IP Multimedia System: general aspects and migration perspectives

Transcription

1 IMS TPC EPC IP Multimedia System: general aspects and migration perspectives Dr. Leo Lehmann Federal Office of Communication, Switzerland ITU Workshop on Developments regarding telecommunication network architectures and services, Kampala 2 April 2012

2 Content IMS definition & features IMS history IMS basic architecture IMS & UMTS/ LTE networks IMS registration and session setup IMS Billing IMS centralized services IMS & NGN IMS migration scenarios Further information

3 IMS definition & features The IP Multimedia Subsystem is an architectural framework for delivering Internet Protocol (IP) multimedia services Do we really need the IMS? Not just for enabling IP services in mobile networks B U T for Combination session establishment with QoS/ security provision (enjoy rather than suffer) Means for appropriate charge of multimedia sessions (e.g. flat rate, time/volume based, QoS based) combination & integration of different type of (multimedia) services (own, 3rd party) by standard interfaces Inhering services like VoIP, Video, IM

4 IMS definition & features cont. Overlay for fixed and mobile IP based networks; merging the cellular world with the internet Multimedia Services Abstraction from underlying network Fix/ mobile convergence IMS Packet Data Networks GW CS NW Interoperability with CS mobile networks (MAP) Roaming/ location awareness (IP domain) Common control platform SIP service enabler Based on SIP (IETF), Diameter (IETF), H.248 (ITU-T)

5 3GPP Release 5: Introduction of SIP based IMS Mobile Multimedia over IP (new applications) End 2 end QoS Voice over MSC server/mgw 3GPP Release 6 IMS phase 2 (realization access independence IPCAN) Voice over IMS 3GPP Release 7 IMS history (some highlights) IMS TISPAN NGN Extensions ecall via IMS ICS Charging and QoS Optimizations IPCAN: IP conncetivity access network

6 IMS history (cont) 3GPP Release 7 IMS centralized services Charging and QoS Optimizations 3GPP Release 8 Common IMS IMS Extensions for packetized switched streaming MM broadcast/multicast services Session mobility support 3GPP Release 9/10 home node B M2M

7 IMS basic architecture (3GPP ) Application Databases HSS/SLF Databases AS P-CSCF I-CSCF S-CSCF MGCF MRF MGCF BGCF IMS Core MGCF MGCF MGCF MGW MGCF SGW IP Core CS mobile, PSTN

8 IMS basic architecture (cont)

9 IMS & UMTS/ LTE EPC networks PSTN MGW IMS AS CSCF 3G Core GMSC MSC/ VLR GGSN SGSN HSS MME PDN GW Serving GW RNC NodeB enb UTRAN E-UTRAN

10 IMS & UMTS/ LTE EPC networks (cont) EPC Components Mobility Management Entity Serving Gateway Home Subscriber Server Packet Data Network Gateway Functions AAA Mobility Management IP over LTE QoS, Charging IMS + Internet HSS MME PDN GW Serving GW enb E-UTRAN

11 IMS registration & session setup xdsl WiFi SGSN IP Network PS Backbone Network PDG/ WAG GGSN Public Internet PDG/ WAG PDG/ WAG Service Provider PDN Data Network PDF Databases AAA DHCP HSS DNS IMS I - CSCF S - CSCF P - CSCF BGCF MGCF - Presence SMS MMS Conversational Streaming SSF Converged Services and Platforms RNC 3G RAN BSC 2G RAN CSCF: Call Session Control Function HSS: Home Subscriber Server (includes HLR) MGW: Media Gate Way MGCF: Media Gateway Control Function PDG: Packet Data Gateway PDN: Packet Data Network RAN: Radio Access Network RNC, BSC: Radio Network Controller (3G), Base Station Controller (2G) IMS IP Multimedia Subsystem SGSN: Serving GPRS Support Node GGSN: Gateway GPRS Support Node access network MGW PSTN PLMN Core network SGW AS (provider, 3rd Party)

12 IMS registration UE SGSN/GGSN IMS Registration in 2G/ 3G access Network (location update) through SGSN/ HLR 1. Bearer Level Registration: GPRS Attach 2. PDP Context Activation IP address assignment by GGSN (Packet Data Protocol Context) 3. P- CSCF Discovery 4. IMS Registration P-CSCF address determination through GGSN or DHCP server Request via P-CSCF I-CSCF to Home network. AAA and S-CSCF Assignment by home network

13 IMS registration (cont) IMSI/ UID Auth. Info Adr. S-CSCF core nw (Home) U_Reg Query HSS Adr(SCSCF) U-Profile UID I-CSCF Forward (REGISTER) S-CSCF Adr. UE Adr. PCSCF OK access nw (home, visited) UID Adr. UE Adr. ICSCF Adr. SCSCF Forward (REGISTER) Adr.ICSCF= f(ui) Adr. GGSN P-CSCF OK IMSI/ UID SGSN OK REGISTER (UI) GGSN PDP Adr. (UE) TEID Adr. PCSCF Adr. SGSN

14 PSTN voice call HSS S_CSCF 4 MGCF 5 SIP 1 ISUP P-CSCF PSTN/ISDN SGSN GGSN 8 MGW TDM VoIP 1. Incomming PSTN call 2. Protocol transformation & localisation 3. S-CSCF addree, UID 4. INVITE Session 5. Forward (INVITE) 6. Ressource reservation confirmation 7. MGW activation 8. IP PDU transformation & transport

