Huawei Ranap Protocol Analysis Iu Cs

8/12/2019 Huawei Ranap Protocol Analysis Iu Cs

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Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

Iu CS Interface and

RANAP Protocol Analysis


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Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved. Page1

Foreword

The Iu interface is specified at the boundary between the

Core Network and UTRAN. All the signalling and service

between UE and CN must go through it. Iu CS is the

interface between RNC and CS. RANAP provides thesignalling service between UTRAN and CN. The course

discusses Iu CS interface protocol stack, RANAP basic

process and Iu interface main service flows.


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Objectives

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

Understand Iu interface protocol stack and Function

Know classification of RANAP messages

Grasp Iu connection Management , RAB assignment, SRNS

Relocation and know other basic processes.

Grasp CS Domain MM, CC signalling procedures in Iu

Interfaces


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Contents

1. Iu Interface Protocol and Functions

2. RANAP Procedure Analysis

3. RANAP Main Procedure


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Contents



3. Iu Interface Main Service Flow


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Iu Interface with tree CN domains

The hierarchy for the CN - UTRAN signalling connection described as below:

Each CN Access Point may be connected to one or more UTRAN Access Points

For the PS and CS domains, each UTRAN Access Point shall not be connected to morethan one CN Access Point per CN domain

For the BC domain, each UTRAN Access Point may be connected to one or more CNAccess Points

Core Network (CN)UTRAN

Node B

Node B

Node B

Node B

RNC

Iu InterfaceIu-BC

Iu-CS

BCDomain

CSDomain

PSDomain

Iu-PS

RNC


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Protocol structure for Iu and Uu

The figure shows the protocol structure for Iu and Uu. The

Application signalling between UE and MSC(NAS) is transferred

through RRC connection and Iu connection, such as MM, CC.

RLC

RRC

L1

MM /CC /SMS

RRC

MAC

ATM

RANAP

AAL5

Relay

ATM

AAL5

MSCRNSMS

IuUu

RLC SCCP

signallingBearer

MAC

L1

signallingBearer

RANAP

SCCP

MM /CC /SMS


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Protocol structure for Iu-CS(1/4)

Q.2150.1

Q.2630.1

RANAP Iu UP Protocol

Layer

Transport

Network

Layer

Physical Layer

Transport

User

Network

Plane

Control Plane User Plane

Transport

User

Network

PlaneTransport Network

Control Plane

RadioNetwork

Layer

ATM

SSCOP

AAL5

SSCOP

SSCF-NNI

AAL2AAL5

MTP3bMTP3b

SCCP

SSCF-NNI


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RANAP

PHY

ATM

SAAL-NNI

MTP-3B

SCCP

PHY

ATM

AAL2

Iu UP

PHY

ATM

SAAL-NNI

MTP-3B

STC

Q.2630.1

Radio Network: Fulfill

the Iu interface

signalling interaction

(RANAP) and Service

(Iu UP)

Transport Network

Layer: Provide

respective transport

function for Radio

Network and service

as well as control

function of User

Plane bear.

HorizontallyRadio Network layer andTransport Network Layer


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RANAP

PHY

ATM

SAAL-NNI

MTP-3B

SCCP

PHY

ATM

AAL2

Iu UP

PHY

ATM

SAAL-NNI

MTP-3B

STC

Q.2630.1

Vertically: Control Plane and User Plane

Control Plane User Plane


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Control Plane for Iu-CS (4/4)

SCCP-SAP

RANAP

MTP3-B

SCCP

SAAL-NNI

ATMAAL5Adapts the upper layer protocol to

the requirements of the Lower ATM cells.

