2S8000BTS功能结构描述.docx

2S8000BTS功能结构描述.docx

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2S8000BTS功能结构描述

因为S8000BTS是北电在国内用的最多的产品，所以我们主要讲述此种类型的BTS。

分三部分讲：

结构

机柜

板子

一、S8000BTS功能结构描述

1ARCHITECTURE

1.1PHYSICALARCHITECTURE

1.1.1Introduction

ThischapterprovidesanoverviewoftheBTSphysicalarchitecture.

1.1.2Subsystems

TheBTScontainsthreemainsubsystems（seeFigure1-1andFigure1-2）:

●oneBCF（CabinetorUnit）oroneCBCFModule

●oneTRXsubsystem

●onecouplingsystem

ThecontentofeachsubsystemislistedinTable1-1.

Figure1-2SUBSYSTEMARCHITECTUREWITHBCF

Figure1-2SUBSYSTEMARCHITECTUREWITHCBCF

Table1-1BTSSUBSYSTEMS

1.1.3Internalbuses

Thefollowingbuses,whichconnectBTScomponents,aredescribedinthissection:

●Frequencyhopping（FH）bus

●PrivatePCM

●GSMTimebus

●InternalPCMbus

●O&Mbus

Note:

TheGSMTimebus,InternalPCMbus,andO&MbusareonlyusedwiththeBCFUnit.

Figure1-1showstheinternalbusesusedwiththeBCFUnitandFigure1-2showsthebusesusedwiththeCBCFModule。

（图见上面）

1.2BCFFUNCTIONALARCHITECTURE

DependingontheBCFphysicalarchitecture,thefollowingfunctionsareenabled（seeFigure1-3）:

●

Figure1-3BCFARCHITECTURE

●controlandswitching

●datachannelconcentrator

●dualtrunkinterface

●synchronization

●alarmregrouping

1.2.1BCFControl,SWitchingandManagement（CSWM）

1.2.1.1Functions

TheCSWMunitisduplicatedforsafetyreasons,givingCSWMAandCSWMB.

TheCSWMunitisthemasterBCFunit.ItenablescommunicationwiththeBSC,organizes,storesandbroadcastsallthedataitreceivesfromtheBSC,supervisesandusesdefenseactionontheequipmentitcontrols.Itmustdothefollowing（seeFigure1-4）:

Figure1-4ORGANIZATIONOFCSWMFUNCTIONS

●setupcommunicationwiththeBSC

●Downloading

●manageBTSsynchronization

●managetheswitchingmatrix

●managetheFHbus

●manageslaveunits（DSC,PCMI,ALCO,SYNC,GTW,andtheTXpartoftheTRX）.Onlythedefenseactionsonslaveprocessorsisdiscussedbelow.

●enableduplexoperations

1.2.2DataSignalingConcentrationunit（DSC）

TheDSCiscontrolledbytheCSWM.ItcommunicateswiththeCSWMviatheO&Mbus.Itserveschannelmultiplexing,demultiplexing,andOperationsandMaintenance（O&M）functions.

1.2.2.1Multiplexinganddemultiplexing

TheCSWMusestheDSCtosetupcommunicationbetweentheBSCandtheotherentitiesthatmakeuptheBTS.TheLAPDprotocolignorestheDSCthatservesconcentratorandroutingfunctions.

TheDSCreadslevel2addresses（TEI）containedinLAPDframesand,usingaroutingtable,sendstheinformationontoanothertimeslot.Thetimeslotmaybeconcentrated（anumberofTEIarrive）ornot（singleTEI）.

1.2.2.2OperationsandMaintenance（O&M）functions

Configuration

TheCSWMsendsthefollowingtotheDSC:

●overallconfiguration

●connectanddisconnectconfigurations

Overallconfigurationdataincludesthefollowing:

●thesizeofmessagequeues

●twoqueueoverflowthresholds

●theperioddefiningthemomentobservationmessagesaresent

AconnectionconfigurationconnectsaTEIinasingletimeslottoasecondconcentratedtimeslot.

