IP Multimedia Subsystem IMS Concepts and Architecture Contribution

IP Multimedia Subsystem (IMS): Concepts and Architecture Contribution to: NANC Fo. N October 4, 2006 Copyright © 2006 Telcordia Technologies Copyright © 2005 Telcordia Technologies All Rights Reserved Contact: Zehan Zeb zzeb@telcordia. com (732) 699 -6163

IMS Concepts and Architecture Outline § IMS Concepts – Introductory concepts and IMS general terminology § Functional Entities and their Roles Major nodes/entities – Roles and functions provided – Architecture associated with major functional entities – § Overall Architecture § Summary 2

IMS Concepts § How Did We Arrive At IMS? § Definition of IMS § UE § User Identities § IP Connectivity Access Network (IP-CAN) § IP Multimedia Sessions § Transition to IMS Architecture 3

How did we arrive at IMS? Technology Evolution PSTN § § § Wireless IP § Internet Circuit switched § Circuit switched Analog § Analog Digital SS 7 § Digital ISDN § 2 G (GSM – Vo. IP 3 G Wireless IMS § § W-CDMA § GPRS/UMTS – Instant Messaging – Web Applications 3 G wireless + IP ++ – Standard Services Platform – Converged Applications & Content – Access Independence & CDMA ANSI-41) 4

IMS Concepts What is IMS? § IP Multimedia Subsystem (IMS) is a Service Delivery Architecture • Standardized architecture to provide Internet Protocol (IP)-based mobile and fixed multimedia services § IMS architecture has evolved over the past few years § Today, IMS could allow operators who own different types of networks with varying architectures to offer the same services to all of their customers 5

IMS Concepts User Equipment (UE) § UE: A device that has IP connectivity and is able to request an IP address from the network – Examples: SIP phone, PC, PDA § UE negotiates its Qo. S requirements and other capabilities during a session setup § UE negotiates items, such as: Media Type – Direction of traffic – Bit rate, packet size, bandwidth adaptation – 6

IMS Concepts IMS User Identification An IMS user is allocated one or more Public User Identities by the home operator § A Public User Identity is either a SIP URI or a TEL URL § – – § When the Public User Identity contains a SIP URI, it typically takes the form of sip: first. last@operator. com When the Public User Identity contains a TEL URL representing a phone number in international format it typically takes the form of tel: +1 -212 -555 -0293 It is possible to include a telephone number in a SIP URI using the following format: sip: +1 -212 -555 -0293@operator. com; user=phone TEL URLs are needed for inter-working with PSTN phones In IMS, Public User Identities are used to route SIP signaling 7

IMS Concepts IMS User Identification (contd. ) § Each IMS subscriber is assigned a Private User Identity by the home operator § Unlike Public User Identities, Private User Identities are not SIP URIs or TEL URLs They take the format of a NAI (Network Access Identifier) – The format of a NAI is username@operator. com – § Private User Identities are exclusively used for subscription identification and authentication purposes § Private User Identities are not used for routing SIP requests 8

Relationship Between User Identities Sip: zehan. zeb@newstore. com tel: +17324567888 zzeb@tmobile. com IMS Subscriber Private User Identity Sip: zehan. zeb@example. com tel: +88028112347 Public User Identities 9

IMS Concepts 3 GPP IP-CAN UE IP-CAN (GPRS -based) IMS Nodes RAN SGSN GGSN • IMS network utilizes IP-CAN to transport multimedia signaling and bearer traffic • It is the network that connects the UE to the IMS network 10

IMS Concepts IP Multimedia Session (contd. ) UE 1 IP-CAN IMS Session control signaling IP-CAN UE 2 Media (data) Flow • An IP Multimedia Session is comprised of session management control connections and media flow connections between two or more users • IMS users are able to mix and match a variety of IP-based services in a way they choose during a single communication session 11

IMS Concepts- Transition Public Land Mobile Network (PLMN) HLR SCP MSC Carrier A GSM / ANSI Network SS 7/ ISUP HLR SCP MSC Carrier B GSM / ANSI Network 12

IMS Concepts-Transition IMS Architecture: High Level View HSS SIP UE 1 ASs CSCFs IMS Network Carrier A HSS ASs CSCFs UE 2 IMS Network Carrier B 13

IMS Concepts-Transition Interoperability: High Level View HSS SIP UE HSS ASs CSCFs IMS Network Carrier A CSCFs Interworking Functions UE IMS Network Carrier B ISUP SCP ISPs SSP PSTN 14

