1 IMS Architecture Past Present and Future By

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IMS Architecture: Past, Present and Future By Dhananjay Shukla and Vinay Rao Centillium Communications Inc.

IMS Architecture: Past, Present and Future • Introduction – – – What is IMS? Convergence and IMS Drivers IMS Evolution IMS Origins Who is involved? ITU IMT-2000 Framework • 3 GPP – About 3 GPP – Standards Releases – IMS Reference Architecture • 3 GPP 2 3 – About 3 GPP 2 – Standards Releases – MMD Architecture

IMS Architecture: Past, Present and Future • 3 GPP/3 GPP 2 – Differences – Harmonized Architecture • Evolution from Wireless to Wireline • NGN TISPAN – About TISPAN – Standards – Architecture 4

What is IMS? • IP Multimedia Subsystem [IMS] is an architectural framework for delivering IP multimedia services to end users. • IMS provides a network-independent, common service delivery environment for both wireless and fixed network users. • IMS standards define common signaling and media interfaces that are open, vendor independent, and abstract the underlying network complexities. 5

Convergence and IMS Drivers • Convergence – Fixed, mobile, broadband – Convergence is a reality • IMS motivations – – New services and revenue Fast time-to-market Harmonized (any terminal) Lower infrastructure cost • IMS technology components 6 – IP … (while keeping legacy) – SIP – Multimedia high compression/ quality and adaptation – Any access and IMS arch support FIXED IMS BROADBAND MOBILE

IMS Evolution • IMS evolved from early packet data over mobile wireless architectures called 3 G. IP to provide internet services over mobile networks. • IMS was incorporated into 3 GPP standards efforts first appearing in Release 5. • IMS was incorporated into 3 GPP 2 standards efforts as part of Multimedia Domain [MMD]. • ETSI-TISPAN and ITU-T also incorporated IMS into their Next-Generation-Network [NGM] Wireline standards developments. • Other consortia such as OMA are involved in specifying IMS services. 7

IMS Origins 2002 2001 Rel. 4. 0 2003 2004 2005 Rel. 5. 0 Rel. 6. 0 Rel. 7. 0 IMS IMS Rel. 0 Rel. A Rel. B MMD MMD Rel. 1. 0 Rel. 2. 0 NGN 2006 Rel. 1. 0 NGN FG Other OMA 8 * IP multimedia subsystem (IMS), multimedia domain (MMD), Next Generation Network (NGN)

Who is involved? 9 Standards Organization or Consortium Scope or Focus Standards Contribution Internet Engineering Task Force (IETF) All IP networks SIP, SDP, RTP, DIAMETER, etc Third-Generation Partnership Project (3 GPP) UTRA, GSM, GPRS, EDGE, UMTS, W-CDMA, etc IP Multimedia Subsystem [IMS] Third-Generation Partnership Project 2 (3 GPP 2) CDMA 2000, etc Multimedia Domain [MMD] European Telecom Standards Institute (ETSI) Next-generation wireline networks NGN effort by TISPAN International Telecommunication Union (ITU-T) IMT-2000 and Next-generation wireline networks Framework for 3 G efforts, FG-NGN effort by ITU-T SG 13 NGN, etc Open Mobile Alliance Mobile Services and Applications Instant Messaging, OMAPOC, Presence, etc Cable. Labs® Cable IP Networks Packet. Cable™ 2. 0 project

ITU IMT-2000 Framework The 5 IMT 2000 terrestrial interfaces agreed by ITU-R UMTS Direct sequence Time Code Single Carrier Multi-Carrier Frequency Time DS TC SC MC FT UTRA FDD UTRA TDD High & low chip rates UWC 136 CDMA 2000 DECT™ TR 45 10 3 GPP 2

3 GPP: About 3 GPP • The 3 rd Generation Partnership Project (3 GPP) Collaboration agreement formalized in December 1998 by signing of “The 3 rd Generation Partnership Project Agreement”. – Collaboration agreement brings together as “Organizational Partners”, a number of telecommunications standards bodies from around the world, namely ETSI (Europe), ARIB/TTC (Japan), CCSA (China), ATIS (North America) and TTA (South Korea). • 3 GPP scope is to specify a global (3 G) mobile phone system under ITU's IMT-2000 framework. • 3 GPP specs are based on evolved GSM specs. • 3 GPP standardization encompasses Radio, Core Network and Service architectures. 11

3 GPP: Standards Releases • Release '99 – functionally frozen December 1999. Defines UTRA and many other initial features • The basis for early 3 G deployment • Release 4 – functionally frozen March 2001. Enhancements to Release '99 plus separation of control plane from user plane in core network • First steps towards IP-based operation • Also defines the low chip rate TDD mode (TD-SCDMA) • Release 5 – functionally frozen March/June 2002. This release introduces: • IMS - IP-based Multimedia Services • HSDPA - High Speed Downlink Packet Access • Release 6 – functionality frozen September/ December 2004 • Includes 2 nd phase of IMS, High Speed Uplink, plus many other features designed to deliver the full 3 G experience • Release 7 – Stage 1: Dec 2005; Stage 2: 2 nd half 2006; Stage 3: mid-2007 • Enhanced uplink, other spectrum; multiple input multiple output antennas (MIMO), Advanced Global Navigation Satellite System concept, IMS emergency call handling, e-call, back-up algorithms (UEA 2 and UIA 2) 12