DisconnectingmayaffectaTEIinasingletimeslotorinaconcentratedtimeslot.

DisconnectingaconcentratedtimeslotautomaticallytriggersdisconnectionoftheconcentratedTEIitcontained.

Observations

TheDSCreturnsitsstatustotheCSWMasrequested.Thestatusreportcontainsoverloadalarmsandhardwarefailures.

TheDSCsendsregularobservationmessagestotheCSWMthatcontainthefollowingforthelasttrafficperiodandpertimeslotandTEI:

●queuesize

●themaximumsizereachedbythequeue

●numberofmessageshandledsincethelaststatusrequest

Tests

TheDSCconstantlytestsunusedtimeslots.ItperformsexternallooptestsonCSWMrequest.

TheresultsofunusedtimeslottestsarereturnedtotheCSWMinregularstatusmessages.

TheCSWMmayrequesttheDSCtoperformexternaltests.TheDSCchecksthatlinksarefreeandaccepts（orrefuses）start-up.TheDSCreturnstheresultsofthesetestsasrequested.

Monitoring

TheDSCsupervisesitsownequipmentpartsandissuesonethefollowingfaultmessages:

●queueoverload

●receiptofunexpectedframes

●PCMlinkhardwaremalfunction

Faultdetection

TheDSCreceivestwothresholdvaluesfromtheCSWMthatgivetheoverloadsituationinmessagetransmissionqueues.Whenqueuethresholdsarereached,theDSCissuesstartandend-of-alarmmessagestotheCSWMontheO&Mbus

1.2.3PCMInterface（PCMI）

ThePCMIinterfacesandsynchronizesincomingandoutgoingPCMlinks.ItconvertstheexternalPCMcomingfromtheBSCintointernalPCMusedbytheBSC,andviceversa.

EachPCMIhandlesoneexternalPCMlink.APCMIunitdoesthefollowing:

●convertsexternalPCMlinksintointernalPCMforBTSuse

●verifieslinkqualityusingerrordetectioncodes

●matchesimpedanceonthetypeofPCMlinkusedbytheoperator

1.2.3.1Configuration

ThePCMIcanoperatewithoutCSWMinvolvement.However,theCSWMsendsaconfigurationmessageontheO&Mbusthatcontainsthefollowing:

●thenumberoferroneousseconds,whichdefinesawindowusedtoevaluatePCMalarms

●thresholdM1forframealignmenterrorcounters

●thresholdM2fortheCRCerrorcounter

●thresholdM3forcodingtypeerrorcounters

1.2.3.2Monitoring

ThePCMImonitorsitsownequipmentandPCMlinks,andissuesfaultmessagesconcerninghardwarealarmsorPCMalarms.

1.2.3.3PCMalarmmanagement

ManagingPCMalarminvolvesframe,multiframe,submultiframe,zerotimeslot,andframealignment;CRCisnotmanagedyet.

Aframeintervalis125μs.

Thedurationofamultiframeis2ms,representingthetimeof16frames.

Thelengthofasubmultiframeis1ms.

TheTS0issetasidefortheframealignmentsignal,multiframealignmentbits,CRCbits,andalarmsending.

Framealignment帧队列

FramealignmentisoperatedbytheframealignmentbyteoccupyingtheTS0ineveryotherframe.

Uponlossofframealignmentthealarmbitissetto1andtheframealignmentcounterisincreased.

ThePCMalarms

EachPCMalarmcorrespondstothedetectionofoneanomalytypeonthePCMreception.

AseriouslyerroneoussecondisasecondinwhichanNOS,SIA,RRA,orLOSalarmconditionoccurredoranFEorCRCcounterwasoverrun.

ThesealarmsareindicatedbyLEDsonthefrontoftheDTIboard.