Functional Entities § IMS Architecture Planes or Layers § Various Functional Entities and their Roles 15

Functional Entities IMS Architecture Planes Services plane (Application Layer) Session Control Plane (Session and DB Layer) Media Control Plane (Media Control & Gateway Layer) Network Plane (Access and Transport) Wireline Broadband Res. / Enterprize Application Server Session Control Application Server DB Centralized Databases Media Control & Gateways Wireless Broadband 2 G/3 G Mobile PSTN 16

Functional Entities Network Plane: Access and Transport Circuit Switched Gateways Session Controllers Network Plane (Access and Transport) IP IP 2 G Mobile/ PLMN MSC Wireline Broadband Res. / Enterprize SS 7 PSTN EO/ SSP Wireless Broadband/ 3 G 17

Functional Entities tr n l. P o Co n ne la es S io s 18

Functional Entities Session Control Plane CSCF CX DB HSS 19

Functional Entities Session Control Plane: CSCF Call Session Control Function Cx P-CSCF UE’s first point of contact ISC I-CSCF Interrogating to load balance ISC DB HSS S-CSCF UE session management 20

Functional Entities Session Control Plane: P-CSCF Roles Proxy- CSCF v. UE’s first point of contact v. Authenticates and asserts an identity to the UE v. Manages Qo. S, resource allocation, and controls charging function v. May contain a PDF which v. Manages resource allocation and Qo. S v. May reside in the visited or home network PDF 21

Functional Entities Session Control Plane: I-CSCF Roles Interrogating- CSCF HSS DB v. Determines UE location by communicating with the HSS v. Finds the appropriate S-CSCF v. Performs load balancing v. Typically resides in the home network 22

Functional Entities Session Control Plane: S-CSCF Roles Serving- CSCF v. Responsible for all session management activities HSS DB v. Retrieves user profile and authentication information from the HSS v. Enforces the policy of the network operator v. Finds the appropriate AS v. Provides SIP routing v. Always resides in the home network 23

Functional Entities Session Control Plane: HSS § Home Subscriber Server (HSS) is the main data storage for all subscriber and service-related data of the IMS subscriber § The HSS contains all the user-related subscription data required to handle multimedia sessions o All the data related to a particular user are stored in a single HSS § The HSS is always located in the home network § Although the functionalities are the same, 3 GPP and 3 GPP 2 HSSs are described differently 24

Functional Entities Session Control Plane: HSS (3 GPP) CSCF Home Subscriber Server • IMS Functionality • HLR/AUC Function for PS • HLR/AUC Function for CS PDF Contains a user profile - bound to a Private User Identity and to the collection of Public User Identities The user profile contains a number of service profiles The service profile is divided into three parts: • a collection of one or more public identifications • an optional service authorization • zero or more filter criteria 25

Relationship Between User Identities and Service Profiles Sip: zehan. zeb@newstore. com tel: +17324567888 zzeb@tmobile. com IMS Subscriber Private User Identity a user profile is bound to a Private User Identity and to the collection of Public User Identities Service Profile 1 Public User Identities Sip: zehan. zeb@example. com tel: +88028112347 user profile Service Profile 2 26

Functional Entities ol tr ia d ne la P on C e M 27

Functional Entities Media Control Plane: MRFC MRF Signaling Plane Media Plane MRFP v. The MRF (Media Resource Function) deals with the media in the IMS network v MRFC: The MRFC handles communication with the S-CSCF and controls the resources in the MRFP v MRFP: The MRFP in the media plane implements all the media-related functions, such as playing media, providing announcements and mix media v MRF resides in the home network. 28

Inter-working Functions BGCF, SGW, MGCF, & MGW SGW BGCF MGW v The MGCF receives SIP call control signal from the IMS network and performs conversion to ISUP/IP and sends to SGW. MGCF also controls MGW. v The SGW performs signaling conversion in the transport layer and interfaces with PSTN in the control plane v The MGW performs media conversion and interfaces with PSTN. v The BGCF selects another BGCF OR an appropriate PSTN/CS gateway 29

Inter-working Functions BGCF, SGW, MGCF, & MGW (ctd. ) SGW BGCF SIP Signaling (e. g. , ISUP/MTP) MGCF Switch MGW IMS Network Media (e. g. , Voice bit stream) PSTN Network 30

