owb000001(multimedia slide)gprs principle 20080523 b v1.0

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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

GPRS Principle

Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page2

Foreword

GPRS principle is the basic part of the whole system

and the later products learning. This slide will help

us to understand the GPRS system networking and

some important procedure.


References

3GPP protocol 23060

3GPP protocol 29060

3GPP protocol 24008


Objectives

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

Describe the GPRS networking structure

Describe the GPRS mobility management procedure

Describe the GPRS session management procedure


Contents

1. GPRS Network Structure

2. Mobility Management

3. Radio Resource Management

4. Session Management


GPRS Network Structure What is GPRS?

General Packet Radio Service

What is the function of GPRS?

In order to provide the data service out the scope of the fixed network

GPRS network classification

GSM GPRS

UMTS GPRS

GPRS network background

GSM GPRS network reuse the existed GSM network

UMTS GPRS network just change the RAN side


GPRS Network Structure

FR

EIREIRHLRHLRSMS-GMSCSMS-IWMSCSMS-GMSCSMS-IWMSC

MSC/VLRMSC/VLR

BSSBSS

UTRANUTRAN

SGSNSGSN

SGSNSGSN

GGSNGGSN

BGBG

CGCG

TE TEPDN

SS7

ATM

DDN

ISDN

Ethernet.etc

GPRSBackbone

Gs Gd Gr Gf Gc

Gb

Iu

Um

Um

Gp

Gi

Gn

Gn

ATMGa

SCPSCP GMLCGMLC

Ge Lg

Ga



Some Abbreviation

GPRS: General Packet Radio Service

BSS: Base Station Subsystem

UTRAN: UMTS Terrestrial Radio Access Network

SGSN: Service GPRS Support Node

GGSN: Gateway GPRS Support Node

CG: Charging Gateway

BG: Border Gateway

PDN: Packet Data Network



Abbreviations:

MSC/VLR: Mobile Switch Center/Visitor Location Register

SMS-GMSC: Gateway MSC For Short Message Service

SMS-IWMSC: Short Message Service Interworking MSC

SCP: Service Control Point

GMLC: Gateway Mobile Location Center

HLR: Home Location Register

EIR: Equipment Identity Register


GPRS Network Structure Important Entity Function: SGSN

Mobility management The MM functions are used to keep track of the current

location of an MS within the PLMN or within another PLMN. Session management

SM function manages the PDP context of MS. Routing and transfer

SGSN performs routing and forwarding of service data between MS and GGSN.

Charging SGSN can generate, store, convert and send CDRs.

Lawful Interception NTP


GPRS Network Structure Important Entity Function : GGSN

Session management

SM function manages the PDP context of MS.

Routing and transfer

GGSN performs routing and forwarding of service data between

MS and internet.

Charging

GGSN can generate, store, convert and send CDRs.

Dynamic IP allocation

Service management

Manage APN



Important Entity Function: CG

Real-time collection of GPRS CDRs

Temporary storage and buffering of GPRS CDRs

Pre-processing of GPRS CDRs

Sending GPRS CDRs to the billing center



Important

Entity

Function:

DNS

SGSN GGSN(A)

MS

BSS

GPRS backboneGPRS backboneGPRS backboneGPRS backbone

ISP AISP AISP AISP A

ISP BISP BISP BISP B

Internet/

IntranetGGSN(B)DNS

Resolve the APN to a GGSN IP in the PDP active procedure

Resolve the RAI to a SGSN IP in the inter-SGSN RAU procedure

Resolve the RNCID to a SGSN IP in the relocation procedure (UMTS)



Important Entity Function: HLR/AUC

Saving and updating GPRS subscriber subscription data

User authentication

Providing location information and processing needed

in mobility management and routing, for example

Saving and updating user service SGSN number and

address

GPRS user location deletion indication

Whether MS is reachable


Typical Application

E-mail from mobile to fixed network

BTS/NodeB

SGSN

MS

BSC/RNC

GGSNBackboneBackbone

ISPISP

Accessserver

Mailserver

e-mail

HLR


Typical Application

E-mail from fixed to mobile network

BTS/NodeB

SGSN

MS

BSC/RNC

GGSNBackboneBackbone

ISPISP

Accessserver

Mailserver

e-mail

HLR


Summary

GPRS network provides data service to the mobile

subscribers.

GPRS network is composed of SGSN, GGSN and CG.

BG and DNS provide special function during the data

service.


Contents






Contents


2.1 Basic concepts

2.2 Attach and Detach

2.3 Security Function

2.4 Location Management

2.5 Service Request (UMTS only)


GMM (GPRS Mobility Management) Function of the Mobility Management

keep track of the current location of an MS within the

PLMN or within another PLMN

Subscription data management

MS states management


GMM (GPRS Mobility Management) GMM main procedures

Attach procedure

RAU and periodic procedure

Detach procedure

GMM other procedures

P-TMSI reallocation procedure

Authentication procedure

Identification procedure

Subscriber management procedure


GMM States

PDU transmission

Implicit Detachor

Cancel Location

GPRS Attach

READY timer expiryorForce to STANDBY

GPRS Detach GPRS Attach

PDU reception

GPRS Detachor

Cancel Location

MM State Model of MS MM State Model of SGSN

IDLE

READY

STANDBY

IDLE

READY

STANDBY

READY timer expiryorForce to STANDBYorAbnormal RLC condition


PMM (Packet Mobility Management) The function of PMM is similar to GMM.

