This presentation discusses 3GPP's System Architecture Evolution (SAE) which aims to provide services over any access network through a common IP-based core network. It covers migration from GSM to a multi-access system using SAE/LTE, including support for SIM/USIM/ISIM, security evolution, and interworking of multi-mode terminals and networks through service continuity, multiple registration, and voice call continuity. IMS is also discussed as the service platform for multimedia services in 3GPP networks.

1. 3GPP presentation
Architecture evolution
Moscow, October 2008
3GPP TSG CT Chairman
Hannu Hietalahti
1

2. Contents
Migration from GSM to multi-access IP multimedia
• From GSM to multi-access
• SIM/USIM/ISIM support
• Security evolution
• System Architecture Evolution (SAE)
• IMS
• Multi-mode terminals and networks
–
–
–
–
–
Service continuity
Multiple registration
Voice Call Continuity
CS Fallback
Network selection
2

3. From GSM to multi-access
Continuous improvement of access technologies
Provision of services over any access network
Gb
GERAN
Iu
Common Core network
Visited
Network
GPRS Core
Home
Network
vPCRF
SGSN
hPCR F
S7
UTRAN
S3
Evolved RA N
S9
S1
MME
UP E
Rx +
S4
HSS
S6
S7
S6
S5a
Home
Inter AS
Anchor
S8
3GPP
Anchor
Visited EPC
SGi
Home EPC
Op . IP
Serv
(IMS,
PSS,
etc.)
S2
S2
WLAN
non 3GPP
* Color coding: red indicates new functional element / interface
GSM 1800 GSM 1900
GSM 900
GSM ph.1
GPRS
R97
3G
EDGE
R98
R99
Packet
Cable
HSPA
WLAN
Fixed
Rel-5/6
Rel-6/7
WiMAX?
E-UTRAN
?
Rel-8 and onwards
...and let’s make it IP all the way to the terminal !
3

4. SIM / USIM / ISIM support
GSM Ph.2 – R98
R99 – Rel-4
Rel-5 – Rel-7
Rel-8 ->
???
GSM phone
UMTS 3G phone
IP Multimedia
SAE
GSM phase 2
Mandatory SIM
No USIM support
Optional GPRS
(R97 ->)
WCDMA or EDGE
Mandatory SIM
USIM support is:
Mandatory for
WCDMA
Optional for
GSM/EDGE
IMS
Mandatory USIM
No SIM specs
Optional support of
legacy SIM
ISIM support
mandatory for IMS
ME
WLAN (Rel-6)
SAE
USIM mandatory
for SAE access
3G AKA security
SIM access not
allowed any more
No need to update
legacy USIM
IMC as alternative
to ISIM for non3GPP access
4

5. Security evolution
Phase 2 SIM
SIM
2G
AKA
UICC Smartcard, R99 ->
RAND
GSM
security
SRES
Kc
SIM
security
in USIM
SIM
application
in UICC
SIM Appl
USIM Application
2G
AKA
2G
AKA
RAND
SRES
Kc
3G
AKA
ISIM Appl
3G
AKA
RAND+
AUTN
RANDRAND
+AUTN
SRES
Kc
RES
Ck
Ik
RES
Ck
Ik
IMS 3G
AKA in
ISIM
3G AKA
in UICC
Authentication Request (RAND
, AUTN )
SIP 401
Unauthorised
5

6. System Architecture Evolution
(SAE)
•
LTE = E-UTRAN = evolved radio network
– Megabit class data rates
– Short delays
– Short transition from idle to active
•
SAE = System Architecture evolution
– Evolved IP oriented multi access architecture
•
•
•
•
•
•
E-UTRAN integrates only to SAE, A/Gb or Iu not possible
Strongly IP based PS only network
SAE covers both 3GPP and non-3GPP access technologies
Seamless roaming between E-UTRAN, 2G and 3G (tight interworking)
Loose interworking with non-3GPP accesses
Currently work is progressing on GTP for intra-3GPP mobility and
IETF based mobility for non-3GPP mobility
– The main Architecture specifications 23.401 and 23.402 frozen in June 2008
– Protocol work is ongoing with the goal to freeze it in December 2008
6

