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The 3GPP2 Architecture

Sridhar Machiraju

CS294-3, Spring 2002,University of California at Berkeley

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Contents

Introduction


Mobility Management in 3GPP2

Functional comparison of 3GPP and3GPP2.

Architectural comparison of 3GPP and3GPP2

The MWIF Architecture.

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We saw that the 3GPP architecture evolvedfrom the already-existing GPRS network. It

can be viewed as IP-based multimedia

enhancements to 2G networks.

However, 3GPP2 has created a new

architecture (there was no existing packetpacket data service) for the 2G and 3G

CDMA air interfaces.

Introduction

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Contents

Introduction






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Basic Design Philosophy of

3GPP2 Leverage existing globally-accepted IETF

protocols whenever possible e.g., mobile IP (for

mobility), IPSec (for e2e security), AAA(authentication, authorization and accounting for

network access).

Some advantages are

Interoperability/roaming with existing IP networks.

Easy deployment of new services.

Well understood standards.

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The Official Reference Model!

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A Simpler Version!

BTS BSC MSC

HLR VLR

OTAF

PDSN AAA

SMS

IP SCP SN

PDN

PSTN

Control of Services

InternetBase Station

Packet data functions

Traditional

Switching Point

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Much More Simpler!

BTSBase

Transceiver Station

BSCBase Station

Controller

MSCMobile

Switching Center

PDSN - Packet Data

Serving Node

HAHome Agent

IWFInter-Working

Function

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Contents

Introduction






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A Mobility Perspective

Note that, for simple IP, the HA is

not used.

AAA is used for data service

authentication.

The PPP tunnel from the MS

terminates at the PSDN which acts

as the Foreign Agent (FA).

The PSDN is the first hop IP router

and performs Diffserv shaping,

ingress filtering, handoff between

PCFs.

The PDSN is also responsible for

forwarding accounting information

to the appropriate AAA entity. The PCF maintains a layer 2

connection with the PSDN for

sending/receiving packets for MSs

under its control.

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The Ultimate GoalAn All-IP Network

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Contents

Introduction






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Services etc.

The 3GPP model has aSIP-like functionalityin the 3 types of CallState Control

Functions (CSCF). Location service in the

3GPP model is tiedclosely to the access.

GTP is used to providelink-layer mobility.

Though the specificationis yet to be published,3GPP2 has decided to useSIP.

In the 3GPP2 model,

location service is more ofa database i.e., access-independent.

Link layer mobility in the

3GPP2 world is viewed asa direct extension ofmobile IP.

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Note that,

Due to the lack of standards for SIP with all potential

applications like VoIP, there is a danger of 3GPP and

3GPP2 coming up with incompatible extensions to SIP

which would have to be harmonized sometime later.

The 3GPP2 specification is not as complete as the 3GPPspecification.

In the 3GPP specification, there is an option to place a

mobile IP-based Foreign Agent in the GGSN. Still, this

would introduce a lot of tunneling overhead in the GGSN-SGSN path (Mobile IP over GTP over IP).

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Contents

Introduction






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Emergency

ServicesNetwork

3G-HLR

UTRAN BSS/

GERAN

3G-HLRG-MSC Server

IP Multimedia

Subsystem

PS Domain

3G-SGSN 3G-GGSN

R-SGW

MGCF

MGW

PSTN/

Legacy/External

T-SGWLegacy mobile

signalling

Network

Multimedia

IP Networks

Multimedia

IP Networks

MSC Server

Signaling onlyUser Data and Signaling

BGCF

Applications &

Services

SCPCSCF

CSCF

Application

Service

Control

Transport

CS Domain

RAN

3G-HLR

UMS

HSS

MRF

GMLC

MT TE

3GPP All-IP Network Architecture Model

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3GPP NAM - Discussion

3GPP is divided into 4 planesIP Multimedia, Packet-Switched,

Data-Switched and Radio Access.

At each plane, there exist data and control functions.

The picture is very disorganized especially from traditional networking

perspective. Legacy transport gateways are on the same plane as applications.

HLR and Unified Messaging Service are in limbo.

As mentioned earlier, the location service is access dependent because of

its presence in the lowest layer.

The CSCF has all the functionality; there is not much modularity. Transport and Control reside in the same functional node often.

Applications have to talk to either of CSCF, HSS, SGSN.

QoS is implemented in CSCF and GGSN.

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Application

Service

Control

Transport MediaGatewayControl

RoamingSignalingGateway

ServiceApplication

NetworkCapabilityGateway

SubscriptionQoSManager

Databases

EIR DSI Sub Poli

TrunkSignalingGateway

MAP41 & GSM

PSTN

IPNetwork

SessionControl

Manager

Core QoSManager

MediaGateway

BorderRouter

PositionServer

PositionDeterminingEntity

AAA

Legacy MSDomainSupport

MediaResourceFunction

Mobile IPHomeAgent

Access Net.

AccessGateway

FA/Attendant

BSC+ PCFBTS

MM

OtherAccess Networks

MS

Signaling-Control

BearerRadio

3GPP2 All-IP Network Architecture Model

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3GPP2 NAM - Discussion

3GPP2 fits into the Transport, Control, Service,

Application Plane model much better.

The PSDN will have only the HA/FA functionality unlike

the GSN nodes.

Applications talk to only the NCG.

The modularity of this model over the 3GPP model is seen

in the case of the QoS manager.

The HLR, ESI, location information etc are captured asservices available by querying databases.

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Contents

Introduction


Mobility Management in 3GPP2 Functional comparison of 3GPP and

3GPP2.



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The Mobile Wireless Internet

Forum (MWIF) MWIF is a non-profit association of wireless

companies whose objective is to define a singlemobile wireless and Internet architectureindependent of the access technology.

They have a network reference model to achievethis. Backwards compatibility is still a problem.

Notice the service discovery server in the MWIFarchitecture.

The CSCF functionality is in the CSM and SessionProxy.

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Directory Services

i l

Application

Service

Control

Transport

INTERNET

IntranetPSTN

MAP41 & GSM

Enterprise

HomeMobilityManager

Access Network

Terminal UIM

Access Gateway

IP AddressManager

AccessTransportGateway

MobileAttendant Transport Gateway Functional

Entities

MediaGateway

IPGateway

SignalingGateway

MediaGatewayController

MultimediaResourceFunction

Communications SessionManager (CSM)

SessionProxy

SessionAnchor

AAA Functional Entities

AuthenticationServer

Home IPAddressManager

AuthorizationServer

AccountingServer

LocationServer Global NameServer

PolicyRepository

ProfileServer

Application Functional Entities

Core NetworkApplication(s)

3rd PartyApplication(s)

MultimediaResourceController

ResourceManager

GeographicLocationManager

ServiceDiscoveryServer

Bearer

Signaling-Control

ResourceDirectory

MWIF All-IP Network Architecture Model

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Summary

Though the 3GPP and 3GPP2 NAM differ, activeharmonization initiatives such as MWIF are causefor optimism.

Remember that harmonization on the access is

also being tried for (or else dual mode deviceswould be necessary).

SIP seems to be the choice for session initiationover H.323 and other protocols.

There are strong reasons for using IPv6 in 3Gnetworks. But, all commercial 3G networks tilldate use IPv4 (since it is easier to deploy).

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113GPP2