SSCOP: Connection control, signallingtransport reliability Control

SSCF: Maps the requirements

of the layer above to the requirements

of SSCOP

RANAPsignalling Interactive between Iu interface

SCCPProvide Type 0 and 2 service for RANAP

MTP3-BBandwidth MTP3, similar function as MTP3

SAALATM Signaling Adapter Layer

Iu-CS Control Plane


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Iu Connection in R4 CS

CN is soft switch, bear control and call control is separated, Control planeand User plane in Iu interfaces are:

>Control PlaneRNCMSC Server, RANAP

>User Plane: RNCMGW, IuUP

IP BackboneRNC

MGW MGW

MSC Server MSC Server

RANAP

Iu UP

MC:H.248

Nc:BICC


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Iu-CS Control Plane Function

Iu signalling connection

Management

RAB Assignment

SRNS Relocation

Transfer NAS Signaling

UTRAN Security Mode

Control

CN send IMSI to RNC

Paging UE Activity Tracubg

Location Report

Iu Overload Report

Iu CsControl Plane Function

PHY

ATM

SAAL-NNI

MTP-3B

SCCP

RANAP

PHY

ATM

SAAL-NNI

MTP-3B

SCCP

RANAP

RNC MSC/MSC server


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Iu-CS User Plane Function

Support Mode:

Transfer Data

Initialize User Plane

Rate Control

Time Adjustment

Error Indication

Frame quality

classification.

Iu CSUser Plane FucntionRNC MSC/MGW

PHY

ATM

AAL2

Iu UP

PHY

ATM

AAL2

Iu UP


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Q.2630 (Q.AAL2)

AAL2 RTPUserPlane

Control

Plane Q.2630 (Q.AAL2) IPBCP (Q.1970)

Nb UP:RTP

IP BackboneRNC

MGW MGW

MSC

ServerMSC

Server

PHY

ATM

SAAL-NNI

MTP-3B

STC

Q.2630.1

Q.AAL2 is used for establishment and maintenance AAL2.


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Q.2630 Message

Q.2630 represent message type with one Byte, shown as below:

Message Acronym Message Identifier

Block Confirm BLC 0000 0001

Block Request BLO 0000 0010

Confusion CFN 0000 0011Establish Confirm ECF 0000 0100

Establish Request ERQ 0000 0101

Release Confirm RLC 0000 0110

Release Request REL 0000 0111

Reset Confirm RSC 0000 1000

Reset Request RES 0000 1001

Unblock Confirm UBC 0000 1010

Unblock Request UBL 0000 1011


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Contents





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RANAP provides the signalling service between UTRAN and CN with a

unit of interaction EP(Elementary Procedure). The EPs are definedseparately and are intended to be used to build up complete sequences

in a flexible manner.

Three types of RANAP Service

UE UTRAN

Iu CS EUu

MSC GMSCRANAP

From the point of view SAP (Service Access Points), RANAP provide three services:

General control servicesrelated to the whole Iu interface instance, accessed in CN

through the General Control SAP, connectionless signalling transport.

Notification servicesrelated to specified UEs or all UEs in specified area, through the

Notification SAP, connectionless signalling transport

Dedicated control servicesrelated to one UE, through the Dedicated Control SAP,

connection oriented signaling transport.


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RANAP service modes

RANAP is user part of SCCP, SCCP provideservice Type 0 and Type 2 for RANAP. Therefore,

RANAP EP also provide two related service mode.

Connection oriented data transfer service.

dynamically establish and release based on the

need ,Each active UE shall have its own signalling

connection. Such as Iu Signaling management, RAB

Assignment.

Connectionless data transfer service.No need to

establish logic link, just directly transfer. Messages

related to system maintenance management. Such

as Reset, Reset Resource, Overload Control, Paging

etc.

PHY

ATM

SAAL-NNI

MTP-3B

SCCP

RANAP


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Elementary Procedure Classification

EP ClassificationClass1Class2Class3

An EP consists of an initiating message and possibly a response message.

- Class 1: Elementary Procedures with response (success and/or failure).

- Class 2: Elementary Procedures without response.

- Class 3:Elementary Procedures with possibility of multiple responses.

