Signalling

Anritsu Confidential Information

Signaling Training Iu-PS


Summary

High level Description

Network Diagrams

Protocol Stack

Main Procedures

Messages Flow Diagrams

Typical Problems

Hands On

Acronyms and References


High level Description

Purpose of this presentation is provide an introduction to Iu-PS interface, Protocol Stack and the main procedures

in this interface

The Iu interface is between the Core Network and UTRAN. The Iu interface towards the PS-domain of the

core network is called Iu-PS

In another words Iu-PS is the interface between RNC and SGSN


Network Diagrams

PABX ISDN MAP ISUP

MAP MAP

ISUP

EIR

HLR AUC

IN INAP

GMSC MSC A-bis

Um

BSC

R

GRX Gp

Gf

Gr

Gn

GPRS Gc

Gd

Gn

Gi

Gb

GGSN

Private

Backbone

SGSN

PDN

Internet/Intranet/ISP

PSTN/ISDN SMSC

Gs

A

RNC

RNC Iu-PS

Iu-CS

Iur

Iub

Iub

Uu

Node B

Node B


Protocol Stack

IP SSCOP

AAL5

SCTP

MTP3-B M3UA

SCCP

M3UA

RANAP Iu UP Protocol Layer

Tra

nsp

ort

Net

wo

rk L

ayer

Physical Layer

Transport

User Network

Plane

Control Plane User Plane

Transport

User Network

Plane Transport

Network

Control Plane

Rad

io N

etw

ork

Lay

er

AAL5

IP

UDP

GTP-U

Physical Layer

ATM Data Link

IP

SCTP

Data Link ATM

IP

UDP

GTP-U SSCF-NNI


RANAP - Radio Access Network Application Part

Major Functions of RANAP Overall RAB management. This function is responsible for setting

up, modifying and releasing RABs

Radio Access Bearer (RAB) as a user plane connection provided by the UMTS Terrestrial Radio Access Network (UTRAN) between a User Equipment (UE) and the Core Network.

The general characteristics of a RAB (data rates, QoS, etc) are normally set by the Core Network (CN) based on subscription and/or requirements of the media or set of medias using the RAB.

Relocating serving RNC. This function enables to change the serving RNC functionality as well as the related Iu resources (RAB(s) and Signalling connection) from one RNC to another


RANAP - Radio Access Network Application Part

Sending the UE Common ID (permanent NAS UE identity) to the RNC. This function makes the RNC aware of the UE's Common ID

Paging the user. This function provides the CN for capability to page the UE

Transport of NAS information between UE and CN Controlling the security mode in the UTRAN. This function is

used to send the security keys (ciphering and integrity protection) to the UTRAN, and setting the operation mode for security functions.

Location reporting. the Location Reporting Control procedure is to allow the CN to request information on the location of a given UE


Main Procedures

List of main procedures:

Attach Detach Routing Area Update (RAU) PDP Context Activation Secondary PDP Context Activation PDP Context Deactivation PDP Context Modification Service Request Handovers

SRNS Relocation (With and without Iur interface)


Attach

The GPRS attach procedure is used for two purposes Normal GPRS attach, performed by the MS to IMSI attach for GPRS

services only.

Combined GPRS attach procedure, used to attach the IMSI for GPRS and non-GPRS services.

The MS initiates the GPRS attach procedure by sending an ATTACH REQUEST message to the network. The attach type information element shall indicate "GPRS attach".

If the GPRS attach request is accepted by the network, an ATTACH ACCEPT message is sent to the MS.

If the attach request cannot be accepted by the network, an ATTACH REJECT message is transferred to the MS. This message will include a cause value indicating the reason for reject

Attach procedure can used to reallocate P-TMSI/TMSI. In such cases MS will send ATTACH COMPLETE message after receiving ATTACH ACCEPT message


