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Iu CS Interface and
RANAP Protocol Analysis
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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
1. Iu Interface Protocol and Functions
2. RANAP Procedure Analysis
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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Protocol structure for Iu-CS(2/4)
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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Protocol structure for Iu-CS(3/4)
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
1. Iu Interface Protocol and Functions
2. RANAP Procedure Analysis
3. Iu Interface Main Service Flow
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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
Relocation Request Ack
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 ]:
Source RNC To Target RNC Transparent Container
L3 Information
RABs To Be Released List
MSCSource
RNC
Relocation Command
Relocation Required
Target
RNC
Relocation Request
Relocation Request Ack
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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
Source RNC To Target RNC Transparent Container
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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SRNS Relocation: Relocation
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 Request Ack
Relocation Detect
SRNS R l ti R l ti
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SRNS Relocation: Relocation
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 Request Ack
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
Security Mode Control
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 COMMAND
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 COMMAND
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
Paging and Common ID
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
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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Contents
1. Iu Interface Protocol and Function
2. RANAP Procedure Analysis
3. Iu Interface Main Service Flow
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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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UE Calling Flow signalling in Iu
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).
UE Calling Flow signalling in Iu
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UE Calling Flow signalling in Iu
interface
MSCRNC
5. DIRECT TRANSFER(setup)
6. DIRECT TRANSFER(call proceeding)
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
5. DIRECT TRANSFER(setup)
6. DIRECT TRANSFER(call proceeding)
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)
UE Calling Flow signalling in Iu
interface
UE C lli Fl i lli i I
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MSCRNC
9. DIRECT TRANSFER(connect)
10. DIRECT TRANSFER(connect acknowledge)
Conversation
ConversationVoice streams of Voice Conversation are formatted intoIu UP frame and transferred in AAL2 connection of IuUP .
UE Calling Flow signalling in Iu
interface
UE C lli Fl i lli i I
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MSCRNC
12. DIRECT TRANSFER(release)
10. DIRECT TRANSFER(connect acknowledge)
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.
UE Calling Flow signalling in Iu
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
4. SECURITY FUNCTION
5. DIRECT TRANSFER(setup)
6. DIRECT TRANSFER(call proceeding)
7. RAB ASSIGNMENT
12. DIRECT TRANSFER(release)
9. DIRECT TRANSFER(connect)
10. DIRECT TRANSFER(connect acknowledge)
Conversation
11. DIRECT TRANSFER(disconnect )
13. DIRECT TRANSFER(release complete)
8. DIRECT TRANSFER(alerting)
14. Iu Release Request/Response
15. SCCP connection Release
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
4. SECURITY FUNCTION
5. DIRECT TRANSFER(setup)
6. DIRECT TRANSFER(call confirm)
7. RAB ASSIGNMENT
12. DIRECT TRANSFER(release)
9. DIRECT TRANSFER(connect)
10. DIRECT TRANSFER(connect acknowledge)
Conversation
11. DIRECT TRANSFER(disconnect )
13. DIRECT TRANSFER(release complete)
8. DIRECT TRANSFER(alerting)
14. Iu Release Request/Response
15. SCCP connection Release
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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