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Dr. Sorin Georgescu sorin.georgescu@ericsson

IMS: An Architecture for Convergent Next Generation Multimedia Services. Research and Standardisation Challenges. Dr. Sorin Georgescu sorin.georgescu@ericsson.com. Agenda. IMS Architecture Overview Standardisation Status The Service Layer View IMS and SOA

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Dr. Sorin Georgescu sorin.georgescu@ericsson

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  1. IMS: An Architecture for Convergent Next Generation Multimedia Services. Research and Standardisation Challenges Dr. Sorin Georgescu sorin.georgescu@ericsson.com

  2. Agenda • IMS Architecture Overview • Standardisation Status • The Service Layer View • IMS and SOA • Research and Standardisation Challenges

  3. Next Generation Networks Evolution Drivers • Societal and Business trends • Internet is becoming a major enabler of communications • Consumers are embracing computing, mobile and digital technology in their everyday life • Evolution of Business models require increased levels of personal mobility • Convergence • Converged devices (Mobile, WLAN, Internet etc.)  Connectivity • Converged services  Ease of use • Converged networks  Reliability, Security, Reduced OPEX/CAPEX • Converged business models  Increased margins, Avoidance of twin pitfalls risk • Access Technology Enhancements • HSPA (High Speed Packet Access) – evolved WCDMA • OFDMA (Orthogonal Frequency Division Multiple Access) – 3GPP LTE, WiMAX, MBWA, ADSL/VDSL, DVB-T/H etc. • Spatial Processing – multi-antennas Base Stations supporting advanced spatial processing

  4. Non-Interactive Multimedia Movies Video Music Ring tone Person-to-Contentknown usability patterns Photos Internet Streaming Text/Pictures Download Interactive Multimedia HTTP Video SMS/MMS Active phonebook Person-to-Persondominates traffic growth Image Sharing Text Presence Voice Push-To-Talk MMS SMS Voice The Evolution to IMS Multimedia Applications

  5. Watch and Communicate service • While out in town, Bob stopped by at the Jazz festival. He made a short clip and would like to ask his friends if they are interested to go to the evening performance. • He checks the presence information of Alice and Dave. • Bob opens a Chat session and sends the clip to his friends. He asks if they are interested to go to the evening performance. • Dave is watching TV, therefore the chat session is diverted to his IMS enabled STB. Communication services Personalised content services Group and context support

  6. IMS – a Standard-based Architecture for NG Services • IMS defines an open IP-based service infrastructure where service intelligence is located in the servers and mobile devices. • IMS as originally specified by 3GPP, was aiming to enable real-time multimedia services over the IP bearer in GSM and W-CDMA networks. • 3GPP2 defined later the MMD for CDMA2000 networks which is now aligned with IMS. • TISPAN provided the specifications for DSL access. • CableLabs provided the specifications for the cable access and now their work together with 3GPP to incorporate PC 2.0 specifications into IMS release 8. • Since release 6, interworking with WLAN is supported. • If IMS is not used: • Multimedia communication at best effort • Service orchestration can be complex • Service roaming can be difficult to implement • Provisioning and charging are service specific • Compliance with LI requirements can be an issue


  8. Functional Overview (1) • CSCF (Call Session Control Function) consists of 3 separate functions: P-CSCF, I-CSCF, S-CSCF • P-CSCF (Proxy-CSCF): • Entry point to IMS from any access network • Performs integrity protection • Local outbound stateful proxy for all SIP requests/responses, ensuring all signalling is sent via the home network • Includes a Policy Decision Function (PDF) that authorizes bearer resources • I-CSCF (Interrogating-CSCF): • First contact point in home network • Selects assigned S-CSCF • Performs network hiding (THIG) • S-CSCF (Serving-CSCF): • Stateful proxy that provides session control • Performs subscriber authentication • Acts as SIP registrar • Invokes the AS’ (Application Servers) based on IFC (Initial Filter Criteria) • SLF (Subscriber Location Function): • Look-up function used in networks where multiples HSS’ exist • HSS (Home Subscriber Server): • IMS subscriber records and service profile • IMS authentication data • MRF (Media Resource Function) consists of 2 separate functions: MRFC, MRFP • MRFC (Media Resource Function Controller): • Controls media resources in MRFP • Acts as SIP B2BUA • MRFP (Media Resource Function Processor): • Media stream processing (transcoding etc.) • Multimedia announcements • Incoming streams mixing