Attach (Successful) - Messages Flow

MS Network

ATTACH REQUEST

ATTACH ACCEPT

ATTACH REJECT

or

ATTACH COMPLETE

ATTACH REQUEST

If P-TMSI and/or TMSI allocated


Attach (Successful) - Messages Flow

SGSN RNC HLR

CR Attach Request

CC

DTI GPRS Identity Request

DTI - GPRS Identity Response

DTI Authentication and Ciphering Req

DTI - Authentication and Ciphering Resp

DTI - Security Mode Command

DTI - Security Mode Complete

DTI - Attach Accept

BEGIN - SendAuthenticationInfoArg

END SendAuthenticationInfoRes

DTI Iu Release Command

DTI Iu Release Complete

RLSD

RLC

RANAP Connection Release

SCCP Connection Release

Attach Request send by MS

Attach is accepted by the

network after successful update GPRS Location procedure

Scenario: GPRS Attach

Attach type information element in

Attach Request message indicates

"GPRS attach"

OLD SGSN

UpdateGPRSLocation and

InsertSubscriberData

procedures

Cancel Location procedure

DT1 - Common ID

DTI - Attach Complete

Attach Complete message is

send by the UE if there is a P-TMSI and/or a TMSI was included

within the attach accept message

(Implicit P-TMSI reallocation)


Attach (Unsuccessful) - Messages Flow

SGSN RNC HLR

CR Attach Request

CC

DTI GPRS Identity Request

DTI - GPRS Identity Response

DTI Authentication and Ciphering Req

DTI - Authentication and Ciphering Resp



DTI - Attach Reject

BEGIN - SendAuthenticationInfoArg

END SendAuthenticationInfoRes



RLSD

RLC

Attach Request send by MS

Attach is Rejected by the

network with the cause value

Roaming not allowed in this location area

Scenario: GPRS Attach

Attach type information element in

Attach Request message indicates

"GPRS attach"

UpdateGPRSLocation

procedure failed

UpdateGPRSLocation

procedure fails with the cause

value, RoamingNotAllowed

DT1 - Common ID


Detach

The GPRS detach procedure is used To detach the IMSI for GPRS services only As a combined GPRS detach procedure used to detach the IMSI

for GPRS and non-GPRS services or for non-GPRS services only

Detach procedure can be initiated by the MS or the Network The GPRS detach procedure is initiated by the MS by sending a

DETACH REQUEST message. The detach type information element may indicate "GPRS detach with switching off", "GPRS detach without switching off", "IMSI detach", "GPRS/IMSI detach with switching off" or "GPRS/IMSI detach without switching off".

In case the network initiates the GPRS detach procedure it sends a DETACH REQUEST message to the MS. The DETACH REQUEST message shall include a detach type IE. The detach type IE indicates "re-attach not required" or "re-attach required"


Detach Message Flow

MS Network

DETACH REQUEST

DETACH ACCEPT

or at MS power switch off

DETACH REQUEST

MS Network

DETACH REQUEST

DETACH ACCEPT

MS initiated Detach

Network initiated Detach


Detach (Successful) Message Flow

SGSN RNC GGSN

CR Detach Request

CC

DTI Common ID

DTI Detach Accept

DTI Iu-Release Command

DTI Iu-Release Complete

RLSD

RLC

SGSN sends Detach Accept message back to

UE

UE sends Detach Request message to

SGSN. Detach type IE indicates GPRS detach without switching off

All ongoing control plane procedures

are aborted

The SGSN sends Delete PDP Context

Request messages for all active PDP

contexts to the peer GGSNs


Routing Area Update (RAU)

This procedure is used for: Normal routing area updating to update the registration of

the actual routing area of an MS in the network

Combined routing area updating to update the registration of the actual routing and location area of an MS in the

network

Periodic routing area updating. This procedure is used to notify periodically the availability of the mobile station to

the network

IMSI attach for non-GPRS services when the MS is IMSI attached for GPRS services


RAU Message Flow

MS Network

ROUTING AREA UPDATE REQUEST

ROUTING AREA UPDATE ACCEPT

ROUTING AREA UPDATE COMPLETE

or

ROUTING AREA UPDATE REJECT

ROUTING AREA UPDATE REQUEST


RAU (Successful) Message Flow

SGSN RNC HLR

CR Routing Area Update Request

CC



DTI Routing Area Update Accept



RLSD

RLC

Routing Area Update Request send

by UE. The update type IE indicates

RA updating

Routing Area Update is accepted by

the network after successful update GPRS Location procedure

OLD SGSN

UpdateGPRSLocation and

InsertSubscriberData

procedures

Cancel Location procedure

DT1 - Common ID

DTI - Routing Area Update Complete

Routing Area Update Complete

message is send by the UE if there

is a P-TMSI and/or a TMSI was

included within the attach accept

message (Implicit P-TMSI

reallocation)


