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3GPP2 MMD Status

3GPP2 MMD Status. Jack Nasielski jackn@qualcomm.com. Outline. IP Multi-media Subsystem (IMS)/ Multi-Media Domain (MMD) Background and Overview IMS Network Architecture 3GPP/PP2 differences Status of MMD work, current and future Bonus material SIP Overview SIP Functions SIP Messages

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3GPP2 MMD Status

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  1. 3GPP2 MMD Status Jack Nasielskijackn@qualcomm.com Page 1

  2. Outline • IP Multi-media Subsystem (IMS)/ Multi-Media Domain (MMD) • Background and Overview • IMS Network Architecture • 3GPP/PP2 differences • Status of MMD work, current and future • Bonus material • SIP Overview • SIP Functions • SIP Messages • References • NB : MMD is IMS + Packet Data Subsystem Page 2

  3. IMS/MMD Background • Goals • Operator cost saving (CAPEX & OPEX) • Flexible, fast service creation • Independence of access technology • Re-use IETF protocols (SIP/SDP/RTP/Diameter/etc.) • 3GPP IP Multimedia Subsystem (IMS) • First All-IP Workshop in February 2000 • IMS developed in 3GPP Release 5 and 6 • Now working on Release 7 • 3GPP2 Multi-Media Domain (MMD) • Formed All-IP ad hoc group in 1999 • Published MMD Rev 0 in December 2003 • Published MMD Rev A in November 2005 • Now wrapping up MMD Rev B, starting Rev C • PP/PP2 agreed to “harmonize” at OHG workshop in April 2002 Page 3

  4. Introduction to IMS (1) • IMS is standardized in 3GPP, 3GPP2, ETSI TISPAN, CableLabs, and ITU-T (NGN) • IMS defines a framework for delivering multimedia services over IP (Internet Protocol) • Framework provides following • Architecture (Defines Functional Entities and Interfaces) • Security (Authentication, Authorization, Integrity Protection) • Accounting (Offline, Online) • Application Server Architecture • IMS claims to be Access Network Agnostic • Single IMS core can support devices on different access networks e.g. cdma2000, WLAN, WCDMA, cable-modem etc. Page 4

  5. Introduction to IMS (2) • Uses protocols defined by IETF • e.g., Session Initiation Protocol (SIP), Session Description Protocol (SDP), Diameter • IMS defines a number of services • Services are delivered over IP • End to end IP between AT (or UE) and network • Enables interaction of dissimilar user devices. • Facilitates convergence of multimedia services, such as gaming, messaging, and voice. Page 5

  6. MMD (Multimedia Domain) • Standardized in 3GPP2 • Consists of following: • IMS (IP Multimedia Subsystem) • Packet Data Subsystem • 3GPP2 IMS • 3GPP IMS with added flexibility • Supports alternate authentication schemes • Access network specific changes • Single radio voice call continuity Page 6

  7. The IMS Network: Access Agnostic Residential Voice Network Residential Cable or DSL Network IMS Application Servers 802.11/802.16 IP Network Enterprise IP Network HSS P/S/I-CSCF Media Gateway Circuit Switched Mobile Network Packet Switched Mobile Network Page 7

  8. IMS Home Network Concept Application Servers HSS IMS Media Gateway S-CSCF IP Network • Signaling traffic routed via user’s home network to provide the same experience when roaming. • Bearer traffic routing may or may not go through the home network. • Transcoding occurs only when necessary. Page 8

  9. Basic IMS Elements (1) • Call Session Control Function • SIP registration • SIP session control • Application servers (e.g.) • Push-to-talk • Instant messaging • Telephony AS • Other 3rd party AS • Home Subscriber Server • Centralized DB • HLR successor • User profile & filter criteria Visited or Home Network • Media Resource Function Controller • Controls MRFP (and charging processing) AS Backbone Packet Network AS HSS AS Access MRFC P-CSCF I-CSCF S-CSCF V-PCRF H-PCRF MRFP Home Network • Proxy CSCF • Initial entry point for user • Access security • Routes to I/S-CSCF • Performs SIP compression • V-PCRF controls local policy; interacts with H-PCRF • Serving CSCF • Allocates resources • Maintains session states • Queries AAA/HSS • Performs session processing and charging processing • H-PCRF provides QoS and charging rules • Interrogating CSCF • Entry point to IMS, for incoming calls • Assigns S-CSCF for users • Masks network topology from external networks • Media Resource Function Processor • Tone & Announcement Play back • Conference Bridges Page 9

