequencyUser2UsernCode.
.
.
CDMA(CodeDivisionMultipleAccess)InformationbitsCodeattransmittingendTransmittedsignalReceivedsignalCodeatreceivingendDecodedsignalatthereceiverTransmittedandReceivedSignalsinCDMASystemsFrequencyf5f4f3f2f1FrameSlotTimeFrequencyHoppinginCDMABSMS1.
Needtoestablishpath2.
Frequency/timeslot/codeassigned(FDMA/TDMA/CDMA)3.
ControlInformationAcknowledgement4.
StartcommunicationConnectionSetup(ServiceDelivery)BSMS2.
Readytoestablishapath3.
Usefrequency/timeslot/code(FDMA/TDMA/CDMA)4.
Readyforcommunication5.
Startcommunication1.
CallforMS#pendingConnectionSetup(ServiceOrigination)Informationtobetransmitted(Voice/Data)CodingModulatorTransmitterInformationreceived(Voice/Data)DecodingDemodulatorReceiverAntennaAntennaCarrierCarrierSimplifiedFrameworkofWirelessCommunicationsWiredandWirelessMediaWiredmediaReliable,guidedlink:electricalsignalassociatedwiththetransmissionofinformationfromonefixedterminaltoanother.
Likefiltersthatlimitthemaximumtransmitteddatarateofthechannelbecauseofbandlimitingfrequencyresponsecharacteristics.
Radiatesoutsideofthewiretosomeextentwhichcancauseinterferencetoclose-byradiosorotherwiredtransmission.
WirelessmediaRelativelyunreliable,lowbandwidth,andofbroadcastnature(unguidedmedium).
Allwirelesstransmissionssharethesamemedium-air,whereasdifferentsignalsthroughwiredmediaviadifferentwires.
LicensedversusUnlicensedBandsLicensedbandsCellularsystemsoperatearound1GHzPCSandWLANsaround2GHzWLANaround5GHzLMDS(localmultipointdistributionservice)at28-60GHzIR(InfraRed)foropticalcommunicationsUnlicensedbandsISM(Industrial,Scientific,andMedical)bandU-NII(UnlicensedNationalInformationInfrastructure)bands,werereleasedin1997,PCSunlicensedbandswerereleasedin1994.
ElectromagneticSpectrumRelationshipbetweenf,,andc(invacuum)isf=cSpeed,Frequency,andWavelength10-7m1015HzUltravioletlight15mm20GHzKabandsatellite37.
5cm800MHzCellular3m100MHzFMradio5,000km60HzACcurrentWavelengthFrequencySystemLightspeed(c)=Wavelength()*Frequency(f)3x108m/s=300,000km/sAfterClassReadingmaterialsChapter1Chapter2Chapter3.
1-3.
4Chapter4ExercisesListatleastfourarchitecturesofwirelessnetworking.
WhatarethemaintechnologiesorchallengesofthesenetworkarchitecturesWhatarethemaindifferencesbetweenthesenetworksCanyouidentify2applicationscenariosforeachofthemListatleastthreefunctionsforeachlayerinawirelessnetwork