LTE System Signaling Procedures Huawei eNODEb

2010-09

Security Level: Internal Use

LTE system signaling procedure www.huawei.com

Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.

Objectives 

Upon completion of this course, you will be able to ： 

Know the LTE/SAE system architecture and functions



Know main elementary procedures of S1/X2/Uu interfaces



Know the procedure of service setup, service release, intra-

eUTRAN handover


Page2

References 

3GPP TS 36.300



3GPP TS 23.401



3GPP TS 36.413



3GPP TS 36.331



3GPP TS 36.423


Page3

Contents 1. Overview 2. Elementary Procedures

3. Service signaling flow


Page4




Page5

System Architecture Overview 



Main functions of the Serving GW is: 

the local Mobility Anchor point for handover (inter-eNodeB/inter-3GPP)



Packet routeing and forwarding

Main functions of the PDN GW is: 

UE IP address allocation



UL and DL service level charging UTRAN SGSN HSS

GERAN S3 S1-MME

S6a MME

PCRF S11

S10

LTE-Uu UE

S12 S4 Serving Gateway

E-UTRAN

S5

Rx

Gx PDN Gateway

SGi

S1-U


Page6

Operator's IP Services (e.g. IMS, PSS etc.)

Bearer service architecture 





A radio bearer transports the packets of an EPS bearer between a UE and an eNB. There is a one-to-one mapping between an EPS bearer and a radio bearer. An S1 bearer transports the packets of an EPS bearer between an eNodeB and a Serving GW An eNB stores a one-to-one mapping between a radio bearer and an S1 to create the binding between a radio bearer and an S1 bearer in both the uplink and downlink.


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Service request procedure


Page8

Bearer level QoS 

Basically, bearers can be classified into two categories  



GBR bearers Non-GBR bearers

Each bearer has an associated QoS Class Identifier (QCI), and an Allocation and Retention Priority (ARP) 

 

QoS Class Identifier (QCI) 

QCI is characterized by priority, packet delay budget and acceptable packet loss rate



QCI is used to control bearer level packet forwarding treatment



The set of standardized QCIs is listed in the table of next page

The ARP of a bearer is used for call admission control A GBR bearer is additionally associated with the following bearer level QoS parameters: 

Guaranteed Bit Rate (GBR)



Maximum Bit Rate (MBR)


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Bearer level QoS(Cont.) 

The set of standardized QCIs


Page10

Application protocol identities 

EPS bearer identity   



eNB UE S1AP ID 



An Old eNB UE X2AP ID shall be allocated so as to uniquely identify the UE over the X2 interface within a source eNB

New eNB UE X2AP ID 



A MME UE S1AP ID shall be allocated so as to uniquely identify the UE over the S1 interface within the MME

Old eNB UE X2AP ID 



A eNB UE S1AP ID shall be allocated so as to uniquely identify the UE over the S1 interface within an eNB

MME UE S1AP ID 



An EPS bearer identity uniquely identifies an EPS bearer for one UE accessing via E-UTRAN The EPS Bearer Identity is allocated by the MME There is one to one mapping between EPS RB and EPS Bearer, and the mapping between EPS RB Identity and EPS Bearer Identity is made by E-UTRAN

An New eNB UE X2AP ID shall be allocated so as to uniquely identify the UE over the X2 interface within a target eNB

C-RNTI: The C-RNTI provides a unique UE identification at the cell level identifying RRC Connection and used for scheduling


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Page12

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


Page13

UE states 



RRC_IDLE 

A UE specific DRX may be configured by upper layers



UE controlled mobility



The UE: 

Monitors a Paging channel to detect incoming calls;



Performs neighbouring cell measurements and cell (re-)selection;



Acquires system information.

RRC_CONNECTED 

Transfer of unicast data to/from UE.



At lower layers, the UE may be configured with a UE specific DRX.



Network controlled mobility



The UE: 

Monitors control channels associated with the shared data channel to determine if data is scheduled for it;



Provides channel quality and feedback information;



Performs neighbouring cell measurements and measurement reporting;



Acquires system information


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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. the following

three SRBs are defined: 

SRB0 is for RRC messages using the CCCH logical channel;



SRB1 is for RRC messages as well as for NAS messages prior to the

establishment of SRB2, all using DCCH logical channel; 

SRB2 is for NAS messages, using DCCH logical channel. SRB2 has a lowerpriority than SRB1 and is always configured by E-UTRAN after security activation


Page15

System information UE

E-UTRAN

MasterInformationBlock SystemInformationBlockType1

SystemInformation



System information is divided into the MasterInformationBlock (MIB) and a number of SystemInformationBlocks (SIBs).



