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Chapter 5 Ad Hoc Wireless (1)

It is abut wireless network

Teweldebrhan
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Chapter 5 Ad Hoc Wireless (1)

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  1. Chapter5AdHocWireless Network JangPingSheu

  2. Introduction • AdHocNetworkisa multi-hoprelaying network • ALOHAnetdevelopedin1970 • Ethernetdevelopedin1980 • In1994,BluetoothproposedbyEricssonto developashort-range,low-power,low- complexity,andinexpensiveradiointeface • WLAN802.11spec.isproposedin1997 2009/11/2

  3. CellularandAdHocWirelessNetworks • CellularWirelessNetworks:infrastructure dependentnetwork • AdHocNetworks:multi-hopradiorelaying andwithoutsupportofinfrastructure • WirelessMeshNetworks • WirelessSensorNetworks • Themajordifferencesbetweencellular networksandadhocnetworksassummarized inTable5.1 2009/11/2

  4. WirelessMesh Networks CellularWirelessNetworks HybridWireless Networks WirelessSensor Networks InfrastructureDependent (Single-HopWirelessNetworks) AdHocWireless Networks (Multi-HopWireless Networks) Figure5.1.Cellularandadhocwirelessnetworks. 2009/11/2

  5. B A C D E SwitchingCenter + Gateway BaseStation MobileNode Figure5.2.Acellular networks. PathfromCtoE 2009/11/2 5

  6. B A C F E D MobileNode WirelessLink Figure5.3.Anadhocwirelessnetworks PathfromCtoE 2009/11/2 6

  7. Table5.1Differencesbetweencellularnetworksandadhoc wirelessnetworks 2009/11/2 7

  8. Table5.1Differencesbetweencellularnetworksandadhoc wirelessnetworks(cont.) 2009/11/2 8

  9. ApplicationsofAdHocWirelessNetworks • MilitaryApplications • Establishingcommunicationamongagroupofsoldiersfor tacticaloperations • Coordinationofmilitary objectmovingathighspeeds suchasfleetsofairplanesorships • Requirements:reliability,efficiency,securecommunication, andmulticastingrouting, • CollaborativeandDistributedComputing • Conference,distributedfilessharing • EmergencyOperations • Search,rescue,crowdcontrol,andcommandooperations • Supportreal-timeandfault-tolerantcommunicationpaths 2009/11/2

  10. WirelessMeshNetworks • Analternatecommunicationinfrastructurefor mobileorfixednodes/users • Providesmanyalternatepathsforadata transfersessionbetweenasourceand destination • AdvantagesofWirelessMeshNetworks • –Highdatarate,quickandlowcostofdeployment, enhancedservices,highscalability,easy extendability,highavailability,andlowcostperbit 2009/11/2

  11. WiredNetwork Gatewaynode Transmissionrange Ahousewithrooftoptransceiver Wiredlink totheInternet Wirelesslink Figure5.4.Wirelessmeshnetworksoperatinginaresidentialzone 2009/11/2

  12. Internet Radiorelaynode Lamp Multi-hopradiorelaylink Wiredlink totheInternet Coveragearea Figure5.5Wirelessmeshnetworkcoveringahighway 2009/11/2

  13. WirelessSensorNetworks • Acollectionofalargenumberofsensornodes thataredeployedinaparticularregion • Applications: • military,healthcare,homesecurity,and environmentalmonitoring • Differenceswiththeadhocwirelessnetworks: • Mobilityofnodes,sizeofnetwork,densityof deployment,powerconstraints,data/information fusion,trafficdistribution 2009/11/2

  14. HybridWirelessNetworks • HWNsuchasMulti-hopcellularnetworksand integratedcellularadhocrelaynetworks • Thebasestationmaintainstheinformationaboutthe topologyofthenetworkforefficientrouting • Thecapacityofacellularnetworkcanbeincreasedifthe networkincorporatesthepropertiesofmulti-hoprelaying alongwiththesupportofexistingfixedinfrastructure • Advantages: • Highercapacitythancellularnetworksduetobetter channelreuse • Increasedflexibilityandreliabilityinrouting • Bettercoverageandconnectivityinholes 2009/11/2

  15. B A C D E SwitchingCenter + Gateway BaseStation MobileNode Figure5.6.MCNarchitecture. MCNcommunication 2009/11/2

  16. IssuesinAdHocWirelessNetworks • Mediumaccessscheme • Routing,Multicasting,TPCprotocol • Pricingscheme,QoS,Self-organization • Security,Energymanagement • Addressingandservicediscovery • Deploymentconsiderations 2009/11/2

