02a Iu-PS Interface

PCNSIG Iu-PS interface

Objectives  After the module, the the participants participants will be able able to:

• Describe the main functions of RANAP signalling protocols in Iu-PS interface

• Explain the Attach procedure in the Iu-PS interface • Explain the PDP Context Activation procedure in the Iu-PS interface

• Describe the main Function of GTP-U in Iu-PS

Objectives  After the module, the the participants participants will be able able to:

• Describe the main functions of RANAP signalling protocols in Iu-PS interface

• Explain the Attach procedure in the Iu-PS interface • Explain the PDP Context Activation procedure in the Iu-PS interface

• Describe the main Function of GTP-U in Iu-PS

NSN - Fully ETSI Compliant Interfaces HLR

IuPS UE

RAN Uu

SGSN

Gn

Gc

Gr

Gi GGSN

SGSN Gn Gp

Gp

GGSN SGSN Other PLMN

Signalling Interface Signalling and Data Transfer Interface

PDN

TE

User Plane protocol stacks for Iu-PS

Relay

GTP-U

UDP/IP

GTP-U

UDP/IP

 AAL5

L2

 ATM

L1

IuPS over ATM

IuPS over IP

Control Plane protocol stacks for Iu-PS

Iu -PS Control Plane

RANAP

SCCP-SAP

SCCP M3UA

MTP-3b

SCTP

SSCF SSCOP  AAL5  ATM

IP L2

IuPS over IP IuPS over ATM

SAAL-NNI

SCCP services

Services provided by the SCCP

Connectionless Services

Protocol Class

0

1

Basic Connectionless Service

Sequenced Connectionless Service

Connection-oriented Services

2

3 Basic Connectionoriented Service

Flow Control Connectionoriented Service

(not used in GSM)

Data packets delivered out of

Data packets delivered in sequence using the same path

bi-directional transfer of data

SCCP connectionless messages Message

Protocol class

Description

UDT

0,1

Unitdata

UDTS

0,1

Unitdata Service. Used to indicate to the originating SCCP that a UDT cannot be delivered to its destination.

XUDT

0,1

Extended Unitdata. Used to send data along with optional parameters.

XUDTS

0,1

Extended Unitdata Service. Used to indicate to the originating SCCP that an XUDT cannot be delivered to its destination.

LUDT

0,1

Long Unitdata. Used to send data along with optional parameters over MTP3b (Q.2210). Up to 3952 octets without segmentation are allowed.

LUDTS

0,1

Long Unitdata Service. Used to indicate to the originating SCCP that an LUDT cannot be delivered to its destination.

SCCP connection-oriented messages Message

Service type

Description

CC

2,3

Connection Confirm

CR

2,3

Connection Request

REF

2,3

Connection Refused

 AK

3

Data acknowledgement. Used to control the window flow control mechanism selected for the data transfer phase.

DT1

2

Data Form 1 (=protocol class 2)

DT2

3

Data Form 2 (=protocol class 3)

ED

3

Expedited Data. Similar to DT2 but it can bypass the flow control mechanism.

EA

3

IT

2,3

Expedited Data acknowledgement. Every ED message must be acknowledged with EA message before another ED is sent. Inactivity Test. Sent periodically to check if the connection is still active at both ends and to audit the consistency of data.

ERR

2,3

Protocol Data Unit Error. Sent on detection of the SCCP protocol error.

RLSD

2,3

Released

RLC

2,3

Release Complete

RSC

3

Reset Confirm.

RSR

3

Reset Request. Indicates that the SCCP needs to reset the sequence numbers.

Example of SCCP Messages 1 CR - CONNECTION REQUEST Source Local Reference - 61F144h Protocol Class - 2h, connection oriented Called Party Address - length 2 (02h) - no global title present - routing based on SSN and MTP routing label - subsystem: RANAP Calling Party Address - length 4 (04h) - no global title present - routing based on SSN and MTP routing label - point code : 4144 (1030h) - subsystem: RANAP SCCP User Data - length: 97 (61h) - data : 00 13 40 5D 00 00 07 0 0 03 40 01 80 00 0F 4 0 40 01 02 00 3A 40 08 00 32 F4 02 00 05 00 A 2 00 79 07 02 05 F4 38 A9 05 5A 32 F4 02 00 05 3C A0 60 19 63 92 B6 17 16 00 4F 40 03 01 61 01

