OEA300020 LTE Signaling Flow ISSUE 1.00.ppt

LTE Signaling Flow
Describe the LTE/SAE system architecture and functions
Describe main elementary procedures of S1/X2/Uu interfaces
Describe the procedure of service setup, service release, intra-eUTRAN handover

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Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved.
英文标题 :40-47pt
副标题:26-30pt
字体颜色 :反白
内部使用字体 :
FrutigerNext LT Medium
外部使用字体 : Arial
中文标题 :35-47pt
字体:黑体
副标题:24-28pt
字体颜色 :反白
字体:细黑体
LTE Signaling
Flow

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References

3GPP TS 36.300

3GPP TS 23.401

3GPP TS 36.413

3GPP TS 36.331

3GPP TS 36.423

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Objectives

Upon completion of this course, you will be able to:

Describe the LTE/SAE system architecture and functions

Describe main elementary procedures of S1/X2/Uu
interfaces

Describe the procedure of service setup, service release,
intra-eUTRAN handover

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Contents
1.Overview
2.Elementary Procedures
3.Service signaling flow

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System Architecture Overview

SGi
S12
S3
S1-MME
PCRF
Gx
S6a
HSS
Operator's IP
Services
(e.g. IMS, PSS etc.)
Rx
S10
UE
SGSN
LTE-Uu
E-UTRAN
MME
S11
S5 Serving
Gateway
PDN
Gateway
S1-U
S4
UTRAN
GERAN

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Bearer service architecture

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Bearer level QoS

The bearer level QoS parameters are QCI, ARP, GBR, and AMBR

QoS Class Identifier (QCI)

A reference to access node-specific parameters that control bearer level
packet forwarding treatment (e.g. scheduling weights, admission
thresholds, queue management thresholds, link layer protocol
configuration, etc.)

ARP is the Priority of Allocation and Retention

A GBR bearer is additionally associated with the following bearer level
QoS parameters:

Guaranteed Bit Rate (GBR)

Maximum Bit Rate (MBR)

AMBR denotes a bit rate of traffic per group of bearers

8. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page9
Application protocol identities

EPS bearer identity

eNB UE S1AP ID

MME UE S1AP ID

Old eNB UE X2AP ID

New eNB UE X2AP ID

C-RNTI

9. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page10
Contents
1.Overview
2.Elementary Procedures
3.Service signaling flow

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Contents
2. Elementary Procedures
2.1 Elementary Procedures of S1
2.2 Elementary Procures of Uu
2.3 Elementary Procures of X2

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Paging

Purpose

The purpose of the Paging procedure is to enable the MME
to page a UE in the specific eNB

PAGING
eNB MME

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Context Management
procedures

Purpose

To establish the necessary overall initial UE Context
including SAE Bearer context, Security context, Handover
Restriction List, UE capability information, NAS-PDU etc

Other message in this category includes: UE Context
Release Request /release/modify

INITIAL CONTEXT SETUP RESPONSE
INITIAL CONTEXT SETUP REQUEST
eNB MME

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SAE Bearer Management procedures

Purpose

To assign resources on Uu and S1 for one or several SAE
bearers and to setup corresponding SAE Radio Bearers for
a given UE

Other message in this category includes: SAE bearer
modify and SAE bearer release

SAE BEARER SETUP RESPONSE
SAE BEARER SETUP REQUEST
eNB MME

14. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page15
NAS transport

Purpose

The purpose of the NAS Transport procedure is to carry UE
– MME signalling over the S1 Interface.

