R107.docx

R107.docx

《R107.docx》由会员分享，可在线阅读，更多相关《R107.docx（13页珍藏版）》请在冰豆网上搜索。

R107

3GPPTSGRANWG1Meeting#49R1-072051

Kobe,Japan,7-11May,2007

Source:

Sharp

Title:

UplinkInter-cellInterferenceManagementforLTE

AgendaItem:

7.7

Documentfor:

DiscussionandDecision

1.Introduction

ThreekindsofschemeshavebeendiscussedinRANWG1forICIManagement:

1.Intra-cellpowercontrolparameteradjustmentwithoutanycommunicationbetweencells[1][2][3]

2.ICIManagementbasedonInter-cellpowercontrolbasedonsomeinformationexchange

withneighborcells[4][5][6]

3.SimpleResourceCoordination[7][8][9]

Theperformanceofthesimplerschemesofthefirstcategorycanbesignificantlyimprovedifsomeminimalinformationexchangewiththeneighborcellsisused,hencethesecondcategorycomesintobeing[10].

Recently,thissecondcategoryhasbeenextensivelydiscussedinRAN1.IntheMaltaRANWG1meeting（#48bis）,inter-cellpowercontrolbasedonknowledgeoftheuplinkloadofneighborcellsthroughbackhaulOverloadIndicatorexchangehasbeenagreedastheWorkingAssumption.

AlsoattheMaltameeting（#48bis）,someschemesinthethirdcategorywerere-proposed[8][9].TheseschemesaimtoincreasetheperformancebenefitsbyenhancementstotheWorkingAssumption,combatingtheuplinkinterferencemoreeffectively.

SchemesinthethirdcategoryaimtoprotectthoseedgeUEswithrelativelypoorgeometry,byallocatingadedicatedsub-bandtothem.SuchmethodswillimprovethethroughputsoftheedgeUEs,asthededicatedsub-bandisgenerallymorethanenoughfortheedgeUEs,buttheyhavethedisadvantageofcost,ofalargereductioninthetotalthroughput.Further,theseschemesrequirerigidcoordinationamongthecells（involvingsomelow-ratebackhaulcommunicationbetweenthecells）.

Itisourviewthatthedisadvantagesofthethirdcategory,SimpleResourceAllocationScheme,shouldbealleviatedandthustheresourcecoordinationschemes’benefitsenhanced.Hence,weproposethatsomeresourceallocationrestrictionsshouldbeplacedontheUEswithagreaterpotentialtointerferewithUEsinadjacentcells,andtheirthroughputsshouldbesomewhatconstrainedtoachieveatotalthroughputimprovement.

Inthiscontribution,weproposeanuplinkinterferencemitigationSchemebasedonEnhancedResourceCoordination.Simulationresultsshowthatsubstantialimprovementcanbeexpected.

2.

ProposedULICIMitigationscheme

Toincreaseefficientcelledgethroughputwithlowertotalthroughputdegradation,weconsideraschemewhich

（1）partitionsthesetofaservingcell’sUEsintotwoadditionalcategories,inadditiontojustthetwocategoriesbasedonwhetheraUEisatthecelledgeorinthecell-interior;and

（2）appliesfineresourcecontrolpoliciestoeachofthese4resultingUEgroups.Forthetwoadditionalgroups,anadditionalcriterionisappliedbasedonthelevelofinterferencegeneratedbytheservingcell’sUEintoadjacentcells,dividingtheUEsintomajorinterference-generatingUE&minorinterference-generatingUE.Combiningthesecategorieswiththecelledge/cellinteriorcategories,weget4Types（groups）ofservingcellUEsorganizedinto2categorieseachalongtheverticalaxisandthehorizontalaxisrespectively,asshowninFigure1.

Figure1FourtypesofUEsfortheproposedscheme

Inthefollowingsection,wedescribethedetailstorealizetheabovescheme.ThecellularsystemdeploymentisrepresentedinAnnexA,wherethreecellsconstituteoneNode-B.

2.1.CategorizationofUEsinto4groups

2.1.1–SimpleResourceCoordinationSchemeasbaseline

Firstly,weconsideraSimpleResourceCoordinationScheme[7],inwhicheachcellreservessomeresources（EdgeUE’sResource,EURs）fortheedgeUEs.UEsaregroupedintotheEdgeUEcategoryifthereportedpathlossvalue（plusshadowing）oftheUEfromitsservingcellislargerthanthe

-percentilepathloss,correspondingtopathlossthreshold

whiletheUEsaregroupedintotheinteriorUEcategoryifitissmallerthan

.（Pathlossvalueincludespropagationloss,antennagainpatternandshadowing,andtheedgeUEhasalargerpathlossvalue）.ThedivisionintothesetwotypesofUEsisillustratedinFigure2.

Figure2TwotypesofUEsforthesimpleresourcecoordinationscheme

OneEURdoesn’toverlaptheotherEURsofadjacentcellsinthefrequencydomain,whichpreventstwoedgeUEsinadjacentcellsfromusingthesameresource.TheEURscanbereusedbytheInteriorUEs,inadjacentcells.

Inordertoachievefrequencydiversitygain,it’sbettertoconstructtheEURsinahoppingFDMmanner.Figure3isanexampleofthisconfigurationinthecaseofthecelllayoutinAnnexA.NotethatE1,E2andE3don’tnecessarilyhavetobeequalsizedandthesumofE1,E2andE3doesn’thavetobeequaltothewholeband.

