1、IP Multimedia Subsystem (IMS): Concepts and Architecture,Contact: Zehan Zeb (732) 699-6163,Contribution to: NANC FoN October 4, 2006,IMS Concepts and Architecture Outline,IMS Concepts Introductory concepts and IMS general terminology Functional Entities and their Roles Major nodes/entities Roles an
2、d functions provided Architecture associated with major functional entities Overall Architecture Summary,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,How did we arrive at IMS?
3、 Technology Evolution,PSTN,Circuit switched Analog Digital SS7 ISDN,Circuit switched Analog Digital 2G (GSM & CDMA ANSI-41),3G Wireless,Wireless,3G wireless + IP + Standard Services Platform Converged Applications & Content Access Independence,IP,IMS,Internet VoIP Instant Messaging Web Applications,
4、W-CDMA GPRS/UMTS,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
5、 own different types of networks with varying architectures to offer the same services to all of their customers,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 QoS requirement
6、s and other capabilities during a session setup UE negotiates items, such as: Media Type Direction of traffic Bit rate, packet size, bandwidth adaptation,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 ei
7、ther a SIP URI or a TEL URL When the Public User Identity contains a SIP URI, it typically takes the form of sip: 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 teleph
8、one number in a SIP URI using the following format: sip:+1-212-555-;user=phone TEL URLs are needed for inter-working with PSTN phones In IMS, Public User Identities are used to route SIP signaling,IMS Concepts IMS User Identification (contd.),Each IMS subscriber is assigned a Private User Identity b
9、y 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 Private User Identities are exclusively used for subscription identification and authentication purposes Private U
10、ser Identities are not used for routing SIP requests,Relationship Between User Identities,Public User Identities,Private User Identity,IMS Subscriber,IMS Concepts 3GPP IP-CAN,UE,IP-CAN (GPRS -based),IMS Nodes,SGSN,GGSN,RAN,IMS network utilizes IP-CAN to transport multimedia signaling and bearer traf
11、fic It is the network that connects the UE to the IMS network,IMS Concepts IP Multimedia Session (contd.),UE1,IP-CAN,IMS,Media (data) Flow,Session control signaling,UE2,IP-CAN,An IP Multimedia Session is comprised of session management control connections and media flow connections between two or mo
12、re 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,IMS Concepts- Transition Public Land Mobile Network (PLMN),SS7/ ISUP,MSC,SCP,HLR,Carrier A GSM / ANSI Network,MSC,HLR,Carrier B GSM / ANSI Network,SCP,IMS Concepts-T
13、ransition IMS Architecture: High Level View,UE1,SIP,IMS Network Carrier A,IMS Network Carrier B,ASs,HSS,HSS,ASs,CSCFs,CSCFs,UE2,IMS Concepts-Transition Interoperability: High Level View,UE,SIP,IMS Network Carrier A,IMS Network Carrier B,ASs,HSS,Interworking Functions,SSP,SCP,PSTN,ISUP,HSS,ASs,CSCFs,
14、CSCFs,ISPs,UE,Functional Entities,IMS Architecture Planes or Layers Various Functional Entities and their Roles,Functional Entities IMS Architecture Planes,Application Server,Application Server,Application Server,Session Control,Centralized Databases,Media Control & Gateways,PSTN,2G/3G Mobile,Wirele
15、ss Broadband,Wireline Broadband Res./ Enterprize,Services plane (Application Layer),Session Control Plane (Session and DB Layer),Media Control Plane (Media Control & Gateway Layer),Network Plane (Access and Transport),Functional Entities Network Plane: Access and Transport,PSTN,2G Mobile/ PLMN,Wirel
16、ess Broadband/3G,Wireline Broadband Res./ Enterprize,Network Plane (Access and Transport),IP,IP,MSC,EO/ SSP,Circuit Switched Gateways,Session Controllers,SS7,Functional Entities,Session Control Plane,Functional Entities Session Control Plane,CSCF,HSS,CX,Functional Entities Session Control Plane: CSC
17、F,Call Session Control Function,P-CSCF,I-CSCF,S-CSCF,UEs first point of contact,Interrogating to load balance,UE session management,ISC,ISC,Cx,Functional Entities Session Control Plane: P-CSCF Roles,Proxy- CSCF,UEs first point of contact Authenticates and asserts an identity to the UE Manages QoS, r
18、esource allocation, and controls charging function May contain a PDF which Manages resource allocation and QoS May reside in the visited or home network,PDF,Functional Entities Session Control Plane: I-CSCF Roles,Interrogating- CSCF,Determines UE location by communicating with the HSS Finds the appr