RAU (Unsuccessful) - Messages Flow

SGSN RNC HLR

CR Routing Area Update Request

CC



DTI Routing Area Update Reject



RLSD

RLC

Routing Area Update Request send

by UE

Routing Area Update is Rejected by

the network with the cause value

#17 Network Failure

UpdateGPRSLocation

procedures failed with error

System Failure

DT1 - Common ID

UpdateGPRSLocation procedure is

failed because of System Failure


PDP Context Activation

The purpose of this procedure is to establish a PDP context between the MS and the network for a specific QoS on a specific NSAPI. The PDP context activation may be initiated by the MS or the initiation may be requested by the network

In order to request a PDP context activation, the MS sends an ACTIVATE PDP CONTEXT REQUEST message to the network. The message contains the selected NSAPI, PDP type, requested QoS

Upon receipt of an ACTIVATE PDP CONTEXT REQUEST message, the network selects a radio priority level based on the QoS negotiated and may reply with an ACTIVATE PDP CONTEXT ACCEPT message

Or, the network may reject the MS initiated PDP context activation by sending an ACTIVATE PDP CONTEXT REJECT message to the MS

In case network request a PDP context activation, its sends a REQUEST PDP CONTEXT ACTIVATION message to the UE


PDP Context Activation Message Flow

MS Network

ACTIVATE PDP CONTEXT REQUEST

ACTIVATE PDP CONTEXT

ACCEPT

ACTIVATE PDP CONTEXT REJECT

or

MS Network

REQUEST PDP CONTEXT ACTIVATION

ACTIVATE PDP CONTEXT ACCEPT

ACTIVATE PDP CONTEXT REQUEST

ACTIVATE PDP CONTEXT REJECT

or

or

REQUEST PDP CONTEXT ACTIVATION REJECT

MS initiated PDP context activation

Network initiated PDP context activation


PDP Context Activation (Successful) Message Flow

SGSN RNC GGSN

CR Service Request

CC

DTI Security Mode Command


DTI Common ID DTI Activate PDP Context Request

DTI RAB Assignment Response

DTI RAB Assignment Request

DTI - Activate PDP Context Accept

GTP Create PDP Context Request

GTP Create PDP Context Response



RLSD

RLC

Iu Connection Release


DTI Iu-Release Request

Cause = #128 Request Accepted

Service Type = Signalling


PDP Context Activation (Unsuccessful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Activate PDP Context Request

DTI - Activate PDP Context Reject

GTP Create PDP Context Request

GTP Create PDP Context Response



RLSD

RLC

Iu Connection Release


Cause = #209 User Authentication Failed

Cause = #29 User Authentication Failed



Secondary PDP Context Activation

This procedure is used to establish an additional PDP context between the MS and the network for a specific QoS profile

It is invoked when one or more PDP contexts have already been established for the particular PDP address and APN

In order to request a secondary PDP context activation, the MS shall send an ACTIVATE SECONDARY PDP CONTEXT REQUEST

The network will reply with ACTIVATE SECONDARY PDP CONTEXT ACCEPT message, if the request can be accepted

Or, the network may reject the MS initiated PDP context activation by sending an ACTIVATE SECONDARY PDP CONTEXT REJECT message to the MS

Secondary PDP context activation also can be initiated by the network by sending REQUEST SECONDARY PDP CONTEXT ACTIVATION message to the MS


Secondary PDP Context Activation - Message Flow

MS Network

ACTIVATE SECONDARY PDP CONTEXT REQUEST

ACTIVATE SECONDARY PDP CONTEXT ACCEPT

ACTIVATE SECONDARY PDP CONTEXT REJECT

or

MS Network

ACTIVATE SECONDARY PDP CONTEXT REQUEST

ACTIVATE SECONDARY PDP CONTEXT ACCEPT

ACTIVATE SECONDARY PDP CONTEXT REJECT

or

REQUEST SECONDARY PDP CONTEXT ACTIVATION

REQUEST SECONDARY PDP CONTEXT ACTIVATION

or

MS initiated Secondary PDP context activation

Network initiated Secondary PDP context activation


Secondary PDP Context Activation (Successful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Activate Second PDP Context Req



