通信工程师考试复习题高级英语试卷试卷及答案

通信工程师考试复习题高级英语及答案SectionIVocabulary&Terminology(30points)1.Single-choice:Selectthewordorphrasethatbestcompleteseachsentence.(1point×20)1.The___________ofamicrowavelinkisprimarilylimitedbythefademarginallocatedforrainattenuation.A.availabilityB.latencyC.throughputD.granularity2.Inmassive-MIMOsystems,thebasestationperforms___________toseparatespatiallymultiplexedusers.A.beamformingB.scramblingC.interleavingD.ciphering3.The3GPPspecificationthatfirstintroducedthe5GNRairinterfaceis___________.A.Release8B.Release10C.Release15D.Release174.Apassiveinter-modulation(PIM)productgeneratedinarustyRFconnectorisclassifiedas___________interference.A.co-channelB.adjacent-channelC.inter-symbolD.passive5.The___________algorithmiscommonlyadoptedforcarrier-phaseambiguityresolutioninhigh-precisionGNSSreceivers.A.ViterbiB.KalmanC.LAMBDAD.Baum-Welch6.Inopticalnetworking,the___________layerisresponsibleforend-to-endroutingofwavelengthpaths.A.ODUkB.OChC.OTUkD.OSC7.The___________fieldinanIPv6headercanbeleveragedforlow-latencyforwardinginsegmentrouting.A.TrafficClassB.FlowLabelC.NextHeaderD.HopLimit8.A___________antennaconfigurationprovidesthehighestergodiccapacityinani.i.d.Rayleighchannel.A.ULAB.UPAC.UCyAD.UCA9.The___________protocolisusedtosecurelyprovisionsubscribercredentialsineSIMarchitectures.A.GTPB.HTTP/2C.RSPD.Diameter10.Incloud-RAN,theinterfacebetweentheDUandRUisstandardizedas___________.A.eCPRIB.S1C.X2D.F111.The___________techniquemitigatesfour-wavemixinginlong-haulcoherentopticalsystems.A.dispersionpre-compensationB.frequencyditheringC.RZpulsecarvingD.distributedRamanamplification12.A___________attackexploitsthetimingside-channelintheTCPthree-wayhandshake.A.SYNfloodB.TeardropC.ACKspoofingD.RSTreplay13.The___________metricquantifiestheaveragenumberofhandoverspercallincellularnetworks.A.ErlangB.GoSC.MHTD.HFR14.InNB-IoT,the___________sub-carrierspacingisusedforextended-coveragemode.A.3.75kHzB.7.5kHzC.15kHzD.30kHz15.The___________ciphermodeprovidesbothconfidentialityandintegrityin5Guser-planetraffic.A.128-EEA1B.128-EEA2C.128-EEA3D.128-5G-EIA16.The___________layerintheOSImodelisresponsiblefortokenmanagementinIEEE802.11ax.A.MACB.LLCC.PHYD.PLCP17.The___________methodispreferredforchannelestimationinmmWavehybridbeamforming.A.least-squaresB.compressedsensingC.decisionfeedbackD.blindequalization18.The___________registerinanFPGAstoresthephaseincrementforDDS-basedmodulation.A.phaseaccumulatorB.barrelshifterC.LUTD.FIFO19.The___________standarddefinestheinterworkingbetween5Gcoreandwirelineaccess.A.ETSITS103570B.ITU-TY.3100C.3GPPTS23.501D.IEEE802.1CM20.The___________phenomenoncausestheapparentfrequencyofaGPSsignaltoshiftwhenreceivedonahigh-speedtrain.A.DopplerB.FaradayC.ScintillationD.multipath2.Matching:MatcheachabbreviationwithitsfullEnglishphrase.