●LOS:

framelocklosssignal（LFALED）Framelockisconsideredlostwhenthreeconsecutivelocksignalsarereceivedwitherrors.Thisisalsothecasewhenbit2ofTS0inframesthatcontainnolockingsignalisreceivedthreetimesinarowwitherrors.

●AIS:

Alarmindicationsignal（AISLED）.NotusedintheGSM1900frequencyband.

●RRAorRAI:

RemoteReceiveAlarmsignalorRemoteAlarmIndicator（RRALED）.

●NOS:

noframesignal（NOSLED）UpondetectingthebeginningofanNOSfaultsignal,a64-kbit/sSIAisgeneratedoneachTSoftheassociatedinternalPCMlink,anRRAissentontheexternalPCMlink,andtheapplicationassociatesanNOSerrortotheerroredsecond,bringingontheNOSLED.

●FE:

Frameerror（FELED）.

Usedincaseof2Mbit/sexternalPCMlink.ErrordetectioniseffectedonlyinoperationwithoutCRC.Theapplicationcountstheincorrectframelockwordsreceived,andcomparesthemwiththeupperandlowerthresholds（programmable）.

●SKP:

hopindicationreception.Notused.

●CRC:

CRCerrorsignal（CRCLED）.NotusedintheGSM1900frequencyband.

ThequestforCRCmultiframelockisassociatedwiththatforframelock,toensurethattheframelockwordfounddoesindeedcorrespondtoasinglelockwordtowhichonecanlockpermanently.

ThealarmLEDsonthefrontoftheboardaretheLFA,AIS,RRA,NOS,FE,SKP,andCRC.EachalarmeventturnsontheassociatedLEDforaminimumtimeof200ms.

Onecauseisassociatedwitheachseriouslyerroneoussecond.Thealarmcauseisdefinedinthefollowingdescendingorderofseverity:

NOS,AIS,LOS,RRA,FE,CRC,andSKP.

Whenthenumberofseriouslyerroneousconsecutivesecondsreachesthenumberoferroneousseconds（NBSEC）definedintheconfigurationmessage,thePCMisdesignatedinfaultconditionandamessageissenttotheCSW.

Theend-of-faultconditionisthenumberNBSECofconsecutivesecondswithouterrorsandtheend-of-faultmessageissenttotheCSW

1.2.4Synchronization（SYNC）

ThesynchronizationunitmustsynchronizetheDRXsonasinglereferencetime,GSMtime.Itsupervisesthedifferentdefensestages.Therearetwoidenticalsynchronizationunits,thathavethesamesoftware（seeFigure1-5）.

Figure1-5GSMTIMEBUSSYNCHRONIZATION

1.2.4.1GSMtime

ThenetworksuppliesthereferencetimeviathreePCMIunits.TheCSWMselectsoneofthesixclocksandsendsittothesynchronizationunit.Theclockselectedmusthavegoodlong-termaccuracybecauseitisusedbythesynchronizationmoduletogeneratereferencetimefortheradiointerfacewithanaccuracyof5xl0-8.

Iftheexternalreferencesignalisabsent,theCSWMselectsalocalclockderivedfromtheSYNCmoduleactivein"freerunning"mode.

1.2.4.2Monitoring

Thesynchronizationunitismonitoredbyitsowncontrolandmonitoringmechanisms,whichcheckthattheunitisoperatingcorrectlyandGSMtimeisavailableontheGSMTIMEbus.

Alarmsareasfollows:

●SYNOunitoutage

●CSWMclockfailure

●referenceclockfailure

ThelasttwoeventsarefedbacktotheCSWM.DefenseactionsarecoveredinsectiondedicatedtotheCSWM.

Incaseofasynchronizationunitfault,thesynchronizationunitsmaketheswitchoverdecision（active<=>standby）.ThefaultisthenfedbacktotheCSWMovertheO&Mbus.

1.2.5Alarmcollectingfunction（ALCO）

1.2.5.1Functions

Thealarmcollectingboard（ALCO）,loc