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.
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.
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!
Control of Services
IP
SCP
SN
PSTN
Base Station
Internet
BTS
BSC
Traditional MSC
“Switching Point”
SMS
Packet data functions
PDSN
AAA
HLR
VLR
OTAF
PDN
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 • Though the specification
is yet to be published,
SIP-like functionality
3GPP2 has decided to use
in the 3 types of Call
SIP.
State Control
• In the 3GPP2 model,
Functions (CSCF).
location service is more of
• Location service in the
a database i.e., accessindependent.
3GPP model is tied
• Link layer mobility in the
closely to the access.
3GPP2 world is viewed as
• GTP is used to provide
a direct extension of
link-layer mobility.
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 GGSNSGSN 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.
3GPP All-IP Network Architecture Model
Applications &
Services
IP Multimedia
Subsystem
CSCF
SCP
MGCF
CSCF
Legacy mobile
signalling
Network
Multimedia
IP Networks
T-SGW
BGCF
MRF
UMS
R-SGW
PSTN/
Legacy/External
MGW
HSS
CS Domain
3G-HLR
3G-HLR
G-MSC Server
3G-SGSN3G-HLR
Emergency
Services
Network
3G-GGSN
PS Domain
MSC Server
GMLC
RAN
BSS/
GERAN
UTRAN
MT
Signaling only
User Data and Signaling
TE
Application
Service
Control
Transport
Multimedia
IP Networks
3GPP NAM - Discussion
• 3GPP is divided into 4 planes – IP Multimedia, Packet-Switched, DataSwitched 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.
3GPP2 All-IP Network Architecture Model
Application
Databases
EIR
DSI
Sub
Service
Service
Application
Poli
Subscription
QoS
Manager
Roaming
Signaling
Gateway
Network
Capability
Gateway
Control
Position
Server
AAA
Transport
Position
Determining
Entity
Access
Gateway
Access Net.
Signaling-Control
Bearer
Radio
BTS
BSC
+ PCF
MM
Other
Access Networks
MS
FA/
Attendant
MAP
41 & GSM
Trunk
Signaling
Gateway
Session
Control
Manager
Core QoS
Manager
Media
Gateway
Control
Media
Resource
Function
Media
Gateway
Mobile IP
Home
Agent
PSTN
Border
Router
Legacy MS
Domain
Support
IP
Network
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.
MWIF All-IP Network Architecture Model
Resource
Directory
Directory Services
Location
Server
Global Name
Server
Application Functional Entities
Policy
Repository
Profile
Server
Core Network
Application(s)
3rd Party
Application(s)
Application
Geographic
Location
Manager
Service
Discovery
Server
AAA Functional Entities
Service
Control
Transport
Authentication
Server
Multimedia
Resource
Controller
Session
Proxy
Home IP
Address
Manager
Resource
Manager
Session
Anchor
Multimedia
Resource
Function
Mobile
Attendant
Access Gateway
i
Accounting
Server
Communications Session
Manager (CSM)
Home
Mobility
Manager
Bearer
Signaling-Control
Authorization
Server
l
Access
Transport
Gateway
IP Address
Manager
Media
Gateway
Controller
Transport Gateway Functional
Entities
IP
Gateway
Signaling
Gateway
Media
Gateway
Access Network
Terminal
UIM
Intranet
INTERNET
Enterprise
PSTN
MAP
41 & GSM
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).