3 GPP: IMS Reference Architecture 13

IMS Reference Architecture • IMS reference architecture is based on multi-standard and multiindustry architecture. • IMS reference architecture is being defined by all major wireless and wireline standards bodies including, 3 GPP 2, ETSITISPAN, IETF, Wi. MAX Forum, OAM and others. • IMS reference architecture unifies next-generation services across the user applications, user devices, access networks, and core network. • IMS provides an infrastructure for multimedia services such as telephony, video, multimedia messaging and games – for one-to -one or one-to-many multimedia communications. 14

IMS Architecture: Simplified view • Simplified View – Three Layers Service Layer AS MRF HSS CSCF Control Layer 15 Access Layer MFCF/ MGC IP PSTN/PLMN

IMS Architecture: Session Control Layer • Session Control Layer – consists of network control servers for managing calls, establishing sessions and making modifications. – two main elements: the call session control function (CSCF) and the home subscriber server (HSS). – the call session control function (CSCF) handles end-point registration and inspect/routing the SIP signaling messages to the application server. The CSCF is also responsible for interoperating with the access layers. – the home subscriber server (HSS) maintains the end user’s service profile. The service profile includes date such as registration information, roaming and end user’s preferences. 16

IMS Architecture: Service Layer • Service/Application Layer – provides value-added services using application and content servers. – two main elements: the Application Server (AS) and the Media Resource Function (MRF). – the application server (AS) is responsible for call flows, database accesses and user interface interactions. – the MRF provides the media processing capability for the application layer. It has two componenets: media resource function controller (MRFC) and media resource function processor (MRFP). – the MRFC is a signaling plane node (SIP user agent to the S -CSCF) and the MRFP is a media plane node (provides all media-related functions). 17

3 GPP 2: About 3 GPP 2 • The Third Generation Partnership Project 2 (3 GPP 2) is a collaboration of North American and Asian interests also under the framework of ITU’s IMT-2000. – Collaboration brings together as “Organizational Partners”, Five Standards Development Organizations, namely, ARIB (Japan); CCSA (China); TIA (North America); TTA (Korea) and TTC (Japan) with market representation by CDMA development group, IPv 6 forum, International 450 association. • 3 GPP 2 specs are based on evolving ANSI/TIA/EIA 41 specs commonly known as CDMA 2000 • Four Technical Specifications Groups 18 – – TSG-A (Access Network Interfaces) TSG-C (cdma 2000®) TSG-S (Services and Systems Aspects) TSG-X (Core Networks)

3 GPP 2: MMD Architecture 19

3 GPP/3 GPP 2: Differences 3 GPP • Mandates IPv 6 • Special GPRS procedure is used for Address. • GGSN and P-CSCF need to be located in the same network. 20 • 3 GPP uses GPRS packet services • Smart cards are mandatory • 3 GPP doesn’t allow HTTP digest authentication • IP Multimedia Subsystem [IMS] • • 3 GPP 2 Allows both IPv 4 and IPv 6 DHCP or P-CSCF address on MS/R-UIM for IP Address. PDSN and P-CSCF allowed to be located in different networks (e. g. , PDSN in visiting network and P-CSCF in home network. ) 3 GPP 2 uses packet data service and Mobile IP Smart Cards are optional 3 GPP 2 allows HTTP digest authentication. Multimedia Domain [MMD] = IMS + CDMA Packet Data

3 GPP/3 GPP 2: Harmonized Architecture IP MULTIMEDIA SUBSYSTEM P-CSCF S-CSCF I-CSCF APP SRV 3 GPP 2 GPRS Core Network Packet Data Subsystem SGSN PDSN GGSN MIP HA CORE NETWORK 3 GPP RAN 21 RNC NODE-B RADIO ACCESS NETWORK (RAN) 3 GPP 2 RAN BSC BTS

Evolution from Wireless to Wireline 22 Source: Cisco Paper - Supporting the IP Multimedia Subsystem for Mobile, Wireline, and Cable Providers.