15 IP media session establishment HSS 1. Session initiation (URI callee) HSS request for callee localization (IP domain) CSCF Forward session initiation CSCF Caller notification, Bearer establishment UMTS/ GPRS SGSN GGSN GGSN SGSN 5. UMTS/ GPRS 5. IP PDU streaming

16 offline charging online charging IMS Billing (3GPP ) OCF IMS GWF account information charging information P-CSCF S-CSCF AS MGCF BGCF CTF CTF CTF CTF CTF charging Events CDF Billing System CDR CDR CGF CDF Charging Data Function CGF Charging Gateway Function OCF Online Charging Function CTF Charging Trigger Function

17 IMS centralized services (3GPP ) Enables IMS services when using CS devices (CS access) Enables CS access to transport IMS voice/video services where PS access is not available for VoIP/ IP-Video (no full duplex speech/video component by PS)

18 IMS centralized services (cont) Service Centralization and Continuity Application Server (SCC AS): SCC AS is a home network based IMS Application that provides functionality required to enable IMS Centralized Services Acts as ICS User Agent (IUA) and provides SIP UA behavior on behalf of the UE for setup and control of for IMS sessions using CS bearers processes as CAA (CS Access Adaptation) the service control signaling received via the CS access for interworking with other IMS functional elements Directs an incoming session to an ICS User ICS provision in UE Communicates with the SCC AS for service control signaling. Establishes the Bearer Control Signaling Path to setup the media through the CS domain ICS provision in MSC Server: MSC Server processes the user-network signaling received over the CS access for interworking with IMS SIP and vice versa. It controls the MGW functions described to enable the interworking between CS access and RTP bearers. It performs the interworking to support multimedia call in ICS.

19 Multimedia session continuity (3GPP TR ) Media component transfer Different network access Different UE Continuation of ongoing media session

20 IMS & NGN (ITU-T Y.2021) Application Platform IMS NGN Service Stratum NGN Transport Stratum The 3GPP IMS is the central service control component in NGN

21 IMS & NGN (cont) Service Stratum Applications Application Support Functions and Service Support Functions Application Functions Legacy Terminals Legacy Terminals GW GW S. User Profile Functions Access T. User Network Attachment Profile Control Functions Attachment (NACF) Functions Functions Other NGN Service Components IPTV Service Component PSTN / ISDN Emulation Service Component IP Multimedia IP Multimedia Component &PSTN/ISDN Simulation Service Component Resource and Admission Control Functions (RACF) Service Control Functions Other Networks Customer Networks NGN Terminals End - U ser Functions Access Transport Network Functions ETSI TISPAN Edge Functions Core Core transport Transport Functions Functions Transport Stratum

22 IMS & NGN (cont) The 3GPP IMS is the central service control component in NGN 3GPP functional entities S-CSCF P-CSCF I-CSCF MGCF MRFC BGCF NGN functional entities S-CSC-FE P-CSC-FE I-CSC-FE MGC-FE MRC-FE BGC-FE

23 Relationship EPC/ NGN-FE s Access network HSS Core network 3GPP entity Functions performed ITU-T Y.2018 entity responsible NAS signalling NACF S6a Home Gx PDN gateway hpcrf S9 SGi Rx Operator's IP services (IMS, etc.) NAS signalling security AS security control Inter CN node signalling for mobility between 3GPP access networks Idle mode UE reachability (including control and execution of paging retransmission) Tracking area list management (for UE in idle and active mode) NACF NACF NACF TBD* TBD (Note 1) S10 PDN GW and serving GW selection TBD (Note 2) Mobility management entity (MME) MME selection for handovers with MME change NACF MME S1-MME S3 S1-U E-UTRAN S11 Serving gateway S8 Gxc vpcrf SGSN selection for handovers to 2G or 3G 3GPP access networks Roaming Authentication NACF NACF (TAA- FE) NACF (TAA- FE) S4 2G/3G SGSN Visited Y2018(09)_FIII.2 Bearer management functions including dedicated bearer establishment Support for ETWS message transmission The local mobility anchor point for inter-enb handover HDC-FE NACF L2HE-FE Mobility anchoring for inter-3gpp mobility L2HE-FE E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure L2HE-FE Lawful interception EN-FE Serving gateway Packet routing and forwarding Transport level packet marking in the uplink and the downlink EN-FE EN-FE Accounting on user and QCI granularity for interoperator charging EN-FE UL and DL charging per UE, PDN, and QCI EN-FE Originator of PMIP signalling. Proxy point for PMIP signalling (chained PMIP) MLM-FE(P) tunnel end point L3HEF

24 IMS migration scenarios Not at all network without IMS From the beginning (Greenfield) time IMS based network time

25 IMS migration scenarios (cont) Full introduction network without IMS IMS based network Stepwise migration time IMS Introduction together with new network without IMS broadbad services ICS to cover CS time

26 Summary IMS has left the trial stage and has become an adequate System to enhance IP sessions in mobile networks with QoS/ security provision and appropriate billing capabilities IMS enables fix-mobile convergence and is the 3GPP-TISPAN implementation of the service control in the NGN service stratum (e.g. VoIP services via DSL and mobile access) Large IMS deployment is feasible in the next years based on PSTN migration from CS to IP by big incumbents as well as the deployment of LTE. The IMS benefits and the practical application have been understood and identified by the operators IMS expectations Source: Hype Cycle according Gartner Inc.

27 Thank You!