  9. Functional Overview (2) • SIP AS (Application Server): • Hosts IMS native applications • IM SSF (IP Multimedia Switching Service Function): • Provides interworking with CAMEL, ANSI-41, INAP or TCAP services • OSA SCS (Open Service Architecture Service Capability Server): • Provides interworking with OSA services • BGCF (Breakout Gateway Control Function): • Selects the network in which PSTN breakout is to occur and within that network selects the MGCF • MGCF (Media Gateway Control Function): • Controls media channels in IMS MGW • Performs conversion between ISUP/TCAP and IMS call control protocols • IMS MGW (IMS Media Gateway): • Terminates bearer channels from CS networks and PS media streams • Owns/handles resources (echo cancellers, codes, etc.) • SGW (Signaling Gateway): • Performs conversion at transport level (SCCP, SCTP) • SBC (Session Border Controller): • PDF/SPDF (Policy Decision Function / Serving Policy Decision Function): • A-RACF (Access - Resource and Admission Control Function): • NASS (Network Attachment Subsystem): • DSLAM (Digital Subscriber Line Access Multiplexer):

  10. IMS Service Routing – the IFCs • In comparison to IETF SIP Routing where the originator of SIP request may specify a preferred path in the Route header, in IMS the P-CSCF removes this path and ensures that IMS SIP Routing is followed. • SIP requests in IMS architecture are always routed to the Home S-CSCF, in both the originating and terminating network. • The S-CSCF uses subscriber’s Service Profile (downloaded during registration), to link-in the SIP AS’ which will process the SIP request. • The Initial Filter Criteria (IFC) within the Subscriber Profile provide a simple service logic to decide which AS shall be linked-in. These rules are of static nature i.e. they do not change on a frequent basis. IMS AS HSS Home B IMS AS HSS Home A 2 7 9 5 1 8 6 S-CSCF I-CSCF S-CSCF 4 10 Visited B Visited A P-CSCF P-CSCF 3 11 IMS Service Routing = Service Profile based Routing

  11. Appl 1 Appl 2 IARI2 IARI2 IARI1 CS 1 CS2 ICSI1 ICSI2 SIP Stack Service/application identification – ICSI/IARI A Communication Serviceis an aggregation of one or several media components and the service logic managing the aggregation, represented in the protocols used. An IMS application is an application that uses an IMS Communication Service(s) in order to provide a specific service to the end-user. Only IMS applications other than the default application associated to the Communication Service are identified through IARIs. • 3GPP TS 23.228 R7 introduced the ICSI/IARI identifiers as a mechanism for UEs to provide a hint to the network on the AS’ they wish to be linked-in the signalling path. • The introduction of ICSI/IARI in 3GPP aims to address to a certain extent the limitations due to the use of the Service Profile routing paradigm. The ICSI/IARI are used as parameters in the IFC, therefore the AS selection process becomes more dynamic. • The ICSI/IARI provides a mechanism to control rating based on selected pricing model. For example, it is possible to rate differently a Messaging Communication Service when invoked from a Multimedia application then when invoked from a Gaming application. ICSI = IMS Communication Service ID IARI = IMS Application Reference ID CS = Communication Service

  12. Service Convergence in Quadruple Play Industry consolidation and alliances = Convergence at Service Provider level. End User experience = Access to subscribed services from any device in the bundle Service continuity Common provisioning, mgmt and billing Common service and subscriber management Fixed Mobile Convergence = Converged Service Architecture Setup of the appropriate QoS and resources

  13. Agenda • IMS Architecture Overview • Standardisation Status • The Service Layer View • IMS and SOA • Research and Standardisation Challenges

  14. VCC CSI Presence PoC Messaging GLMS Standardisation fora Multimedia Telephony IP GSM/WCDMA Access to IMS Broadband Access to IMS WLAN Access to IMS PacketCable™ WiMAX Forum DOCSIS DSL Forum Mobile Enterprise Residential