TISPAN: About TISPAN • Telecoms and Internet converged Services and Protocols for Advanced Networks [TISPAN] • ETSI core competence centre for fixed networks and for migration from switched circuit networks to packet-based networks with an architecture that can serve in both. • Responsible for all aspects of standardisation for present and future converged networks including the NGN (Next Generation Network) and including, service aspects, architectural aspects, protocol aspects, Qo. S studies, security related studies, mobility aspects within fixed networks, using existing and emerging technologies. 23

TISPAN: 3 GPP Collaboration • Building upon the work already done by 3 GPP in creating the SIP-based IMS (IP Multimedia Subsystem), TISPAN and 3 GPP are now working together to define a harmonized IMS-centric core for both wireless and wireline networks. • This harmonized “All IP” network has the potential to provide a completely new telecom business model for both fixed and mobile network operators. • Access independent IMS will be a key enabler for fixed/mobile convergence, reducing network installation and maintenance costs, and allowing new services to be rapidly developed and deployed to satisfy new market demands. 24

TISPAN: NGN Standards • NGN Release 1 was launched by TISPAN in December 2005, providing the robust and open standards that industry can use as a reliable basis for the development and implementation of the first generation of NGN systems. – Terminology, Strategy, Qo. S, Security, NNA & Identification, ENUM – Requirements, General architecture, Early services and protocols – Detailed architecture, Base services/protocols, 3 GPP endorsements – Operations Support Systems, Congestion control, NGN user data, PSTN/ISDN emulation • TISPAN is now working on NGN Release 2 (due sometime this year), with a focus on enhanced mobility, new services and content delivery with improved security and network management. 25 – Content delivery: Streaming, IP-TV, Vo. D – Optimized resource usage – Corporate users specific requirements

TISPAN: NGN Architecture Applications Based on 3 GPP IMS IP Connectivity Access Network And related functionality Data Base Other Multimedia Components … ICF IP Multimedia Component (Core IMS) (SIP-based) PSTN / ISDN Emulation (SIP-I based) “Go” interface Legacy Terminals Network Attachment Functionality NASS GW GW Legacy Terminals NGN Terminals Customer Networks NGN Terminals Resource and Admission Control Functionality RACS “Go” interface IP Access Transport Network PSTN / ISDN Legacy Terminals Other Networks Streaming Services (RTSP-based) TGW MBG Core Transport Network 3 GPP IP-CAN 3 GPP Terminals * Diagram from ETSI TISPAN Ref. 26

TISPAN: New 3 G-NGN MGW Function v. TISPAN NGN functional architecture Rel. 1. • Media Gateway Function (MGF)* – The residential MGF (R-MGF) is located on customer premises. – The access MGF (A-MGF) resides on the network operator’s premises (IP access network or core network). – The trunking MGF (T-MGF)** resides in the boundary between an IP core network and the PSTN/ISDN. * From Rel 1. Doc ** Same as IMS-MGW in 3 GPP 27

TISPAN: New 3 G-NGN MRFP Function v. TISPAN NGN functional architecture Rel. 1. • Media Resource Function Processor (MRFP) – Specialized resource processing functions beyond those available in media gateway functions – Multimedia conferences – Multimedia announcements – IVR capabilities – Media content analysis 28

IMS Common Platform FMC MGW/MRFP Vision • Common HW/SW IMS MGW/MRFP – Safeguards future network deployments – Accelerates delivery of real-time multimedia services – Enables fixed mobile convergence today! • PSTN/ PLMN MTA BB Access Single, all-in-one, common software – – – PSTN NGN-Vo. IP GSM/W-CDMA/3 GPP CDMA 2000/3 GPP 2 Next-gen session boarder controller (SBC) with media functions. Media services • • 29 IP Announcements/rec Rich conf. Rich and programmable tones Video and other (roadmap) IMS-MGW MGF MGCF Other Blocks MRFP MRFC IMS Bearer 3 GPP (WCDMA) (& TD-SCDMA China) 3 GPP 2 (CDMA Evolution) Control

What’s in store? 2005 2007 2006 Rel. 7. 0 2008 2009 Rel. 8. 0 Rel. 2. 0 Rel. 3. 0 NGN Rel. 2. 0 NGN FG 30 * IP multimedia subsystem (IMS), multimedia domain (MMD), Next Generation Network (NGN)

Standard updates in the works -1 • 3 GPP – Rel 7. 0 Stage 3 Mid-2007 • IMS Emergency Call handling, e. Call, Backup algorithms, etc. – Rel. 8. 0 • Security related updates: Multimedia Priority Service, Voice Group Call Service [VGCS] enhancements for public safety and public warning, • Emergency Calling Data transfer, etc; • IMS updates for Packet Cable, • 3 GPP 2 – IMS Bridge – IMS/MMD Superstructure 31

Standard updates in the works -2 • ETSI – TISPAN NGN Release 3. 0 based on 3 GPP Rel. 7. 0 – – Inter-network domain nomadicity User-controlled roaming Higher bandwidth access Fully nomadic (Wi. MAX, VDSL. . ) • ITU NGN FG Release 2. 0 32

Glossary of Terms 33 • • • CSCF = Call Session Control Function P-CSCF = Proxy Call Session Control Function I-CSCF = Interrogating Call Session Control Function S-CSCF = Serving Call Session Control Function GPRS = General Packet Radio Service GGSN = Gateway GPRS Support Node SGSN = Serving GPRS Support Node PDSN = Packet Data Serving Node MIP HA = Mobile IP Home Agent RNC = Radio Network Controller BTS = Base Transceiver Subsystem BSC = Base Station Controller