毕设外文原文及译文

1北京联合大学毕业设计（论文）任务书题目：OFDM调制解调技术的设计与仿真实现专业：通信工程指导教师：张雪芬学院：信息学院学号：2011080331132班级：1101B姓名：徐嘉明一、外文原文EvolutionTowards5GMulti-tierCellularWirelessNetworks:AnInterferenceManagementPerspectiveEkramHossain,MehdiRasti,HinaTabassum,andAmrAbdelnasserAbstract—Theevolvingfifthgeneration(5G)cellularwirelessnetworksareenvisionedtoovercomethefundamentalchallengesofexistingcellularnetworks,e.g.,higherdatarates,excellentend-to-endperformanceanduser-coverageinhot-spotsandcrowdedareaswithlowerlatency,energyconsumptionandcostperinformationtransfer.Toaddressthesechallenges,5Gsystemswilladoptamulti-tierarchitectureconsistingofmacrocells,differenttypesoflicensedsmallcells,relays,anddevice-to-device(D2D)networkstoserveuserswithdifferentquality-of-service(QoS)requirementsinaspectrumandenergy-efficientmanner.Startingwiththevisionsandrequirementsof5Gmulti-tiernetworks,thisarticleoutlinesthechallengesofinterferencemanagement(e.g.,powercontrol,cellassociation)inthesenetworkswithsharedspectrumaccess(i.e.,whenthedifferentnetworktierssharethesamelicensedspectrum).Itisarguedthattheexistinginterferencemanagementschemeswillnotbeabletoaddresstheinterferencemanagementprobleminprioritized5Gmultitiernetworkswhereusersindifferenttiershavedifferentprioritiesforchannelaccess.Inthiscontext,asurveyandqualitativecomparisonoftheexistingcellassociationandpowercontrolschemesisprovidedtodemonstratetheirlimitationsforinterferencemanagementin5Gnetworks.Openchallengesarehighlightedandguidelinesareprovidedtomodifytheexistingschemesinordertoovercometheselimitationsandmakethemsuitablefortheemerging5Gsystems.IndexTerms—5Gcellularwireless,multi-tiernetworks,interferencemanagement,cellassociation,powercontrol.I.INTRODUCTION2Tosatisfytheever-increasingdemandformobilebroadbandcommunications,theIMT-Advanced(IMT-A)standardshavebeenratifiedbytheInternationalTelecommunicationsUnion(ITU)inNovember2010andthefourthgeneration(4G)wirelesscommunicationsystemsarecurrentlybeingdeployedworldwide.ThestandardizationforLTERel-12,alsoknownasLTE-B,isalsoongoingandexpectedtobefinalizedin2014.Nonetheless,existingwirelesssystemswillnotbeabletodealwiththethousand-foldincreaseintotalmobilebroadbanddata[1]contributedbynewapplicationsandservicessuchaspervasive3Dmultimedia,HDTV,VoIP,gaming,e-Health,andCar2xcommunication.Inthiscontext,thefifthgeneration(5G)wirelesscommunicationtechnologiesareexpectedtoattain1000timeshighermobiledatavolumeperunitarea,10-100timeshighernumberofconnectingdevicesanduserdatarate,10timeslongerbatterylifeand5timesreducedlatency[2].Whilefor4Gnetworksthesingle-useraveragedatarateisexpectedtobe1Gbps,itispostulatedthatcelldatarateoftheorderof10Gbpswillbeakeyattributeof5Gnetworks.5Gwirelessnetworksareexpectedtobeamixtureofnetworktiersofdifferentsizes,transmitpowers,backhaulconnections,differentradioaccesstechnologies(RATs)thatareaccessedbyanunprecedentednumbersofsmartandheterogeneouswirelessdevices.Thisarchitecturalenhancementalongwiththeadvancedphysicalcommunicationstechnologysuchashigh-orderspatialmultiplexingmultiple-inputmultiple-output(MIMO)communicationswillprovidehigheraggregatecapacityformoresimultaneoususers,orhigherlevelspectralefficiency,whencomparedtothe4Gnetworks.Radioresourceandinterferencemanagementwillbeakeyresearchchallengeinmulti-tierandheterogeneous5Gcellularnetworks.Thetraditionalmethodsforradioresourceandinterferencemanagement(e.g.,channelallocation,powercontrol,cellassociationorloadbalancing)insingle-tiernetworks(evensomeofthosedevelopedfortwo-tiernetworks)maynotbeefficientinthisenvironmentandanewlookintotheinterferencemanagementproblemwillberequired.First,thearticleoutlinesthevisionsandrequirementsof5Gcellularwirelesssystems.Majorresearchchallengesarethenhighlightedfromtheperspectiveofinterferencemanagementwhenthedifferentnetworktierssharethesameradiospectrum.Acomparativeanalysisoftheexistingapproachesfordistributedcellassociationandpowercontrol(CAPC)isthenprovidedfollowedbyadiscussionontheirlimitationsfor5Gmulti-tiercellularnetworks.Finally,anumberofsuggestionsareprovidedtomodify3theexistingCAPCschemestoovercometheselimitations.II.VISIONSANDREQUIREMENTSFOR5GMULTI-TIERCELLULARNETWORKS5Gmobileandwirelesscommunicationsystemswillrequireamixofnewsystemconceptstoboostthespectralandenergyefficiency.Thevisionsandrequirementsfor5Gwirelesssystemsareoutlinedbelow.·Datarateandlatency:Fordenseurbanareas,5Gnetworksareenvisionedtoenableanexperienceddatarateof300Mbpsand60Mbpsindownlinkanduplink,respectively,in95%oflocationsandtime[2].Theend-to-endlatenciesareexpectedtobeintheorderof2to5milliseconds.Thedetailedrequirementsfordifferentscenariosarelistedin[2].·Machine-typeCommunication(MTC)devices:Thenumberoftraditionalhuman-centricwirelessdeviceswithInternetconnectivity(e.g.,smartphones,super-phones,tablets)maybeoutnumberedbyMTCdeviceswhichcanbeusedinvehicles,homeappliances,surveillancedevices,andsensors.·Millimeter-wavecommunication:Tosatisfytheexponentialincreaseintrafficandtheadditionofdifferentdevicesandservices,additionalspectrumbeyondwhatwaspreviouslyallocatedt