  10. Basic IMS Elements (2) AS UE RAN PSTN/PLMN Backbone Packet Network • Media Gateway Control Function • Translates between session based IP signaling and ISUP for session control. Calling Party Home Network Calling Party Visited Network HSS DIAMETER SIP P-CSCF S-CSCF BGCF MGCF SIP SIP SIP ISUP H.248 PCM MGW RTP Stream • Media Gateway • Provides an interface between the packet switched core network and the circuit switched PSTN for user traffic. • Breakout Gateway Control Function • Selects network in which PSTN breakout occurs and the appropriate MGCF Page 10

  11. IMS Services (1) • Voice Over IP (VoIP) • Voice call continuity between IMS (VoIP) and Circuit Switched (CS) domains • Call delivery over IMS and CS using single DN • Inter-working with PSTN • Video Telephony • Voice and Video services • Presence Service • Allows exchange of presence information between users • SMS delivery over IMS Page 11

  12. IMS Services (2) • Push to Talk Over Cellular (PoC) • Walkie-talkie like service on cell phones • Messaging • Pager-mode messaging, Session-based messaging • Conferencing • Set up multi-media conferences • Conference management • Create conference, Add participants, Delete participants etc • Group Management • E.g, buddy list management for Presence, PoC Page 12

  13. IMS User Identification • Private User Identity • Assigned by the home network operator to identify an IM subscription (one per subscription) • Used for registration, authentication, administration, and accounting • Not used for routing SIP messages • In the form of Network Access Identifier as defined in RFC 2486 • Eg: alice@atlanta.com • Public User Identity • A subscriber may have one or more public user identities. • Used to address the user for establishing communication • In the form of SIP URL or E.164 number • Eg: sip:alice@atlanta.com or tel:+18586514444 • (a public user ID may also be shared between private user IDs) Page 13

  14. Steps in IMS Registration Page 14

  15. Mobile to Mobile Session Setup 1 Initiate SIP Invitation 6 Retrieve Subscriber Profile (if needed) 2 Retrieve Subscriber Profile (if needed) 7 Apply Service Logic 3 Apply Service Logic 8 Forward INVITE to CLD Party 4 Retrieve Address of CLD Party Home Network and Forward INVITE. 9 SDP Negotiation / Resource Reservation Control 10 Ringing / Alerting Control 5 Identify Registrar of CLD Party and Forward INVITE. 11 Answer / Connect Bearer 12 Session Active Calling Party Home Network Called Party Home Network HSS DNS HSS AS 2 Diameter 6 Diameter Diameter 4 AS 5 3 7 S-CSCF I-CSCF S-CSCF SIP SIP UE UE 8 SIP SIP Calling Party Visited Network Called Party Visited Network P-CSCF P-CSCF RAN RAN 11 10 Backbone Packet Network Backbone Packet Network 1 9 12 RTP Stream RTP Stream Page 15

  16. Home S-CSCF I-CSCF Visited IMS Security 1. REGISTER & Authentication vector distribution 4. Protection of all further SIP signalling using agreed session key between mobile and P-CSCF HSS 1. REGISTER 1. REGISTER P-CSCF 1. REGISTER 3. Session key distribution from S to P-CSCF 2. Mutual authentication and session key agreement Page 16

  17. Policy Control • Service-Based Bearer Control (SBBC) • Bearer QoS authorization and charging control at PDSN based on IMS service authorization • Tx interface connects the Policy and Charging Rules Function (PCRF) to an Application Function (e.g., P-CSCF) that is responsible for application level service decisions • Ty interface connects the PCRF to the AGW (e.g., PDSN) that is responsible for bearer resources policy enforcement. • Part of MMD Rev B. • To be enhanced for Rev C (e.g., extend Ty to Packet Data Interworking Function (PDIF) for WLAN access) Page 17

  18. 3GPP/3GPP2 IMS/MMD Differences Page 18

  19. IMS in 3GPP/PP2 Page 19

  20. 3GPP IMS Releases • 3GPP IMS Release 5, 6 complete; Release 7 in progress • IMS Release 5 • IMS Registration, routing and call flows, Security Architecture, Accounting (Offline and Online Charging), Application Server Architecture • IMS Release 6 • Presence, Conferencing, Messaging, Flow based charging (Gx and Rx), Group management, Early IMS (security + IPv4 support), Interworking non-IMS, Service based local policy (Gq interface) • IMS Release 7 • CSI - combination of CS and IMS services (parallel operation of a CS service and an IMS session between the same two users), FBI – IMS over fixed broadband, VCC – Voice Call Continuity, PCC – Policy and Charging Control, Emergency Services Page 20