Figure3ExampleofEURconfigurationinahoppingFDMmanner

2.1.2–EnhancedResourceCoordinationSchemetocreate4UEgroups

Inadditiontotheabovediscussionandinasimilarmanner,wefurtherusethepathlossofaservingcellUEtoanadjacentnon-servingcell,observedattheUE,togroupalltheservingcellUEsinto2newcategories.ForeachUE,twosmallestpathlossesfromthenon-servingcellstotheUEareselectedtoconstructaninterferenceprofilelist.The

-percentileofthepathlosses,labeledthethreshold

isusedtosegmentalltheUEsintotwogroups:

MajorInterference-generatingUEandMinorInterference-generatingUE.

Combiningthesetwogroupingscreatesa2-dimensional2×2matrixwhichdescribesfourgroupsofUEs,asillustratedinFigure1.EachofthegroupsthencontainsaTypeofUE,TypeItoTypeIV.

ThecategorizationoftheUEsintheservingcellisperformedbytheservingeNB.TheservingeNBmustacquireeachUE’spathlossestothenon-servingcells.Onewaythatthemeasurementofthepathlossestothenon-servingcellscanbeaccomplishedbytheUEs,isbymonitoringtheCPICHorSCHoftheadjacentcells.

Note1:

FortheservingeNB,onewaytoacquirethepathlossesfromthenon-servingeNBstotheUEinthecell,isbyreadingthecorrespondingpathlossmeasurements,ifavailable,inthenormalUEhandovermeasurementreport.

AnotherwayisbyusingbackhaulcommunicationsbetweeneNBs.Forexample,inUMTS,everyNodeBbroadcaststheneighbourNode-Bs’DLCPICHTxpowersontheBCH.Theseparametersarefairlystaticanddonotneedtobeupdatedexceptveryoccasionally,andthusthebackhaulsignallingloadisextremelylow.ThustheservingeNBcanobtaintheDLCPICHTxpowersofneighboureNBs’viabackhaulcommunications,andwiththeneighbourcells’CPICHRSCPsreportedbytheUEs,theeNBcancalculatethenon-servingpathlossesfortheUEs.

Note2:

EachservingeNBcalculatesthenon-servingpathlossesoftheUEsinthecellfromtimetotime.However,duetotheslowvariationofthepathloss,theupdaterateofnon-servingpathlossescouldbeintheorderofhundredsofmillisecondsorless.

2.2.

Resourceallocationstrategiesforthe4groups

AfterthepreviousstepofgroupingofUEsinto4groupsandcreating4Types,fourdifferentresourceallocationstrategiesareappliedforeachofthefourTypesofUEs:

●TypeI:

UEsatcelledgewithahighlevelofinterference

Policies:

authorizedtoaccessthe

oftheservingBS;forbiddentouse

●TypeII:

UEsatcelledgewithalowlevelofinterference

Policies:

authorizedtoaccess

oftheservingBS;forbiddentouse

;optionalpowerboost

●TypeIV:

UEsintheinteriorareawithalowlevelofinterference

Policies:

authorizedtoaccess

oftheservingBS;limitedrighttouse

oftheservingBS

Note:

thelimitedrightisdefinedinAnnexC.3

●TypeIII:

UEsintheinteriorareawithahighlevelofinterference

Policies:

forbiddentouse

oftheservingBSandthepotentialinterferedBS;optionalpowerreduction;

SomedetailedexplanationsandcorrespondingexamplesaregiveninAnnexC.

3.PerformanceSimulation

WesimulatedtheEnhancedResourceCoordinationSchemeandcompareditsperformancewiththeSimpleResourceCoordinationScheme.Fourscenariosweresimulated:

1.NoMitigation

2.SimpleResourceCoordination（

=10）

3.EnhancedResourceCoordination–Parameterset1（

=9;

=98）

4.EnhancedResourceCoordination–Parameterset2（

=10;

=99）

SimulationassumptionsaregiveninAnnexD.

Table1givesthe5-percentileUEthroughput（asthecell-EdgeUEthroughput）,overallthroughputperformanceandthetradeoffefficiencybetweenthecell-EdgeUEthroughputandtheoverallthroughputofthefourschemes.

Table1.PerformanceResults:

Throughput---Cell-edge&Overall

Scheme

Cell-Edge5-percentileUEThroughput（Kbps）

OverallCell

Throughput（Kbps）

EdgeUEThroughputgainatthecostof1%cellthroughputreduction

1.NoMitigation

82

9916

/

2.SimpleResourceCoordination

144

9532

19.5%

3.EnhancedResource

Coordination–Parameterset1

136

9655

25.1%

4.EnhancedResourceCoordination–Parameterset2

148

9649

29.9%

TheSchemewithNointerferencemitigationachievesthehighestoverallthroughput（9916Kbps）butwithaverypooredgeUEthroughput（82kbps）.ThesimpleresourcecoordinationschemeachievesmuchhigheredgeUEthroughput（144kbps,up75.6%comparedtoNointerferencemitigationscheme）butarelativelypooroverallthroughput（9532,down3.87%）.Generallyspeaking,1percentlossinoverallthroughputcangeta19.5percentgaininedgethroughput.

ThustheNomitigationcaseandtheSimplecaserepresenttwoextremesintermsofperformance.

TheproposedEnhancedResourceCoordinationSchemeachievestwodistinctadvantages:

A.Itoffersimprovementsinperformancecomparedwiththesimplescheme

B.Itallowsatrade-offbetweenthecostinoverallthrough