EPS專有承載建立流程

與缺省的EPSi^載不同，專有EPSi^載的建立，是為了滿足用戶特定QoS的需求。EPS專有承載建立之前，必須存在相應(yīng)的缺省EPS承載。EPS專有承載的建立，可以由網(wǎng)絡(luò)側(cè)來發(fā)起，也可以由終端側(cè)來發(fā)起。在網(wǎng)絡(luò)側(cè)發(fā)起的專有承載建立過程中，專有承載建立的信令流程由網(wǎng)絡(luò)側(cè)發(fā)起，不要求UE上的應(yīng)用層了解EPS承載層QoS的具體信息，UE上的應(yīng)用層可以通過應(yīng)用層的信令與網(wǎng)絡(luò)協(xié)商QoS的相關(guān)信息，如SIP/SDPRTS詔，但這種應(yīng)用層的QoS協(xié)商并不包含承載層QoS的內(nèi)容。在UE側(cè)發(fā)起的EPS專有承載的建立中（也稱為承載資源分配過程），UE上的應(yīng)用層直接向網(wǎng)絡(luò)側(cè)提出承載層QoS（包括QCI,GBR等）的申請，如果網(wǎng)絡(luò)側(cè)接受UE的請求，就會與UE進(jìn)一步信令交互，建立專有的EPSBearer在網(wǎng)絡(luò)側(cè)發(fā)起的EPS專有承載的建立過程中，觸發(fā)網(wǎng)絡(luò)側(cè)建立專有承載的條件可以是來自網(wǎng)絡(luò)的應(yīng)用層信令，也可以是來自UE的應(yīng)用層信令。例如，UE發(fā)起基于IMS的VoIP呼叫或者UE需要接收基于IMS的VoIP呼叫。下圖是在基于GTP的S5接口下，網(wǎng)絡(luò)側(cè)發(fā)起的EPS專有承載的建立流程。LtLIElAiST-CLtLIElAiST-C住息收CaHTIETUIHd器海3rl■RCConnKnRCConnmneniRARCroatsB?€iirw

RM時MBRAR首先，PCRF根據(jù)UE應(yīng)用層所需要的QoS信息，生成相應(yīng)的QoS準(zhǔn)則，通過基于Diameter的RAR（Re—AuthenticationRequest）命令發(fā)送給PGW。PGW根據(jù)相應(yīng)的QoS準(zhǔn)則來配置EPSBearer的QoS,并發(fā)送CreateBearerRequest消息給SGW,SGW將相應(yīng)的消息轉(zhuǎn)發(fā)給MME,SGW與MME之間的信息示例如下：GPRSTunnelingProtocolV2CreateBearerRequestFlags:72010=Version:2....1...=T:1MessageType:CreateBearerRequest(95)MessageLength:743TunnelEndpointIdentifier:3300033(MME的GTP—C的TEID值)SequenceNumber:0Spare:256LinkedEPSBearerID(LBI):IEType:EPSBearerID(EBI)(73)IELength:1000.....=CRflag:0....0000=Instance:0....0101=EPSBearerID(EBI):5BearerContext:[GroupedIE]IEType:BearerContext(93)IELength:69000.....=CRflag:0....0000=Instance:0EPSBearerID(EBI):IEType:EPSBearerID(EBI)(73)IELength:1000..…=CRflag:0....0000=Instance:0....0000=EPSBearerID(EBI):0(EBI是由MME分配的，由于此時并沒有分配，所以設(shè)置為零)FullyQualifiedTunnelEndpointIdentifier(F-TEID):IEType:FullyQualifiedTunnelEndpointIdentifier(F-TEID)(87)IELength:9000..…=CRflag:0....0000=Instance:01=V4(True-IPV4addressfieldExists,False-Doesn'tExistinF-TEID):True.0=V6(True-IPV6addressfieldExists,False-Doesn'tExistinF-TEID):False...00001=InterfaceType:S1-USGWGTP-Uinterface(1)TEID/GREKey:34F-TEIDIPv4:30.0.2.1(30.0.2.1)FullyQualifiedTunnelEndpointIdentifier(F-TEID):IEType:FullyQualifiedTunnelEndpointIdentifier(F-TEID)(87)IELength:9000..…=CRflag:0....0001=Instance:11=V4(True-IPV4addressfieldExists,False-Doesn'tExistinF-TEID):True.0=V6(True-IPV6addressfieldExists,False-Doesn'tExistinF-TEID):False...00101=InterfaceType:S5/S8PGWGTP-Uinterface(5)TEID/GREKey:34F-TEIDIPv4:20.0.0.1(20.0.0.1)EPSBearerLevelTrafficFlowTemplate(BearerTFT):IEType:EPSBearerLevelTrafficFlowTemplate(BearerTFT)(84)IELength:8000..