DTI - Activate Second PDP Context Accpt



RLSD

RLC




Secondary PDP context

activation is initiated by the UE


activation is accepted by the

network

GTP Create PDP context Request

GTP Create PDP context Response


Secondary PDP Context Activation (Unsuccessful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID

DTI Activate Second PDP Context Req



DTI - Activate Second PDP Context Reject



RLSD

RLC


RAB assignment is failed with

cause value Requested traffic class not available

Service Type = Data


activation is initiated by the UE


activation is Rejected by the

network




PDP Context Modification

The PDP context modification procedure is invoked by the network or by the MS, in order to change the QoS negotiated, the Radio priority level, or the TFT, negotiated during the PDP context activation procedure

In order to initiate the procedure, the MS sends the MODIFY PDP CONTEXT REQUEST message to the network. The message may contain the requested new QoS and/or the TFT

Upon receipt of the MODIFY PDP CONTEXT REQUEST message, the network

may reply with the MODIFY PDP CONTEXT ACCEPT message in order to accept the context modification

Or, the network may reject the MS initiated PDP context modification request by sending a MODIFY PDP CONTEXT REJECT message to the MS

In case the network initiates the PDP context modification procedure, the network sends the MODIFY PDP CONTEXT REQUEST message to the MS


PDP Context Modification Message Flow

MS Network

MODIFY PDP CONTEXT

REQUEST

MODIFY PDP CONTEXT ACCEPT

MODIFY PDP CONTEXT REJECT

or

MS Network

MODIFY PDP CONTEXT REQUEST

MODIFY PDP CONTEXT ACCEPT

MS initiated Modify PDP Context

Network initiated Modify PDP Context


PDP Context Modification (Successful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Modify PDP Context Request

DTI - Modify PDP Context Accept

GTP Update PDP Context Request

GTP Update PDP Context Response



RLSD

RLC

Once the PDP context is modified

Modify PDP Context Accept message is send to the UE


In order to Modify the PDP context,

Modify PDP Context Request by the UE to the SGSN

This message may contain the new

QOS parameters

Update PDP Context procedure is

executed in the Gn interface


PDP Context Modification (Unsuccessful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Modify PDP Context Request

DTI - Modify PDP Context Reject

GTP Update PDP Context Request

GTP Update PDP Context Response



RLSD

RLC

PDP context modification is rejected

by the SGSN by sending Modify PDP Context Reject message to the UE

This message has the cause value

Service option not supported


In order to Modify the PDP context,

Modify PDP Context Request by the UE to the SGSN

This message may contain the new

QOS parameters

Update PDP Context procedure is

executed in the Gn interface. Update

pdp context response contains the

cause value Service not supported'


PDP Context Deactivation

The purpose of this procedure is to deactivate an existing PDP context between the MS and the network.

The PDP context deactivation may be initiated by the MS or by the network

In order to deactivate a PDP context, the MS sends a DEACTIVATE PDP CONTEXT REQUEST message to the network.

The message contains the cause which is typically #26:insufficient resources, #36: regular deactivation or #37: QoS not accepted

The network shall reply with the DEACTIVATE PDP CONTEXT ACCEPT message

In case of network initiated PDP context deactivation, the network sends a DEACTIVATE PDP CONTEXT REQUEST message to the MS.

The message contains the cause which is typically #8: operator Determined Barring, #36: regular deactivation, #38: network failure, or # 39: reactivation requested

The MS shall, upon receipt of this message, reply with a DEACTIVATE PDP CONTEXT ACCEPT message


PDP Context Deactivation Message Flow

MS Network

DEACTIVATE PDP CONTEXT REQUEST

DEACTIVATE PDP CONTEXT ACCEPT

MS Network

DEACTIVATE PDP CONTEXT ACCEPT

DEACTIVATE PDP CONTEXT REQUEST

MS initiated PDP Context Deactivation

Network initiated PDP Context Deactivation


PDP Context Deactivation (Successful) Message Flow

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Deactivate PDP Context Request

