Thetraditionalwayofallocatingasinglechannelamongmultiplecompetingusersistochopupits()byusingoneofthemultiplexingschemessuchasFDM(FrequencyDivisionMultiplexing).IfthereareNusers,thebandwidthisdividedintoNequal-sizedportions,witheachuserbeingassignedoneportion.Sinceeachuserhasaprivatefrequency(),thereisnointerferenceamongusers.Whenthereisonlyasmallandconstantnumberofusers,eachofwhichhasasteadystreamoraheavyloadof(),thisdivisionisasimpleandefficientallocationmechanism.AwirelessexampleisFMradiostations.EachstationgetsaportionoftheFMbandandusesitmostofthetimetobroadcastitssignal.However,whenthenumberofsendersislargeandvaryingorthetrafficis(本题),FDMpresentssomeproblems.IfthespectrumiscutupintoNregionswhilefewerthanNusersarecurrentlyinterestedincommunicating,alargepieceofvaluablespectrumwillbewasted.IfmorethanNuserswanttocommunicate,someofthemwillbedenied()forlackofbandwidth.??
A.CONTINUOUS
B.STEADY
C.BURSTY
D.FLOW
正确答案是C