UE RNC

Iu CSUu

MSC

Request

Response


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Class2:request without responseElementary Procedure Message

RAB Modification Request RAB MODIFY REQUESTRAB Release Request RAB RELEASE REQUEST

Iu Release Request IU RELEASE REQUEST

Relocation Detect RELOCATION DETECT

Relocation Complete RELOCATION COMPLETE

SRNS Data Forwarding Initiation SRNS DATA FORWARD COMMAND

SRNS Context Forwarding from Source RNC to

CN

FORWARD SRNS CONTEXT

SRNS Context Forwarding to Target RNC fromCN

FORWARD SRNS CONTEXT

Paging PAGING

Common ID COMMON ID

CN Invoke Trace CN INVOKE TRACE

CN Deactivate Trace CN DEACTIVATE TRACE

Location Reporting Control LOCATION REPORTING CONTROL

Location Report LOCATION REPORT

Initial UE Message INITIAL UE MESSAGE

Direct Transfer DIRECT TRANSFER

Overload Control OVERLOAD

Error Indication ERROR INDICATION


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Class3:request with more than one

response

Elementary Procedure Initiating Message Response Message

RAB Assignment RAB ASSIGNMENT

REQUEST

RAB ASSIGNMENT

RESPONSE x N (N>=1)

RAB ASSIGNMENT REQUESTone request can require more than one RAB to

establish, modify. RAB is distinguish by RAB ID

More details in next chapter.


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RANAP Message Format

RANAP message adopts ASN.1 PER code. Its massage need decoding tolls

to analysis. The type of message is fixed in front two bytes of position in

message code. The following code example is RANAP message Relocation

Complete

0x00 0x0D 0x40 0x03 0x00 0x00 0x00 0x00

ThereintoThe first byte 0x00 denotes procedure initiating message; The

second byte 0x0D denotes process codeand 0x0D denotes Relocation

Complete procedureAccording to the front of two bytesWe can judge that

the message is Relocation Complete message.

A RANAP message only with message type, its ASN.1 PER code is 7 bytes

which likes last example. the length of RANAP message can not less than

7bytes after ASN.1 PER coding.relocationComplete RANAP-ELEMENTARY-PROCEDURE ::= {

INITIATING MESSAGE RelocationComplete

PROCEDURE CODE id-RelocationComplete

CRITICALITY ignore}


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RANAP Message Classification

For better understand so many messages, We make a summary

RANAPMessage

Iu signalling

Management

RAB Management

SRNS Relocation

Paging and Common ID

Security Mode Control

Related

Maintenance

Initial UE Message

Direct Transfer

Iu Release

RAB setup

RAB modify

RAB Release

Relocation Required

Relocation Request

Relocation Complete

Cancel, Failure

Common IDPaging

Reset

Reset Recourse

Overload Control


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Iu signalling

The signalling between UE and CN is through RRC and Iu

interface signalling, shown as below.

UE RNC

Iu CSUu

MSC

RRC Iu signalling

NAS signalling between UE and MSCCCMM)

Iu signalling

Management

Iu signalling Initial

NAS Direct Transfer

Iu signalling release

NASnon-Access Stratum


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Iu signalling connection

Establishment Initial UE Message procedure is to establish an Iu signalling

connection between a CN domain and the RNC and to

transfer the initial NAS-PDU to the default CN node.

The procedure uses connection oriented signalling.

MSCRNC

Initial UE Message

[ Initial UE Message ]

CN domain indicatorIndicate CS or PSLAILocation Area Identifier

SAIService Area IdentifierIu signaling connection identifierGlobal RNC identifierRNC IDNAS-PDUNon Access StratumPacket Date Unit


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MSCRNC

Direct Transfer

Direct Transferor

NAS signalling Direct Transfer

Direct Transfer procedure is to carry UECN signalling messagestransparently over the Iu Interface. Not interpreted by the UTRAN.

It belongs to connection oriented signalling and class 2 message.