The NAS messages are not interpreted by the eNB

Besides INITIAL UE MESSAGE, DOWNLINK NAS TRANSPORT
and UPLINK NAS TRANSPORT messages are used for NAS
Transport procedure

INITIAL UE MESSAGE
eNB MME

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Handover Signalling

Purpose

The purpose of the Handover Preparation procedure is to
request the preparation of resources at the target side via
the EPC.

source
eNodeB
HANDOVER REQUIRED
MME
HANDOVER COMMAND

HANDOVER REQUIRED
MME
HANDOVER PREPARATION FAILURE
source
eNodeB

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Handover Signalling

Purpose

The purpose of the Handover Resource Allocation
procedure is to reserve resources at the target eNodeB for
the handover of a UE

HANDOVER REQUEST
MME
HANDOVER REQUEST ACKNOWLEDGE
target
eNodeB

HANDOVER REQUEST
MME
HANDOVER FAILURE
target
eNodeB

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Handover Signalling

Purpose

The target eNodeB shall send the HANDOVER NOTIFY
message to the MME when the UE has been identified in
the target cell and the S1 handover has been successfully
completed.

HANDOVER NOTIFY
MME
target
eNodeB

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Handover Signalling

Purpose

The purpose of the Path Switch Request procedure is to
request the switch of a downlink GTP tunnel towards a new
GTP tunnel endpoint

eNodeB
PATH SWITCH REQUEST
MME
PATH SWITCH REQUEST ACKNOWLEDGE

PATH SWITCH REQUEST
MME
PATH SWITCH REQUEST FAILURE
eNodeB

19. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page20
S1 Setup

Purpose

The purpose of the S1 Setup procedure is to exchange
application level data needed for the eNodeB and MME to
interoperate correctly on the S1 interface.

This procedure shall be the first S1AP procedure triggered
after the TNL association has become operational

eNodeB
S1 SETUP REQUEST
MME
S1 SETUP RESPONSE

eNodeB
S1 SETUP REQUEST
MME
S1 SETUP FAILURE

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MME/eNodeB Configuration Update

Purpose

The purpose of the MME/ eNB Configuration Update
procedure is to update application level configuration data
needed for the eNB and MME to interoperate correctly on
the S1 interface.

eNB
ENB CONFIGURATION UPDATE
MME
ENB CONFIGURATION UPDATE ACKNOWLEDGE

eNB
ENB CONFIGURATION UPDATE
MME
ENB CONFIGURATION UPDATE FAILURE

eNB
MME CONFIGURATION UPDATE
MME
MME CONFIGURATION UPDATE ACKNOWLEDGE

eNB
MME CONFIGURATION UPDATE
MME
MME CONFIGURATION UPDATE FAILURE

21. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page22
Contents
2. Elementary Procedures
2.1 Elementary Procedures of S1
2.2 Elementary Procures of Uu
2.3 Elementary Procures of X2

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UE states

RRC_IDLE

RRC_CONNECTED

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Signalling radio bearers

"Signalling Radio Bearers" (SRBs) are defined as Radio
Bearers (RB) that are used only for the transmission of
RRC and NAS messages.

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System information

E-UTRAN
MasterInformationBlock
UE
SystemInformationBlockType1
SystemInformation

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Paging

Purpose

To transmit paging information to a UE in RRC_IDLE and/ or
to inform UEs in RRC_IDLE and UEs in RRC_CONNECTED
about a system information change or about an ETWS
(Earthquake and Tsunami Warning System ) primary
notification

Paging
UE EUTRAN

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RRC connection establishment

Purpose

RRC connection establishment involves SRB1
establishment. The procedure is also used to transfer the
initial NAS dedicated information/ message from the UE to
E-UTRAN

RRCConnectionSetup
RRCConnectionRequest
UE EUTRAN
RRCConnectionSetupComplete

RRCConnectionReject
RRCConnectionRequest
UE EUTRAN

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Initial security activation

Purpose

To activate AS security upon RRC connection establishment

When only SRB1 is established and prior to establishment
of SRB2 and/ or DRBs.

