Policy and Regulatory Requirements for
Future Mobile NetworksFuture Mobile Networks June 22nd 2005
F. COURAU M. OLSSON
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Introduction
Policy and Regulation Network Sharing
IP Multimedia System IMS
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Network Sharing
NETWORK SHARING:
Regulation to impose sharing of part of the network elements between two or more operators on a regional basis
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Network sharing in Release 99, 4 and 5
CN PLMN1CN PLMN1 CN PLMN2 CN PLMN2
CN PLMN3CN PLMN3
One Radio per PLMN
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Network sharing in Release 6
CN PLMN1CN PLMN1 CN PLMN2CN PLMN2 CN PLMN3CN PLMN3
Different PLMNS on a single radio
IP Multimedia System
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IP support in Mobile Network
A bit of history Support of IP services was first introduced in GSM networks
in Release 97 of the specifications as complement to the Circuit Switched Services
The packet services was introduced in such a way that it did not destabilize the provision of Circuit Switched services and it also minimized the impact on the Radio part.
The specifications defines a mobile specific architecture taking the roaming and the mobility aspects into account and offering a differentiated Quality of Service
When defining the third generation systems (Release 99) the support of packet services was fully integrated in the architecture
Release 99 for both GSM and UMTS introduced the notion of Quality of Service (Background, Real time, Interactive)
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GPRS Architecture Overview
MSC/VLR
HLR
ISDNISDN
SGSN GGSN
GPRSGPRSBackboneBackbone
InternetInternetX.25X.25GPRS
Mobile
BSS with PCU
DNS
DHCP
FrameFrameRelayRelay
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General Architecture Overview
Circuit Switched Domain
Packet Switched Domain
IP Multimedia Subystem
Other Accesses(e.g.WiFi
CDMA2000)
IP MultimediaNetwork
UTRAN
BSS/GERAN
IP Network
PSTN / CS PLMN
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Main IMS FeaturesA Multi-phase Standardisation
IMS Phase 2 - 3GPP Rel6 Inter-working with non-IMS IP networks (e.g. Internet) Inter-working with CS networks (e.g. PSTN, CS PLMN) IMS Services combining CS (rt) & PS (nrt) : CSI Phase 1 Access agnostic IMS specifications UTRAN QoS optimisation for PS conversational services WLAN/3GPP inter-working for using PS/IMS services Presence/Instant Messaging (SIMPLE) OMA Group management & Conferencing (SIP) Immediate and Session based messaging Service enablers for IMS : PoC OMA Dynamic QoS policy (including Gq (P-CSCF/PDF)) Lawful interception SIP forking Full charging framework (incl. Online and Flow based) IPv4 option & IPv6 evolution guidelines still applicable
IMS Phase 1 - 3GPP Rel5 SIP Session Control for IMS Signalling Security & IMS Authentication :
SIP signalling integrity (IPSec : UE / P-CSCF) IMS User/Service authentication (IMS-AKA)
QoS : SBLP (Go : P-CSCF-PDF / GGSN-PEF) SIP Compression (Sigcomp, UE/P-CSCF) Header compression in RAN (UE / RNC, re-use of RoHC)
Charging (mainly Offline) and OAM&P Multimedia codecs OSA support CAMEL (Phase 4) for IM-SSF IPv6 use for SIP signalling and IMS user traffic
IPv4 optional (guidelines & IPv6 evolution)
Emergency services IMS local services Enhanced QoS (extension for IP Inter-working) MRFP / MRFC (Mp) & ALG/Tr-GW (Ix) interfaces GERAN optimisation for PS conversational services
IMS ‘Phase 3’ - 3GPP Rel7 (Draft contents, depends on Rel6 and company proposals) IMS enhancements for Fixed Broadband access Interim Security (IP based authentication) Merging of Go and Gx (TPF/FBC) interfaces
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I M S IP Multimedia Subsystem
IMS Primarily designed (3gpp R5) to work on top of GPRS using SIP signalling But extended (3gpp R6) to work on top on non-GPRS based access and SIP TEs(Harmonised with the 3GPP2 (CDMA 2000) IP Multimedia Domain (MMD)) On going work with ETSI TISPAN to adapt IMS for requirements of fixed networks
Services on top of IMS (e.g. MMS, PoC, IM/PM, DRM, DM are also developed by other organizations like OMA.