19、opriate S-CSCF Performs load balancing Typically resides in the home network,Functional Entities Session Control Plane: S-CSCF Roles,Serving- CSCF,Responsible for all session management activities Retrieves user profile and authentication information from the HSS Enforces the policy of the network o
20、perator Finds the appropriate AS Provides SIP routing Always resides in the home network,HSS,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 su
21、bscription data required to handle multimedia sessions 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, 3GPP and 3GPP2 HSSs are described differently,Functional Entities Session Control Plane
22、: HSS (3GPP),CSCF,PDF,Home Subscriber Server,IMS Functionality HLR/AUC Function for PS HLR/AUC Function for CS,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 divi
23、ded into three parts: a collection of one or more public identifications an optional service authorization zero or more filter criteria,Relationship Between User Identities and Service Profiles,Service Profile1,Service Profile2,Public User Identities,Private User Identity,IMS Subscriber,a user profi
24、le is bound to a Private User Identity and to the collection of Public User Identities,user profile,Functional Entities,Media Control Plane,Functional Entities Media Control Plane: MRF,The MRF (Media Resource Function) deals with the media in the IMS networkMRFC: The MRFC handles communication with
25、the S-CSCF and controls the resources in the MRFPMRFP: The MRFP in the media plane implements all the media-related functions, such as playing media, providing announcements and mix mediaMRF resides in the home network.,MRF,Media Plane,Signaling Plane,Inter-working Functions BGCF, SGW, MGCF, & MGW,T
26、he MGCF receives SIP call control signal from the IMS network and performs conversion to ISUP/IP and sends to SGW. MGCF also controls MGW. The SGW performs signaling conversion in the transport layer and interfaces with PSTN in the control plane The MGW performs media conversion and interfaces with
27、PSTN. The BGCF selects another BGCF OR an appropriate PSTN/CS gateway,Inter-working Functions BGCF, SGW, MGCF, & MGW (ctd.),Signaling (e.g., ISUP/MTP),Media (e.g., Voice bit stream),Switch,SIP,IMS Network,PSTN Network,Functional Entities,Services Plane: Applications Servers,Functional Entities Servi
28、ces Plane: Applications Servers,SIP AS,OSA-SCS,IM-SSF,S-CSCF,HSS,ISC,Sh,Cx,MRFC,Mr,Overall IMS Architecture,IMS Architecture (3GPP View),UE,IP-CAN (GPRS -based),SGSN,GGSN,RAN,Ut,Gm,Mw,Sh, Si,Dh,Mg,Mn,Mb,Mb,Cx,Dx,Other IP/IMS,Mw,Mj,Mk,Mp,Mb,Mi,SGW,CS,Gq,Go,Mr,ISC,Example: CNAM Call Flow,Control,Beare
29、r,Called Party Visited Network,Calling Party Home Network,Calling Party Visited Network,UE1,P-CSCF,HSS,S-CSCF,SIP,SIP,Diameter,UE2,P-CSCF,AS,HSS,S-CSCF,SIP,IM-SSF,SIP,I-CSCF,Diameter,ENUM,Backbone Packet Network,RAN,Backbone Packet Network,RAN,Identify Registrar of CLD Party and Forward INVITE,5,6,R
30、etrieve Subscriber Profile,6,7,Apply Service Logic to access IM-SSF AS,Ringing / Alerting,11,10,Answer / Connect,12,11,13,13,Session Active,7,8,IM-SSF queries a GSM-SCF if inter-working with PLMN needed,Called Party Home Network,8,SCF,5,Summary IMS Architecture: High Level View,UE,SIP,IMS Network Ca
31、rrier A,IMS Network Carrier B,ASs,HSS,Interworking Functions,SSP,SCP,PSTN,ISUP,HSS,ASs,CSCFs,CSCFs,IMS Architecture,Comments/Questions?Thank You!,IMS White Paper Acronyms,3G Third Generation 3GPP 3rd Generation Partnership Project 3GPP2 3rd Generation Partnership Project 2 AAA Authentication, Author
32、ization and Accounting AMF Account Management Function ANI Application-to-Network Interface ANSI American National Standards Institute API Application Programming Interface AS Application Server ASN Abstract Syntax Notation ATIS Alliance for Telecommunications Industry Solutions ATM Asynchronous Tra
33、nsfer Mode ATP Acceptance Test Plan AUC Authentication Center BGCF Breakout Gateway Control Function BT British Telecom CAMEL Customized Applications for Mobile Network Enhanced Logic CAP CAMEL Application Part CBF Charging and Billing Function CCF Charging Collection Function CDF Charging Data Func
34、tion CDMA Code Division Multiple Access,IMS White Paper Acronyms,CDR Charging Data Records CGF Charging Gateway Function CLEC Competitive LEC CN Core Network COPS Common Open Policy Service CPE Customer Premises Equipment CS Circuit-switched CSCF Call Session Control Function CTIA Cellular Telecommu