  17. MediumAccessScheme • Distributedoperation • fullydistributedinvolvingminimumcontroloverhead • Synchronization • MandatoryforTDMA-basedsystems • Hiddenterminals • CansignificantlyreducethethroughputofaMACprotocol • Exposedterminals • ToimprovetheefficiencyoftheMACprotocol,theexposed nodesshouldbeallowedtotransmitinacontrolledfashion withoutcausingcollisiontotheon-goingdatatransfer • Accessdelay 2009/11/2

  18. TheMajorIssuesofMACScheme • Throughputandaccessdelay • Tominimizetheoccurrenceofcollision,maximizechannel utilization,andminimizecontroloverhead • Fairness • Equalshareorweightedshareofthebandwidthtoall competingnodes • Real-timetrafficsupport • Resourcereservation • SuchasBW,bufferspace,andprocessingpower • Capabilityforpowercontrol • Adaptiveratecontrol • Useofdirectionalantennas 18 2009/11/2

  19. TheMajorChallengeofRoutingProtocol • Mobilityresultinfrequentpathbreak,packet collision,anddifficultyinresourcereservation • Bandwidthconstraint:BWissharedbyeverynode • Error-proneandsharechannel:highbiterrorrate • Location-dependentcontention:distributingthe networkloaduniformlyacrossthenetwork • Otherresourceconstraint:computingpower,battery power,andbufferstorage 2009/11/2

  20. TheMajorRequirementofRoutingProtocol • Minimumrouteacquisitiondelay • Quickroutereconfiguration:tohandlepathbreaks • Loop-freerouting • Distributedroutingapproach • Minimumcontroloverhead • Scalability • ProvisioningofQoS: • supportingdifferentiatedclassesofservices • Supportfortime-sensitivetraffic • Securityandprivacy 2009/11/2

  21. TheMajorIssuesinMulticastRouting Protocols • Robustness • recoverandreconfigurequicklyfromlinkbreaks • Efficiency • minimumnumberoftransmissionstodeliveradatapacket toallthegroupmembers • MinimalControloverhead • QoSsupport • Efficientgroupmanagement • Scalability • Security 2009/11/2

  22. TransportLayerProtocols • Objectives: settingupandmaintaining • End-to-endconnections,reliableend-to-end data delivery,flowcontrol,andcongestioncontrol • Majorperformancedegradation: • Frequentpathbreaks,presenceofoldrouting information,highchannelerrorrate,andfrequent networkpartitions 2009/11/2

  23. QualityofServiceProvisioning • QoSoftenrequiresnegotiationbetweenthehostand thenetwork,resourcereservationschemes,priority schedulingandcalladmissioncontrol • QoSinAdhocwirelessnetworkscanbeonaper flow,perlink,orpernode • QosParameters:differentapplicationshavedifferent requirements • Multimedia:bandwidthanddelayarethekeyparameters • Military:BW,delay,securityandreliability • Emergencysearch–and-rescue:availabilityisthekey parameters,multiplelinkdisjointpaths • WSN:batterylife,minimumenergyconsumption 2009/11/2

  24. QualityofServiceProvisioning • QoS-awarerouting: • TohavetheroutinguseQoSparametersforfindingapath • Theparametersarenetworkthroughput,packetdelivery ratio,reliability,delay,delayjitter,packetlostrate,biterror rate,andpathloss • QoSframework: • AframeworkforQoSisacompletesystemthatattempts toprovidethepromisedservice • TheQoSmodulessuchasroutingprotocol,signaling protocol,andresourcemanagementshouldreact promptlyaccordingtochangesinthenetworkstate 2009/11/2

  25. Self-Organization • Animportantpropertythatanadhocwireless networkshouldexhibitisorganizingandmaintaining thenetworkbyitself • Majoractivities:neighbordiscovery,topology organization,andtopologyreorganization • Adhocwirelessnetworksshouldbeabletoperform self-organizationquicklyandefficiently 2009/11/2

  26. Security • Theattackagainstadhocwirelessnetworksare classifiedintotwotypes:passiveandactiveattacks • Passiveattack:maliciousnodestoobservethe natureofactivitiesandtoobtaininformationinthe networkwithoutdisruptingtheoperation • Activeattack:disrupttheoperationofthenetwork • Internalattack:nodesbelongtothesamenetwork • Externalattack:nodesoutsidethenetwork 2009/11/2

  27. MajorSecurityThreats • Denialofservice:eitherconsumethenetworkBWor overloadingthesystem • Resourceconsumption • Energydepletion:bydirectingunnecessarytrafficthrough nodes • Bufferoverflow:fillingunwanteddata,routingtableattack (fillingnonexistentdestinations) • Hostimpersonation:Acompromisednodecanactas anothernodeandrespondcontrolpacketstocreate wrongrouteentriesandterminatethetraffic • Informationdisclosure:supportusefultrafficpattern • Interference:createwide-spectrumnoise 2009/11/2