PMM other procedures

P-TMSI reallocation

Authentication

Identification

Subscriber management

PMM main procedures

Attach

RAU and periodic

RAU

Detach

Service request

SRNS relocation


PMM States

DOCUMENTTYPE

TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere

PM M-DETACHED

PS Attach

PS S ignallingConnection Releas e

PS S ignallingConnection Establish

PS Detach

PMM-CONNECTEDPMM-IDLE

Detach,PS Attach Reject,RAU Reject

PMM-DETACHED

PS Detach

PMM-CONNECTED

Serving RNCreloc ation

3G-SGSN MM StatesMS MM States

SM-ACTIVE orINACTIVE




Detach,PS Attach Reject,RAU RejectPS Attach

PS SignallingConnection Establish

PS S ignallingConnection Releas e

PMM-IDLE


Mobility Management Timer Functions

READY Timer Function (GSM only)

The READY timer controls the time an MS remains in READY state in the

MS and the SGSN. When the READY timer expires, the MS and SGSN MM

contexts shall return to STANDBY state.

Periodic RA Update Timer Function

Upon expiry of the periodic RA update timer, the MS shall start a

periodic routeing area update procedure.

Mobile Reachable Timer Function

If the mobile reachable timer expires, the SGSN shall clear PPF.

After expiry of the mobile reachable timer the SGSN may perform an

implicit detach.


MS Operation Modes for GSM

Class‑A mode of operation: The MS is attached to both

GPRS and other GSM services, and the MS supports

simultaneous operation of GPRS and other GSM

services.

Class‑B mode of operation: The MS is attached to both

GPRS and other GSM services, but the MS can only

operate one set of services at a time.

Class‑C mode of operation: The MS is exclusively

attached to GPRS services.


UE Operation Modes for UMTS PS/CS mode of operation: The MS is attached to both

the PS domain and CS domain, and the MS is capable of simultaneously operating PS services and CS services.

PS mode of operation: The MS is attached to the PS domain only and may only operate services of the PS domain. However, this does not prevent CS-like services to be offered over the PS domain (e.g. VoIP).

CS mode of operation: The MS is attached to the CS domain only and may only operate services of the CS domain. However, this does not prevent PS-like service to be offered over the CS domain.


Network Operation Modes for GSM

Mode Circuit Paging Channel

GPRS Paging Channel

Paging co-ordination

I

Packet Paging Channel


YesCCCH Paging

ChannelCCCH Paging

Channel

Packet Data Channel

Not Applicable

IICCCH Paging

ChannelCCCH Paging

ChannelNo

III

CCCH Paging Channel


NoCCCH Paging

ChannelCCCH Paging

Channel


Network Operation Modes for UMTS

Mode

Network configuration

Combined procedure by

MT

I Gs interface is present

Yes

II Gs interface is not present

No


Contents


2.1 Basic concepts






Attach Procedure

Function

An MS/UE shall perform a GPRS Attach to the SGSN in

order to obtain access to the GPRS services.

If the MS/UE is connected via a GSM radio, it shall

perform a GSM GPRS Attach procedure.

If the MS/UE is connected via a UMTS radio access

network, it shall perform a UMTS GPRS Attach

procedure


Attach Procedure

(IMSI or PTMSI+RAI) (PTMSI)

(IMSI)

(Identity Type = IMSI) (IMSI)


Attach Procedure


Attach Procedure

Results after any attach procedure:

SGSN get subscriber data from HLR

HLR recorded the MS’s serving SGSN number

SGSN and MS create MM context for the MS

MS can request Session Management services


Reject Caused by GPRS Core Network

Cause in attach reject Actions in PS domain Actions in CS domain

Illegal MS The MS shall set the GPRS update status to GU3 ROAMING NOT ALLOWED The SIM/USIM shall be considered as invalid for GPRS services until switching off or the SIM/USIM is removed

If the MS is IMSI attached, the MS shall in addition set the update status to U3 ROAMING NOT ALLOWED, shall delete any TMSI, LAI and ciphering key sequence number

Illegal ME

GPRS services not allowed The MS shall set the GPRS update status to GU3 ROAMING NOT ALLOWED; The SIM/USIM shall be considered as invalid for GPRS services until switching off or the SIM/USIM is removed.

no effect

GPRS services not allowed in this PLMN

shall set the GPRS update status to GU3 ROAMING NOT ALLOWED

PLMN not allowed shall set the GPRS update status to GU3 ROAMING NOT ALLOWED), shall reset the GPRS attach attempt counter and shall change to state GMM-DEREGISTERED

The MS shall perform a PLMN selection

Location area not allowed

Roaming not allowed in this location area

No Suitable Cells In Location Area

shall set the GPRS update status to GU3 ROAMING NOT ALLOWED

The MS shall search for a suitable cell in another location area in the same PLMN


MM ContextField Description A/Gb

modeIu

mode

IMSI IMSI is the main reference key. X X

MM State Mobility management state, IDLE, STANDBY, READY, PMM‑DETACHED, PMM‑IDLE, or PMM‑CONNECTED.