(1point×10)A.SDN_____B.BER_____C.QAM_____D.MIMO_____E.RAN_____F.PDN_____G.SINR_____H.OFDM_____I.URLLC_____J.RSRP_____1.QuadratureAmplitudeModulation2.ReferenceSignalReceivedPower3.Software-DefinedNetworking4.Multiple-InputMultiple-Output5.PacketDataNetwork6.BitErrorRatio7.Signal-to-Interference-plus-NoiseRatio8.OrthogonalFrequency-DivisionMultiplexing9.RadioAccessNetwork10.Ultra-ReliableandLow-LatencyCommunicationsSectionIIReadingComprehension(30points)Passage1Theevolutionfromcentralizedbasebandpoolstowarddisaggregatedopen-RANarchitecturesintroducesstringentsynchronizationconstraints.Time-alignmenterrorsexceeding65nsbetweendistributedunits(DUs)andremoteunits(RUs)collapsetheorthogonalityofsub-carriersin100MHz-wide5GNRcarriersoperatingat3.5GHz.Toaddressthis,theO-RANAlliancespecifiestheuseofIEEE1588-2019PrecisionTimeProtocol(PTP)withtelecomprofile,augmentedbysynchronousEthernet(SyncE)forfrequencylayering.Thecombinedpacket-basedandphysical-layerapproachyieldsamaximumtimeerror(max|TE|)budgetof±130nsovera10-hoptransportpath.Inaddition,theopenfronthaulinterfacemandatesa10.1376GbpseCPRIlinerate,encapsulatedinEthernetframeswith802.1Qbupreemptablepriorityqueuingtoboundjitterbelow30ns.FieldtrialsconductedinSeoulmetropolitansubwaytunnelsrevealthatPTPgrandmasterredundancywithhybridclockportstate-machinereducespacket-timingwanderby42%comparedtolegacyboundaryclocks.Consequently,thepacket-loss-resilientschemesustainsa99.999%time-availabilityevenunder0.3%randompacketdrop,corroboratingthefeasibilityofopen-RANdeploymentinchallengingpropagationenvironments.Questions1–5(2pointseach)1.Whichsynchronizationerrorthresholdcauseslossofsub-carrierorthogonality?2.Nametwotechnologiescombinedtomeetthemax|TE|budget.3.Calculatethejitterboundmandatedbytheopenfronthaulinterface.4.Bywhatpercentagedidhybridclockportstate-machinesreducetimingwander?5.Whatpacket-dropratiowassimulatedduringthesubwaytrial?Passage2Coherentopticaltransmissionleveragingprobabilisticconstellationshaping(PCS)hasredefinedcapacity-approachingtransport.PCSdynamicallyadaptstheentropyofQAMsymbolstotheinstantaneoussignal-to-noiseratio(SNR),yieldingashapinggainofupto1.53dBatabit-errorrate(BER)of10⁻².AkeyimplementationaspectistheselectionoftheMaxwell-Boltzmanndistributionparameterλ.Alargerλincreasesthepeak-to-averagepowerratio(PAPR),exacerbatingfibernon-linearity,whereasasmallerλreducesthroughput.Tooptimizeλinrealtime,alow-complexityneural-network–aidedalgorithmwasproposedthatmonitorsthegeneralizedmutualinformation(GMI)every0.1ms.Thealgorithm,deployedona400Gb/sper-channelcommercialline-card,improvednetdata-rateby12%acrossthetranspacificsegment(9600km)comparedtofixed-distributionPCS.Critically,theneuralmodelwastrainedofflinewith2×10⁶channelrealizationsgeneratedbytheGaussian-noise-model–enhancedsplit-stepFouriermethod,ensuringrobustnesstopolarization-modedispersionfluctuations.Questions6–10(2pointseach)6.StatethemaximumshapinggainofferedbyPCSatBER=10⁻².7.Identifythetrade-offcontrolledbyparameterλ.8.Howoftendoestheneural-networkmonitorGMI?9.Whatwastheachievednetdata-rateimprovementonthetranspacificlink?10.Whichnumericalmethodgeneratedthetrainingdataset?SectionIIIClozeTest(10points)Filleachblankwiththemostappropriatewordfromthelistbelow.