07 UMTS UTRAN Signaling Procedures

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UMTS UTRAN Signaling Procedures


1 1 UTRAN System Architecture and UTRAN System Architecture and

Protocol StackProtocol Stack

2 Basic Terms Related to the UTRAN2 Basic Terms Related to the UTRAN

3 Basic Signaling Procedures3 Basic Signaling Procedures


UTRAN System Architecture

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub


WCDMA Protocol Architecture

AAL5

RANAPSCCP

Relay

RRCRLC

MAC

L1

RANAPSCCP

AAL5

Uu IuUE RNS MSC/

SGSNN

SignallingBearer

RRCRLC

MACSignalling

Bearer

ATM

L1

ATM

SMS /GMM / MM

SMS /GMM / MM


Comparison: GSM-BSS Protocol Architecture

CM

MM

RR

LAPDm

SigL1

L3

L2

L1

MS

RR BTSM

LAPDm

SigL1

LAPD

SigL1

LAPD

SigL1

BTSM

RR

SCCP

MTP

BSSMAP

CM

MM

BSSMAP

SCCP

MTP

MSCBSCBTS

Um接接 A接接Abis接接


Protocol Architecture for the RNC Control Plane

Node B

RNC

CN

UE

RANAP

NBAP

RNSAPRRC

NBAP ：Node B Application PartRANAP：Radio Access Network Application PartRNSAP：Radio Network Subsystem Application PartRRC ：Radio Resource Control

RNC


Summary

� This part describes the UTRAN

system architecture and the protocol

architecture.


1 UTRAN System Architecture and 1 UTRAN System Architecture and





Basic Terms� UTRAN：provides setup, maintenance, and release of radio access

bearer (RAB) for the Non-Access Stratum (NAS) to shield the focus of

the NAS on the features of the radio access stratum.

� Other terms: UTRAN, RAB, RB, and RL

RAB

RB

RLNodeB

RNC CNUE

UTRAN


Basic Terms

� RAB: The service that the access stratum provides to

the Non-Access Stratum (NAS) for transfer of user data

between User Equipment and CN.

� RB：The service provided by the Layer 2 for transfer of

user data between User Equipment and SRNC.

� RL: A "radio link" is a logical association between single User

Equipment and a single UTRAN access point. Its physical

realisation comprises one or more radio bearer transmissions.


CELL_DCH CELL_FACH

CELL_PCHURA_PCH

IDLE

DEAD - Searching for the network (PLMN)- Camp on the cell

- Monitoring paging channel- Cell reselection

- Dedicated channel - Radio bearers transmission servcie

- Reducing actions, DRX, and saving power

RRC connection

These states are significant only for UTRAN and UE. They are transparent to

CN.

UE States


Working Modes of the UE

� The UE has two working modes: idle mode and connected mode.

� Idle mode: The UE is in the standby state and has no service for

processing. In addition, no connection exists between the UE and

UTRAN, and the UTRAN does not contain any information about the UE. The UE is identified by the NAS identifiers, such as the IMSI,

TMSI, or P-TMSI.

� Connected mode: When the UE completes the RRC connection setup, the UE changes from the idle mode to the connected mode.

In Connected mode, the UE has four states: Cell-DCH, Cell-FACH,

Cell-PCH, and URA-PCH.


UE States in Connected Mode

� Cell-DCH：The UE is in the active state. It communicates over the dedicated

channel. The UE has a dedicated channel in both the uplink and

downlink. The UTRAN accurately knows the cell on which the UE

camps.

� Cell-FACH

The UE is in the active state, but it has few data to send in both the uplink and downlink. It is not required to allocate a dedicated

channel for the UE. The downlink data is transmitted over the FACH,

and the uplink data is transmitted over the RACH. The UE needs to monitors the FACH in the downlink at any time for its information.

The UTRAN accurately knows the cell on which the UE camps and

maintains the resources for the UE and its state.


UE States in Connected Mode

� Cell-PCH

The UE has no data to send in the uplink and downlink. It needs to monitor the PICH for receiving paging messages. Therefore, the UE

enters the discontinuous reception, which saving the power.

