【NR接入流程】

tech2023-03-03  105

1 RRC_IDLE/INACTIVE态下UE的接入流程

2 交互消息内容及作用

1. RRCSetupRequest:

UE发送建立请求

ue-Identity / establishmentCause

CCCH,SRB0

 

2. INITIAL UL RRC MESSAGE TRANSFER:

gNB-DU将RRC建立请求消息发送给gNB-CU

gNB-DU UE F1AP ID

SUL Access Indication

C-RNTI 

RAN UE ID

DU to CU RRC-Container(UE和gNB-CU间消息的载体,gNB-DU不解析)

(UL-CCCH-Message:rrcSystemInfoRequest,RRC请求:建立/恢复/释放 )

 

3. DL RRC MESSAGE TRANSFER:

gNB-CU将RRCSetup消息发送给gNB-DU

gNB-DU UE F1AP ID(DU查找UE上下文)

 Index to RAT/Frequency Selection Priority

 Execute Duplication

RRC-Container(DL-CCCH-Message:RRC建立/拒绝)

 

4. RRCSetup:

gNB-CU给UE发送SRB1配置

 masterCellGroup 

radioBearerConfig 

cellReselectionPriorities

CCCH,SRB0

 

5. RRCSetupComplete:

通知网络侧RRC建立完成

5G-S-TMSI(Temporary Mobile Subscriber Identity)UE在核心网TA内的唯一临时标识

selectedPLMN-Identity

registeredAMF

guami-Type

 s-NSSAI-List (Single Network Slice Selection Assistance Information)

 dedicatedNAS-Message

DCCH,SRB1

 

6. UL RRC MESSAGE TRANSFER

将RRC建立完成的消息发送给gNB-CU

 New gNB-DU UE F1AP ID

Selected PLMN ID

RRC-Container(UL-DCCH-Message:RRC建立/恢复/重配 完成、测量报告、安全激活完成、UE能力信息)

 

7. INITIAL UE MESSAGE:

将UE要入网的消息告诉核心网

RAN UE NGAP ID

NAS-PDU

UE Context Request

5G-S-TMSI 

 

8. INITIAL CONTEXT SETUP REQUEST:

AMF准备UE上下文发送给gNB

AMF UE NGAP ID

RAN UE NGAP ID

PDU Session Resource Setup Request Transfer(QoS)

Security Key

Mobility Restriction List

UE Radio Capability

UE Security Capabilities

 

9. UE CONTEXT SETUP REQUEST:

(gNB-CU -> gNB-DU)建立SRB DRB(只提供相应的配置信息,RB的真正建立是在Uu口的重配消息中建立)

SRB To Be Setup List

DRB To Be Setup Lis

UE-CapabilityRAT-ContainerList

SCell To Be Setup List 

 DRX Cycle 

 CU to DU RRC Information (handover,resource configuration)

 RRC-Container

QoS Flow Mapping Indication

Resource Coordination Transfer Information

 

10. SecurityModeCommand:

AS安全激活

SecurityAlgorithmConfig( IntegrityProtAlgorithm / cipheringAlgorithm)

 

11. UE CONTEXT SETUP RESPONSE:

(gNB-DU -> gNB-CU)将RB建立完成的消息通知给gNB-CU

DRB Setup List 

DRB Failed to Setup List

SRB Setup List 

SRB Failed to Setup List

C-RNTI 

DU to CU RRC Information 

12. SecurityModeComplete:

通知网络侧安全激活完成

rrc-TransactionIdentifier

criticalExtensions

 

13. UL RRC MESSAGE TRANSFER

(gNB-DU -> gNB-CU)将AS安全激活的消息通知给gNB-CU

 New gNB-DU UE F1AP ID

Selected PLMN ID

RRC-Container(UL-DCCH-Message:RRC建立/恢复/重配 完成、测量报告、安全激活完成、UE能力信息)

 

14. DL RRC MESSAGE TRANSFER:

携带RRCReconfiguration给gNB-DU

gNB-DU UE F1AP ID(DU查找UE上下文)

 Index to RAT/Frequency Selection Priority

 Execute Duplication 

RRC-Container(DL-DCCH-Message:RRC重配/释放,UE能力查询)

 

15. RRCReconfiguration:

向UE发送重配命令

AS安全激活后,RB的添加、修改和释放(radioBearerConfig)

测量的建立、修改和释放;(measConfig)

添加、修改和释放SCG和SCell(secondaryCellGroup)

 

15. RRCReconfigurationComplete:

通知基站已完成RRC重配

rrc-TransactionIdentifier

criticalExtensions

 

17. UL RRC MESSAGE TRANSFER

gNB-DU将重配完成的信息通知给gNB-CU

 New gNB-DU UE F1AP ID

Selected PLMN ID

RRC-Container(UL-DCCH-Message:RRC建立/恢复/重配 完成、测量报告、安全激活完成、UE能力信息)

 

18. INITIAL CONTEXT SETUP RESPONSE

通知AMF上下文建立完成

AMF UE NGAP ID IE

RAN UE NGAP ID IE

PDU Session Resource Setup Response Transfer(QoS)

参考:

[1] 3GPP TS 38.331: "NR; Radio Resource Control (RRC) protocol specification";

[2] 3GPP TS 38.413: "NG-RAN; NG Application Protocol (NGAP)";

[3] 3GPP TS 38.473: "NG-RAN; F1 application protocol (F1AP)";

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