The MIB includes a limited number of most essential and most frequently

transmitted parameters that are needed to acquire other information from the cell, and is transmitted on BCH 

SystemInformationBlockType1 and all SI messages are transmitted on DL-

SCH Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.

Page16

Paging UE

EUTRAN

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

Main IE: 

ue-Identity



cn-Domain



pagingCause



systemInfoModification



ETWS notification


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RRC connection establishment UE

EUTRAN

UE

EUTRAN

RRCConnectionRequest

RRCConnectionRequest

RRCConnectionSetup

RRCConnectionSetupComplete



Purpose: 



RRCConnectionReject

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

Main IE: 

establishmentCause



radioResourceConfiguration for Only SRB1



selectedPLMN-Identity



registeredMME



nas-DedicatedInformation


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Initial security activation UE

EUTRAN

SecurityModeCommand

UE

EUTRAN

SecurityModeCommand

SecurityModeComplete





SecurityModeFailure

Purpose: 

To activate AS security upon RRC connection establishment



When only SRB1 is established and prior to establishment of SRB2 and/ or DRBs.

Main IE: 

integrity protection and ciphering


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RRC connection reconfiguration UE

EUTRAN

RRCConnectionReconfiguration

UE


RRCConnectionReconfigurationComplete



RRC connection re-establishment

Purpose: 



EUTRAN

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

Main IE: 

measurementConfiguration



mobilityControlInformation



nas-DedicatedInformation



radioResourceConfiguration (for SRB2 and possibly DRBs)



securityConfiguration



ue-RelatedInformation


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RRC connection release UE

EUTRAN

RRCConnectionRelease



Purpose: 

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


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Mobility from E-UTRA UE

EUTRAN

MobilityFromEUTRACommand



Purpose: 

To move a UE in RRC_CONNECTED to a cell using another Radio Access Technology (RAT), e.g. GERAN, UTRA or CDMA2000 systems



The mobility from E-UTRA procedure covers both: 

handover, i.e. the MobilityFromEUTRACommand message includes radio resources that have been allocated for the UE in the target cell



cell change order, i.e. the MobilityFromEUTRACommand message may include information facilitating access of and/ or connection establishment in the target cell, e.g. system information. Cell change order is applicable only to GERAN.


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DL/UL information transfer UE

EUTRAN

DLInformationTransfer

UE

EUTRAN

ULInformationTransfer



Purpose: 

To transfer NAS or non-3GPP dedicated information from E-UTRAN/UE to a UE/E-UTRAN in RRC_CONNECTED


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UE capability transfer UE

EUTRAN

UECapabilityEnquiry

UECapabilityInformation



Purpose: 

To transfer UE radio access capability information from the UE to E-UTRAN


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Contents 2. Elementary Procedures 2.1 Elementary Procures of Uu

2.2 Elementary Procedures of S1 2.3 Elementary Procures of X2


Page25

Paging eNB

MME

PAGING



Purpose: 



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

Main information: 

UE Paging ID



Paging DRX



Paging Cause



List of TAIs


Page26

Context Management procedures eNB

MME

INITIAL CONTEXT SETUP REQUEST

INITIAL CONTEXT SETUP RESPONSE



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

Main information: 

SAE Bearer Level QoS parameters



Transport Layer Address



NAS-PDU



Security



Handover Restriction List



UE Radio Capability



Subscriber Profile ID for RAT/Frequency priority


Page27

SAE Bearer Management procedures eNB

MME

SAE BEARER SETUP REQUEST

SAE BEARER SETUP RESPONSE



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

Main information : 

SAE Bearer Level QoS parameters



Transport Layer Address



NAS-PDU



SAE Bearer Setup List



SAE Bearer Failed to Setup List


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NAS transport eNB

MME

INITIAL UE MESSAGE



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 also

Main IE: 

NAS-PDU



TAI



E-UTRAN CGI



S-TMSI (optional)



Handover Restriction List in DOWNLINK NAS TRANSPORT (optional)