The UTRAN knows which cell that the UE camps on. Thus, after theUE roams to another cell, the UTRAN needs to update the cell

information of the UE.

� URA-PCHThe UE has no data to send in the uplink and downlink. It needs to

monitor the PICH and enters the discontinuous reception. The

UTRAN knows only the UTRAN registration area (URA) of the UE. A URA contains multiple cells. That is, the UTRAN updates the

location information only after the URA where the UE is located

changes, thus saving resources and reducing signaling.


Serving RNC and Drift RNC

� In the WCDMA system, the SRNC and DRNC are introduced due to the Iur interface.

� The SRNC and DRNC correspond to a specific UE.

� For connections between a UE and the CN, the RNC that is directly connected the CN and controls all resources of the UE is called the SRNC. The RNC that has no direct connection with the CN and only provides resources for the UE is called DRNC.

� A UE in connection state has at least one and only one SRNC, but can have no or

multiple DRNCs.

CN

SRNC DRNC

IuIur


CRNC

� The controller RNC (CRNC) corresponds to a NodeB or cell.

� The RNC that is directly connected to a NodeB and controls the usage of resources of the NodeB is called the CRNC.

� A NodeB corresponds to one and only one CRNC.

� The CRNC allocates the resources of all the NodeBs controlled bythe CRNC properly.

Iub

Node B

Cell Cell Cell

Node B

...

Iu

CRNC

CN


Summary

� This part describes some terms related to the UTRAN.


1 UTRAN System Architecture and 1 UTRAN System Architecture and





Basic Signaling Procedures

�� System Information System Information

BroadcastingBroadcasting

�� PagingPaging

�� Paging ProcedurePaging Procedure

�� HandoverHandover


System Information BroadcastingSystem Information Broadcasting


Overview of the System InformationOverview of the System InformationMIB: includes the PLMN identifier and the scheduling information of the schedule block (SB) and system block (SB).SB1: includes the scheduling information of the SIB.SB2 : includes the scheduling information of the SIB.SIB1: includes the UE timers and counters and the system information at the NAS. SIB2: includes the URA information.SIB3: includes the parameters for cell selection and reselection. SIB4: includes the parameters for cell selection and cell reselection in connected mode. SIB5: includes the parameters for the configuration of the common physical channel in a cell. SIB6: includes the parameters for the configuration of the common physical channel in a cell in connected mode. SIB7: includes the information about the uplink interface and dynamic persistence level. SIB8: includes the static information about the CPCH in the cell. SIB9: includes the dynamic information about the CPCH in the cell. SIB10: includes the information of dynamic resource assignment control (DRAC).SIB11: includes the measurement control information. SIB12: includes the measurement control information in connected mode. SIB13: includes the ANSI-41 system information. SIB14: includes the information in TDD mode. SIB15: includes the information for LCS.SIB16: includes the reconfiguration information about the handover from another system to the UTRAN.SIB17: includes the configuration information of the shared physical channel in connected mode (TDD).SIB18: includes the information of the neighboring PLMN.Note: The network planning engineers should pay more attention to the system information in blue.


SI1SI1

The SIB1 includes the following information:�System information at the NAS, such as LAC, RAC, and T3212�DRX period coefficient of the CS domain: K ＝ 6, that is, DRX period 2^k = 2 ^ 6 = 64 TTI = 640 ms.�DRX period coefficient of the PS domain K ＝ 6, that is, DRX period 2^k = 2 ^ 6 = 64 TTI = 640 ms.�Timers and counters of the UE in connected mode or timers of the UE in idle mode


SI3SI3

The System info type 3 includes the parameters for cell selection and reselection. �Qhyst2s: indicates the cell reselection hysteresis of Ec/Io measurement. �Sintrasearch: indicates the intra-frequency reselection start threshold.�Sintersearch: indicates the inter-frequency reselection start threshold.�SinterRatsearch: includes the inter-system reselection start threshold.�Qqualmin: indicates the minimum quality standard for cell selection. �Qrxlemin: indicates the minimum access level for cell selection. �T reselection: indicates the reselection hysteresis time. �Max Allowed UE TX power: indicates the maximum transmit power allowed by the UE.