  21. 3GPP2 MMD Releases • 3GPP2 MMD Rev 0, A complete, Rev B in progress • MMD Rev 0 • Basic IMS as in Rel 5, SIP/SDP procedures, security, offline charging, service architecture • MMD Rev A • Adds Presence, Conferencing • MMD Rev B • Includes Optimized call flows, Service Based Bearer Control (QoS mappings), VoIP/1x call delivery and handoffs, online charging, messaging Page 21

  22. 3GPP/PP2 differences • 3GPP IMS and 3GPP2 MMD are very similar except for some differences noted in the next few slides • The differences are essential for deploying IMS over CDMA-based 3GPP2 systems. • Access network specific changes • The differences do not affect interoperability between 3GPP and 3GPP2 systems. Page 22

  23. IMS Technical Differences (1) • Access Security • 3GPP IMS mandates IPsec between UE and P-CSCF for integrity protection • 3GPP2 allows for P-CSCF and UE to negotiate other security mechanisms using RFC 3329 (like ipsec-ike, tls, digest etc) • 3GPP IMS mandates using AKA for authentication between S-CSCF and UE • 3GPP2 allows for alternate authentication mechanisms like Digest Page 23

  24. IMS Technical Differences (2) • Smart Cards • 3GPP IMS terminals have smart cards (UICC) • USIM (UMTS SIM), ISIM (IMS SIM) applications • 3GPP2 IMS does not require a UICC • IMS information can be stored in UE or R-UIM. • 3GPP2 now supports UICC + ISIM for operators that choose that method. Page 24

  25. IMS Technical Differences (3) • Temporary Public/Private Identifiers • 3GPP creates temporary Public/Private IDs to support terminals without ISIM application. • MMD Rev 0 (first release of MMD) does not support temporary IDs • MMD Rev A supports temporary IDs • The method of generating these ID’s is different between 3GPP and 3GPP2 • E.212 vs MIN based IMSIs. • Anchored internet access point • In 3GPP, the GGSN is anchored for a given session. • In 3GPP2, the PDSN may change. Page 25

  26. IMS Technical Differences (4) • HSS (Home Subscriber Server) vs AAA • In 3GPP2 IMS, AAA + databases represent an HSS. • Also in 3GPP2 IMS, HSS is used only for PS domain. • In 3GPP, HSS is used for both PS & CS domains. • P-CSCF Discovery procedures • 3GPP2 supports static configuration and DHCP for P-CSCF discovery • 3GPP Rel-5 supports P-CSCF discovery through DHCP and PDP context activation. • IMS Rel 5, 6, 7 roughly equivalent to MMD Rev 0, A, B respectively. Page 26

  27. Other Access Specific Info • P-Access-network-Info • UE includes CDMA specific information in P-Access-network-info • P-Access-network-charging-info • Included by P-CSCF • Contains access network specific information for charging • HRPD-VoIP to 1X-CS interworking • Behavior specific to 3GPP2 systems • 3GPP assumes dual-RF chain • 3GPP2 allows architectures with both single-RF and dual-RF • (dual radio for WLAN/HRPD) Page 27

  28. Current Projects in 3GPP2 MMD • X.P0013 MMD Rev B • Service Based Bearer Control (SBBC) • Optimized call flows • Optimize resource reservations to speed session setup • Show QoS procedures in PDSN and RAN • Based on IS-856-A, IS-835-D • AT can pre-configure QoS reservations for SIP and RTP flows • Online Charging • Messaging • X.P0027 Presence • X.P0029 Conferencing • X.P0042 VoIP/1x interworking (voice call continuity) • X.P0048 SMS over IMS • X.P0049 MMD Emergency Calling Page 28

  29. New Projects in 3GPP2 MMD • Security Enhancements • Policy Enhancements • Roaming • MMD Rev C (under discussion) • WLAN/HRPD VoIP/VoIP handoffs (current) Page 29

  30. 3GPP2 Security Enhancements • For both Multi-Media Domain and packet data network security. • TSG-S will develop security requirements and the security architecture to support the following: • Methods to reuse authentication results to bootstrap keys for SIP and non-SIP applications. • Methods to detect security problems in the network • Methods to remediate problems, whether in network nodes or end-user devices • Ability to update security software on devices when required • Ability to distribute security policies throughout the system. • IETF is developing some of the protocols needed for this. Page 30

