小区选择重选Word下载.docx
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小区选择重选Word下载.docx
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3.2.1,ofthestrongestRFchannelsindescendingorderofreceivedsignalleveltoseewhichareBCCHcarriers.(IfnoBCCHcarriershaveyetbeenfound,searchingwillcontinueuntilatleastoneBCCHcarrierisfound.).ThefirstBCCHcarrierfoundwhichisfromasuitablecellandonwhichthereisanormalpriorityindicationistakenandthatcelliscampedon.Ifatleastthenumber,giveninsubclause
3.2.1,ofthestrongestRFchannelshavebeentriedandtheonlysuitablecellsfoundhavelowpriorityindicationtheMSshallcamponthestrongestofthesecells.
a)通常的小区选择-这里MS事先并不知道哪些RF信道是BCCH载频,
b)Storedlistcellselection(optional)("
Storedlistcellselection"
state)HeretheMShasalistoftheBCCHcarriersusedbythePLMN.(ThislistmaybederivedbytheMSfrominformationgatheredduringpreviousselectionsofthePLMN).TheBCCHcarriersinthelistaresearchedindescendingorderofreceivedsignallevel,andthefirstBCCHcarrierfoundwhichisfromasuitablecellandonwhichthereisanormalpriorityindicationistaken,andthatcelliscampedon.IfanMSdecodesBCCHdatafromacelloftheselectedPLMNbutisunabletocamponthatcell,theBAofthatcellshallbeexaminedandanyBCCHcarriersintheBAwhicharenotinthelistofBCCHcarrierstobesearchedshallbeaddedtothelist.IfalltheseBCCHcarriershavebeentriedandtheonlysuitablecellsfoundhavelowpriorityindication,theMSshallcamponthestrongestofthesecells.
Ifnosuitablecellisfoundusingmethodb),methoda)isthentried.
WhilecampedonacelloftheselectedPLMN("
campednormally"
),theMSmayneedtoselectadifferentcell("
normalcellreselection"
state).Thefollowingeventstriggeracellreselection:
i)ThepathlosscriterionparameterC1(seesubclause
3.6)indicatesthatthepathlosstothecellhasbecometoohigh;
ii)Thereisadownlinksignallingfailure(subclause
3.6);
iii)Thecellcampedon(currentservingcell)hasbecomebarred;
iv)Thereisabettercell(intermsofthepathlosscriterionC2)inthesameregistrationarea,oramuchbettercellinanotherregistrationareaoftheselectedPLMN(usingtheCRHparameter,subclause
3.4);
v)Arandomaccessattemptisstillunsuccessfulafter"
Maxretrans"
repetitions;
"
beingaparameterbroadcastoncontrolchannel.
AGPRSMSinReadystateappliestheREADY_STATECELLRESELECTIONHYSTERESIStogetherwiththepathlosscriterionwhenreselectingthecellwithintheregistrationarea.TheGPRSMSinReadystateshallinformthenetworkaboutcellreselectionwithintheregistrationareabythecellupdateprocedure.ThenetworkmaycontrolcellreselectionofaGPRSMSinReadystate(GSM03.64).
InsteadoftheparameterC2,aGPRSMSappliesthecorrespondingGPRSparameterifprovided.IfthisGPRSparameterisprovidedthecellshallalsobroadcastalistBA(GPRS)indicatingBCCHcarrierstobemonitoredbyGPRSMSsforcellre-selectionpurpose.
TheMSwillthenreselectanewcellinordertofulfiltheprocessgoal(seesubclause
4.1).
Beforecampingonthecellafterreselection,theMSshallattempttodecodethefullsetofsysteminformation.TheMSshallcheckthattheparametersaffectingcellreselectionareunchanged.IfachangeisdetectedtheMSshallcheckifthecellreselectioncriterionisstillvalidusingthechangedparameters.Ifthecellselectioncriteriaarestillvalid,theMSshallcamponthecell.Iftheyarenotstillvalid,theMSshallrepeatthisprocessforthecellwiththenexthighestvalueofC2orcorrespondingGPRSparameter,respectively.
OncetheMShasretunedtothechosencell,itshallmonitoritspagingsubgroup(ifknown)forthatcell.IftheMSandthecellsupportgrouporbroadcastcalls,itshallalsomonitorthenotificationchannel.AGPRSMSshallmonitortherelevantGPRScontrolchannel(s).IftheMSreceivesapagebeforehavingdecodedtherelevantsysteminformationforthenewcell,theMSshallstorethepageandrespond,ifpermitted,oncetherelevantsysteminformationhasbeendecoded.Ifnotpermitted,nopageresponseshallbemade.
WhentheMSleavesidlemodeandenters"
connectedmode"
(e.g.,tomakeacall),onreturntoidlemodeattheendofthecall,acellmustbechosen("
choosecell"
state)assoonaspossiblee.g.,toallowanewcalltobemadeassoonaspossible.ThechosencellwillnotnecessarilybethesamecellastheMSwascampedonwhenthecallstartede.g.,iftheMSmovedasignificantdistancewhilethecallwasinprogress.TwocasesaredistinguishedinGSM
05.08,forwhichthealgorithmisslightlydifferent:
a)NormalcaseThecallisterminated,eitherbecausetheuser(ornetwork)hasterminatedthecall,orbecausearadiolinkfailurehasoccurredandcallreestablishmentisnotbeingattempted.
b)CallreestablishmentAradiolinkfailurehasoccurredandacallreestablishmentisbeingattempted.(TheMSreturnstoidlemodetostartthecallreestablishmentattemptandneedstoselectanewcellonwhichtomaketheattemptassoonaspossibleinordertominimizetheinterruptiontothecall).
