搜索
LTEPOWERCONTROLANDINTER-CELLINTERFERENCECOORDINATIONLTE功率控制和小区间干扰协调LTEprovides(intra-cell)orthogonalitybetweenusersinbothuplinkanddownlink,thatis,atleastintheidealcase,nointerferencebetweentransmissionswithinthesamecellbutonlyinterferencebetweencells.Hence,LTEperformanceintermsofspectrumefficiencyandavailabledataratesis,relativelyspeaking,morelimitedbyinterferencefromothercells(inter-cellinterference)comparedtoWCDMA/HSPA,especiallyforusersatthecelledge.Therefore,themeanstoreduceorcontroltheinter-cellinterferencepotentiallycanprovidesubstantialbenefitstoLTEperformance,especiallyintermsoftheservice(datarates,etc.)thatcanbeprovidedtousersatthecelledge.LTE提供（小区内）的用户之间的正交性在上行链路和下行链路，即，至少在理想的情况下，在同一小区内的传输之间没有干扰，但小区之间仅干扰。因此，在频谱效率和可用的数据速率方面的LTE的性能，相对来说，更多通过从相对于WCDMA/HSPA其它小区（小区间干扰）的干扰的限制，尤其是对于用户位于小区边缘。因此，该装置减少或潜在控制小区间干扰可以提供很大的好处到LTE的性能，特别是在服务的条款（数据率，等等），可以在小区边缘被提供给用户。UplinkpowercontrolisoneofthemechanismsinLTEusedforthispurpose.Itisusedtocontrolnotonlythereceivedsignalstrengthintheintendedcell,butalsotocontroltheamountofinterferenceinneighboringcells.LTEuplinkpowercontrolsupportsfractionalpath-losscompensation,implyingthatusersclosetothecellborderuserelativelylesstransmitpower,andthusgeneraterelativelylessinterferencetoneighborcells.However,LTEprovidesmoreadvancedinterference-handlingschemesaswell.上行链路功率控制是用于此目的LTE中的机制之一。它用于不仅控制在预定的小区的接收信号强度，而且要控制在相邻小区中的干扰量。LTE的上行链路功率控制支持分数路径损耗补偿，这意味着用户接近小区边界使用相对较少的发射功率，并由此产生向相邻小区相对较少的干扰。然而，LTE提供了更先进的干扰处理方案也是如此。Inter-cellinterferencecoordination(ICIC)isinessenceaschedulingstrategyusedtolimittheinter-cellinterference.Asimplemethodtoimprovecell-edgedataratesistorestricttheusageofpartsofthebandwidthstatically,forexample,throughareuselargerthanone.Suchschemesimprovethesignal-to-interferenceratiosoftheusedfrequencies.However,thelossduetoreducedbandwidthavailabilityistypicallylargerthanthecorrespondinggainduetohighersignalto-interferenceratio,leadingtoanoveralllossofefficiency.Therefore,theLTEstandardprovidestoolsfordynamicinter-cell-interferencecoordinationoftheschedulinginneighborcellssuchthatcell-edgeusersindifferentcellspreferablyarescheduledoncomplementarypartsofthespectrumwhenrequired.NotethatamajordifferencefromstaticreuseschemesisthatLTEstillallowsforthetotalavailablespectrumtobeusedinallcells.Bandwidthrestrictionsareappliedonlywhenmotivatedbytrafficandradioconditions.小区间干扰协调（ICIC）在本质上是一个调度策略来限制小区间干扰。一个简单的方法来提高小区边缘的数据速率是限制的使用的带宽，静态的部分，例如，通过重复使用大于1信号。这种方案提高了信号干扰比使用频率。然而，由于降低带宽可用性的损失通常是大于由于较高的信号干扰比的相应的增益，导致整体的效率损失。因此，LTE标准提供了动态的小区间干扰协调的调度在相邻小区，不同小区边缘用户最好安排在光谱的补充部分，在需要的时候。注意，从静态复用方案的主要区别是，LTE仍然允许总的可用频谱可用于所有的小区。只有当受流量和无线环境的激励时，带宽才被限制。Interferencecoordinationcanbeappliedtobothuplinkanddownlink,althoughwithsomefundamentaldifferencesbetweenthetwolinks.Intheuplink,theinterferenceoriginatesfromseveralgeographicallyseparatedterminals,andthus,theoverallinterferencevariesovertimewiththeschedulingdecisions.Ontheotherhand,inthedownlink,theinterferenceoriginatesfromthestationarybasestations.Hence,theobservedinterferencedependsmoreheavilyontheschedulingdecisionintheuplinkcase,comparedtothedownlinkcase,anditcouldbearguedthatintercellinterferencecoordinationcanbemoresuitedtotheuplink.Also,astheLTEinterference-coordinationmechanismisbasedonschedulingrestrictionsinthefrequencydomain,itissuitedmainlyforrelativelynarrowbandservicesnotrequiringthefullsystembandwidth.Astheuplinktransmissionpowergenerallyissignificantlysmallerthanthedownlinktransmissionpower,uplinktransmissionstendtobemorenarrowbandinnaturethandownlinktransmissions.Also,thisindicatesthatinter-cell-interferencecoordinationtendstofinditsmainapplicationintheuplink.干扰协调可以应用于上行和下行,尽管两个链接之间有一些基本差异。在上行链路中，干扰从几个地理上分开的终端发起，并且因此总体干扰会随时间变化的调度决定。另一方面，在下行链路中，干扰来源于固定基站。因此，观测到的干扰更严重依赖于在上行链路情况下，调度决定，相对于下行链路的情况下，同时也可以说明，小区间干扰协调更适合上行链路。同时，作为LTE的干扰协调机制是基于在频域调度的限制，它主要针对相对窄带服务不要求全系统带宽。由于上行链路的传输功率一般是明显小于下行链路的传输功率。上行链路传输往往会在自然界比下行链路传输更多的窄带。而且，这表示小区间干扰协调往往主要应用在上行。Toaiduplinkinter-cellcoordination,LTEdefinestwoindicatorsexchangedbetweenbasestations:thehigh-interferenceindicatorandtheoverloadindicator.为了有助于上行小区间协调，LTE中定义了基站之间交换的两个指标：高干扰指示符和过载指示器。Thehigh-interferenceindicatorprovidesinformationtoneighboringcellsaboutthepartofthecellbandwidthuponwhichthecellintendstoscheduleitscell-edgeusers.Becausecell-edgeusersaresusceptibletointer-cellinterference,uponreceivingthehigh-interferenceindicator,acellmightwanttoavoidschedulingcertainsubsetsofitsownusersonthispartofthebandwidth.Thissubsetincludesusersclosetothecellthatissuesthehigh-interferenceindicator.高干扰的指示符提供的信息到邻近小区的小区的带宽的一部分，该细胞打算安排其小区边缘的用户。由于小区边缘用户很容易受到小区间干扰，在接收到高干扰的指示符时，一个小区可能要避免调度它自己的用户群这部分的带宽。这个子集包括用户接近小区高干扰指标的问题。Theoverloadindicatorprovidesinformationontheuplinkinterferencelevelexperiencedineachpartofthecellbandwidth.Acellreceivingtheoverloadindicatormayreducetheinterferencegeneratedonsomeoftheseresourceblocksbyadjustingitsschedulingstrategy,forexample,byusingadifferentsetofresources,andinthisway,improvetheinterferencesituationfortheneighborcellthatissuestheoverloadindicator.所述过载指示符提供有关在经历了小区带宽的各部分的上行线路干扰电平信