X X

P‑TMSI Packet Temporary Mobile Subscriber Identity. X X

P‑TMSI Signature A signature used for identification checking purposes. X X

IMEI International Mobile Equipment Identity X X

MSISDN The basic MSISDN of the MS. X X

Routeing Area Current routeing area. X X

Cell Identity Current cell in READY state, last known cell in STANDBY or IDLE state. X

Cell Identity Age Time elapsed since the last LLC PDU was received from the MS at the SGSN. X

Service Area Code Last known SAC when initial UE message was received or Location Reporting procedure was executed.

X

Service Area Code Age Time elapsed since the last SAC was received at the 3G‑SGSN. X

VLR Number The VLR number of the MSC/VLR currently serving this MS. X X

New SGSN Address The IP address of the new SGSN where buffered and not sent N‑PDUs should be forwarded to.

X X

Authentication Vectors Authentication and ciphering parameters (authentication triplets or quintets). X X

Kc Currently used A/Gb mode ciphering key. X 2)

CKSN Ciphering key sequence number of Kc. X 2)

Ciphering algorithm Selected ciphering algorithm (GEA). X X

CK Currently used Iu mode ciphering key. 1) X


MM ContextIK Currently used Iu mode integrity key. 1) X

KSI Key Set Identifier. 1) X

MS Radio Access Capability MS radio access capabilities. X

MS Network Capability MS network capabilities. X X

DRX Parameters Discontinuous reception parameters. X X

Radio Priority SMS The RLC/MAC radio priority level for uplink SMS transmission. X

MNRG Indicates whether activity from the MS shall be reported to the HLR. X X

NGAF Indicates whether activity from the MS shall be reported to the MSC/VLR.

X X

PPF Indicates whether paging for PS and CS services can be initiated. X X

Subscribed Charging Characteristics

The charging characteristics for the MS, e.g. normal, prepaid, flat-rate, and/or hot billing subscription.

X X

SMS Parameters SMS-related parameters, e.g. operator-determined barring. X X

Recovery Indicates if HLR or VLR is performing database recovery. X X

GPRS‑CSI Optional GPRS CAMEL subscription information, see 3GPP TS 23.016 X X

ODB for PS parameters Indicates that the status of the operator determined barring for packet oriented services.

X X

The information marked with a "1)" may be maintained if authentication is performed by the UMTS authentication procedure.

The information marked with a "2)" may be maintained if authentication is performed by the GSM authentication procedure.


Detach Procedure Function

The GPRS Detach procedure allows an MS to inform the network that it does not want to access the SGSN-based services any longer

The GPRS Detach procedure allows the network to inform an MS that it does not have access to the SGSN-based services any more

The following three entity can initiate the detach procedure MS

SGSN

HLR


Detach Procedure Results after any Detach procedure:

The SGSN shall not service the detached MS, unless reattach

The MS is in idle or PMM-DETACHED state

The MS is detached either explicitly or implicitly: Explicit detach: The network or the MS explicitly requests

detach

Implicit detach: The network detaches the MS, without notifying the MS, a configuration-dependent time after the mobile reachable timer expired, or after an irrecoverable radio error causes disconnection of the logical link.


Detach Types The different types of detach are:

IMSI detach;

GPRS detach;

combined GPRS / IMSI detach (MS-initiated only).

The MS can make an IMSI detach in one of two ways depending on whether it is GPRS-attached or not:

A GPRS-attached MS sends a Detach Request message to the SGSN, indicating an IMSI detach. This can be made in combination with GPRS detach.

An MS that is not GPRS-attached makes the IMSI detach as already defined in A/Gb mode or UMTS.


Detach Procedure (MS Initiated)

3. IMSI Detach Indication

2. Delete PDP Context Response

1. Detach Request

2. Delete PDP Context Request

5. Detach Accept

MS BSS/UTRAN GGSNSGSN MSC/VLR

4. GPRS Detach Indication

6. PS Signalling Connection Release

C2

C1


Detach Type IE of Detach Request

Power off (octet 1)

In the MS to network direction:

Bit

4

0 normal detach

1 power switched off

In the network to MS direction the Power off bit shall be spare and set to zero.

8 7 6 5 4 3 2 1

Detach typeIEI

Power

off

Type of detach

Type of detach (octet 1)

In the MS to network direction:

Bits

3 2 1

0 0 1 GPRS detach

0 1 0 IMSI detach

0 1 1 Combined GPRS/IMSI detach

All other values are interpreted as Combined GPRS/IMSI detach by this version of the protocol.

In the network to MS direction:

Bits

3 2 1

0 0 1 re-attach required

0 1 0 re-attach not required

0 1 1 IMSI detach (after VLR failure)

All other values are interpreted as re-attach not required by this version of the protocol.