[ Direct Transfer ]NAS-PDUUE-CN SINGALLING

LAILocation Area ID

SAIService Area ID

SAPIService Access Point ID


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Iu Release Request

Iu Release Request procedure is to enable UTRAN to request the CN torelease the Iu connection for a particular UE due to some UTRAN

generated reason . e.g. "O&M Intervention", "Unspecified Failure", "User

Inactivity etc.

The procedure uses connection oriented signalling and has no response.

MSCRNC

Iu Release Request

[ Iu Release Request ]

Iu Release Request Cause


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Iu Release

Iu Release procedure is to enable the CN to release the Iu connectionand all UTRAN resources related only to that Iu connection to be released.

The procedure uses connection oriented signalling and has response.

MSCRNC

Iu Release Command [Cause]

Iu Release Complete

Iu Release Request

[ Iu Release ]

Iu Release Command has Iu release cause

Iu Release Complete has RABs Released List ( RAB ID)


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RAB Concept

RAB, Radio Access Bear, is the service bear between UE andCN(MSC) . RAB includes RB (radio bear) and Iu interface bear.

Shown as below.

UE RNC

Iu CSUu

MSC

RB AAL2

Connection

RAB

RAB ManagementRAB EstablishRAB Modify

RAB Release


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RAB Assignment

MSCRNC

RAB Assignment Request

RAB Assignment Response

Could be more than

one responses

RAB Assignment is originated by CN(MSC/MSC Server), but CN

only specify RAB ID and other RAB parameters. It is RNC toexecute the command to assign the resource for USER PART

and send them back to CN with response message.

The procedure is connection originated


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MSCRNC

RAB Assignment Request (Setup)

RAB Assignment Response (Setup)

Establish AAL2

Connection

ERQ(Q.2630.1 Message)

ECF(Q.2630.1 Message)

[RAB ASSIGNMENT REQUEST ]

RAB ID8BitsRAB ParametersQoS Mapping

User Plane ModeTransparent or Support Mode

UP Mode VersionsIuUP mode version

Transport Layer AddressNSAP (ATM Address)

Iu Transport AssociationBinding ID(Termination ID)

RAB Establishment

RAB Establishment: create RL in Uu, RB in Iub and AAL2 in Iu CS


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RAB Release Request procedure is to enable UTRAN to request the release of

one or several radio access bearers. The procedure uses connection oriented

signalling and has no response.

[ RANAP:RAB ASSIGNMENT REQUEST(release) ]

RAB IDs

Cause

Release AAL2connection

MSCRNC

RAB Assignment Request (release)

RAB Assignment Response (release)

REL(Q.2630.1 Message)

RLC(Q.2630.1 Message)

RAB Release Request RAB ID,Cause

Causes: "RAB pre-empted", "Release due to UTRAN Generated Reason",

"Radio Connection With UE Lost".

RAB Release


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Iu Release Command has the cause of Iu Release. Iu

Release Complete has the RABs Released List ( RAB ID)

AAL2 Release

MSCRNC

Iu Release Command

Iu Release Complete

REL(Q.2630.1 Message)

RLC(Q.2630.1 Message)

Iu Release Request

Iu Release with RAB

Release

Iu Release companied with RAB

Release RAB ReleaseRAB Release after Iu Release.


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SRNS Relocation

SRNS Relocation is a UMTS functionality used to relocatethe serving RNS role from one RNS to another RNS. it may

involve a change in the radio resources used between

UTRAN and UE. Resources include signalling and service

bear.

Target RNS

Source SRNS

UE

Uu

MSCUu

Iur

Source RNS decides to perform SRNS Relocation with

the measurement of neighbor LAI.


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SRNS Relocation: Procedures

SRNS Relocation procedure includes Relocation Preparation,

Relocation Resource Allocation, Relocation Detect, Relocation

Complete, Cancel etc.

MSCSource RNC

Relocation Command

Relocation Required

Target RNC

Relocation Request

Relocation Request Ack

Relocation Detect

Relocation Complete


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SRNS Relocation: Preparation

Relocation: PreparationThe source RNC shall initiate the procedure by generating

RELOCATION REQUIRED message. The source RNC shall

decide whether to initiate Relocation by RNS measurement.