35、nications and Internet Association DB Database DHLR Distributed Home Location Register DIAMETER AAA or HSS protocol; successor/upgrade of RADIUS DMS Dual Mode Services DNS Domain Name System DSL Digital Subscriber Line E9-1-1 Emergency Services ECF Event Charging Function EDGE Enhanced Data Rates fo
36、r GSM Evolution EIA Electronics Industry Association ENUM Telephone Number Mapping GGSN Gateway GPRS Support Node GPRS General Packet Radio Service GSA Global Mobile Suppliers Association GSM Global System for Mobile Communication HLR Home Location Register HSS Home Subscriber Server,IMS White Paper
37、 Acronyms,HTTP HyperText Transfer Protocol I-CSCF Interrogating Call Session Control Function IETF Internet Engineering Task Force IM Instant Messaging IM-SSF IP Multimedia Services Switching Function IMS IP Multimedia Subsystem IMS-MGW IMS Media Gateway Function IMT-2000 International Mobile Teleco
38、mmunications 2000 IN Intelligent Networks IP Internet Protocol IP-CAN IP Connectivity Access Network IPDR Internet Protocol Detail Record IPsec IP Security IPv4 IP Version 4 IPv6 IP Version 6 ISC IMS Service Control ISDN Integrated Services Digital Network ISG Intelligent Services Gateway ISO Intern
39、ational Organization for Standards ISUP ISDN User Part IT Information Technology LAN Local Area Network LEC Local Exchange Carrier LNP Local Number Portability MAP Mobile Application Part MCS Multimedia Communications Server,IMS White Paper Acronyms,MEGACO Media Gateway Control (protocol) MGCF Media
40、 Gateway Control Function MGF Media Gateway Function MGIF Mobile Gaming Interoperability Forum MGW Media gateway MPLS Multi-Protocol Label Switching MRF Media Resource Function MRFC Media Resource Function Controller MRFP Media Resource Function Processor MSF Multiservice Switching Forum MSO Multi-S
41、ervice Operator MTP Message Transfer Part NAI Network Access Identifier NANP North American Numbering Plan NE Network Element NGN Next Generation Network NNI Network Node Interface OAM&P Operations, Administration, Maintenance and Provisioning OCF Online Charging Function OCS Online Charging System
42、OMA Open Mobile Alliance OSA Open Service Access OSI Open Systems Interconnection OSS Operations Support System PC Policy Controller P-CSCF Proxy Call Session Control Function,IMS White Paper Acronyms,PDA Personal Digital Assistant PDF Policy Decision Function PDS Packet Data Subsystem PDSN Packet D
43、ata Service Node POTS Plain Old Telephone Service PSTN Public Switched Telephone Network PLMN Public land Mobile Network QoS Quality of Service RAN Radio Access Network RADIUS Remote Authentication Dial In User Service RF Rating Function RTP Real-Time Transport Protocol RTCP RTP Control Protocol SBC
44、 Session Border Controller SCCP Signaling Connection Control Part SCF Session Charging Function SCIM Service Capability Interaction Manager SCP Service Control Point S-CSCF Serving Call Session Control Function S-CSCF Serving CSCF SCTP Stream Control Transmission Protocol SCF Service Control Functio
45、n SCP Service Control Point SCS Service Capability Server SDO Standards Development Organization SDP Session Description Protocol,IMS White Paper Acronyms,SGF Signaling Gateway Function SGSN Serving GPRS Support Node SGW Signaling Gateway SIGTRAN Signaling Transport SIP Session Initiation Protocol S
46、LA Service Level Agreement SLF Subscriber Locator Function SMS Short Message Service SNMP Simple Network Management Protocol SOA Service Oriented Architecture SS7 Signaling System 7 SSL Secure Sockets Layer SSF Service Switching Function SSP Service Switching Point TAS Telephony Application Serer TB
47、CP Talk Burst Control Protocol TCAP Transaction Capabilities Application Part TCP Transmission Control Protocol TDM Time Division Multiplexing TIA Telecommunications Industry Association TSG-CT TSG Core Network and Terminals (3GPP) TSG-GERAN TSG GSM EDGE Radio Access Network (3GPP) TSG-RAN TSG Radio
48、 Access Network (3GPP) TSG-SA TSG Service and System Aspects (3GPP) UDP User Datagram Protocol,IMS White Paper Acronyms,UE User Equipment UMTS Universal Mobile Telecommunications System UNI User-to-Network Interface URI Universal Resource Identifier URL Uniform Resource Locator UTRA Universal Terres
49、trial Radio Access UWB Ultra-Wideband VCC Voice Call Continuity VoIP Voice over IP VPN Virtual Private Network VSP Virtual Service Provider WCIT World Conference on International Telecommunications WIN Wireless Intelligent Network WG Working Group WiFi 802.11x wireless technology WiMAX 802.16x wireless technology WIN Wireless Intelligent Network WLAN Wireless LAN WTSC Wireless Technologies and Systems Committee (ATIS) xDSL Variations of DSL,