(1point×10)List:mitigate,granularity,ciphering,orchestration,preamble,elliptical,polarization,backhaul,refractive,stochastic1.Therandom___________rotationoftheelectricfieldvectorinsingle-modefiberiscombatedusingdigitalsignalprocessing.2.Network-slicing___________enableson-demandinstantiationofvirtualizedRANfunctions.3.Alonger___________sequenceimprovesthecell-searchperformanceinlow-SNRscenarios.4.___________indexmapsareexploitedinorbital-angular-momentummultiplexing.5.___________codingatthePDCPlayerprotectsbothuser-planeandcontrol-planetraffic.6.The___________outagemodelcapturesrain-fadingdynamicsintropicalregions.7.Adaptivemodulationisperformedwithsub-carrier-level___________tomaximizespectralefficiency.8.Alow___________indexprofilereducesmodaldispersioninmultimodefiber.9.The___________linkbetweentheaggregationrouterandthegNodeBisengineeredfor25Gbps.10.Machine-learning-based___________techniquespredictcongestionbeforebufferoverflow.SectionIVTranslation(15points)1.Chinese→English(7points)随着3GPPRelease18的冻结，网络控制的中继（NCJR）技术首次被纳入标准化框架。该机制允许集成接入与回传（IAB）节点在不牺牲时延预算的前提下动态选择父链路，从而将毫米波覆盖范围扩展至地下停车场等传统盲区。仿真表明，在曼哈顿网格场景下，NCJR可将用户体验速率的中位数提升约34%，同时将控制面信令开销降低18%。2.English→Chinese(8points)Emergingterahertzbandspromiseultra-massivespatialmultiplexingviagraphene-basedplasmonicantennas.Nevertheless,molecularabsorptionpeaksaround350GHzand410GHzintroducefrequency-selectivepath-lossexceeding30dB/km.Tocircumventthisimpediment,ahybridfree-space-optics–terahertzlinkisproposed,wheretheopticalcarrierprovidesastablelocaloscillatorforcoherentdetectionwhiletheTHzwaveconveyshigh-ratedata.Experimentaldemonstrationsinthe3mindoorcorridorvalidatea200Gb/sQPSKtransmissionwithEVMbelow5%.SectionVErrorCorrection&Proofreading(10points)Thefollowingparagraphcontainstengrammatical,lexicalorpunctuationerrors.Identifyeacherrorandwritethecorrectedwordintheblank.(1point×10)OriginalparagraphTheopen-RANfronthaulinterfacerequirestricttime-synchronizationbecauseevena100nsoffsetcanresultsindestructiveinterferenceamongsub-carriers.Tomitigatingthis,theO-RANAlliancehavespecifiedIEEE1588-2019PTPwithaoptionaltelecomprofile.Fieldtrailsshownthathybridclockalgorithmsreduceswanderby42%,achieving99.999%availabilityunder0.3%packetlost.Moreover,preemptableEthernetframeskeepsjitterbelow30ns,whatiscriticalfor100MHzNRcarriers.Thesemeasurecorroboratesthefeasibilityofdisaggregatedarchitecturesinharshpropagationenvironments.Corrections1.________2.________3.________4.________5.________6.________7.________8.________9.________10.________SectionVIWriting(25points)Youaretheleadengineerofagreen-field5GStand-Alone(SA)rollout.Writea300-wordtechnicalmemorandumtotheCTOarguingwhyatransportnetworkbasedon400Gb/scoherentpluggableopticswithMACsecencryptionshouldbepreferredovertraditional100Gb/sdirect-detecttransceiverswithseparatesecurityappliances.Yourmemomustincludeatleastthreequantitativecomparisons(latency,power,TCO)andonereferencetorecent3GPPsecurityspecification.Donotusebulletpoints;writecontinuousprose.SectionVIIAdvancedProblemSolving(30points)1.A5GNRcelloperatesat28GHzwith400MHzbandwidthand64×64hybridbeamforming.TheOFDMnumerologyisμ=3.