SI5SI5

The System info type 5 includes the feature parameters of the following common physical channels and the configuration information of the corresponding common transport channels:�PICH�AICH�PCCPCH�PRACH�SCCPCH


SI7 and SI11SI7 and SI11

System info type 7

� UL interference: The open-loop power control uses the

Preamble_Initial_Power=Primary CPICH DL TX power - CPICH_RSCP + UL

interference + Constant Value.

�Expiration Time Factor: indicates the update period for the SIB7 by the UE. The

value can be : (2, 4, 8, 16, 32, 64, 128, 256)times. The existing value is 16 times, that

is, the period is “4096 / 16 = 32 TTI = 320 ms”.

System info type 11

�The intra-frequency neighbor list, inter-frequency neighbor list, and inter-

RAT frequency list and the measurement configuration information of the

UE in Idle state are used for cell resection of the UE in the idle state.





�� PagingPaging




CN-Initiated Paging

Paging type 1

CN RNC1 RNC2 NODEB1.1 NODEB2.1 UE

RANAPRANAP

RANAP RANAP

PCCH: PAGING TYPE 1

PAGING

PAGING

PCCH: PAGING TYPE 1


CN-Initiated Paging� Paging type 2

If the UE is in the CELL_DCH or CELL_FACH state, the UTRAN sends the paging type 2 message to

the paged UE over the DCCH.

CN SRNC UE

RANAPRANAP

PAGING

RRCRRC

DCCH: PAGING TYPE 2


UTRAN-Initiated Paging

UE RNC1NodeB1

RRCPaging Type 1RRC

�When the system information changes, the UTRAN triggers the paging procedure to notify the UE in the idle mode, CELL_PCH state, andURA_PCH state to update the system information, so that the UE can obtain the updated system information. �To trigger the state change (for example, the state changes to the CELL_FACH) of the UE in the CELL_PCH and URA_PCH states, the UTRAN initiates the paging procedure. As an acknowledgment for the paging, the UE initiates the cell update or URA update.





�� PagingPaging




3 Call Procedure3 Call Procedure

3.1 Call Overall Procedure3.1 Call Overall Procedure

3.2 RRC Setup Procedure3.2 RRC Setup Procedure

3.3 NAS Signaling Setup Procedure3.3 NAS Signaling Setup Procedure

3.4 RAB Setup Procedure3.4 RAB Setup Procedure

3.5 RAB Release Procedure3.5 RAB Release Procedure

3.6 RRC Connection Release Procedure3.6 RRC Connection Release Procedure


Call Overall Procedure—UE as Calling Party

Process of signaling connection setup between the UE and UTRAN

Signaling exchange between the UE and CN

Process of service connection between the UE and


When the NAS of the UE in idle mode requests for signaling connection setup,

the UE initiates the RRC connection setup procedure. Each UE has a maximum of one RRC connection.

The RRC connection setup is used to configure the signaling channel at the UTRAN side.

RRC Connection Setup Procedure


RRC CONNECTION REQUEST

UE identifier

RRC connection setup cause

RACH measurement report


RRC CONNECTION SETUP

Configure the dedicated transport channel format.

Configure the message bearer format over the DCCH.

Configure the ID of the UE in the RNC.

Configure the physical channel format.


RRC CONNECTION SETUP COMPLETE

Authentication parameters of the CS and PS domains

UE capability parameters


SETUP

Voice service

Called number


There are more than one ALCAP setup procedures on Iu Interface, and more than one user plane RABs can be established simultaneously. After the user plane is established, the UE enters the call connection.In the protocols, the RAB is defined as the bearer for the NAS by the access stratum. The RAB refers to the bearer of the user plane and is used to transmit voice services, data services, and multimedia services between the UE and CN.The RAB setup consists of the setup of the service bearer AAL2 PATH of the Iu interface and Iub interface and the reconfiguration of radio resources of the RAN and UE.

QAAl2QAAl2QAAl2QAAl2QAAl2QAAl2QAAl2QAAl2

QAAl2QAAl2QAAl2QAAl2 QAAl2QAAl2QAAl2QAAl2

RAB Setup Procedure


RAB Assignment Request

If there are multiple types of services, each type of service establishes an RAB respectively.