Functional Entities P s ce vi rs er e S rv Se lic p Ap : ne la ns tio a 31

Functional Entities Services Plane: Applications Servers SIP AS OSA-SCS Sh HSS IM-SSF ISC Cx S-CSCF Mr MRFC 32

t c te i S al r ve O IM l h rc A re u 33

IMS Architecture (3 GPP View) Dh Ut UE IP-CAN (GPRS -based) Mw GGSN Gq Go PDF Mb HSS ISC I-CSCF Gm P-CSCF RAN SGSN Sh, Si AS S-CSCF Mg MGCF Cx Dx Mw Mr Other IP/IMS MRFC Mi Mj BGCF Mn IMMGW SLF Mk Mp SGW Mb CS MRFP Mb 34

Example: CNAM Call Flow 1 Initiate SIP Invite 7 Apply Service Logic to access IM-SSF AS 2 Retrieve Subscriber Profile (if needed) 8 IM-SSF queries a GSM-SCF if inter-working with PLMN needed 3 Apply Service Logic 9 Forward INVITE to CLD Party 4 Retrieve Address of CLD Party Home Network 10 SDP Negotiation / Resource Reservation Control 5 Identify Registrar of CLD Party and Forward INVITE 11 Ringing / Alerting 12 Answer / Connect 6 Retrieve Subscriber Profile Control 13 Session Active Calling Party Home Network Bearer HSS 2 Diameter AS 3 SIP ENUM Called Party Home Network SCF 6 4 7 S-CSCF 5 I-CSCF S-CSCF 9 P-CSCF LIDB/ CNAM 8 Diameter SIP Calling Party Visited Network HSS SIP IM-SSF SIP P-CSCF Called Party Visited Network 11 10 1 UE 1 RAN Backbone Packet Network RTP Stream Backbone Packet Network 12 RAN UE 2 13 35

Summary IMS Architecture: High Level View HSS SIP UE HSS ASs CSCFs IMS Network Carrier A CSCFs Interworking Functions IMS Network Carrier B ISUP SCP SSP PSTN 36

IMS Architecture § Comments/Questions? § Thank You!! 37

IMS White Paper Acronyms § § § § § § 3 G 3 GPP 2 AAA AMF ANI ANSI API AS ASN ATIS ATM ATP AUC BGCF BT CAMEL CAP CBF CCF CDMA Third Generation 3 rd Generation Partnership Project 2 Authentication, Authorization and Accounting Account Management Function Application-to-Network Interface American National Standards Institute Application Programming Interface Application Server Abstract Syntax Notation Alliance for Telecommunications Industry Solutions Asynchronous Transfer Mode Acceptance Test Plan Authentication Center Breakout Gateway Control Function British Telecom Customized Applications for Mobile Network Enhanced Logic CAMEL Application Part Charging and Billing Function Charging Collection Function Charging Data Function Code Division Multiple Access 38

IMS White Paper Acronyms § § § § § § § CDR CGF CLEC CN COPS CPE CS CSCF CTIA DB DHLR DIAMETER DMS DNS DSL E 9 -1 -1 ECF EDGE EIA ENUM GGSN GPRS GSA GSM HLR HSS Charging Data Records Charging Gateway Function Competitive LEC Core Network Common Open Policy Service Customer Premises Equipment Circuit-switched Call Session Control Function Cellular Telecommunications and Internet Association Database Distributed Home Location Register AAA or HSS protocol; successor/upgrade of RADIUS Dual Mode Services Domain Name System Digital Subscriber Line Emergency Services Event Charging Function Enhanced Data Rates for GSM Evolution Electronics Industry Association Telephone Number Mapping Gateway GPRS Support Node General Packet Radio Service Global Mobile Suppliers Association Global System for Mobile Communication Home Location Register Home Subscriber Server 39

IMS White Paper Acronyms § § § § § § § HTTP I-CSCF IETF IM IM-SSF IMS-MGW IMT-2000 IN IP IP-CAN IPDR IPsec IPv 4 IPv 6 ISC ISDN ISG ISO ISUP IT LAN LEC LNP MAP MCS Hyper. Text Transfer Protocol Interrogating Call Session Control Function Internet Engineering Task Force Instant Messaging IP Multimedia Services Switching Function IP Multimedia Subsystem IMS Media Gateway Function International Mobile Telecommunications 2000 Intelligent Networks Internet Protocol IP Connectivity Access Network Internet Protocol Detail Record IP Security IP Version 4 IP Version 6 IMS Service Control Integrated Services Digital Network Intelligent Services Gateway International Organization for Standards ISDN User Part Information Technology Local Area Network Local Exchange Carrier Local Number Portability Mobile Application Part Multimedia Communications Server 40