7. SAE/LTE Deployment
• Deployments are expected to start with overlapping
cellular coverage
– E-UTRAN overlapping with legacy 3GPP GERAN / UTRAN coverage
– E-UTRAN overlapping with legacy 3GPP2 coverage
– Multi-mode networks and terminals
• E-UTRAN is a packet-only radio with no CS capacity
• Initially E-UTRAN is foreseen as “islands” in the sea of
legacy cellular access
–
–
–
–
Mobility between E-UTRAN and legacy access is required
Mobility between PS and CS domains is required
Multi-mode terminals expect to use PS coverage where available
Desire to keep the connectivity and services
7

8. IP Multimedia Subsystem
(IMS)
•
•
PS domain IP Multimedia service platform
Based on open IETF standards
– End to end IP (SIP)
– Multi access
Internet
• GPRS, I-WLAN, fixed xDSL, Packet Cable defined
• More access technologies to follow...
Find & route
to destination
PSTN
IP
Multimedi
a
Core
Circuitswitched
network
( 2G or 3G )
IP
connectivity
User data
( GPRS,
3G,...)
Any IP connectivity
(3G, WLAN,...)
End-to-End IP
services
8

9. Common IMS
•
3GPP members, 3GPP2, WiMAX forum, ETSI TISPAN and CableLabs
contribute to 3GPP common IMS specifications
– Different requirements are supported in common implementation
•
All IMS specifications are harmonized to 3GPP specifications
– Common parts are defined in 3GPP specifications only
• Core IMS entities (CSCFs, AS, UE IMS client,...) + agreed common functions
– Other organisations either reference or re-use 3GPP specification as it stands
– Any changes or additions in the Common IMS area are made in 3GPP
• All 3GPP members can contribute on their favourite work items
• Ongoing work initiated by 3GPP members, CableLabs, 3GPP2 and ETSI TISPAN
– The scope and coverage of Common IMS have been agreed by the SDOs
•
Common version of IMS specifications in Rel-8
– Business or architecture specific additions to 3GPP Common IMS are possible
outside the agreed Common IMS area
9

10. Multi-mode,
Service continuity
• Call control protocols
– E-UTRAN is a PS only radio, speech and other services are IMS based
– PS domain IMS uses SIP protocol for call control (3GPP TS 24.229)
– CS domain uses Call Control defined in 3GPP TS 24.008
• Voice Call Continuity
– Domain transfer of ongoing call
– Typically from E-UTRAN to 2G or 3G access
• CS fallback
– Paging the mobile in E-UTRAN to start CS service in 2G or 3G access
– Not an E-UTRAN service, but fallback to existing service via 2G/3G
• IMS service continuity
– IMS service between E-UTRAN and other PS only, such as WLAN
• IMS Centralized Service Control (ICS)
– Common telephony services between CS and PS domain
10

11. Multi-mode,
IMS registration in Rel-7
•
•
When S-CSCF detects that the same UE registers again, it considers
this as an update and overwrites existing registration
In some cases it may not be possible to de-register when changing
from one access technology to another
– UE might lose radio coverage before being able to de-register
•
S-CSCF detects that the registration is from the same UE based on the
same privateID, which is practically a device-ID
E (privateID-A)
S-CSCF
REGISTER 1 (privateID-A, IPaddress: 1.2.3.4) registered with 1.2.3.4
UE
oss of
radio
REGISTER 2 (privateID-A, IPaddress: a.b.c.d)
UE registered ONLY wit
a.b.c.d – REGISTER 1 got
overwritten with REGISTE
11

12. Multi-mode,
IMS Multiple registration, Rel-8
•
•
•
A UE is able to register the same public user identity with multiple IP
addresses at the same time
Used e.g. for IMS Service Continuity (e.g. handing over from I-WLAN
to GPRS)
No gap in reachability of the mobile
HSS
GPRS
IP: 1.2.3.4
P-CSCF 1
S-CSCF
I-WLAN
IP: a.b.c.d
P-CSCF 2
user1 / 1.2.3.4 / UE-A
user1 / a.b.c.d / UE-
UE-A
12

13. Multi-mode,
Single Radio Voice Call Continuity
Transfer from E-UTRAN to GERAN with active call
(not all entities shown)
HO command
MME
E-UTRAN
IMS
HO required
measurements
relocation
request
relocation
response
session
transfer
PLMN serving
remote user
MSC server
prepare HO
HO complete
2G or 3G
MSC
13

