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The 3GPP2 Architecture
Sridhar Machiraju
CS294-3, Spring 2002,
University of California at Berkeley
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
We saw that the 3GPP architecture evolved from 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 packet
packet data service) for the 2G and 3G CDMA air interfaces.
Introduction
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
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.
The Official Reference Model!
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”
Much More Simpler!
• BTS – Base Transceiver Station
• BSC – Base Station Controller
• MSC – Mobile Switching Center
• PDSN - Packet Data Serving Node
• HA – Home Agent
• IWF – Inter-Working Function
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
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.
The Ultimate Goal – An All-IP Network
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
Security and Mobility Management
• 3GPP uses GGSN, SGSN nodes.
• 3GPP does not allow heterogeneous access.
• The HLR is likely to be used by the SGSN for authenticating data users. Thus, access and data network authentication are integrated.
• 3GPP2 uses mobile IP and PSDN as FA/HA .
• It allows heterogeneous access.
• The PDSN uses an AAA infrastructure to authenticate data users. Access and data network authentication are separate.
Services etc.• The 3GPP model has a
SIP-like functionality in the 3 types of Call State Control Functions (CSCF).
• Location service in the 3GPP model is tied closely to the access.
• GTP is used to provide link-layer mobility.
• Though the specification is yet to be published, 3GPP2 has decided to use SIP.
• In the 3GPP2 model, location service is more of a database i.e., access-independent.
• Link layer mobility in the 3GPP2 world is viewed as a direct extension of mobile IP.
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 3GPP specification.
• 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).
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
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
signallingNetwork
MultimediaIP Networks
MultimediaIP Networks
MSC Server
Signaling only User 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
3GPP NAM - Discussion
• 3GPP is divided into 4 planes – IP 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.
Application
Service
Control
Transport Media Gateway Control
Roaming Signaling Gateway
Service Application
Network Capability Gateway
Subscription QoS Manager
Databases
EIR DSI Sub Poli
Trunk Signaling Gateway
MAP41 & GSM
PSTN
IPNetwork
Session Control Manager
Core QoS Manager
Media Gateway
Border Router
Position Server
Position Determining Entity
AAA
Legacy MS Domain Support
Media Resource Function
Mobile IP Home Agent
Access Net.AccessGateway
FA/Attendant
BSC+ PCFBTS
MM
OtherAccess Networks
MS
Signaling-ControlBearerRadio
3GPP2 All-IP Network Architecture Model
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 as services available by querying databases.
Contents
• Introduction• The 3GPP2 Architecture• Mobility Management in 3GPP2• Functional comparison of 3GPP and
3GPP2.• Architectural comparison of 3GPP and
3GPP2• The MWIF Architecture.
The Mobile Wireless Internet Forum (MWIF)
• MWIF is a non-profit association of wireless companies whose objective is to define a single mobile wireless and Internet architecture independent of the access technology.
• They have a network reference model to achieve this. Backwards compatibility is still a problem.
• Notice the service discovery server in the MWIF architecture.
• The CSCF functionality is in the CSM and Session Proxy.
Directory Services
i l
Application
Service
Control
Transport
INTERNETIntranet
PSTNMAP
41 & GSM
Enterprise
Home Mobility Manager
Access Network
Terminal UIM
Access Gateway
IP Address Manager
Access Transport Gateway
Mobile Attendant Transport Gateway Functional
Entities
Media Gateway
IP Gateway
Signaling Gateway
Media Gateway Controller
Multimedia Resource Function
Communications Session Manager (CSM)
Session Proxy
Session Anchor
AAA Functional Entities
AuthenticationServer
Home IP Address Manager
AuthorizationServer
AccountingServer
Location Server
Global Name Server
Policy Repository
Profile Server
Application Functional Entities
Core Network Application(s)
3rd Party Application(s)
Multimedia Resource Controller
Resource Manager
Geographic Location Manager
Service Discovery Server
BearerSignaling-Control
Resource Directory
MWIF All-IP Network Architecture Model
Summary• Though the 3GPP and 3GPP2 NAM differ, active
harmonization initiatives such as MWIF are cause for optimism.
• Remember that harmonization on the access is also being tried for (or else dual mode devices would be necessary).
• SIP seems to be the choice for session initiation over H.323 and other protocols.
• There are strong reasons for using IPv6 in 3G networks. But, all commercial 3G networks till date use IPv4 (since it is easier to deploy).
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