Detach Procedure (SGSN Initiated)


1. Detach Request 2. Delete PDP Context Request

4. Detach Accept

MS BSS/UTRAN GGSNSGSN MSC/VLR



C1

C2


Detach Procedure (HLR Initiated)

HLRMS BSS/UTRAN GGSNSGSN MSC/VLR


1. Cancel Location


2. Detach Request

6. Cancel Location Ack


5. Detach Accept


C2

C1


Purge Function Function

The Purge function allows an SGSN to inform the HLR that it has

deleted the MM and PDP contexts of a detached MS

After the MS detach from the network:

The SGSN may delete the MM/PDP context immediately

the SGSN may keep the MM/PDP context for some time of the

detached MS

Purge Timer Function

Allows the SGSN to inform the HLR that it has deleted the MM and

PDP contexts of a detached MS.

The purge timer is set longer than the mobile reachable timer


Purge Function

1. Purge MS

2. Purge MS Ack

SGSN HLR


Contents


2.1 Basic concepts






Authentication Function

Function

Permit the network to check whether the identity

provided by the mobile station is acceptable or not;

Provide parameters enabling the mobile station to

calculate a new ciphering key ; （ UMTS and GSM ） Provide parameters enabling the mobile station to

calculate a new UMTS integrity key; （ UMTS only ） Permit the mobile station to authenticate the network.

（ UMTS only ）


Authentication Function Authentication types:

GSM Authentication

Using triplet: RAND, SRES, Kc

Using GPRS Encryption Algorithm (GEA)

UMTS Authentication

Using quintet: RAND, XRES, AUTN, CK, IK

– AUTN: for UE authenticate network

– IK: for data integrity function

Using UMTS Encryption Algorithm (UEA)

These procedures are used independent of the GSM or UTRAN

RANs, i.e. each procedure may be executed in A/Gb mode or in

Iu mode.


Authentication Function

1a. Send Authentication Info

2a. Authentication and Ciphering Request

1b . Send Authentication Info ack

2b. Authentication and Ciphering Response

MS BSS/UTRAN HLR/Auc SGSN


Authentication Function(3G)MS VLR/SGSN HE/HLR

Generate authenticationvectors AV(1..n)

Store authentication vectors

Select authentication vector AV(i)

Authentication data request

Authentication data responseAV(1..n)

User authentication requestRAND(i) || AUTN(i)

User authentication responseRES(i)

Compare RES(i) and XRES(i)

Verify AUTN(i)Compute RES(i)

Compute CK(i) and IK(i) Select CK(i) and IK(i)

Authentication andkey establishment

Distribution ofauthenticationvectors from HEto SN


Release 99+ VLR/SGSN Release 98- VLR/SGSN

Release 99+ HLR/AuC

USIM

RAND AUTN RES

CK IK

CK, IK Kc

UTRAN

ME capable of UMTS AKA

RAND AUTN RES

[Kc]

CK, IK Kc

GSM BSS

CK, IK Kc RES SRES

CK, IK Kc

ME not capable of UMTS

AKA

CK, IK Kc

CK, IK Kc RES SRES

RAND [AUTN]

SRES

[Kc]

Kc

RAND SRES

[Kc]

Kc

ME

CK, IK Kc RES SRES

Quintets Triplets

CK, IK Kc RES SRES

UMTS security context

GSM security context

CK, IK Kc

GSM security context

Release 99+VLR/SGSN

Release 98-VLR/SGSN

Release 98- or Release 99+HLR/AuC

SIM

RANDSRES

CKIK

Kc

UTRAN

R99+ UE

RANDSRES

[Kc]

Kc

GSM BSS

Kc CK, IK

R98- UE

Kc CK, IK

RANDSRES

[Kc]

Kc

RANDSRES

[Kc]

Kc

R99+ UEor

R98- UE

Triplets Triplets

Authentication Function (2G-3G)


Scope and Start of Ciphering In A/Gb mode, the scope of ciphering is from the ciphering function in

the SGSN to the ciphering function in the MS.

In Iu mode, the scope of ciphering is from the ciphering function in the UTRAN to the ciphering function in the MS.

In A/Gb mode, the MS starts ciphering after sending the Authentication and Ciphering Response message.

In Iu mode, the start of ciphering is controlled by the security mode procedure after authentication procedure.

MS BSS/UTRAN SGSN

Scope of GSM GPRS ciphering

Scope of UMTS ciphering


Identity Check

Function Get IMSI from MS Check the IMEI

1. Identity Response

2. Check IMEI

1. Identity Request

2. Check IMEI Ack

MS BSS/UTRAN EIRSGSN


P‑TMSI Reallocation Function

The SGSN may reallocate the P‑TMSI at any time

The reallocation procedure can be performed by the P‑TMSI Reallocation procedure

The P‑TMSI can be included in the Attach or Routeing Area Update procedures.