  31. MMD Policy • MMD Rev B defined Service Based Bearer Control (SBBC) which enables an operator apply policy to SIP services, and to provision flow based charging rules at the PDSN. • SBBC provides the mapping between application layer signaling and resource management in the RAN via the Tx/Ty interfaces. SBBC is somewhat limited however, in that the PDSN is the only policy enforcement point. • New work item expands the scope of MMD policy • to include overall coordination of network resource usage (for SIP and non-SIP applications) • to enable policy exchange with other operators for roaming subscribers. Page 31

  32. MMD Roaming • Inter-operator roaming architecture and protocols to allow MMD operators to provide services to their customers roaming on other networks. • Includes IMS and PDS aspects. • The MMD system will provide home operator control of MMD services. It is expected that all bearer traffic is not required to be routed via the home system. This will allow for low latency of real time traffic in the visited system. • This work item will result in a technical report or specification on MMD roaming. Page 32

  33. Bonus Material Page 33

  34. SIP Overview • Internet Multimedia Protocols and Services • SIP Fundamentals • Multimedia Stack • SIP Operations • SIP Trapezoid • SIP Session Establishment • Wireline vs. Wireless SIP Usage • SIP Messages • SIP Methods • SIP Response Codes • SIP Message Headers and Bodies. Page 34

  35. SIP Fundamentals • Application Layer Signaling Protocol • Client-Server protocol • Used to Establish, Modify & Terminate Multimedia sessions • Part of Internet Multimedia architecture • Can use TCP, UDP, SCTP, TLS etc • Can run on IPv4 and IPv6 • Based on HTTP • Similar text based structure • Uses URIs (Uniform Resource Identifiers) Eg: sip:alice@atlanta.com Page 35

  36. Multimedia stack Page 36

  37. Example Services Enabled by SIP • Value-added telephony services • Real-time multimedia communication • Multimedia conferencing, gaming, and work sharing • Personal mobility between different terminals and networks • Presence and Instant Messaging • 3rd party call control • Flexible service creation environment • IP-based video streaming • Computer-Telephony Integration (CTI) Page 37

  38. SIP Trapezoid DNS Server Location Service Signaling Flow Outbound SIP Proxy Inbound SIP Proxy Media Flow Calling User Agent Called User Agent Page 38

  39. Sample SIP Call Flow Page 39

  40. SIP Session Establishment • User location • determination of the end system to be used for communication; • User availability • determination of the willingness of the called party to engage in communications; • Terminal capability negotiation • determination of the media and media parameters to be used; • Session setup • "ringing", establishment of session parameters at both called and calling party; • Session handling • including transfer and termination of sessions, modifying session parameters, and invoking services. Page 40

  41. Example INVITE message INVITE sip:user2_public@home2.netSIP/2.0 Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7 Max-Forwards: 70 Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr> P-Preferred-Identity: "John Doe" <sip:user1_public1@home1.net> P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11 Privacy: none From: <sip:user1_public1@home1.net>; tag=171828 To: < sip:user2_public@home2.net> Call-ID: cb03a0s09a2sdfglkj490333 Cseq: 127 INVITE Require: precondition, sec-agree Proxy-Require: sec-agree Supported: 100rel Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi=87654321; port1=7531 Contact: <sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp> Content-Type: application/sdp Content-Length: (…) v=0 o=- 2987933615 2987933615 IN IP6 5555::aaa:bbb:ccc:ddd s=- c=IN IP6 5555::aaa:bbb:ccc:ddd t=907165275 0 m=video 3400 RTP/AVP 98 99 <…SDP parameters skipped…> m=audio 3456 RTP/AVP 97 96 0 15 <…More SDP parameters skipped…> Page 41

  42. Wireline vs. Wireless SIP Usage • Wireline SIP assumptions • High processing power • Easily upgraded • Bandwidth plentiful • Wireless terminal properties • Limited processing power • Limited bandwidth • SIP characteristics • Large messages, with text encoding • Chatty message exchanges • Favoring generality and modularity over efficiency • SIP adaptation for wireless terminals • SIP message compression • Service implementation on SIP servers  • Use of SIP proxy servers instead of SIP redirect servers. Page 42