Service type

Service bearer rate


RB Setup

Mapping information of the RAB, including three RB sub-flows

Configure both uplink and downlink transport channels, reconfigure the DCH, and add three DCHs to carry services.

Configuration process of the physical channel


The RAB release is initiated by the CN. When the UE is exceptional, the SRNC also requests for RAB release.

RAB Release Procedure

For multiple RABs For a single RAB, the RAB release is initiated by the RNC.

The contents of the RAB assignment request message are different from that of the RAB setup message. The message contains Release.


The RRC connection release is initiated by the CN. When the UE is exceptional, the SRNC also requests for RRC connection release.The connection to the UE is released first, and then the connection to the NodeB is released. The RRC connection release means the termination of a call.

UE NodeB SRNC

RRC CONNECTION RELEASE

RRC CONNECTION RELEASE COMPLETE

RL DELETION

RL DELETION RESPONSE

ALCAP ：Iub Date Bearer Release

RRC Connection Release Procedure





�� PagingPaging




Decision to setupnew RL

7. DCCH : Active Set Update Complete

6.DCCH: Active Set Update

UE Node B(new) SRNC

NBAP1. Radio Link Setup RequestNBAP

NBAP2. Radio Link Setup ResponseNBAP

3 ALCAP Iub Data Transport Bearer Setup

Start RX description

DCH-FP4. Downlink SynchronisationDCH-FP

DCH-FP5.Uplink SynchronisationDCH-FP

Start TX description

RRC

RRC

RRC

RRC

Intra-RNC Soft Handover Procedure (Adding a Branch)


Decision to deletea RL

2. DCCH : Active Set Update Complete

1.DCCH: Active Set Update

UE Node B(old) SRNC

NBAP3. Radio Link Deletion RequestNBAP

NBAP4. Radio Link Deletion ResponseNBAP

RRC

RRC

RRC

RRC

Stop RX and Tx

5 ALCAP Iub Transport Bearer release

Intra-RNC Soft Handover Procedure (Deleting a Branch)Intra-RNC Soft Handover Procedure (Deleting a Branch)


Before soft handover After soft handover

When a radio link between the RNC and another NodeB is added,

the original radio link between the SRNC and a NodeB is deleted.

CN

SRNC RNC

NodeB NodeBNodeB

CN

SRNC RNC

NodeB NodeBNodeB

Inter-RNC Soft HandoverInter-RNC Soft Handover


7. Uplink Synchronisation

RNSAP RNSAP

1. Radio Link Setup Request

Start TX description

RNSAP RNSAP

4. Radio Link SetupResponse

NBAP NBAP2. Radio Link Setup Request

NBAP NBAP3. Radio Link Setup Response

Start RX description

Decision to setupnew RL and

release old RL

NBAP10. Radio Link Deletion Request

NBAP NBAP11. Radio Link Release Response

Stop RX and TX

12. ALCAP Iub Data Transport Bearer Release

RRCRRC9. DCCH : Active Set Update Complete

RRCRRC8. DCCH: Active Set Update

[Radio Link Addition & Deletion]

NBAP

UE Node BDrift RNS

Node BServing RNS

Drift RNC Serving RNC

ALCAP Iur Bearer Setup5. ALCAP Iub Data Transport Bearer Setup

DCH-FPDCH-FP

DCH-FPDCH-FP

6. Downlink Synchronisation

Inter-RNC Soft Handover Procedure (Replacing a Radio Link)Inter-RNC Soft Handover Procedure (Replacing a Radio Link)


Before hard handover After hard handover

The SRNC cannot maintain two radio links with two NodeBs at the same time.