[ Relocation Required ]:

Relocation Type: involving UE or not

Cause

Source ID: Source RNC ID

Target ID: Target RNC ID

Source RNC To Target RNC Transparent Container

Relocation Command

Relocation Required

Relocation Request


MSCSource RNC Target RNC


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SRNS Relocation: Preparation

Successful Preparation Successful

The source RNC shall send the RELOCATION REQUIRED message to the CN

and the source RNC shall start the timer TRELOCprep.. When the preparation

including resource allocation in the target system is ready and the CN has decided

to continue the relocation of SRNS, the CN shall send RELOCATION COMMAND

message to the source RNC.

[ Relocation Command ]:


L3 Information

RABs To Be Released List

MSCSource

RNC

Relocation Command

Relocation Required

Target

RNC

Relocation Request



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SRNS Relocation:Relocation Resource

Allocation

Relocation Resource Allocation :Allocate resources from target RNS for arelocation of SRNS. Procedure shall be co-ordinated in all Iu signalling connections

existing for the UE. The procedure uses connection oriented signalling.

[ Relocation Request ]:

Permanent NAS UE IdentityIMSI

Cause

CN Domain IndicatorCS or PSIu signalling Connection IdentifierIu signaling connection ID

RABs To Be Setup List (RAB ID,User Plane Mode


Integrity signallingn Information (O)

Encryption Information (O)

Target Resource

Allocation

MSCSource RNC

Relocation Command

Relocation Required

Target RNC

Relocation RequestRelocation Request Ack


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SRNS Relocation: Successful

Resource Allocation

Relocation Resource Allocation: SuccessfulAfter all necessary resources for accepted RABs including the Iu user plane, are

successfully allocated, the target RNC shall send RELOCATION REQUEST

ACKNOWLEDGE message to the CN

[ Relocation Request Ack]:

Source RNC To Target RNC Transparent ContainerRABs To Be Setup ListRAB IDTransport Layer AddressIu

Transport AssociationAssigned RAB Parameter Values

RABs Failed To Setup List (O)(RAB ID,Cause

Choosen Integrity Protection Information (O)

Choosen Encryption Information (O)

MSCSource

RNC

Relocation Command

Relocation Required

Target

RNC

Relocation Request

Relocation Request AckTarget Resource

Allocation


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SRNS Relocation: Unsuccessful

Resource Allocation Relocation Resource Allocation: Unsuccessful

If the target RNC can not accept the relocation of SRNS or a failure occurs in the

target RNC, the target RNC shall send RELOCATION FAILURE message to the

CN. CN shall stop timer TRELOCalloc and shall assume possibly allocated

resources within target RNC completely released.

MSCSource RNC

Relocation Required

Target RNC

RELOCATION REQUEST

RELOCATION FAILURE

RELOCATION PREPARATION FAILURE

[ RELOCATION FAILURE ]:

Cause

Target

Resource

Allocation

S S


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SRNS Relocation: Relocation

Cancel Relocation Cancel

Enable source RNC to cancel an ongoing relocation of SRNS. The procedure shall be co-

ordinated in all Iu signalling connections existing for the UE. The procedure uses connection

oriented signaling.It could be two situation:

1. If Source RNC can not receive Relocation Required ACK message, it will start the

procedure.

2. Source RNC starts the procedure if UE reason.

MSCSource

RNC

Relocation Cancel Ack

Relocation Required

Target

RNC

Relocation RequestRelocation Cancel

[ RELOCATION CANCEL ]:

Cause

SRNS R l ti R l ti


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Detect Relocation Detect

To indicate by the RNC the detection of SRNS relocation execution to the CN. The target RNC

shall send RELOCATION DETECT message to the CN when relocation execution trigger is

received. The target RNC shall start SRNC operation. The procedure uses connection

oriented signalling.