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S1 Setup eNodeB



MME

MME

S1 SETUP REQUEST

S1 SETUP REQUEST

S1 SETUP RESPONSE

S1 SETUP FAILURE

Purpose: 





eNodeB

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

Main IE: 

Global eNB ID

MME Name



eNB Name

Served PLMNs



Supported TAs of the eNodeB

Served GUMMEIs


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MME/eNodeB Configuration Update eNB

MME

MME

ENB CONFIGURATION UPDATE

ENB CONFIGURATION UPDATE

ENB CONFIGURATION UPDATE ACKNOWLEDGE

ENB CONFIGURATION UPDATE FAILURE

eNB



eNB

MME

eNB

MME

MME CONFIGURATION UPDATE

MME CONFIGURATION UPDATE

MME CONFIGURATION UPDATE ACKNOWLEDGE

MME CONFIGURATION UPDATE FAILURE

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. 

This procedure doesn’t affect existing UE-related contexts


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Contents 2. Elementary Procedures 2.1 Elementary Procures of Uu

2.2 Elementary Procedures of S1 2.3 Elementary Procures of X2


Page32

Handover Preparation source eNB

target eNB HANDOVER REQUEST

HANDOVER REQUEST ACKNOWLEDGE



target eNB HANDOVER REQUEST

HANDOVER PREPARATION FAILURE

Purpose: 



source eNB

To establish necessary resources in an eNB for an incoming handover

Main IE: 

Cause



Target Cell ID and GUMMEI



SAE Bearer Info


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SN Status Transfer source eNB

target eNB 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 

Main IE: 

SAE Bearers Subject To Status Transfer List


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UE Context Release source eNB

target eNB 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


Page35

Load Indication eNB1

eNB2 LOAD INFORMATION



Purpose: 

To transfer load and interference co-ordination information between intrafrequency neighboring eNBs



Main IE: 

UL Interference Overload Indication



UL High Interference Indication



Relative Narrowband Tx Power (RNTP)


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Resource Status Reporting Initiation /Reporting eNB1

eNB2

eNB1

eNB2

RESOURCE STATUS REQUEST RESOURCE STATUS UPDATE

RESOURCE STATUS RESPONSE



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


Page37

X2 Setup eNB2

eNB1



eNB2

eNB1

X2 SETUP REQUEST

X2 SETUP REQUEST

X2 SETUP RESPONSE

X2 SETUP FAILURE

Purpose: 

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



Main IE: 

Served Cell Information 

PhyCID and Cell ID (CGI)



TAC



Broadcast PLMNs



UL EARFCN/DL EARFCN and Cell Transmission Bandwidth


Page38

BB




Page39

Service request procedure UE

E-NODEB

MME PAGING

RRC PAGING

NAS: Service request

RRC CONN SETUP REQ


RRC CONN SETUP

eNB S1 signaling connection ID

RRC CONN SETUP CMP INITIAL UE MESSAGE

MME S1 signaling connection ID

1.直直直直直直直直直直直直直 authentication INITIAL UE CONTEXT SETUP REQ

SRB2 setup DRB1 setup


RRC SECURITY MODE CMD

Security context UE capability information

RRC SECURITY MODE CMP

Bearer setup (Qos profile, S-GW TEID)

RRC CONN RECFG

eNB S1 signaling connection ID RRC CONN RECFG CMP

Uplink data could be sent INITIAL UE CONTEXT SETUP RSP

bearer confirm (eNB TEID)

Downlink data could be sent 直直直直直直直直直直直直直直直 2. NAS message (service negotiation)

NAS: Session management request

SAEB SETUP REQ RRC CONN RECFG RRC CONN RECFG CMP

DRB2 setup

SAEB SETUP RSP

Uplink information transfer

NAS: Session management response

UPLINK NAS TRANSPORT


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RRC CONN SETUP REQ


Page 41

RRC CONN SETUP


Page 42

RRC CONN SETUP CMP


Page 43

Direct transfer message of S1interface Initial UE Message eNB UE S1AP ID NAS-PDU TAI E-UTRAN CGI S-TMSI (O) CSG Identity (O) RRC Establishment cause GUMMEI (O) eNB