IMS White Paper Acronyms § § § § § § § MEGACO MGCF MGIF MGW MPLS MRFC MRFP MSF MSO MTP NAI NANP NE NGN NNI OAM&P OCF OCS OMA OSI OSS PC P-CSCF Media Gateway Control (protocol) Media Gateway Control Function Media Gateway Function Mobile Gaming Interoperability Forum Media gateway Multi-Protocol Label Switching Media Resource Function Controller Media Resource Function Processor Multiservice Switching Forum Multi-Service Operator Message Transfer Part Network Access Identifier North American Numbering Plan Network Element Next Generation Network Node Interface Operations, Administration, Maintenance and Provisioning Online Charging Function Online Charging System Open Mobile Alliance Open Service Access Open Systems Interconnection Operations Support System Policy Controller Proxy Call Session Control Function 41

IMS White Paper Acronyms § § § § § § § PDA PDF PDSN POTS PSTN PLMN Qo. S RAN RADIUS RF RTP RTCP SBC SCCP SCF SCIM SCP S-CSCF SCTP SCF SCP SCS SDO SDP Personal Digital Assistant Policy Decision Function Packet Data Subsystem Packet Data Service Node Plain Old Telephone Service Public Switched Telephone Network Public land Mobile Network Quality of Service Radio Access Network Remote Authentication Dial In User Service Rating Function Real-Time Transport Protocol RTP Control Protocol Session Border Controller Signaling Connection Control Part Session Charging Function Service Capability Interaction Manager Service Control Point Serving Call Session Control Function Serving CSCF Stream Control Transmission Protocol Service Control Function Service Control Point Service Capability Server Standards Development Organization Session Description Protocol 42

IMS White Paper Acronyms § § § § § § § SGF SGSN SGW SIGTRAN SIP SLA SLF SMS SNMP SOA SS 7 SSL SSF SSP TAS TBCP TCAP TCP TDM TIA TSG-CT TSG-GERAN TSG-SA UDP Signaling Gateway Function Serving GPRS Support Node Signaling Gateway Signaling Transport Session Initiation Protocol Service Level Agreement Subscriber Locator Function Short Message Service Simple Network Management Protocol Service Oriented Architecture Signaling System 7 Secure Sockets Layer Service Switching Function Service Switching Point Telephony Application Serer Talk Burst Control Protocol Transaction Capabilities Application Part Transmission Control Protocol Time Division Multiplexing Telecommunications Industry Association TSG Core Network and Terminals (3 GPP) TSG GSM EDGE Radio Access Network (3 GPP) TSG Service and System Aspects (3 GPP) User Datagram Protocol 43

IMS White Paper Acronyms § § § § § UE UMTS UNI URL UTRA UWB VCC Vo. IP VPN VSP WCIT WIN WG Wi. Fi Wi. MAX WIN WLAN WTSC x. DSL User Equipment Universal Mobile Telecommunications System User-to-Network Interface Universal Resource Identifier Uniform Resource Locator Universal Terrestrial Radio Access Ultra-Wideband Voice Call Continuity Voice over IP Virtual Private Network Virtual Service Provider World Conference on International Telecommunications Wireless Intelligent Network Working Group 802. 11 x wireless technology 802. 16 x wireless technology Wireless Intelligent Network Wireless LAN Wireless Technologies and Systems Committee (ATIS) Variations of DSL 44

IMS Architecture References 1. 2. 3. 4. 5. The 3 G IP Multimedia Subsystem (IMS), Merging the Internet and the Cellular Worlds, by Gonzalo Camarillo and Miguel A. Garc´ıa-Mart´ın, 2006 IP Multimedia Concepts and Services by Mikka Poikselka, Georg Mayer, Hisham Khartabill, Aki Niemi, 2006 3 GPP TS 23. 228: Technical Specifications Group Services and System Aspects; IP Multimedia Subsystems (IMS), Stage 2, 12/2005 3 GPP 2 X. S 0013 -000 -A: All-IP Core Network Multimedia Domain, Overview , 11/2005 3 GPP 2 X. S 0013 -002 -A: All-IP Core Network Multimedia Domain, IMS, Stage 2 , 11/2005 45