[ DETECT ] No Parameter

MSCSource RNC

Relocation Command

Relocation Required

Target RNC

Relocation Request


Relocation Detect

SRNS R l ti R l ti


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Complete Relocation Complete

To indicate by the Target RNC the completion of relocation of SRNS to the CN. When the new

SRNC-ID + S-RNTI (Serving RNC Radio Network Temporary Identity) are successfully

exchanged with the UE by the radio protocols, target RNC shall initiate Relocation Complete

procedure by sending RELOCATION COMPLETE message to CN.

Fulfill Relocation

MSCSource RNC

Relocation Command

Relocation Required

Target RNC

Relocation Request


Relocation Detect

Relocation Complete


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UMTS Security Mode Control

UMTS Security Mode Control scope is between RNC and UE.

UE RNC

Iu CSUu

MSCSecurity ModeControl Scope

Security Mode Control include cipher and integrity mode. Integrity is for

signalling protection. Cipher is for signalling and service.

When RLC using confirm or non-confirm mode, cipher is in RLC. When

RLC using transparent mode, cipher is in MAC.

IKCK is generated during authentication. They are transferred from

MSC to RNC in Security Mode Control.


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Security Mode Control Command


To allow the CN to pass cipher and integrity mode information to the

UTRAN. UTRAN uses this information to select and load the encryption

device for user and signalling data with the appropriate parameters, and

also to store the appropriate parameters for the integrity algorithm. The

procedure uses connection oriented signalling.

[ SECURTIY MODE COMMAND ]:

Integrity Protection Information

Encryption Information

Key Status

MSCRNC

SECURITY MODE COMMAND

SECURITY MODE

COMPLETE


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Security Mode Control: Successful

Security Mode Complete

Successful IK, integrity algorithm, CK and encryption algorithms.

[ SECURTIY MODE COMPLETE ]:

Chosen Integrity Protection Algorithm

Chosen Encryption Algorithm

MSCRNC


SECURITY MODE COMPLETE


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Security Mode Control: Unsuccessful Security Mode Reject

Unsuccessful IK, integrity algorithm, CK and encryption algorithms IK

negotiation with the cause:

Requested Ciphering and/or Integrity Protection Algorithms are not Supported ,

Failure in the Radio Interface Procedure

MSCRNC


SECURITY MODE REJECT

[ SECURTIY MODE COMMAND ]:Integrity Protection InformationEncryption InformationKey Status

[ SECURTIY MODE REJECT ]:Cause


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COMMON ID

Common ID To inform the RNC about the permanent NAS UE Identity (i.e. IMSI) of

a user. This is used by the RNC e.g. to create a reference between

the permanent NAS UE identity of the user and the RRC connection

of that user for UTRAN paging co-ordination. The procedure uses

connection oriented signalling.

MSCRNC

COMMON ID

[ COMMON ID ]:

Permanent NAS UE Identity ( such as IMSI


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Paging

To enable the CN to page a UE for a UE terminating service request. Theprocedure uses connectionless signalling. It will use common paging

channel when UE is in idle mode. It will use specified RRC if UE has

already RRC connection.

MSCRNC

PAGING

[ PAGING ]:

CN Domain IndicatorPermanent NAS UE Identity

Temporary UE Identity

Paging Area ID

Paging Cause


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UE Location Reporting Control

Location Reporting Control Allow the CN to request information on the location of a given

UE. The procedure uses connection oriented signalling

MSCRNC

LOCATION REPORTING CONTROL

[ LOCATION REPORTING CONTROL ]:

Request Type

Vertical Accuracy Code

Response Time

Positioning Priority

Client Type


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UE Location Report

UE Location Report Provide the UE's location information to the CN. The procedure

uses connection oriented signalling..

[ LOCATION REPORT ]:

Request Type

Area Identity

Cause

Last Known Service Area

MSCRNC

LOCATION REPORT


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Overload Control

Give some degree of signalling flow control. Algorithms areused to stem the traffic at source with known effect on the

service. The procedure uses connectionless signalling.