MME Initial UE Message


Page 44

Direct transfer message of S1interface


Page 45

Direct transfer (Authentication & ciphering) Uu interface trace

S1 interface trace


Page 46

S1 Initial Context Setup Request


Page 47

S1 Initial Context Setup Request


Page 48

RRC Security Mode Command Security Mode Command Ciphering Algorithm Integrity Protection Algorithm UE

eNB Security Mode Command Security Mode Complete Security Mode Failure


Page 49

UE capability report UE

EUTRAN

UECapabilityEnquiry

UECapabilityInformation


Page 50

RRC connection reconfiguration Used to establish SRB2 and default DRB1. UE

EUTRAN


RRCConnectionReconfigurationComplete


Page 51

INITI UE CONTEXT SETUP RSP

eNB

Initial Context Setup Response MME UE S1AP ID eNB UE S1AP ID E-RAB Setup List - E-RAB ID - Transport Layer Address - GTP-TEID E-RAB Failed to Setup List (O) Criticality Diagnostics (O)

MME

S-GW

Initial Context Setup Request Modify Bearer

Initial Context Setup Response eNB Address and TEID

S-GW Address and TEID

E-RAB ID = 5


Page 52

INITI UE CONTEXT SETUP RSP


Page 53

Service request procedure Uu interface trace

S1 interface trace


Page 54

S1 release procedure UE

eNodeB

MME

Serving GW

1. S1-AP: S1 UE Context Release Request 2. Update Bearer Request 3. Update Bearer Response 4. S1-AP: S1 UE Context Release Command

5. RRC Connection Release 6. S1-AP: S1 UE Context Release Complete



Purpose: 

To release the logical S1-AP signalling connection (over S1-MME) and all S1 bearers (in S1-U) for a UE. The procedure will move the UE from ECMCONNECTED to ECM-IDLE in both the UE and MME, and all UE related context information is deleted in the eNodeB


Page55

Intra EUTRAN X2-based handover without Serving GW relocation UE

Target eNodeB

Source eNodeB

MME

Serving GW

PDN GW

Downlink and uplink data Measurement report Handover decision

Handover request

Handover request ack Handover command

Forwarding of data

Handover completion

Downlink data

Uplink data 1 Path Switch Request 2 User Plane Update Request 3 User Plane Update Response Downlink data 4. End marker

4. End marker 5 Path Switch Request Ack 6 Release Resource

7. Tracking Area Update procedure



See notes for details


Page56

Intra EUTRAN X2-based handover with Serving GW relocation UE

Target eNodeB

Source eNodeB

MME

Source Target Serving GW Serving GW

PDN GW

Downlink and uplink data Handover preparation

Handover execution Forwarding of data

Handover completion

Downlink data

Uplink data 1. Path Switch Request 2. Create Bearer Request 4. Create Bearer Response

3a. Update Bearer Request (A) 3b. Update Bearer Response

Downlink data 5. Path Switch Request Ack Uplink data 6. Release Resource 7a. Delete Bearer Request

(B) 7b. Delete Bearer Response

8. Tracking Area Update procedure


Page57

Intra EUTRAN S1-based handover UE

Source eNodeB

Source Target MME eNodeB Downlink User Plane data

Target MME

Source Serving GW

Target Serving GW

PDN GW

1. Decision to trigger a relocation via S1 2. Handover Required 3. Forward Relocation Request 4. Create Bearer Request 5. Handover Request

4a. Create Bearer Response

5a Handover Request Acknowledge 6. Create Bearer Request 6a. Create Bearer Response 7. Forward Relocation Response 8.. Create Bearer Request 8a. Create Bearer Response 9. Handover Command 10. Handover Command 11a. Only for Direct forwarding of data 11b. Only for Indirect forwarding of data Detach from old cell and synchronize to new cell 12. Handover Confirm Downlink data

Uplink User Plane data 13. Handover Notify


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HSS

Intra EUTRAN S1-based handover UE

Source eNodeB

Target eNodeB

Source MME

Target MME

Source Serving GW

Target Serving GW

PDN GW

HSS

14. Forward Relocation Complete 14b. Forward Relocation Complete Acknowledge 15. Update Bearer Request 16. Update Bearer Request

(A) 16a. Update Bearer Response

17. Update Bearer Response Downlink User Plane data 18. Tracking Area Update procedure 19c. Delete Bearer Request 19a. UE Context Release Command

(B) 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


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LTE System Signaling Procedures Huawei eNODEb

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