(a)Calculatethesub-carrierspacing.(2points)(b)Determinethenumberofusablesub-carriersif8%guard-bandoverheadisreserved.(3points)(c)ComputethepeakPHYdata-rateassuming256-QAMwithcodingrate0.925and8spatiallayers.(5points)2.AmetrocoherentopticallinkusesPCS-64-QAMshapedbyMaxwell-Boltzmanndistributionwithλ=0.8.Thegeneralizedmutualinformation(GMI)ismeasuredas5.45bits/symbol.Thesymbolrateis64GBaudandtheEthernetoverheadis7%.Calculatetheusablebit-rateafterFECoverheadof12%isfurtherdeducted.(5points)3.Amulti-hopIEEE1588-2019PTPchaincontains5boundaryclocks.Eachclockaddsaconstanttime-errorof3nsplusastochasticcomponentuniformlydistributedwithin±2ns.Usingtheroot-sum-squaremethod,estimatethe99%bound(≈2.58σ)ofthetotaltimeerror.(5points)4.AnurbanIABnetworkismodeledasaPoissonpointprocesswithdensityλ=80nodes/km².Eachnodehasa30mbackhaullinkbudgetat60GHz.ComputetheprobabilitythatarandomlychosendonorIABhasatleastonechildIABwithinitscoveragearea.(5points)5.A400Gb/sMACsec-encryptedinterfaceincursanadditional64nslatencyper256-bytepacketduetoAES-256-GCMprocessing.Iftheaveragepacketsizeinthe5Guser-planeis512bytes,calculatetheequivalentthroughput-delayproductfora100kmfiberspan(n=1.468).Expresstheresultinbits.(5points)SectionVIIIOralDefenceSimulation(25points)Assumetheexaminerasks:“Whydoes3GPPmandatesupportfor256-QAMonlyinthedownlinkbutnotintheuplinkforFR2?”Providea150-wordanswerthatciteslink-budgetconstraints,UEpoweramplifierlinearity,anderror-vector-magnituderequirements.Writeyourresponseasifspeaking.AnswerKey&GradingNotesSectionI1A2A3C4D5C6B7B8B9C10A11A12A13D14A15B16A17B18A19A20AMatching:A3B6C1D4E9F5G7H8I10J2SectionII165ns2IEEE1588-2019PTPandSynchronousEthernet330ns442%50.3%61.53dB7Throughputvs.PAPR(non-linearity)8Every0.1ms912%10Split-stepFouriermethodenhancedbyGaussian-noisemodelSectionIII1polarization2orchestration3preamble4elliptical5ciphering6stochastic7granularity8refractive9backhaul10mitigationSectionIV1Withthefreezingof3GPPRelease18,network-controlledjointrelay(NCJR)technologyhasforthefirsttimebeenincorporatedintothestandardizedframework.Thismechanismallowsintegratedaccessandbackhaul(IAB)nodestodynamicallyselectparentlinkswithoutsacrificingthelatencybudget,therebyextendingmillimeter-wavecoverageintotraditionalblindspotssuchasundergroundcarparks.SimulationsshowthatinaManhattangridscenarioNCJRcanincreasethemedianuser-experienceddata-ratebyroughly34%whilereducingcontrol-planesignalingoverheadby18%.2新兴太赫兹频段通过基于石墨烯的等离子体天线有望实现超大规模空间复用。然而，350GHz与410GHz附近的分子吸收峰会造成超过30dB/km的频率选择性路径损耗。为克服这一障碍，提出了一种混合自由空间光–太赫兹链路，其中光载波为相干检测提供稳定本振，而太赫兹波承载高速数据。在三米室内走廊的实验验证中实现了200Gb/sQPSK传输，EVM低于5%。SectionV1requires2result3mitigate4has5an6trials7reduce8loss9keep10whichSectionVISampleresponse(abridgedforbrevity;examinersgradeonargumentstrength,dataaccuracy,andlanguage):Deploying400GcoherentpluggableswithMACsecinlineyields2.3μsone-waylatency,38%lowerthanthe3.7μsincurredby100Gdirect-detectchainsplusexternalsecurityboxes.Powerconsumptiondropsfrom380Wper