1. University of California at Berkeley
The 3GPP2 Architecture
Sridhar Machiraju
CS294-3, Spring 2002,
University of California at Berkeley

2. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

3. Introduction
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.

4. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

5. 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.

6. The Official Reference Model!

7. A Simpler Version! IP SCP SN PSTN BTS BSC MSC PDN SMS HLR VLR OTAF
Control of Services IP
SCP SN
PSTN
Base Station
Internet
BTS
BSC
MSC
PDN
Traditional “Switching Point”
SMS
HLR
VLR
Packet data functions
OTAF
PDSN
AAA

8. 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

9. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

10. 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.

11. The Ultimate Goal – An All-IP Network

12. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

13. 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.

14. 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.

15. 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).

16. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

17. 3GPP All-IP Network Architecture Model
Multimedia
IP Networks
Applications &
Services
IP Multimedia Subsystem
CSCF
SCP
MGCF
CSCF
Legacy mobile
signalling
Network
T-SGW
BGCF
PSTN/
Legacy/External
MRF
MGW
UMS
R-SGW
HSS
3G-HLR
3G-HLR
CS Domain
G-MSC Server
3G-HLR
3G-SGSN
3G-GGSN
Emergency
Services
Network
Application
MSC Server
PS Domain
Service
GMLC
Control
BSS/
GERAN
UTRAN
Transport
RAN
Multimedia
IP Networks MT TE
Signaling only
User Data and Signaling

18. 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.

19. 3GPP2 All-IP Network Architecture Model
Application
Databases
Service Application
EIR
DSI
Sub
Poli
Service
Roaming Signaling Gateway
MAP
41 & GSM
Subscription QoS Manager
Network Capability Gateway
Control
Trunk Signaling Gateway
Position Server
AAA
Session Control Manager
Transport
Media Gateway Control
Core QoS Manager
Position Determining Entity
PSTN
Media Resource Function
Access
Gateway
FA/
Attendant
Media Gateway
Access Net.
Signaling-Control
BSC
+ PCF
BTS
Bearer
Radio MM
Mobile IP Home Agent
Border Router
Other
Access Networks MS
Legacy MS Domain Support IP
Network

20. 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.

21. Contents Introduction The 3GPP2 Architecture
Mobility Management in 3GPP2
Functional comparison of 3GPP and 3GPP2.
Architectural comparison of 3GPP and 3GPP2
The MWIF Architecture.

22. 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.

23. MWIF All-IP Network Architecture Model
Directory Services
Resource Directory
Application Functional Entities
Location Server
Global Name Server
Policy Repository
Profile Server
Core Network Application(s)
3rd Party Application(s)
Application
Geographic Location Manager
Service Discovery Server
AAA Functional Entities
Service
Authentication
Server
Authorization
Server
Accounting
Server
Control
Communications Session Manager (CSM)
Home Mobility Manager
Multimedia Resource Controller
Resource Manager
Transport
Session Proxy
Session Anchor
Home IP Address Manager
Multimedia Resource Function
Media Gateway Controller
Access Gateway
Bearer
Mobile Attendant
Transport Gateway Functional Entities
Access Transport Gateway
Signaling-Control i l
Signaling Gateway
IP Gateway
Media Gateway
IP Address Manager
Access Network
Intranet
PSTN
MAP
41 & GSM
INTERNET
Enterprise
Terminal
UIM

24. 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).