…=CRflag:00000=Instance:0001=OperationCode:CreateNewTFT(1)....0001=NumberofPacketFilters:1...0=Ebit:FalsePacketFilter1....0000=PacketFilterIdentifier:0..11....=Direction:bidirectional(3)(上行和下行雙向的Filter)EvaluationPrecedence:0LengthofPacketFilter:3ComponentType:Singleremoteporttype(80)Singleremoteporttype:80BearerLevelQualityofService(BearerQoS):IEType:BearerLevelQualityofService(BearerQoS)(80)IELength:22000..…=CRflag:00000=Instance:01=PVI(Pre-emptionVulnerability):True..0000..=PL(PriorityLevel):0.0......=PCI(Pre-emptionCapability):False(PVI,PL,以及是ARP的屬性，具體內(nèi)容參見3GPP23.401)Label(QCI):9MaximumBitRateForUplink:65535000MaximumBitRateForDownlink:65535000GuaranteedBitRateForUplink:65535000GuaranteedBitRateForDownlink:65535000MME為每個EPSBearer分配相應(yīng)的EBI(EPSBearerI[D,構(gòu)造相應(yīng)的ActivateDedicatedEPSBear消息，將其作為NASPDU包含在發(fā)送至UeNodeB的BearSetupRequest消息中。eNodeB將EPSBearer的QoS映射到空口上的QoS,然后通過向UE發(fā)送RRCConnectionReconfiguration消息來建立相應(yīng)的DRB,并對DRB進(jìn)彳tPDCP層，邏輯層，以及RLC層等進(jìn)行配置。在消息中還作為NASPDU傳輸來自MME的ActivateDedicatedEPSBear。在NASPDU中，LBI(LinkedEPSBearID給出了與DedicatedEPSBeare對應(yīng)的DefaultEPSBear的標(biāo)識，TFT表示應(yīng)用到UE的上行TFT,其中的Precedence指出了PacketFilter的優(yōu)先級，數(shù)值越低，表示優(yōu)先級越高。UE在發(fā)送上行數(shù)據(jù)包的時候，按照PacketFilter的優(yōu)先級對數(shù)據(jù)包進(jìn)行匹配，如果匹配成功，UE就會在相應(yīng)的EPSBearer(RadioBearer)上發(fā)送數(shù)據(jù)，否則的話，UE會在缺省的EPSBearer上發(fā)送數(shù)據(jù)。+-Rrc\-Dcch[Union]+-message_\-c1[Union]\-rrcConnectionReconfiguration[Union]+-rrc_TransactionIdentifier=0[INTEGER]+-criticalExtensions\-c1[Union]\-rrcConnectionReconfiguration_r8[Union]+-measConfig=omit+-mobilityControlInfo=omit+-dedicatedInfoNASList=omit+-radioResourceConfigDedicated|+-srb_ToAddModList=omit|+-drb_ToAddModList[RecordOf]||[0]||+-eps_BearerIdentity=6[INTEGER]||+-drb_Identity=2[INTEGER]||+-pdcp_Config|||+-discardTimer=infinity_[ENUM]|||+-rlc_AM||||+-statusReportRequired=true[BOOLEAN]|||+-rlc_UM=omit|||+-headerCompression|||\-notUsed[Union]=NULL||+-rlc_Config|||\-am[Union]|||+-ul_AM_RLC||||+-t_PollRetransmit=ms80[ENUM]||||+-pollPDU=p128[ENUM]||||+-pollByte=kB125[ENUM]||||+-maxRetxThreshold=t4[ENUM]|||+-dl_AM_RLC|||+-t_Reordering=ms80[ENUM]|||+-t_StatusProhibit=ms60[ENUM]||+-logicalChannelIdentity=4[INTEGER]||+-logicalChannelConfig||+-ul_SpecificParameters||+-priority=13[INTEGER]||+-prioritisedBitRate=infinity_[ENUM]||+-bucketSizeDuration=ms100[ENUM]||+-logicalChannelGroup=2[INTEGER]|+-drb_ToReleaseList=omit|+-mac_MainConfig=omit|+-sps_Config=omit||+-physicalConfigDedicated=omit|+-securityConfigHO=omit|+-nonCriticalExtension=omit+-Nas[RecordOf][0]+-SecurityProtection|+-Status='