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
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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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Contents 1. Overview 2. Elementary Procedures
3. Service signaling flow
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Contents 1. Overview 2. Elementary Procedures
3. Service signaling flow
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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
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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
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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
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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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Contents 1. Overview 2. Elementary Procedures
3. Service signaling flow
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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
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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
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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-
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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
RRCConnectionReconfiguration
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
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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
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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
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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
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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
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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
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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
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BB
Contents 1. Overview 2. Elementary Procedures
3. Service signaling flow
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Service request procedure UE
E-NODEB
MME PAGING
RRC PAGING
NAS: Service request
RRC CONN SETUP REQ
NAS: Service request
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
NAS: Service request
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
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RRC CONN SETUP
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RRC CONN SETUP CMP
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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
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Direct transfer message of S1interface
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Direct transfer (Authentication & ciphering) Uu interface trace
S1 interface trace
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S1 Initial Context Setup Request
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S1 Initial Context Setup Request
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RRC Security Mode Command Security Mode Command Ciphering Algorithm Integrity Protection Algorithm UE
eNB Security Mode Command Security Mode Complete Security Mode Failure
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UE capability report UE
EUTRAN
UECapabilityEnquiry
UECapabilityInformation
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RRC connection reconfiguration Used to establish SRB2 and default DRB1. UE
EUTRAN
RRCConnectionReconfiguration
RRCConnectionReconfigurationComplete
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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
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INITI UE CONTEXT SETUP RSP
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Service request procedure Uu interface trace
S1 interface trace
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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
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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
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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
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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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