MSCRNC

OVERLOAD

[ OVERLOAD ]:

Number Of Steps

Global RNC-ID

CN Domain Indicator


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Reset

Initialize the UTRAN in the event of a failure in the CN or viceversa. used by the UTRAN to release affected RAB and to erase

all affected references, After a guard period of T(RatC) seconds,

UEs which were involved in a call are no longer transmitting and

that all references at the UTRAN have been cleared. The

procedure uses connectionless signalling.

[ RESET ]:Cause

CN Domain Indicator

Global RNC-ID

Global CN-ID

MSCRNC

RESET ACKNOWLEGE

RESET

[ RESET ACKNOWLEGE ]:Criticality Diagnostics

CN Domain Indicator

Global RNC-ID

Global CN-ID


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Reset Resource

To initialize part of the UTRAN(Iu connection) in the event of anabnormal failure in the CN or vice versa (e.g. signalling Transport

processor reset). The procedure uses connectionless signalling.

MSCRNC

RESET RESOURCE ACK

[ RESET RESOURCE ]:

CauseCN Domain Indicator

Global RNC-ID

Global CN-ID

Reset Resource List (Iu signalling Connection Identifier )

RESET RESOURCE


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Error Indication Initiated by a node to report detected errors in one incoming message, provided

they cannot be reported by an appropriate failure message. If the error situationarises due to reception of a message utilising dedicated signalling, then the Error

Indication procedure uses connection oriented signalling. Otherwise the procedure

uses connectionless signalling.

Direction: RNCCN and CNRNC.

MSCRNC

Error Indication

[ Error Indication ]:

Cause Global RNC-ID

Criticality Diagnostics Global CN-ID

CN Domain Indicator


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Summary

This chapter analyzed RANANP processes and messages in details inthe area of Iu connection Management, RAB Management, SRNS

Relocation, Security Mode Control, Paging and Maintenance.

RANAPMessages

Iu signallingManagement

RAB Management

SRNS Relocation


Security ModeControl

RelatedMaintenance

RAB is the bear for User Plane service, whichmanaged by RANAP. RAB Assignment Request is toestablish , modify and release RAB.

Relocate serving RNS role from one RNS to another andservice from old Iu to new Iu interface. Includes RelocationPreparation, Resource Allocation, Detect, Complete etc

Common ID:IMSI from MSC to RNCPaging

ResetReset RecourseOverload Control

Iu signalling is used for transferring NAS signaling betweenUE and MSC. Including Initial UE Message, Direct Transfer,Iu Release Command

MSC send IK, CK to RNC and manage Integrity andencryption algorism


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RANAP Message Classification

For better understand so many messages, We make a

summary

R

ANAPMessage

Iu signalling

Management

RAB Management

SRNS Relocation



Related

Maintenance

Initial UE Message

Direct Transfer

Iu Release

RAB setup

RAB modify

RAB Release

Relocation Required

Relocation Request

Relocation Complete

Cancel, Failure

Common IDPaging

Reset

Reset Recourse

Overload Control


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Contents

1. Iu Interface Protocol and Function




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Iu Interface Service Flow

In previous chapter we have already analyzed control plane,user plane of Iu interface and related message. Next, we

will analyze signalling interface of call flow and location

upgrade flow how to transferr in Iu interface.

CN

UTRAN

Iu CS

MSC MSC UTRAN

Iu CS

UE Calling Flow signalling in Iu


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interfaceMSCRNC

2. SCCP:CC

1. SCCP:CR(Initial UE Message(CM Service Request))

3. COMMON ID

4. SECURITY FUNCTION

5. DIRECT TRANSFER(setup)

6. DIRECT TRANSFER(call proceeding)

7. RAB ASSIGNMENT

Iu Connection Establishment

UE originate service request in calling flow, which included in NAS-PDU ofInitial UE message. SCCP make a connect with CRCC message.(step 1,2)

MSC send IMSI to RNCCommon ID (step 3).