0010'B[BITSTRING]+-Pdu+-Msg\-aCTIVATE_DEDICATED_EPS_BEARER_CONTEXT_REQUEST[Union]+-epsBearerId='6'H[HEXSTRING]+-protocolDiscriminator='0010'B[BITSTRING]+-procedureTransactionIdentifier='00'O[OCTETSTRING]+-messageType='11000101'B[BITSTRING]+-spareHalfOctet='0'H[HEXSTRING]+-linkedEpsBearerId|+-idValue='0101'B[BITSTRING]+-epsQos|+-iei=omit|+-iel='09'O[OCTETSTRING]|+-qci='00000100'B[BITSTRING]|+-maxBitRateUl='01101000'B[BITSTRING]|+-maxBitRateDl='01101000'B[BITSTRING]|+-guaranteedBitRateUl='01001000'B[BITSTRING]|+-guaranteedBitRateDl='01001000'B[BITSTRING]|+-maxBitRateUlExt='00000000'B[BITSTRING]|+-maxBitRateDlExt='00000000'B[BITSTRING]|+-guaranteedBitRateUlExt='00000000'B[BITSTRING]|+-guaranteedBitRateDlExt='00000000'B[BITSTRING]+-tft|+-iei=omit|+-iel='23'O[OCTETSTRING]|+-tftOperationCode='001'B[BITSTRING]表示創(chuàng)建TFT|+-eBit='0'B[BITSTRING]|+-noOfPktFilter='0010'B[BITSTRING]|+-packetFilterList[RecordOf]||[0]|||+-iei='10'O[OCTETSTRING]其中可以表示Filter的方向。|||+-precendence='00000000'B[BITSTRING]||||+-iel='0E'O[OCTETSTRING]IPV4remoteAddresstype(具體內(nèi)容參見10.5.162/3GPP24.008)||||+-contents='10C0A80101FFFFFFFF5079B83011'O[OCTETSTRING]|||[1]|||+-iei='20'O[OCTETSTRING]|||+-precendence='00000001'B[BITSTRING]|||+-iel='0E'O[OCTETSTRING]|||+-contents='10C0A80101FFFFFFFF50EE483011'O[OCTETSTRING]||+-parameterList=omit|+-transactionIdentifier=omit|+-negotiatedQos=omit|+-negotiatedLlcSapi=omit|+-radioPriority=omit|+-packetFlowIdentifier=omit|+-protocolConfigurationOptions=omit+-PiggybackedPduList=omitUE存貯得到的相應(yīng)QoS信息，并作相應(yīng)的處理，然后向eNodeB回應(yīng)RRCConnectionReconfigurationComplete消息。eNodeB接收至UUE的回應(yīng)后，回復(fù)給MMEBearSetupResponse消息。UENAS層同時會構(gòu)造ActivateDedicatedEPSBearerContextComplete消息，并將其作為NASPDU通過ULInfoTransfer發(fā)送給eNodeB,eNodeB將此NASPDU透傳給MME。MME接收到后，生成CreateBearerResponse消息，發(fā)送給SGW和PGW。GPRSTunnelingProtocolV2CreateBearerResponseFlags:72010=Version:2....1...=T:1MessageType:CreateBearerResponse(96)MessageLength:424TunnelEndpointIdentifier:1SequenceNumber:0Spare:256Cause:IEType:Cause(2)IELength:2000.....=CRflag:0....0000=Instance:0Cause:Requestaccepted(16)0=CauseSource(CS:True-Errororiginatedbyremotenode,False-ErrororiginatedbyNodesendingtheMessage):FalseBearerContext:[GroupedIE]IEType:BearerContext(93)IELength:37000.....=CRflag:0....0000=Instance:0Cause:IEType:Cause(2)IELength:2000..…=CRflag:0....0000=Instance:0Cause:Requestaccepted(16)0=CauseSource(CS:True-Errororiginatedbyremotenode,False-ErrororiginatedbyNodesendingtheMessage):FalseEPSBearerID(EBI):IEType:EPSBearerID(EBI)(73)IELength:1000..…=CRflag:0