2. P-TMSI Reallocation Complete

1. P-TMSI Reallocation Command

MS BSS/UTRAN SGSN


Contents


2.1 Basic concepts






Location Management Function

A mechanisms for cell and PLMN selection;

A mechanism for the network to know the Routeing Area for MSs in STANDBY, PMM‑IDLE, READY, and PMM‑CONNECTED states;

A mechanism for the 2G‑SGSN to know the cell identity for MSs in READY state;

A mechanism for the UTRAN to know the URA identity or cell identity for MSs in PMM‑CONNECTED state;

A mechanism for the UTRAN to indicate to an MS in RRC Connected mode when a Routeing Area Update procedure shall be performed by providing the RAI;

A mechanism for the network to know the address of the serving RNC handling an MS in PMM‑CONNECTED state. This mechanism is the serving RNC relocation procedure


Layered Location Management Mode (2G)

•SGSN

•HLR

•BSS

•MS

•SGSN number

•ready state: cell number

•Standby state: RAI


Layered Location Management Mode (3G)

•SGSN

•HLR

•RNC

•MS

•SGSN number

•PMM-connect state: RNCID,RAI,SAI

•PMM-idle: RAI


Network Architecture Routeing area update

procedure

SGSN can manage the MS

location information via RAU

procedure in RAI level

Relocation procedure (UMTS

only)

Move the Iu interface to the

other RNC

Handover procedure

Move the radio link to the

other BTS/NodeB

old SGSN

RNC2RNC1

MS

GGSN

Iu

new SGSN

RNC4 RNC3

IU

HLR/AUC

Gn/Gp Gn/Gp

PDN

Gi

Gr GrIU

Iu

Gn

RA1 RA2 RA3

RA4 RA5

RA6 RA7 RA9

RA9 RA10

Iur


Routeing Area Update Procedure RAU procedure will happen in the following two case:

MS entered a new Route Area

Periodic RAU ( after periodic timer expires)

In the viewpoint of SGSN:

intra-SGSN RAU

Inter-SGSN RAU


Routeing Area Update Procedure

MS

RAI 2 RAI 4

SGSN SGSN

RAI 1 RAI 3

cell

Intra SGSN-RAU

Inter SGSN -RAU

Gn


Inter-SGSN RAU Procedure (2G)


Serving RNS Relocation Procedure

Before relocation

LA1, RA1

HLR/AuC

old SGSN

GGSN

LA2, RA2

new SGSN

source SRNC

new MSC/VLRold MSC/VLR

MS

target RNC

LA1, RA1

MS

HLR/AuC

old SGSN

source RNC

GGSN

LA2, RA2

new SGSNold MSC/VLR new MSC/VLR

target SRNC

After

relocation


Serving RNS Relocation Procedure 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

12. Relocation Complete

12. Forward Relocation Complete

10. UTRAN Mobility Information

10. UTRAN Mobility Information Confirm

Establishment of Radio Access Bearers

14. Routing Area Update

11. Update PDP Context Request

13. Iu Release Command

13. Iu Release Complete

C1

C2

1. Decision to perform SRNS relocation

8. Relocation Commit

7. Forwarding of data

11. Update PDP Context Response

12. Forward Relocation Complete Acknowledge

C3


Contents


2.1 Basic concepts






Service Request Procedure The Service Request procedure is used by a 3G‑MS in

PMM‑IDLE state to request the establishment of a secure

connection to a 3G‑SGSN.

The MS in PMM‑IDLE state initiates this procedure in order to

send uplink signalling messages (e.g. Activate PDP Context

Request), user data, or as paging response, or after the MS

has regained radio coverage.

This procedure is also used by an MS in PMM‑CONNECTED

state to request resource reservation for active PDP

contexts.


D O C U M E N T T Y P E

T y p e U n i t O r D e p a r t m e n t H e r eT y p e Y o u r N a m e H e r e T y p e D a t e H e r e

S G S NM S

2 . S e r v i c e R e q u e s t

3 . S e c u r i t y F u n c t i o n s

R N C1 . R R C C o n n e c t i o n R e q u e s t

8 . U p l i n k P D U

1 . R R C C o n n e c t i o n S e t u p

4 . R a d i o A c c e s s B e a r e r A s s i g n m e n tR e q u e s t

6 . R a d i o A c c e s s B e a r e r A s s i g n m e n tR e s p o n s e

5 . R a d i o B e a r e r S e t u p

6 . R a d i o B e a r e r S e t u pC o m p l e t e

H L R G G S N

7 . S G S N - I n i t i a t e d P D P C o n t e x t M o d i f i c a t i o n

4 . S e r v i c e A c c e p t

MS Initiated


7. SGSN-Initiated PDP Context Modification Procedure

8. Downlink PDU

SGSNMS

5. Security Functions

RNC

3. RRC Connection Request

1. Downlink PDU

3. RRC Connection Setup

6. Radio Access Bearer AssignmentRequest

6. Radio Access Bearer AssignmentResponse

6. Radio Bearer Setup

6. Radio Bearer SetupComplete

2. Paging

2. Paging

4. Service Request

HLR GGSN

Network Initiated


Service Type IE of Service Request Msg. MS initiated

Service type= signalling.

Service type= data.

Network initiated

Service type= paging response


Summary

Attach, location management, security function and

detach procedures are the main procedures in PS

core network.

SRNS relocation procedure and Service request

procedure are newly added in UMTS PS core

network.


Contents






Paging Summary The MM state in SGSN and MS before paging:

PMM-IDLE

STANDBY mode

Change MM state in MS to PMM-Connected or Ready after

successful paging.

Identification of MS in Paging message:

P-TMSI is used to identify the MS

If P-TMSI is invalid or MS not respond ,then use IMSI


Paging for GPRS (2G)

Function

An MS in STANDBY state is paged by the SGSN before a

downlink transfer to that MS

Paging move the MS state from STANDBY to READY.