CN

SRNC

NodeBNodeB

CN

SRNC

NodeBNodeB

Intra-RNC Hard Handover Intra-RNC Hard Handover


UE Node B Source Node B Target SRNC

8. DCCH : Physical Channel Reconfiguration Complete

6.DCCH : Physical Channel Reconfiguration

1. Radio Link Setup Request

2. Radio Link Setup Response

9. Radio Link Deletion Request

10. Radio Link Deletion Response

3 ALCAP Iub Data Transport Bearer Setup

7. Radio Link Failure IndicationRRCRRC

NBAPNBAP

NBAP

RRCRRC

NBAP

NBAP

NBAP NBAP

Decide tohandover

Start Rx

Start Tx

DCH-FP4. Downlink SynchronisationDCH-FP

DCH-FP5.Uplink SynchronisationDCH-FP

NBAP

NBAP

NBAP


Intra-RNC Hard Handover Procedure Intra-RNC Hard Handover Procedure


Before hard handover After hard handoverThe radio link between the SRNC and a NodeB and the radio link between the RNC

and another NodeB cannot exist at the same time.

CN

SRNC RNC

NodeBNodeB

CN

SRNC RNC

NodeBNodeB

Inter-RNC Hard HandoverInter-RNC Hard Handover


RNSAPRNSAP1. Radio Link Setup Request

UE Node B Source

Node BTarget

RNCSource

RNCTarget

SRNC

RRCRRC

10. DCCH : Physical Channel Reconfiguration Complete

RRC7.DCCH : Physical Channel Reconfiguration

RRC

6. ALCAP Iur Data Transport Bearer Setup

NBAP NBAP2. Radio Link Setup Request

NBAP NBAP3. Radio Link Setup Response

NBAP NBAP12. Radio Link Deletion Request

NBAP NBAP13. Radio Link Deletion Response

4. ALCAP Iub Data Transport Bearer Setup


RNSAP RNSAP15. Radio Link Deletion Response

16. ALCAP Iur Data Transport Bearer Release

RNSAP5. RL Setup Response

RNSAP

RNSAP11. Radio Link Deletion Request

RNSAP

NBAP NBAP8. Radio Link Failure Indication

RNSAPRNSAP

9. Radio Link Failure Indication

Inter-RNC Hard Handover Procedure (over the Iur Interface)Inter-RNC Hard Handover Procedure (over the Iur Interface)


SRNC RelocationSRNC Relocation

SRNS

Core Network

Iu

DRNS Iur

UE

RNS

Core Network

Iu

SRNS

UE

After SRNS Relocation Before SRNS Relocation

Cells


Types of SRNS RelocationTypes of SRNS Relocation

According to existing realization modes of the RNC, the SRNS relocation can be classified into the following types:

� Static relocation

� Relocation after the DRL is established when the UE is in the CELL_DCH state. It is called the static state.

� Relocation after the IUR CCH is established when the UE is in the CELL_FACH state. It is called the FACH static relocation.

� Relocation with hard handover: indicates the relocation triggered by inter-RNC handover when the UE is in the CELL_DCH state.

� Relocation with forward handover: indicates the relocation triggered by the cell update or URA update when the UE is in the CELL_FACH, CELL_PCH, or URA_PCH state.

� Inter-RAT handover: The handover procedure between WCDMA and GSM is basically the same as the relocation with hard handover.


Static RelocationStatic Relocation


Relocation with Hard Handover (CS)Relocation with Hard Handover (CS)

SourceRNC TargetRNCCN

Relocation Reqired

Reloc Req

RANAP RANAP

RANAP RANAP

RANAP RANAPReloc Req Ack

RANAP RANAPRelocation Cmd

RANAP

RANAPIU Rel Complete

RNSAP RNSAPReloc Detect

UE

RRC Physical Channel Recfg Req

NodeB

RNSAP RNSAPRL Restore Ind

RRC

RRCRRC Physical Channel Recfg Complete

NodeB

RANAP RANAPRL Del Req

RANAP RANAPRL Del Rsp

RANAP

RANAP IU Rel Cmd

RL Setup ReqNBAP NBAP

NBAP NBAPRL Setup Rsp

Est Req

Est Conf

DL Sync

UL Sync

Q.AAL2

Q.AAL2

Q.AAL2

Q.AAL2

DCH-FP

DCH-FP

DCH-FP

DCH-FP

The handover procedure is similar to the inter-BSC handover

procedure in the GSM system.


Relocation with Hard Handover (PS)Relocation with Hard Handover (PS)


Inter-RAT Handover Procedure (from UMTS to GSM)Inter-RAT Handover Procedure (from UMTS to GSM)

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07 UMTS UTRAN Signaling Procedures

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