Ifnosuitablecellisfoundbyeitherthestoredlistcellselection,normalcellreselection,orchoosecelltasks(allofwhichusealimitedsearch),thenormalcellselectiontask(whichsearchesallRFchannelsforasuitablecell)isentered.
Ifnosuitablecellisfoundbythenormalcellselectiontask,orifthereisnoSIMintheMS,theMSattemptstofindan"
acceptablecell"
onwhichitmaycampsothatemergencycallsmaybemade("
anycellselection"
state).TheMSignoresthePLMNinformationwhenselectinganacceptablecell,andnoattemptatlocationregistrationismade.ThistaskisalsoenteredifanLRrejectisreceivedwithoneofthefollowingcausevalues:
IMSIunknowninHLR"
(onlyfornon-GPRSMSasthisimpactsonlythenon-GPRSupdatestate,MSscapableofGPRSandnon-GPRSservicestakeacellselectionstateaccordingtotheoutcomeoftheroutingareaupdate);
IllegalMS"
;
illegalME"
PLMNnotallowed"
(However,thiswilltriggeranewPLMNselectioniftheMSisinautomaticmode);
-"
GPRSnotallowed“(onlyforMScapableofGPRSonly,wherethiswilltriggeranewPLMNselectioniftheMSisinautomaticmode;
MSscapableofGPRSandnon-GPRSservicestakeacellselectionstateaccordingtotheoutcomeoflocationupdatingas"
GPRSnotallowed“hasonlyimpactontheGPRSupdatestatus).
Ifanacceptablecellisfound,theMScampsonit("
Campedonanycell"
state).Ifoneofthecellreselectiontriggerevents(i)to(v)aboveoccurs,theMSattemptstofindanewacceptablecelltocampon("
anycellreselection"
state)butusingazerodBvalueofCRH.Ifnoacceptablecellcanbefound,the"
taskisreentered.
Ifwhilecampedonanacceptablecell,anemergencycalloriginationismade,theMSentersaconnectedmodeandattheendofthecall,choosesanacceptablecell("
chooseanycell"
state)sothatitisreadyforthenextemergencycallorigination.
Inallcases,ifanewPLMNisselected,theMSsearchesforasuitablecellofthatPLMN.However,iftheMShasrecentlysearchedthestrongestRFchannelswhileapreviousPLMNwasselected,itmayalreadyhaveinformationaboutotherPLMNs.
TheusermayrequestasearchofRFchannelstodeterminewhichPLMNsareavailable.ThissearchshallbedoneinsuchawayastominimizeinterruptionstotheMS'
smonitoringofitspagingsubchannel.
0508v620
6Idlemodetasks
6.1Introduction
Whilstinidlemode,anMSshallimplementthecellselectionandreselectionproceduresdescribedinGSM
03.22.Theseproceduresmakeuseofmeasurementsandsubproceduresdescribedinthisclause.
TheproceduresensurethattheMSiscampedonacellfromwhichitcanreliablydecodedownlinkdataandwithwhichithasahighprobabilityofcommunicationsontheuplink.OncetheMSiscampedonacell,accesstothenetworkisallowed.
ThisclausemakesuseoftermsdefinedinGSM
03.22.
TheMSshallnotusethediscontinuousreception(DRX)modeofoperation(i.e.poweringitselfdownwhenitisnotexpectingpagingmessagesfromthenetwork)whileperformingthecellselectionalgorithmdefinedinGSM
03.22.Howeveruseofpoweringdownispermittedatallothertimesinidlemode.
Forthepurposeofcellselectionandreselection,theMSshallbecapableofdetectingandsynchronizingtoaBCCHcarrierandreadtheBCCHdataatreferencesensitivitylevelandreferenceinterferencelevelsasspecifiedinGSM
05.05.AnMSinidlemodeshallalwaysfulfiltheperformancerequirementspecifiedinGSM
05.05atlevelsdowntoreferencesensitivitylevelorreferenceinterferencelevel.Theallowederrorrates(seeGSM
05.05)mightimpactthecellselectionandreselectionprocedure,e.g.triggercellreselection.Moreover,oneconsequenceoftheallowederrorratesisthatinthecaseofnofrequencyhoppingandaTU3(TU1.5forDCS
1
800)propagationprofileitcannotbeexpectedthatanMSwillrespondtopagingunlessthereceivedlevelis2dBhigherthanthespecifiedreferencelevel.
Forthepurposesofcellselectionandreselection,theMSisrequiredtomaintainanaverageofreceivedsignalstrengthsforallmonitoredfrequencies.Thesequantitiestermedthe"
receivelevelaverages"
shallbeunweightedaveragesofth
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