Any uplink data from MS is a valid response to paging


Paging for GPRS (2G)

5. Any LLC Frame

4. Any LLC Frame

3. GPRS Paging Request

2. Paging Request

1. PDP PDU

MS BSS SGSN

STANDBY

READY

(IMSI, P‑TMSI, Area, Channel Needed, QoS, DRX Parameters)

(Receive Ready or Information frame)


Paging Initiated by CN (3G)

PS Paging Initiated by 3G‑SGSN without RRC

Connection for CS

A CN node requests paging only for MSs in PMM‑IDLE

state

The RNS controls whether the MS has an established

RRC connection or not

MS has no RRC connection

Paging Type 1 is transferred on the Paging channel



4. Service Request

4. Service Request

3. Paging Type12. Paging

MS RNS MSC/VLR

3G-SGSN

1. PDP PDU orDownlink signalingPMM IDLE

PMM CONNECTED

(PCH paging)(IMSI, P‑TMSI, Area, CN Domain Indicator, DRX parameters)

PS Paging Initiated by 3G‑SGSN without RRC

Connection for CS



PS Paging Initiated by 3G‑SGSN with RRC Connection

for CS

A CN node requests paging only for MSs in PMM‑IDLE

state

The RNS controls whether the MS has an established

RRC connection or not

In this case, MS has an established RRC connection for

CS service

Paging Type 2 is base on the establish RRC connection


PS Paging Initiated by 3G‑SGSN with RRC Connection

for CS

4. Service Request

4. Service Request

3. Paging Type22. Paging

MS RNS MSC/VLR

3G-SGSN

Connection Established

1. PDP PDU orDownlink signalling

(RRC paging)

(IMSI, P‑TMSI, Area, CN Domain Indicator, DRX parameters)

PMM IDLE

PMM CONNECTED



CS Paging (GSM only) When an MS is both IMSI and GPRS-attached in a network that operates

in mode I, the MSC/VLR executes paging for circuit-switched services via

the SGSN. If the MS is in STANDBY state, it is paged in the routeing area

and in the null routeing area (see clause "Routeing Area Identity “ of

TS23060). If the MS is in READY state, it is paged in the cell. The SGSN

converts the MSC paging message into an SGSN paging message.

4. SABM (Paging Response)

5. SCCP Connection Request (Paging Response)

1. Page

3. Paging Request

2. Paging Request

MS BSS SGSN MSC/VLR


CS Paging (UMTS only) When an MS is both IMSI- and GPRS-attached in a network

that operates in mode I, the MSC/VLR executes paging for

circuit-switched services via the SGSN.

In the MSC, a paging timer supervises the paging procedure.

4. RRC Initial Direct Transfer (Paging Response)

5. RANAP Initial UE (Paging Response)

1. Page

3. Paging Request

2. Paging

MS RNS 3G-SGSN MSC/VLR


Summary

In UMTS, Paging type 1 for UE without RRC

connection with RNC, Paging type 2 for UE with RRC

connection with RNC.

CS paging can be executed via PS.


Contents






Contents


4.1 Basic concepts

4.2 PDP Context Activation Procedure

4.3 PDP Context Modification Procedure

4.4 PDP Context Deactivation Procedure

4.5 Preservation Procedure (UMTS only)


Session Management Function

Establish and monitor a packet tunnel from MS to GGSN, and

allocate system resource for the packet service.

Important Procedure

PDP Context Activation

PDP Context Modification

PDP Context Deactivation


PDP Context

PDP Context: Packet Data Protocol context

PDP context contains all the information needed to

transfer user data between MS and GGSN.

The context includes parameters such as RA, QoS

(Quality of Service), Charging ID etc.

PDP context exists in MS, SGSN, GGSN.


PDP ContextEach MM context contains zero or more of the following PDP contexts:

Field Description A/Gb mode

Iu mod

e

PDP Context Identifier

Index of the PDP context. X X

PDP State Packet data protocol state, INACTIVE or ACTIVE. X X

PDP Type PDP type, e.g. PPP or IP. X X

PDP Address PDP address, e.g. an IP address. X X

APN Subscribed The APN received from the HLR. X X

APN in Use The APN currently used. This APN shall be composed of the APNNetwork Identifier and the APN Operator Identifier.

X X

NSAPI Network layer Service Access Point Identifier. X X

TI Transaction Identifier. X X

TEID for Gn/Gp Tunnel Endpoint Identifier for the Gn and Gp interfaces.

X X

TEID for Iu Tunnel Endpoint Identifier for the Iu interface. X

GGSN Address in Use The IP address of the GGSN currently used. X X

VPLMN Address Allowed

Specifies whether the MS is allowed to use the APN in the domain of the HPLMN only, or additionally the APN in the domain of the VPLMN.

X X

QoS Profile Subscribed

The quality of service profile subscribed. X X


PDP ContextQoS Profile Requested

The quality of service profile requested. X X

QoS Profile Negotiated

The quality of service profile negotiated. X X

Radio Priority The RLC/MAC radio priority level for uplink user data transmission.