Security Modesometime need authentication (through DT message), and start Security mode control (step4).Number AnalysisCalled number is carried in L3 setup message, MSC judges the call attribute (outgoingPSTN, intra office calling etc) and send Call proceeding once successfully analyzed. All these messages aretransferred in DT message.(step5,6).



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interface

MSCRNC



7. RAB ASSIGNMENT

RAB AssignmentAfter MSC send Call Proceeding, MSC send RAB ASSIGNMENT to MSC, require RNCto prepare resource, establish user plane bear (AAL2 connection) in Iu interface and wireless bear RB.

AAL2 connection is fulfilled with Q.2630 sending ERQ and receiving ECF.

C


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MSCRNC



7. RAB ASSIGNMENT

9. DIRECT TRANSFER(connect)

10. DIRECT TRANSFER(connect acknowledge)

8. DIRECT TRANSFER(alerting)

Calling EstablishMsc send Alerting message to calling party when called party alerting,Msc send Connect message to calling party when called party pick hook and calling party

send back Connect Acknowledge . All these messages are L3 message, transfering in

DT(Step8, 9, 10)


interface

UE C lli Fl i lli i I


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MSCRNC



Conversation

ConversationVoice streams of Voice Conversation are formatted intoIu UP frame and transferred in AAL2 connection of IuUP .


interface

UE C lli Fl i lli i I


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MSCRNC

12. DIRECT TRANSFER(release)


Conversation

11. DIRECT TRANSFER(disconnect )

13. DIRECT TRANSFER(release complete)

14. Iu Release Request/Response

15. SCCP connection Release

Conversation Release :MSC send calling party disconnect message while called partyhang hook, Calling party send release message and MSC send back Acknowledge message.All these messages are L3 message transferred in DT messages(step11,12,13)Resource Release:After finish conversation, Iu connection will release if there is no otherservice. RAB (step 14) and SCCP connection(step 15) are released either.


interface

UE Calling Flow signalling in Iu interface


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MSCRNC

2. SCCP:CC

1. SCCP:CR(Initial UE Message(CM Service Request))

3. COMMON ID




7. RAB ASSIGNMENT




Conversation






Call Release

Stage

Call Establish

Stage

Conversation

Flow

UE Calling Flow signalling in Iu interface


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Other Flow

The previous slides analyze UE Calling Flow signalling in Iuinterfaces. In coming slides, please analyze the UE Called

Flow and location update signalling in Iu interfaces.

UE C ll d Fl i lli i I I t f


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UE Called Flow signalling in Iu InterfaceMSCRNC

2. SCCP:CC1. SCCP:CR(Initial UE Message(Paging Response))

3. COMMON ID



6. DIRECT TRANSFER(call confirm)

7. RAB ASSIGNMENT




Conversation






Call Release

Stage

Call Establish

Stage

Paging and

response, Iu

Connection

Establishment

Paging

Conversation

Location Update signalling


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Location Update signalling

Transfer in Iu Interface

MSCRNC

SCCP:CC

SCCP:CR(Initial UE Message(Location Update Request))

DIRECT TRANSFER(Authentication Request)

DIRECT TRANSFER(Authentication Response)

Security Mode Command

Iu Release Complete

DIRECT TRANSFER(Location Updage Accept)

DIRECT TRANSFER(TMSI Relocation Complete)

Iu Release Command

Security Mode Complete

SCCP:RLSD

SCCP:RLC

Connection

Release Stage

signalling

Transfer Stage

Iu Connection

Establishment


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Summary

This chapter introduces NAS signalling how to transfer in Iuinterface. Including call control originating signalling,

terminating signalling and Location Upgrade.

Comprehension of these flow help further understanding of

RANAP protocol


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Thank youwww.huawei.com

Documents

Huawei Ranap Protocol Analysis Iu Cs