  28. AddressingandServiceDiscovery • Anaddressthatisgloballyuniqueisrequiredfora nodetoparticipatecommunication • Auto-configurationofaddressisrequiredtoallocatenon- duplicateaddresstothenodes • Innetworksfrequentpartitioningandmergingofnetwork componentsrequireduplicateaddressdetection mechanisms • Nodesinthenetworkshouldbeabletolocate servicesthatothernodesprovide 2009/11/2

  29. EnergyManagement • Transmissionpowermanagement: • RFhardwaredesignensureminimumpowerconsumption • UsesvariablepowerMACprotocol • Loadbalanceinnetworklayer • Reducingthenumberofretransmissionsatthetransport layer • Applicationsoftwaredevelopedformobilecomputers 2009/11/2

  30. EnergyManagement(cont.) • Batteryenergymanagement:extendingthebattery lifebytakingchemicalproperties,dischargepatterns, andbytheselectionofabatteryfromasetof batteriesthatisavailableforredundancy • Processorpowermanagement:CPUcanbeputinto differentpowersavingmodesduringlowprocessing loadconditions • Devicespowermanagement:canbedonebyOSby selectivelypoweringdowninterfacedevicesthatare notusedorbyputtingdevicesintodifferentpower- savingmodes 2009/11/2

  31. Scalability • Thelatencyofpath-findinginvolvedwithan on-demandroutingprotocolinalargeadhoc wirelessnetworkmaybeunacceptablyhigh • Ahierarchicaltopology-basedsystemand addressingmaybemoresuitableforlargead hocwirelessnetworks 2009/11/2

  32. DeploymentConsiderations • Thedeploymentofacommercialadhocwireless networkhasthefollowingbenefits • Lowcostofdeployment • Incrementaldeployment • Shortdeploymenttime • Re-configurability 2009/11/2

  33. MajorIssuesforDeployment • Scenarioofdeployment • Militarydeployment • Data-centric(e.g.WSN) • User-centric(soldiersorvehiclescarryingwithwireless communicationdevices) • Emergencyoperationsdeployment • Commercialwide-areadeployment • Homenetworkdeployment • Requiredlongevityofnetwork:regenerativepower sourcecanbedeployedwhentheconnectivityis requiredforalongerdurationoftime • Areaofcoverage 2009/11/2

  34. MajorIssuesforDeployment • Serviceavailability:redundantnodescanbe deployedtoagainstnodesfailure • Operationalintegrationwithotherinfrastructure: canbeconsideredforimprovetheperformanceor gatheringadditionalinformation,orforproviding betterQoS • Choiceofprotocols:thechoicesofprotocolsat differentlayersoftheprotocolstackistobedone takingintoconsiderationthedeploymentscenario 2009/11/2

  35. AdHocWirelessinInternet • Similartowirelessinternet,theadhoc wirelessinternetextendstheserviceofthe Internettotheenduseroveranadhoc wirelessnetwork • Gateways:entrypointstothewiredInternet • Addressmobility:similartotheMobileIP • Routing:majorprobleminadhocwirelessInternet • Transportlayerprotocol • Loadbalancing,pricing/billing,security,QoS • Service,address,andlocationdiscovery 2009/11/2

  36. TCP/IPprotocolstack TCP/IPprotocolstack TCP/IPprotocolstack ApplicationLayer (HTTP,TELNET,SMTP, etc.) TransportLayer (TCP/UDP) NetworkLayer (IPv4/IPv6) NetworkLayer (IPv4/IPv6) 802.11/HIPERLAN 802.11 HIPERLAN 802.3/802.4/80 2.5 Internet AdhocwirelessInternet gatewayconnectedtoa subnetoftheInternet Mobilenodethat canbeconnected toanyAPrunning adhocwireless routingprotocol Mobilenodethatcanrelay packetstoanymobilenode runningadhocwireless routingprotocol Multi-hopwirelesspartofadhocwirelessInternetTraditionalwiredInternet FlowofanIPpacketfromthewiredInternettoamobilenode Transceiverantenna Figure5.7.AschematicdiagramoftheadhocwirelessInternet 2009/11/2 36

  37. Internet A GatewayNode Transmissionrange Ahousewithrooftoptransceiver Path1 Path2 Wiredlink totheInternet Wirelesslink Figure5.8.AnillustrationoftheadhocwirelessInternetimplemented byawirelessmesh network 2009/11/2

  38. HomeWork • 4,8,11, 13 2009/11/2

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