X

Packet Flow Id Packet flow identifier. X

Aggregate BSS QoS Profile Negotiated

The aggregate BSS quality of service profile negotiated for the packet flow that this PDP context belongs to.

X

Send N‑PDU Number SNDCP sequence number of the next downlink N‑PDU to be sent to the MS.

X

Receive N‑PDU Number

SNDCP sequence number of the next uplink N‑PDU expected from the MS.

X

GTP‑SND GTP‑U sequence number of the next downlink N‑PDU to be sent to the MS.

X X

GTP‑SNU GTP‑U sequence number of the next uplink N‑PDU to be sent to the GGSN.

X X

PDCP‑SND Sequence number of the next downlink in-sequence PDCP‑PDU to be sent to the MS.

X

PDCP‑SNU Sequence number of the next uplink in-sequence PDCP‑PDU expected from the MS.

X

Charging Id Charging identifier, identifies charging records generated by SGSN and GGSN.

X X

PDP Context Charging Characteristics

The charging characteristics of this PDP context, e.g. normal, prepaid, flat-rate, and/or hot billing.

X X

RNC Address in Use The IP address of the RNC currently used. X


MM Context and PDP Context

HLR

SGSNBSC

or RNC

MS GGSN GnGb/ IuUu

MM context

PDP context #1

. .PDP context #n

MM context

PDP context #1

. .PDP context #n

PDP context #1

. . .PDP context #n


PDP State

Deactivate PDP Contextor

MM state change to IDLEor PMM-DETACHED

Activate PDPContext

INACTIVE

ACTIVE

PDP state inactive ： cannot

transmit data active ： can

transmit data


PDP Type and PDP Address PDP Type

IPV4 IPV6 PPP

PDP Address Static IP

Public IP Allocate by the operator

Dynamic IP Private IP Allocate by GGSN, DHCP or Radius


QoS

QoS: quality of service

It is a group of parameters that can define the network

ability, such as the bit rate for downlink or uplink data

transmission and the reliability class and so on

It is end to end concept


APN APN structure: APN-NI+APN-OI

huawei.com.cn.mnc<MNC>.mcc<MCC>.gprs

APNNetwork ID

APNOperator ID

•Operator ID : fixed extension, must end with “.gprs”

•Network ID shall not end with “.gprs”


APN

MS SGSN

GGSN1

GGSN2

GGSN3

DNS

APN1

APN2

APN3

APN1=GGSN1 IP1

APN2=GGSN2 IP2

APN3=GGSN3 IP3

APN

APN GGSN IP

APN1

APN2

APN3

IP1


SGSN

MS

SGSN

MS

•internet

GGSN GGSN

Roaming

APN:CMNET

•GuangDong province

General

APN

APN


SGSN

MS

SGSN

MS

GGSN GGSN

Roaming

APN:test.xy

VPN tunnel

Province 1

Local APN

Province 2

APN


DNS

BTS/NodeB

SGSN

MS

DNS

BSC/RNC

GGSN (B)BackboneBackbone

DNS

ISP BISP B

ISP AISP A

Corp.Network

Corp.Network

GGSN (A)

•APN-NI/APN-NI/

•Or APN-NI+APN-OIOr APN-NI+APN-OI

•APN-NI+APN-OI APN-NI+APN-OI ＝＝ GGSN IP addressGGSN IP address

•APN-NIAPN-NI

APN


Contents


4.1 Basic concepts






Activation Procedure

PDP context activation procedure

To establish a PDP context between the MS and

the SGSN, the GGSN

Activation procedure types:

PDP context activation procedure

Secondary PDP Context Activation

Procedure

Network-Requested PDP Context Activation

Procedure


2G-GGSN

5. Activate PDP Context Accept

3. Create PDP Context Response

3. Create PDP Context Request

1. Activate PDP Context Request

2G-SGSNBSS


MS

4. BSS Packet Flow Context Procedures

C1

C2

PDP Context Activation Procedure (2G)


(PDP Type, PDP Address, Access Point Name, QoS Requested)

Charging ID allocation

IP address

3G-GGSN




1. Activate PDP Context Request

3G-SGSNUTRANMS

4. Radio Access Bearer Setup （ Qos ）

C1

C2



PDP Context Activation Procedure (3G)


Handling in MS

MS start and send “Active PDP context request” to

SGSN

Provide QoS parameter

Provide a APN-NI

Provide a static IP or null

Receive ACCEPT from SGSN

If the QoS not accept by MS, then starts delete PDP

context procedure.


Handling in SGSN Check subscriber data APN selection

According to TS 23.060 default APN, APN provide from MS and the APN subscribed in HLR APN-NI.APN-OI

Interrogate DNS Hostfile/Cache/DNS server

QoS negotiation QoS provided from MS, default QoS ,QoS subscribed in HLR

Send message “Create PDP context request” to GGSN RAB assignment (UMTS only) Send message “Active PDP context accept” to MS

Dynamic IP address QoS


Handling in GGSN Check the APN provided by SGSN QoS negotiation Allocate a dynamic IP to the MS Allocate a charging ID for the PDP context Return a CREATE PDP CONTEXT ACCEPT

message to SGSN Dynamic IP QoS Charging ID Other information

Update PDP context


Handling in RNC

RAB assignment

MS SGSN GGSN

RNCRAB assignment (Final negotiated Qos)

Allocate Iu interface resource Allocate radio resource


Secondary PDP Context Activation Procedure The Secondary PDP Context Activation procedure may

be used to activate a PDP context while reusing the

PDP address and other PDP context information from

an already active PDP context, but with a different QoS

profile.