06 00 32 F4 02 00 05 00 37 00 10 40 26 25 08 01 02 E5 02 0A 14 F3 82 33 4C 03 26 01 00 56 40 05 32 F4 02 00

Example of SCCP Messages 2 CC - CONNECTION CONFIRM Destination Local Reference - 61F144h

Source Local Reference - 040000h

Protocol Class - 2h, connection oriented

Called Party Address - length 4 (04h) - no global title present - routing based on SSN and MTP routing label - point code : 4144 (1030h) - subsystem: RANAP End of Optional Parameters

Example of SCCP Messages 3 RLSD - RELEASED Destination Local Reference - 61F144h

Source Local Reference - 040000h

Release Cause - end user originated

RLC - RELEASE COMPLETE Destination Local Reference - 040000h

Source Local Reference - 61F144h

3G SGSN-UE Control Plane

UE

Uu

RNC

Iu-PS

SGSN

RANAP Functions The most important functions of RANAP are: • Relocating the Serving RNC. This function facilitates the change of the Serving RNC including the related Iu resources.

• Radio Access Bearer (RAB) management . This function is responsible for setting up, modifying and releasing RABs (for example, PDP contexts).

• Paging. This function provides the SGSN with the capability to page the UE.

• Location reporting. This function is used for transferring the actual location information from the RNC to the SGSN.

Reporting general error situations.

RANAP Procedures RANAP functions are implemented by one or more RANAP elementary procedures. RANAP procedures are divided into three classes depending on the number of possible response messages:

Class 1: procedures have exactly one response message. Class 2: procedures have no response messages. Class 3: procedures have at least one response message.

Initial UE Message The purpose of the 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.

Example of Initial UE-Message INITIAL UE-MESSAGE RANAP-PDU - extension flag: 0 - choice index: 00 initiatingMessage - procedureCode: 19 - padding: 00000 - contents - criticality: ignore - contents (in bits): 01 initiatingMessage - padding: 000000 - opentype length InitialUE-Message - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length - id: 3 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length CN-DomainIndicator: ps-domain -contents (in bits): 1 - trailing bits: 0000000 - id: 15 - contents - criticality: ignore - contents (in bits): 01

LAI - preamble: 0 - pLMNidentity: '32F403'H - padding: 0000000 - contents - lAC: '03EF'H - contents - id: 55 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length RAC: '01'H - contents - id: 58 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length SAI - preamble: 0 - pLMNidentity: '32F403'H - padding: 0000000 - contents - lAC: '03EF'H - contents - SAC: 'EA62'H - contents - id: 16 - contents - criticality: ignore

NAS-PDU: '080C1605F42A00035B32022000'H - length - contents - id: 79 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length IuSignallingConnectionIdentifier: '000000011111011000000000'B - contents - id: 86 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length GlobalRNC-ID - pLMNidentity: '32F403'H - contents -RNC-ID: 3007 - contents

CN originated Direct Transfer Message The purpose of the Direct Transfer procedure is to carry UE-CN signalling messages over the Iu interface.

Example of CN originated Direct Transfer Message DIRECT TRANSFER RANAP-PDU - extension flag: 0 - choice index: 00 initiatingMessage - procedureCode: 20 - padding: 00000 - contents - criticality: ignore - contents (in bits): 01 initiatingMessage - padding: 000000 - opentype length DirectTransfer - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length - id: 16 - contents -criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length

NAS-PDU: '8A47'H - length - contents - id: 59 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length SAPI: sapi-0 - extension range: 0 - contents (in bits): 0 - trailing bits: 000000

UTRAN originated Direct Transfer The purpose of the Direct Transfer procedure is to carry UE-CN signalling messages over the Iu interface.

Example of UTRAN originated Direct Transfer Message DIRECT TRANSFER RANAP-PDU - extension flag: 0 - choice index: 00 initiatingMessage - procedureCode: 20 - padding: 00000 - contents - criticality: ignore - contents (in bits): 01 initiatingMessage - padding: 000000 - opentype length DirectTransfer - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length - id: 16 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length NAS-PDU: '0A4624'H - length - contents - id: 15 - contents - criticality: ignore - contents (in bits): 01

LAI - preamble: 0 - pLMNidentity: '32F403'H - padding: 0000000 - contents - lAC: '03EF'H - contents - id: 55 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length RAC: '01'H - contents - id: 58 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length SAI - preamble: 0 - pLMNidentity: '32F403'H - padding: 0000000 - contents - lAC: '03EF'H

RAB Assignment procedure The purpose of the RAB Assignment procedure is to establish new RABs and/or to enable modifications and/or releases of already established RABs for a given UE.