DTI - Deactivate PDP Context Accept

GTP Delete PDP Context Request

GTP Delete PDP Context Response



RLSD

RLC



SM Cause = #24h Regular Deactivation


Service Request

This procedure is used for

The initiation of CM layer service (e.g. SM or SMS) procedure from the MS in IDLE mode

The network to transfer down link signalling

Uplink and downlink of user data

The MS initiates the Service request procedure by sending a SERVICE REQUEST message. The service type IE shall indicate either "data", "signalling or "paging response

If the Service request cannot be accepted, the network returns a SERVICE REJECT message to the mobile station with appropriate cause


Service Request (Successful) Message Flow Service Type = Signalling

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI Deactivate PDP Context Request

DTI - Deactivate PDP Context Accept

GTP Delete PDP Context Request

GTP Delete PDP Context Response



RLSD

RLC



SM Cause = #24h Regular Deactivation

Scenario 1: Service Request for

Signalling purpose

There is no RAB Assignment in

this scenario


Service Request (Successful) Message Flow Service Type = Data

SGSN RNC GGSN

CR Service Request

CC



DTI Common ID DTI RAB Assignment Request

DTI - RAB Assignment Response



RLSD

RLC

Service Type = Data

Scenario 2: Service Request for

sending Data by the UE


RAB Assignment procedure is

involved in this scenario

IU Connection is released based

when RRC connection is released

in UTRAN


Service Request (Unsuccessful) Message Flow

SGSN RNC GGSN

CR Service Request

CC

DTI Service Reject



RLSD

RLC

Service Request is rejected by

the network because there is no

Active PDP Context for this UE.

Please note the service request

type was Data

Service type = Data


SRNS Relocation Macro Diversity

Macro diversity, refers to the condition that several radio links are active at the same time. These radio links may be towards different Node-Bs which are controlled by different RNCs