Procedures for APN selection and PDP address

negotiation are not executed.

A unique TI and a unique NSAPI shall identify each PDP

context sharing the same PDP address and APN.


Secondary PDP Context Activation Procedure

2G-GGSN

7. Activate Secondary PDP Context Accept



1. Activate Secondary PDP Context Request

2G-SGSNBSS


MS

5. BSS Packet Flow Context Procedures

C1

C2

For GPRS


Secondary PDP Context Activation Procedure

For UMTS

3G-GGSN




1. Activate Secondary PDP Context Request

3G-SGSNUTRANMS

4. Radio Access Bearer Setup

C1

C2




Network-Requested PDP Context Activation Procedure

MS SGSN GGSN

3. PDU Notification Request

HLR

1. PDP PDU

2. Send Routeing Info for GPRS

2. Send Routeing Info for GPRS Ack

4. Request PDP Context Activation

5. PDP Context Activation procedure

3. PDU Notification Response


Contents


4.1 Basic concepts






Modification Procedures Modification procedures modify parameters that were

negotiated during an activation procedure for one or several PDP contexts.

An MS, a GGSN, an SGSN, or an RNC can request a modification procedure.

The following parameters can be modified: QoS Negotiated;

Radio Priority;

Packet Flow Id;

PDP Address (in case of the GGSN-initiated modification procedure);

TFT (in case of MS-initiated modification procedure).


GGSN



SGSNUTRANMS

3. Modify PDP Context Request

4. Modify PDP Context Accept

5. Radio Access Bearer Modification

C1

6. Invoke Trace

SGSN-Initiated Modification Procedure


GGSN



SGSNUTRANMS




C1

GGSN-Initiated Modification Procedure


MS-Initiated Modification Procedure

GGSN



SGSNUTRANMS




C1


RNC modify RAB may cause SGSN modify PDP context.

1. RAB Modify Request

RNC SGSN

2. SGSN initiated PDP Context Modification Procedure

MS GGSN

RNC-initiated RAB Modification Procedure


Contents


4.1 Basic concepts






MS Initiated Deactivation Procedure For GPRS

2G-GGSN

4. Deactivate PDP Context Accept



1. Deactivate PDP Context Request

2G-SGSNMS


C1


MS Initiated Deactivation Procedure For UMTS

3G-GGSN



3G-SGSNUTRANMS



5. Radio Access Bearer Release

C1


GGSN



SGSNUTRANMS




C1

SGSN-initiated Deactivation Procedure


GGSN



SGSNUTRANMS




C1

GGSN-initiated Deactivation Procedure


Contents


4.1 Basic concepts






Preservation Procedures By sending a RAB Release Request or Iu Release Request

message to the SGSN, UTRAN initiates the release of one or

more RABs.

The preservation procedure allows the active PDP contexts

associated with the released RABs to be preserved without

modification in the CN, and the RABs can then be re-

established at a later stage (e.g. by service request

procedure).

UTRAN uses the Iu Release Request to request release of all

RABs of an MS, and the RAB Release Request in other cases.


RAB Release Procedure

UTRAN initiates a RAB release procedure to release

one or several RABs.

3G-GGSN

1. RAB Release Request

3G-SGSNUTRANMS

3. Release RadioBearer(s)

2. RAB Assignment Request

4. RAB Assignment Response


Iu Release Procedure

UTRAN initiates an Iu release procedure to release

all RABs of an MS and the Iu connection.

3G-GGSN

1. Iu Release Request

3G-SGSNUTRANMS

3. Release of RRC Connection

2. Iu Release Command

4. Iu Release Complete


PDP Context Modification after RAB Release After RAB/Iu Release the PDP contexts are modified as

follows:

Background or interactive traffic class PDP context:

Be preserved with no modifications in UE, SGSN and GGSN.

Streaming or conversational traffic class PDP context:

Be preserved, but the maximum bit rate is downgraded to

0 kbit/s (for both uplink and downlink) in UE, SGSN and GGSN.


Re-establishment of RABs In case of uplink data to be transfer for the active

PDP context without RAB: Background or interactive traffic class PDP context:

UE initiates the Service Request procedure (Service Type = Data) to re-establish PDP context.

Streaming or conversational traffic class PDP context: UE initiates the PDP context modification procedure to re-

establish PDP context, or deactivation procedure to delete the PDP context.

In case of downlink data to be transfer for the active PDP context without RAB: CN must first page the UE, then re-establish the RAB by network-initiated service request procedure.


Summary

The session management function includes the

flowing functions:

PDP context activation function;

PDP context modification function;

PDP context deactivation function;

PDP context preservation function.


Course Summary

MM and SM function are the most important function

of GPRS/UMTS PS core network.

Thank youwww.huawei.com

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