Example of RAB Assignment Request Message RANAP-PDU - extension flag: 0 - choice index: 00 initiatingMessage - procedureCode: 0 - padding: 00000 - contents - criticality: ignore - contents (in bits): 01 initiatingMessage - padding: 000000 - opentype length RAB-AssignmentRequest - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length - id: 54 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length RAB-SetupOrModifyList - length - length - id: 53 - contents - firstCriticality: reject - contents (in bits): 00 - padding: 000000 - opentype length firstValue - extension flag: 0 - preamble: 111100 - rAB-ID: '00000101'B - contents (in bits): 00000101 - nAS-SynchronisationIndicator: '1111'B -contents (in bits): 1111

- preamble: 0011010 - trafficClass: interactive - extension range: 0 - contents (in bits): 10 - rAB-AsymmetryIndicator: symmetric-bidirectional - extension range: 0 - contents (in bits): 00 maxBitrate - length (in bits): 0 - MaxBitrate: 64000 - length (in bits): 01 - padding: 0000 - contents - deliveryOrder: delivery-order-not-requested - contents (in bits): 1 - maxSDU-Size: 12000 - padding: 0000000 - contents sDU-Parameters - length (in bits): 000 - extension flag: 0 - preamble: 100 sDU-ErrorRatio - preamble: 0 - mantissa: 1 - contents (in bits): 0000 - exponent: 4 -contents (in bits): 011 residualBitErrorRatio - preamble: 0 - mantissa: 1 - contents (in bits): 0000 - exponent: 5 - contents (in bits): 100 - deliveryOfErroneousSDU: no - contents (in bits): 01 - trafficHandlingPriority: 3 -contents (in bits): 0011 allocationOrRetentionPriority - extension flag: 0 - preamble: 0

- pre-emptionVulnerability: not-pre-emptable - contents (in bits): 0 - queuingAllowed: queueing-allowed - contents (in bits): 1 - relocationRequirement: none - extension range: 0 - contents (in bits): 1 userPlaneInformation - extension flag: 0 - preamble: 0 - userPlaneMode: transparent-mode (user data transfer without framing and control function on user data transfer (SDU size) as Support mode) - extension range: 0 - contents (in bits): 0 - uP-ModeVersions: '0000000000000001'B - contents (in bits): 00000000 0000 0001 transportLayerInformation - extension flag: 0 - preamble: 0 - transportLayerAddress: '10101100000100100110001011000110'- extension range: 0 - length (in bits): 00011111 - padding: 0 - contents iuTransportAssociation (RAB – bearer association) - extension flag: 0 - choice index: 0 - gTP-TEI: '0000011F'H (TEID in SGSN) - padding: 000000 - contents - secondCriticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length secondValue - extension flag: 0 - preamble: 1100000 pDP-TypeInformation - length (in bits): 0 - PDP-Type: ipv4 - extension range: 0

Example of RAB Assignment Response Message RAB-ASSIGNMENT RESPONSE RANAP-PDU - extension flag: 0 - choice index: 11 outcome - procedureCode: 0 - padding: 00000 - contents - criticality: reject - contents (in bits): 00 outcome - padding: 000000 - opentype length RAB-AssignmentResponse - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length - id: 52 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length

RAB-SetupOrModifiedList - length - length - id: 51 - contents - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length RAB-SetupOrModifiedItem - extension flag: 0 - preamble: 1100 - rAB-ID: '00000101'B - contents (in bits): 00000101 - transportLayerAddress: '10101100000100100110000110000011'B - extension range: 0 - length (in bits): 00011111 - padding: 00 - contents iuTransportAssociation - extension flag: 0 - choice index: 0 - gTP-TEI: '00000000'H (TEID in RNC) - padding: 000000 - contents

Iu Release Request The purpose of the Iu Release Request procedure is to enable the UTRAN to request the CN to release the Iu connection for a particular UE due to some UTRAN generated reasons (for example 'O&M Intervention', 'Unspecified Failure', 'User Inactivity', 'Repeated Integrity Checking Failure', 'Release due to UE generated signalling connection release‘).

Example of Iu Release Request Message

Iu-Release Request - extension flag: 0 - preamble: 0 protocolIEs - padding: 000000 - length: 00 01 - id: 4 - contents: 00 04 - criticality: ignore - contents (in bits): 01 - padding: 000000 - opentype length: 02 Cause - extension flag: 0 - choice index: 000 - radioNetwork: radio-connection-with-UE-Lost - contents (in bits): 101101