UE
eNB
MME
PRACH RANDOM ACCESS
PRACH RANDOM ACCESS RESPONSE
PUSCH (Msg3) RRC: Connection Request
random access procedure
RRC: Connection Setup
RRC: Connection Setup Complete + EMM ATT_REQ + ESM PDN CONN_REQ
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业务释放类型
• release
根据业务承载类型，业务释放过程也分为三类：
E-RAB release
The purpose of the E-RAB Release procedure is to enable the release of already established E-RABs for a given UE；
E-RAB释放后，UE仍然可以处于ECM-CONNECTED状态； UE context release
If the eNB wants to remove all remaining E-RABs, e.g., for user inactivity, the UE Context
Release Request procedure shall be used instead. 当UE回到ECM-IDLE状态时，MME向eNodeB发UE CONTEXT RELEASE消息。收到这条
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业务承载类型
• LTE业务承载类型
LTE的业务承载类型分为默认承载、专用承载两种： 默认承载：UE开机时获得承载，一定是MME发起的业务，优先级特别低，Non GBR； 专用承载：一定是由PGW触发建立的； 一个UE可以有不同的专用承载；
S1AP: INITIAL UE MESSAGE + EMM ATT_REQ + ESM PDN CONN_REQ
NAS Security Establishment (Authentication + NAS security start)
RRC: Security Mode Command
S1AP: INITIAL CONTEXT SETUP REQUEST + EMM ATT_ACC + ESM ACT_DEF_BEAR_REQ
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释放流程及异常释放原因分析
• 主要内容
- 业务承载类型及业务建立过程 - 业务释放类型及相应流程、原因
• E-RAB release
• UE context release
– Initial UE context只能由MME发起，一个UE只有一个UE context； – 一个eNB UE context是eNB内和一个处于激活状态的UE相关联的一个信息块。这块信息
是为了维持E-UTRAN提供给这个激活态UE的服务所必须的信息； – eNB UE context是在UE迁移到激活状态之后开始建立的；或者，eNB UE context是在切
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LTE完整业务流程
• RA及RRC连接建立流程
SRB0： RRC connection request、 RRC connection setup（消 息中包含SRB1建立的相关信 息）；
SRB1：
RRC connection setup complete；
optional procedure, P-GW may also trigger dedicated bearer creation without UE requesting it
triggering of Dedicated Bearer activation
GTPv2: Bearer Resource Command
• RRC connection release
- 异常释放的触发情景详解
• UE initiated drop
• eNB initiated drop
- 异常释放related Counter Triggers - Network/Field KPI及Drops分析 - Summary
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• RRC connection release
- Abnormal release的触发情景详解
• UE initiated drop
• eNB initiated drop
- 异常释放related Counter Triggers - Network/Field KPI及Drops分析 - Summary
GTP variant: EPS bearer termination in PGW
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SRB与默认、专用承载关系
业务承载类型
• 无线承载分类
RRC: UL NAS INFO TRANSFER (EMM ATT_COMPLETE + ESM ACT_DEF_BEAR_SUCC
S1AP: UL NAS TRANSPORT (EMM ATT_COMPLETE + ESM ACT_DEF_BEAR_SUCC)
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S1AP: E-RAB SETUP + ESM ACTIVATE DEDICATED BEARER REQUEST
RRC: RRCConnectionReconfigurationComplete
RRC: UL NAS INFO TRANSFER + ESM ACTIVATE DEDICATED BEARER REQUEST ACCEPT
• 释放流程及异常释放原因分析
2016-05 张恒
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概述
• 主要内容说明
本次主要讨论的内容：
LTE业务释放类型及相应信令流程的详解；相关的counter触发定义，以及异常问题分析 ；通过对这些内容的梳理和讨论，能够了解LTE释放的理论知识，并且在日常KPI和Log 分析方面，提供帮助。
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LTE完整业务流程
• 默认承载建立信令流程（Attach）
Steps: 1. Random Access 2. Initial NAS msg 3. NAS security 4. S1 init setup 5. RRC sec + UE cap 6. SRB2/DRB setup 7. NAS reply
Attach and Default Bearer Activation
Triggering of Dedicated Bearer
activation
RRC: UL NAS INFO TRANSFER + ESM BEARER RESOURCE ALLOCATION REQUEST S1AP: UL NAS TRANSPORT (ESM BEARER RESOURCE ALLOCATION REQUEST)
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LTE完整业务流程
• 专用承载建立流程
Dedicated Bearer Establishment： E-RAB建立
UE
eNB
MME
P-GW
S1AP: UL NAS TRANSPORT (ESM ACTIVATE DEDICATED BEARER REQUEST ACCEPT)
释放流程及异常释放原因分析
• 主要内容
- 业务承载类型及业务建立过程 - 业务释放类型及相应流程、原因
• E-RAB release
• UE context release
RRC: RRCConnectionReconfiguration + EMM ATT_ACC + ESM ACT_DEF_BEAR_REQ
RRC: RRCConnectionReconfigurationComplete
S1 AP :
INITIAL CONTEXT SETUP RESPONSE
S1AP: UE CAPABILITY INFO INDICATION
RRC: UECapabilityEnquiry
RRC: Security Command Complete RRC: UECapabilityInformation
UE radio capabilities available à DRB can be established
DRB and SRB2 ConfigurationΒιβλιοθήκη Create Bearer