  43. SIP Methods • INVITE Used for Session Setup • ACK Acknowledgement of final response to INVITE • BYE Session termination • CANCEL Pending session cancellation • REGISTER Registration of user’s URL • OPTIONS Used to query options and capabilities • INFO Mid call signaling support • PRACK Provisional response acknowledgement • REFER Transfer user to a URL • SUBSCRIBE Request notification of event • NOTIFY Transport of subscribed event notification • MESSAGE Transport of instant message body • UPDATE To update session states. Page 43

  44. SIP Response Codes • 1xx Informational • Request received, continuing to process the request. • 2xx Success • The action was successfully received, understood, and accepted. • 3xx Redirection • Further action needs to be taken in order to complete the request. • 4xx Client Error • The request contains bad syntax or cannot be fulfilled at this server. • 5xx Server Error • The server failed to fulfill an apparently valid request. • 6xx Global Failure • The request cannot be fulfilled at any server. Page 44

  45. SIP Message Headers and Bodies • Requests and Responses consist of multiple headers and values • Common headers present in all requests and responses • From logical call source • To logical call destination • Call-ID globally (time, space) unique call identifier • CSeq request sequence number within a call leg • Via records route of SIP request, for routing the response • Other headers present as needed (many) • Examples: • Contact indicates location of redirection • Record-Route forces routing through a proxy for subsequent requests • Route forces routing for a request through a specified path • Content-Type specifies the Internet media type in message body • Content-Length indicates the number of octets in message body • SDP (Session Description Protocol) • Describes multimedia sessions • Carried as message body in SIP messages Page 45

  46. SIP Functions in IMS • User Agent • Application that sends and receives INVITE • Allocated to User Equipment (UE) • Proxy • Intermediary program that makes requests on behalf of other clients • Allocated to CSCFs • Registrar • Server that accepts REGISTER requests and updates location server • Allocated to S-CSCF • Location Service • Maintaining SIP user’s contact information • Allocated to Home Subscriber Server (HSS) • Authentication and Authorization • Mutual authentication between the user and the network • Allocated to UE, S-CSCF, and Home Subscriber Server (HSS) Page 46

  47. SIP Applications • Setting up Voice-Over-IP calls • Setting up multimedia conferences • Event Notifications (Presence) • Text and general Messaging • Signaling Transport • IPTV? Page 47

  48. 3GPP2 MMD Stage 1 & 2 Documents • Stage 1 and Overview Documents • S.R0037 IP Network Architecture Model for cdma2000 Spread Spectrum Systems • X.S0013-000 IP Multimedia Domain - Overview document • Stage 2 Documents • X.S0013-002 IP Multimedia Subsystem (IMS) (based on TS 23.228) • X.S0013-003 IP Multimedia (IM) session handling; IM call model (based on TS 23.218) • X.S0013-007 Accounting  Architecture (based on TS 32.240) • X.S0013-005 IP Multimedia (IM) Subsystem Cx Interface; Signaling flows and message contents (based on TS 29.228) • X.S0013-010 IP Multimedia Subsystem (IMS) Sh Interface signaling flows and message contents (based on TS 29.328) • X.P0013-012 MMD Service Based Bearer Control Page 48

  49. MMD Documents • Stage 3 Documents • X.S0013-004 IP Multimedia Call Control Protocol based on SIP and SDP; (based on TS 24.229) • X.S0013-006 Cx Interface based on the Diameter protocol; Protocol details (based on TS 29.229) • X.S0013-008 Telecommunications management; Accounting management; Accounting data description for the IMS domain (based on TS 32.260, .298, .299) • X.S0013-011 Sh interface based on the Diameter protocol (based on TS 29.329) • X.P0013-013 MMD Service Based Bearer Control – Stage-3 for Tx Interface • X.P0013-014 MMD Service Based Bearer Control – Stage-3 for Ty Interface • X.P0013-015 IP Multimedia Subsystem; Online Charging System (based on same specs as part 008) • X.P0013-016 Messaging Service • Security Documents • S.R0086-A Multimedia Domain Security Framework (based on TS 33.203) • Access network Specific Documents • X.S0011-D Wireless IP Network Standard. Page 49

  50. Other MMD Documents • X.P0027 Presence • X.P0029 Conferencing • X.R0039 Packet Switched Video Telephony • X.P0042 VoIP/1x interworking (voice call continuity) • X.P0048 SMS over IMS • X.P0049 MMD Emergency Calling. Page 50

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