Circuit Switched Domain
Packet Switched Domain
IP Multimedia Subystem
Other Accesses(e.g.WiFi
CDMA2000)
IP MultimediaNetwork
UTRAN
BSS/GERAN
IP Network
PSTN / CS PLMN
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3GPP IMS Architectural Overview
IMS-MGW
IPv6 PDN(IPv6 Network)
MGCF
I-CSCFS-CSCF
BGCF
Application(Ext. SIP AS, OSA AS,
CAMEL SE)
MRFC
MRFP
MRF
IPv4/IPv6BB
CS Networks(PSTN, CS PLMN)
CSCF
P-CSCF
SGW
OSA SCSIM SSF
SIP AS
AS
BG
SLF
ALG
TrGW
‘IMS IPGW
IPv4 PDN(IPv4 Network)
IP CAN ABGTE
AN
IMS Terminal
PEF/TPF
HLR/AuC (‘CS/PS’)
HSS
IMS Data Handling
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Main IMS principles 2 phase registration,
UE IMSGPRS
1. Bearer Level Registration: e.g.GPRS Attach
(2. Establishing signaling link e.g. PDP Context Activation)
3. CSCF Discovery
4. Application (IMS) Level Registration
specific (QoS, charging, security,) at Access and at IMS case
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IMS in PLMNs & Roaming
Service Network
UE
GGSN
SGSN
PDP Context
Access network connecting the user
Gi
IM CN SUBSYSTEM
P-CSCF
Proxy CSCF in Home Network
Proxy CSCF in Home Network
This is in fact the GPRSroaming case
S-CSCF / AS
The S-CSCF is always locatedin the Home Network
Two possible Cases
Home Network
Visited NetworkIM Subsystem
Inter-NetworkIP Backbone
Internet
Intranets
UE
GGSN
BG
BG
SGSN
PDP Context
Visited Network
Gi
Virtual presence of UEin visited network IM subsystem(UE’s IP-address is here)
Proxy CSCF in Visited Network
Proxy CSCF in Visited Network
P-CSCF
S-CSCF / AS
This case is possible too
IM Subsystem
P-CSCF / PDF are located inthe same network as GGSN
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IMS Communication FocusExample with two Roaming IMS Mobile Users
SGSN GGSN GGSN SGSN
UEBUEA
Access Network A
SIP/SDP inviting
P-CSCFCSIP / SDP
S-CSCFAP-CSCFD
Service Platform A(ASA)
S-CSCFB
Go SIP/SDP
IP Backbone Network
Data-Path
PDP ContextSession level (SIP/SDP signalling)Bearer level (PDP context activation / modification / Release)Interaction between session and bearer level (COPS)
Gm Gm
PDP Context
SIP / SDPSIP / SDP
Service Platform B(ASB)
I-CSCF (between P-CSCF and S-CSCF) not shown for simplicity
Go
Serving Network AServing Network B
Access Network B
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IMS charging and QoS: interface between service and access network
IP Multimedia Subystem
Packet Switched Domain (Access)
Access GW (GGSN)
Policy and charging Relay
P-CSCF
Go,Gx
Gq,Rx
Pre-paid
Subscription database Three types
of charging
-On line charging
-Off line charging
-Flow based charging
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Emergency & LI Overview
For the target IMS only service, Emergency calls via IMS to be deployed (3GPP R7) But absence of deployment of an IMS emergency infrastructure does not block
deployment of IMS conversational service provided that UE or Network can detect emergency requests and direct them via CS domain A call back from Emergency Center is always directed to UE via CS domain
LI infrastructure in PLMN (ADMF, DF) to be upgraded to take into account IMS and to inter-operate with CSCF. For 3gpp, IMS specific interception deals only with signaling plane interception. User plane interception is to be carried out at Access level (GPRS)
Note that user plane generally goes directly from UE to UE without being handled by any MGW (only IW with CS networks) in the network
ADMF = LI administrationDF = Delivery Function (to LEA= Law Enforcement Agency)
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LI for 3GPP IP/IMS : Simplified Overview of Functional Architecture
MobileLI target
LEMF
HI1
HI2
3GPP Interfaces
IP-HI3
GGSN*SGSN
IPBackbone
Iu/Gb
Gi
Internet
Gn
LIG
RAN
X3
MM Call Server
P-CSCF/S-CSCF
X1
X2
IMS Domain
* Interception at GGSN is optional
Gi
RadioNetwork
IMC
ADMF
DF2/ DF3
X1_2/3p
Signalling (incl.SIP)User Plane
Management
Interception of signalling is called “IRI” = Intercept Related Information
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Annex: A few abbreviations explained
Definitions GPRS
GGSN Gateway GPRS Support Node SGSN Serving GPRS Support Node
IMSAPI Application Program InterfaceAS Application ServerBCSM Basic Call State ModelBG Border GatewayBGCF Breakout Gateway Control FunctionCSCF Call Session Control Function MGCF Media Gateway Control FunctionMGF Media Gateway FunctionP-CSCF Proxy‑CSCFS-CSCF Serving‑CSCF
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