SecurityModeComplete
SecurityModeCommand
UE EUTRAN

SecurityModeFailure
SecurityModeCommand
UE EUTRAN

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RRC connection reconfiguration

Purpose

To modify an RRC connection, e.g. to establish/ modify/
release RBs, to perform handover, to setup/ modify/
release measurements

RRCConnectionReconfigurationComplete
RRCConnectionReconfiguration
UE EUTRAN

RRC connection re-establishment
RRCConnectionReconfiguration
UE EUTRAN

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RRC connection release

Purpose

To release the RRC connection, which includes the release
of the established radio bearers as well as all radio
resources

RRCConnectionRelease
UE EUTRAN

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Mobility from E-UTRA

Purpose

To move a UE in RRC_CONNECTED to a cell using another
Radio Access Technology (RAT), e.g. GERAN, UTRA or
CDMA2000 systems

MobilityFromEUTRACommand
UE EUTRAN

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DL/UL information transfer

Purpose

To transfer NAS or non-3GPP dedicated information from
E-UTRAN/UE to a UE/E-UTRAN in RRC_CONNECTED

DLInformationTransfer
UE EUTRAN

ULInformationTransfer
UE EUTRAN

32. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page33
UE capability transfer

Purpose

To transfer UE radio access capability information from the
UE to E-UTRAN

UECapabilityInformation
UECapabilityEnquiry
UE EUTRAN

33. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page34
Contents
2. Elementary Procedures
2.1 Elementary Procedures of S1
2.2 Elementary Procures of Uu
2.3 Elementary Procures of X2

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Handover Preparation

Purpose

To establish necessary resources in an eNB for an incoming
handover

source
eNB
HANDOVER REQUEST
HANDOVER REQUEST ACKNOWLEDGE
target
eNB

source
eNB
HANDOVER REQUEST
HANDOVER PREPARATION FAILURE
target
eNB

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SN Status Transfer

Purpose

To transfer the uplink PDCP-SN and HFN receiver status
and the downlink PDCP-SN and HFN transmitter status
from the source to the target eNB during an X2 handover
for each respective SAE bearer for which PDCP SN and HFN
status preservation applies

source
eNB
SN STATUS TRANSFER
target
eNB

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UE Context Release

Purpose

To signal to the source eNB that control plane resources
for the handed over UE context can be released

Upon reception of the UE CONTEXT RELEASE message, the
source eNB can release radio and control plane related
resources associated to the UE context

source
eNB
UE CONTEXT RELEASE
target
eNB

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Handover Cancel

Purpose

To cancel an already prepared handover

source
eNB
HANDOVER CANCEL
target
eNB

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Load Indication

Purpose

To transfer load and interference co-ordination
information between intra-frequency neighboring eNBs

eNB1
LOAD INFORMATION
eNB2

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X2 Setup

Purpose

To exchange application level data needed for two eNBs to
interoperate correctly over the X2 interface

eNB1
X2 SETUP REQUEST
eNB2

X2 SETUP RESPONSE

eNB1
X2 SETUP REQUEST
eNB2


BB
X2 SETUP FAILURE

40. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page41
Resource Status Reporting
Initiation /Reporting

Purpose

To request the reporting of load measurements to another
eNB

And to report the result of measurements requested by
eNB1 using the Resource Status Reporting Initiation

eNB1 eNB2
RESOURCE STATUS REQUEST
RESOURCE STATUS RESPONSE

eNB1 eNB2
RESOURCE STATUS UPDATE

41. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page42
Contents
1.Overview
2.Elementary Procedures
3.Service signaling flow

42. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page43
Service request procedure
UE E-NODEB MME
RRC CONN SETUP REQ
RRC CONN SETUP
RRC CONN SETUP CMP
INITIAL UE MESSAGE
INITIAL UE CONTEXT SETUP REQ
RRC SECURITY MODE CMD
RRC SECURITY MODE CMP
RRC CONN RECFG
RRC CONN RECFG CMP
INITIAL UE CONTEXT SETUP RSP
SAEB SETUP REQ
RRC CONN RECFG
RRC CONN RECFG CMP
SAEB SETUP RSP
直传过程 （鉴权、业务协商 ）
直传过程 （业务协商、流程通知）
PAGING
RRC PAGING
NAS: Service request
NAS: Service request
eNB S1 signaling connection ID
NAS: Service request
MME S1 signaling connection ID
Security context
UE capability information
Bearer setup (Qos profile, S-GW TEID)
1. authentication
Uplink data could be sent
eNB S1 signaling connection ID
bearer confirm (eNB TEID)
NAS: Session management request
Downlink data could be sent
Uplink information transfer
UPLINK NAS TRANSPORT
NAS: Session management response
SRB2 setup
DRB1 setup
DRB2 setup
2. NAS message (service negotiation)

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S1 release procedure

1. S1-AP: S1 UE Context Release Request
MME
5. RRC Connection Release
UE eNodeB Serving GW
2. Update Bearer Request
3. Update Bearer Response
4. S1-AP: S1 UE Context Release Command
6. S1-AP: S1 UE Context Release Complete

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Intra EUTRAN X2-based handover
without Serving GW relocation

Handover completion
UE
Source
eNodeB
Serving
GW PDN GW MME
Target
eNodeB
Downlink and uplink data
Forwarding of data
Downlink data
Uplink data
1 Path Switch Request
2 User Plane Update Request
3 User Plane Update Response
5 Path Switch Request Ack
6 Release Resource
Downlink data
4. End marker
4. End marker
7. Tracking Area Update procedure
Handover decision
Measurement report
Handover request
Handover request ack
Handover command

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Handover completion
UE
Source
eNodeB
Source
Serving GW PDN GW
MME
Target
Serving GW
Target
eNodeB
Handover execution
3a. Update Bearer Request
Downlink and uplink data
Handover preparation
Forwarding of data
Downlink data
Uplink data
1. Path Switch Request
3b. Update Bearer Response
2. Create Bearer Request
4. Create Bearer Response
5. Path Switch Request Ack
6. Release Resource
Downlink data
Uplink data
7a. Delete Bearer Request
7b. Delete Bearer Response
(A)
(B)
8. Tracking Area Update procedure
Intra EUTRAN X2-based handover
with Serving GW relocation

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UE
Source
eNodeB
Source
MME
Source
Serving GW PDN GW
Target
MME
Target Serving
GW
Target
eNodeB
Detach from old cell and
synchronize to new cell
HSS

2. Handover Required
Downlink User Plane data
1. Decision to trigger a
relocation via S1
3. Forward Relocation Request
5. Handover Request
5 a Handover Request Acknowledge
7. Forward Relocation Response
9. Handover Command
10. Handover Command
11a. Only for Direct forwarding of data
12. Handover Confirm
Downlink data
13. Handover Notify
.
8a. Create Bearer Response
11b. Only for Indirect forwarding of data
Uplink User Plane data
8. Create Bearer Request
6a. Create Bearer Response
6. Create Bearer Request
4a. Create Bearer Response
4. Create Bearer Request
Intra EUTRAN S1-based handover

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Intra EUTRAN S1-based handover

UE
Source
eNodeB
Source
MME
Source
Serving GW PDN GW
Target
MME
Target Serving
GW
Target
eNodeB HSS
16. Update Bearer Request
17. Update Bearer Response
15. Update Bearer Request
Downlink User Plane data
14. Forward Relocation Complete
14b. Forward Relocation Complete Acknowledge
16a. Update Bearer Response
(A)
18. Tracking Area Update procedure
19c. Delete Bearer Request
(B)
19a. UE Context Release Command
19b. UE Context Release Complete
19d. Delete Bearer Response
20a. Delete Bearer Request
20b. Delete Bearer Response
21a. Delete Bearer Request
21b. Delete Bearer Response

48. Copyright © 2014 Huawei Technologies Co., Ltd. All rights reserved. Page49
Summary

LTE/SAE System Architecture

RRC Setup procedure

SAE Bearer Management procedures

Paging procedure

Handover Signalling

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