14. Multi-mode, CS fallback
Directing the UE from E-UTRAN to 2G/3G for CS service
MME
E-UTRAN
paging
SETUP
paging
PLMN serving
remote user
call setup
SETUP
paging resp.
2G or 3G
MSC
14

15. Multi-mode,
Network selection
•
Network selection comprises two parts
– Network operator selection (the goal, based on commercial agreement)
• Home operator determines which visited operators are preferred
– Access technology selection (the means, based on technical criteria)
• Serving visited operator determines access technology, frequency band and cell
•
•
•
•
Multi-mode phones supporting many access technologies are a new
challenge
Network selection within each technology is defined for 3GPP and
non-3GPP accesses
The combination of multiple technologies is undefined
Two approaches are foreseen in Rel-8
– 3GPP network selection procedures are extended to cover any non-3GPP
system that supports ITU-T defined concepts of MCC and MNC
– For others the ANDSF can (optionally) download network selection policy
• Access technology preference, policy for changing access technology, etc.
•
•
•
MCC = Mobile Country Code
MNC = Mobile Network Code
ANDSF = Access Network Discovery and Selection Function
15

16. Multi-mode network selection,
Outbound roaming example
•
•
HPLMN is not available
Prioritized VPLMNs are
listed with no associated
RAT in PLMN selector
with access technology:
–
–
–
•
VPLMN5 is not
available
VPLMN1 is available
VPLMN2 is available
VPLMN2 is selected via
2G, 3G or E-UTRAN
–
•
HPLMN has
not
configured
RAT
priority
for this
VPLMN
–
VPLMN1
CDMA
VPLMN5
VPLMN2
VPLMN1
VPLMN1
USIM configured RAT
preference possible
After PLMN selection
normal idle mode is
resumed
–
PLMN
Selector
(USIM):
Cell & RAT may change
within the selected
PLMN
Background scan for
higher priority network
HPLMN
VPLMN1
E-UTRAN
?
VPLMN2
UTRAN
VPLMN2
GERAN
VPLMN2
E-UTRAN
RAT = Radio Access Technology, PLMN = Public Land Mobile Network
VPLMN
2
16

17. Thanks f or your
at t e nt i on !
M e i nf or m i on at
or
at
w w 3gpp. or g
w.
17

18. Ar chi t e ct ur e Anne x:
3GPP and non- 3GPP
acce s s ar chi t e ct ur e
18

19. SAE architecture (23.401)
NAS signaling+sign.
security
HSS
Mobility between 3GPP
ANs
Idle mode UE
reachability
PCRF
S
7
S6a
PDN
Gateway
P-GW and S-GW
selection
SGSN selection at HO
HPLMN
Rx
+
SGi
•Operator’s IP
Services
(e.g. IMS, PSS
etc.)
Authentication
Bearer establishment
VPLMN
UTRAN
S8
Packet screening &
filtering
SGSN
GERAN
S1-MME
Charging support
MME
Legal interception
Packet routing
S11
S10
E-UTRAN
S1-U
User plane
security
(UMTS AKA)
S4
Mobility anchor
Signaling
security
(UMTS AKA)
“LTE -Uu ”
Policy enforcement
S12
S3
UE
UE IP address
allocation
Serving
Gateway
Idle mode
packet
buffering & DL
initiation
Legal
interception
19

20. SAE non-3GPP access
(23.402)
HSS
Wx*
S6a
S4
2G/3G
SGSN
PCRF
S3
S2 for
connectiv
ity via
non-3GPP
acces
Rx+
S7
MME
Rx+
S11
SGi
S1-MME
Operator’s IP
Services
S10
Serving
Gateway
EUTRAN
S5
S6c
S1-U
Trusted IP
access
directly to
P-GW
Untruste
d IP
access via
ePDG
(e.g. IMS, PSS etc.)
PDN
Gateway
S2b
Wm*
ePDG
S2c
3GPP AAA
S2a
Server
Wn*
HPLMN
Non-3GPP
Networks
Trusrted*
Trusted
Non-3GPP IP Access
Wu*
Non-3GPP IP
Access
or 3GPP Access
UE
Untrusted
Non-3GPP IP
Access
UE
Wa*
Ta*
* Untrusted non-3GPP access requires ePDG in the data path
20