RNC Roles Serving RNC

RNC which serves an UE and provides connection to core network

Drift RNC RNC which provides UE radio resources,

but doesn't manage UEs connection with core network

SRNS relocation Procedure by which Drift RNC is made

as the Serving RNC, when the UE is moved towards Drift RNC


Forward Relocation With Iur (Successful) Message

MS Target RNC Source RNC

Old SGSN

New SGSN

GGSN

3. Forward Relocation Request

4. Relocation Request

2. Relocation Required

6. Relocation Command

5. Forward Relocation Response

4. Relocation Request Acknowledge

9. Relocation Detect

10. RAN Mobility Information

10. RAN Mobility Information Confirm

Establishment of Radio Access Bearers

8. Relocation Commit

7. Forwarding of data

11. Relocation Complete

12. Forward Relocation Complete

15. Routing Area Update

13. Update PDP Context Request 14. Iu Release Command

14. Iu Release Complete

13. Update PDP Context Response

12. Forward Relocation Complete Acknowledge

Decision to perform SRNS relocation


Forward Relocation Without Iur (Successful) Message Flow MS Target

RNC Source

RNC Old

SGSN New

SGSN GGSN

3. Forward Relocation Request

4. Relocation Request

2. Relocation Required

6. Relocation Command

5. Forward Relocation Response

4. Relocation Request Acknowledge

10. Relocation Detect

9. Forward SRNS Context



8. RRC message

8. RRC message

7. Forwarding of data

9. Forward SRNS Context Acknowledge

11. Relocation Complete

12. Forward Relocation Complete

13. Update PDP Context Request

14. Iu Release Command

14. Iu Release Complete 13. Update PDP Context Response

12. Forward Relocation Complete Acknowledge

Decision to perform MS

Involved SRNS Relocation

Establishment of Radio Access Bearers

MS detected by target RNC

15. Routing Area Update

Note: Forwarding of data is

through Iu interface

RRC Message, Physical

Channel Reconfiguration is

send by RNC

Mobile responds with

Physical Channel

Reconfiguration complete

when UE has reconfigured

itself


SRNS Relocation Failure

UE UE

RNS-A SGSN RNS-B

Iu-Relocation-Required

Iu-Relocation-Request

Iu-Relocation-Failure Iu-Relocation-Preparation

Failure

Iu- Release-Command

Iu- Release-Complete

Target RNS sends a IU-Relocation-

Failure message to MSC with cause

value No Radio Resources Available in Target cell

SGSN sends a IU-Relocation-

Preparation-Failure message to RNS-

A with cause value No Radio Resources Available in Target cell

The call between the UE and the old

RNS and between the old RNS and

the MSC shall continue as if there had

been no handover attempt

Scenario: Handover Failure due to

resource allocation failure in target

RNS

MSC sends IU-Release-Command

message with the cause "Relocation

Cancelled " to the Target RNS,


Typical Problems

Attach Reject Code 7: GPRS services not allowed

Code 14: GPRS services not allowed in this PLMN

Code 17: Network Failure

PDP Context Activation Failure Code 26: Insufficient resources

Code 29: User Authentication failed

Code 33: Requested service option not subscribed

Code 38: Network failure


Typical Problems

RAB Assignment Failure Code 15: Release due to UTRAN Generated Reason Code 18: Requested Traffic Class not Available Code 23: Invalid RAB Parameters Combination Code 46: Radio Connection With UE Lost Code 114: No Resource Available

Routing Area Update Failure 9 MS identity cannot be derived by the network 10 Implicitly detached 17 Network failure 111 Protocol error-unspecified


Hands On(1/2)

Tracing Attach Reject with #11: Network failure

cause in PAC

Select the appropriate IuPS linksets in PAC

Apply filter for in GMM layer with following criteria

Message Type = Attach Reject

GMM Cause = #11: Network failure


Hands On(1/2)

Filter Setup

Results

in

Detailed

View

Results

in

Overvie

w


Hands On(2/2)

Tracing Activate PDP context failure in CallTrace other than #29: user authentication failed and #33: Requested service option not subscribed

In Calltrace select IuPs-Dialogue

Select the appropriate Linksets and the Time interval

In Filter Condition Select PdpActivationFailureCause

From the selected drop down select #29: user authentication failed and #33: Requested service option not subscribed

Change the criteria from equals to not equals

Now hit the Start Trace button to see the results


Hands On(2/2)

Setup

Results

Right click on

the message

in Sequence

Diagram to

obtain this

view


Q&A


Acronyms and References

Drift Radio Network Controller

Home Location Register

Mobile Switching Center

Radio Network Controller

Radio Network Subsystem

Short Message Service Center

Serving Radio Network Controller

Serving Radio Network Subsystem

User Equipment

UMTS Terrestrial Radio Access Network

Visitor Location Register

Protocols

GPRS tunnelling protocol

Packet Data Protocol

Radio Access Network Application Part

Call Control

Mobile Applications Part

Signalling Connection Control Part

Messages

SCCP - Connection Confirm

SCCP Connection Request SCCP Data Form 1 SCCP Release Complete SCCP Released SCCP - Unit Data

TCAP - BEGIN Message Identifiers

TCAP CONTINUE Message TCAP END Message

Identifiers

Source Local Reference

Destination Local Reference

International Mobile Subscriber Identity

International Mobile Equipment Identity

Mobile Subscriber ISDN Number

Entities

DRNC

HLR

MSC

RNC

RNS

SMSC

SRNC

SRNS

UE

UTRAN

VLR

GTP

PDP

RANAP

CC

MAP

SCCP

CC

CR

DT1

RLC

RLSD

UDT

BEGIN

CONTINUE

END

SLR

DLR

IMSI

IMEI

MSISDN

References

RANAP 3GPP TS: 25.413:

http://www.3gpp.org/ftp/Specs/archive/25_series/25.413/25413-880.zip

MAP 3GPP TS 29.002 :

http://www.3gpp.org/ftp/Specs/archive/29_series/29.002/29002-7f0.zip

SM, GMM: 3GPP TS 24.008

http://www.3gpp.org/ftp/Specs/archive/24_series/24.008/24008-7f0.zip

HANDOVER: 3GPP TS 23.009

http://www.3gpp.org/ftp/Specs/archive/23_series/23.009/23009-711.zip

GPRS Service Description: 3GPP TS 23.060

http://www.3gpp.org/ftp/Specs/archive/23_series/23.060/23060-7b0.zip


Thank you!

Signalling

Documents

iu interface

iups interface

core network cn

words iups

user plane connection

rnc aware

user equipment ue

gprs services