  15. C HLR/AuC* HSS* SMS-GMSCSMS-IWMSC R R Wo Um Wu Uu Wp Wn Ww Mw ** Wf Dw Wg MSC EIR Gb, Iu AF PCRF Wx Gf Gs BM-SC SMS-SC Gi GGSN SGSN IMS-MGW Mb SGSN MRFP OCS* CGF* IMS TE MT UTRAN P-CSCF CSCF PDN Intranet/ Internet Wd Gd Wy Ga Gmb Gr Iu Rx+ (Rx/Gq) Mb Wz Gn/Gp Wa Wa Gm Gx+ (Go/Gx) Gi 3GPP AAAProxy 3GPP AAAServer BillingSystem* BillingSystem* Gy Cx Dx Gn Wf GERAN TE MT WLANUE HLR/AuC* WLAN AccessNetwork CDF HSS* SLF D/Gr Ga Gc Wi OCS* Wm WAG PDG Note: * Elements duplicated for picture layout purposes only, they belong to the same logical entity in the architecture baseline. ** is a reference point currently missing UE CGF* Traffic and signalling Signalling 3GPP R7 Reference Model

  16. S/T S/T GW TISPAN R1 Reference Model Application Servers Rf /Ro Ut Rf /Ro Other types of service logic Charging Ut Functions PSTN/ISDN Emulation logic Network Sh Rf /Ro ISC Dh Attachment UPSF Iw SLF Cx IWF Subsystem Dx Ib P3 PES e2 Mw e2 Mw/Mk/Mm IBCF Ic I/S - CSCF P2 P1 Mk AGCF Mi Mk BGCF Mw Mr Mj Gq ' Gm Mg SGF P - CSCF MGCF MRFC Ie Other IP Networks Gq ' Gq ' PSTN/ISDN Mp Mn Resource and Admission Control Subsystem MRFP Z Z T - MGF S/T S/T IP Transport (Access and Core) I - BGF MG Z Z

  17. WIs in 3GPP release 7 (02/2008) • Coexistence between TISPAN and 3GPP authentication schemes study • SAE (System Architecture Evolution) • RAN LTE (Long Term Evolution) • MMTel (Multimedia Telephony) • VCC (Voice Call Continuity) between IMS VoIP and CS speech • CSiCS (Circuit Switched IMS Combinational Service) • SMS/MMS over IP • FBI (Fixed Broadband access to IMS) • IMS Emergency Calls • PCC (Policy Control and Charging Evolution) • E2E QoS • AIPN (All IP Network) Feasibility Study • Service Identification using ICSI/IARI • Liberty Alliance and 3GPP security interworking • Location Services for WLAN interworking • MRFP-MRFC (Mp) Interface • Parlay X WS: • Message broadcast • Geocoding • Application driven QoS • Device Management • Multimedia Streaming/Multicast Control • ISIM API for Java Card

  18. WIs in 3GPP release 8 (tentative 03/2009) • Architecture impacts of Service Brokering • Enhancements for support of PacketCable 2.0 requirements • Multimedia Priority Service • Personal Network Management • Enhancements for support of machine to machine communication • Enhanced Generic Access Networks • HSPA FDD (Frequency Division Duplex) • Enhancements to SAE/LTE Architecture • OAM&P Studies

  19. Agenda • IMS Architecture Overview • Standardisation Status • The Service Layer View • IMS and SOA • Research and Standardisation Challenges

  20. IMS in OMA Service Environment context

  21. OMA SIMPLE IM Reference Model

  22. Limitations of ISC Service Orchestration Model SIP-AS SIP-AS SIP-AS SIP-AS SIP-AS SIP-AS Req URI = A Req URI = B S-CSCF S-CSCF HSS HSS I-CSCF I-CSCF • The application server decides whether to remain linked-in for the whole session by adding its address to the Record-Route SIP header. • Application Servers are unaware of the existence of other AS', and whether these will be linked-in. • No service or session state will be passed between application servers unless they use proprietary extensions i.e. are co-designed. • Response messages are routed to the AS’s in the reverse order • If during call handling procedure an AS retargets the SIP request by changing the Request URI, subsequent filter analysis in the S-CSCF is stopped and the S-CSCF forwards the request towards the new target without linking-in the other AS’ specified by IFC. 1 2

  23. SCIM vs. Service Broker Camel Services AS AS OSA AS AS AS AS AS OSA API CAP SCIM OSA SCS IM SSF Service Broker Service Broker MAP ISC Si ISC ISC Sh Cx HSS S-CSCF Sh S-CSCF • The Service Broker architecture has been introduced as WI in IMS Release 8. • The objective is to provide a coherent and consistent IP multimedia service experience when multiple applications are invoked. • The work is handled by 3GPP SA2 (Architecture) group in TR 23.810. So far, just the some high level deployment scenarios and some uses cases have been defined. • Can be centralised, distributed or hybrid (as in the figure above). • The Service Capability Interaction Manager (SCIM) orchestrates service delivery among application servers. • Underspecified in TS 23.002, the SCIM has become a sort of “magic box” that would solve all issues related to service orchestration. • Possible types of SCIM: • AS Internal SCIM (figure above) • SIP Broker SCIM / Service Broker SCIM • Legacy SCIM

  24. Parlay X Web Services WS-I Basic Profile: WSDL + SOAP WS-I Secure Profile: WSDL + SOAP + WS-Security • Parlay X Web Services is an abstraction of Parlay WS • Parlay X WS GW acts as a Service Broker SCIM • Enablers which only support WS-I Basic Profile are enhanced with additional WS functionality such as WS-Security, WS-Policy, WS-Addressing • Services defined so far (17) cover: call control, messaging (SMS, MMS), payment, location, geocoding and mapping, presence etc. • Described in WSDL. Service discovery is based on UDDI.

  25. Agenda • IMS Architecture Overview • Standardisation Status • The Service Layer View • IMS and SOA • Research and Standardisation Challenges

  26. SOA Service Description Model SOA Reference Model • What is SOA: • A paradigm which defines concepts and general techniques for the design, encapsulation and instantiation of reusable business functions using loosely coupled service interactions • SOA Reference Model: • Service • Service description • Interaction • Contract & Policy • Visibility • Execution Context • Real world effect

  27. Client SOA Orchestration Routing based on service identity (equivalent to PSI routing in IMS) • SOA Characteristics • Services have well defined Service Contracts • Services are encapsulated • Services share a message bus and messages exchanged are well documented • Services can be discovered dynamically • Services are loosely coupled • Systems of services are assembled at runtime • Service bus functions: • Supports an asynchronous message based communication protocol that uses a common format encoding scheme (SOAP/XML) • Routes, Translates and can Store and Forward exchanged messages • Supports a Discovery mechanism

  28. Service Contract SOA UDDI SOA AS Schema SOAP/XML MLP SIP Service Bus MM7 SB API SB API SB API Enabler IMS AS GW AS Orig. network CSCF IMS JSR 281 Heterogeneous Service Bus IMS-SOA Architecture IMS-SOA Architecture • Service Enablers: • Provide functionality which can be used by other end-user applications (ex. Location Service) • Unaware of the context in which they are used. Only the consumer service is aware. • Service Bus • Handles the communication between IMS Application Servers and the Service Enablers and the communication with SOA Application Servers. • Optimized for Server-to-Server communication • Besides providing support for standard open protocols (ex. SOAP), may provide support for Native Interface protocols (ex. MLP, MM7, SIP etc.) • Service Orchestration • The consumer AS that invokes the Service Enabler implements the SCIM function. An external Service Broker may be used as well. • IMS Service Enablers are invoked from SOA domain through the GW AS.

  29. Agenda • IMS Architecture Overview • Standardisation Status • The Service Layer View • IMS and SOA • Research and Standardisation Challenges

  30. IMS Core Network • Coexistence of access specific authentication methods • Media Adaptation using UE capabilities discovery • Design of efficient algorithms for real-time adaptation of MBMS content • Access agnostic vs. access aware P-CSCF • QoS awareness, access agnostic control of the QoS • Media security

  31. IMS Service Layer • Service Orchestration paradigms. The integration with SOA architecture • Enhancements to presence service to support device capabilities, subscription state, user preferences, context awareness, bearer state • Multimodal interaction • Payment brokerage • Personalised/interactive advertisement • QoS control over the Service Bus.

  32. Thank you for your attention! sorin.georgescu@ericsson.com

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