July 31, 2006 Page 1 3GPP2 MMD Status Jack Nasielski [email protected]

Page 1July 31, 2006

3GPP2 MMD Status

Jack [email protected]

Page 2July 31, 2006

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 3July 31, 2006

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 4July 31, 2006

• 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.

Introduction to IMS (1)

Page 5July 31, 2006

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 6July 31, 2006

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 7July 31, 2006

The IMS Network: Access AgnosticThe IMS Network: Access Agnostic

Residential Cable or DSL Network

Residential Voice

Network

Enterprise IP Network

802.11/802.16 IP Network

Circuit SwitchedMobile Network

Packet SwitchedMobile

Network

IMSApplicationServers

P/S/I-CSCF MediaGateway

HSS

Page 8July 31, 2006

IMS Home Network ConceptIMS Home Network Concept

IP Network

IMS

ApplicationServers

S-CSCFMediaGateway

HSS

• 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 9July 31, 2006

Basic IMS Elements (1)Basic IMS Elements (1)

P-P-CSCFCSCF

P-P-CSCFCSCF

HSSHSSHSSHSS

I-CSCFI-CSCFI-CSCFI-CSCF S-S-CSCFCSCF

S-S-CSCFCSCF

Visited or Home Network

ASASASASASASASASASASASASBackbonePacket

Network

BackbonePacket

Network

AccessAccess

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

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

Home Subscriber Server•Centralized DB•HLR successor•User profile & filter criteria

Application servers (e.g.)•Push-to-talk•Instant messaging•Telephony AS•Other 3rd party AS

Media Resource Function Controller• Controls MRFP (and charging processing)

MRFCMRFCMRFCMRFC

Call Session Control Function

•SIP registration

•SIP session control

Home Network MRFPMRFPMRFPMRFP

Media Resource Function Processor•Tone & Announcement Play back•Conference Bridges

V-V-PCRFPCRF

V-V-PCRFPCRF

H-H-PCRFPCRF

H-H-PCRFPCRF

Page 10July 31, 2006

Basic IMS Elements (2)Basic IMS Elements (2)

Calling Party Visited Network

Calling Party Home Network

UEP-CSCF

HSS

S-CSCF BGCF MGCF

MGW

PSTN/PLMN

H.248

SIP SIP SIP

SIP

ISUP

AS

DIAMETER

BackbonePacket

Network

RAN

RTP Stream

PCM

Breakout Gateway Control Function•Selects network in which PSTN breakout occurs and the appropriate MGCF

Media Gateway Control Function•Translates between session based IP signaling and ISUP for session control.

Media Gateway•Provides an interface between the packet switched core network and the circuit switched PSTN for user traffic.


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


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


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: [email protected]

• 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:[email protected] or tel:+18586514444– (a public user ID may also be shared between private user IDs)

DOCUMENTTYPE

TypeUnitOrDepartmentHereTypeYourNameHere TypeDateHere

Private user identityIM subscription

Public user identity 1 (e.g. SIP URL)

Public user identity 2 (e.g. E.164)

Public user identity 3. . .


Steps in IMS Registration

2. Packet Data Channel Setup for IMS Signaling

3. Outbound SIP Proxy (P-CSCF) Discovery

4. IMS Service Registration/ Subscription for Registration Status

1. Packet Data Service Registration


Control

Bearer

Called PartyVisited Network

Called PartyHome Network

Calling PartyHome Network

Calling Party Visited Network

UE

P-CSCF

HSS

S-CSCFSIP

SIP

Diameter

UE

P-CSCF

AS

HSS

S-CSCF SIP AS

SIP

Diameter

I-CSCF

Diameter

DNS

BackbonePacket

NetworkRAN

BackbonePacket

Network RAN

Initiate SIP Invitation1

1

Retrieve Subscriber Profile (if needed) 2

2

3

3 Apply Service Logic

Retrieve Address of CLD Party Home Networkand Forward INVITE.

4

4

Identify Registrar of CLD Party and Forward INVITE.5

5

Retrieve Subscriber Profile (if needed) 6

6

7

7 Apply Service Logic

Forward INVITE to CLD Party8

8

SDP Negotiation / Resource Reservation Control9

9

RTP Stream

Ringing / Alerting10

10

Answer / Connect11

11

Mobile to Mobile Session Setup

RTP Stream

12

12 Session Active


IMS Security

Visited

HomeHSS

P-CSCF1. REGISTER

I-CSCF1. REGISTER

S-CSCF

1. REGISTER

4. Protection of all further SIP signalling using agreed session key between mobile and P-CSCF

2. Mutual authentication and session key agreement

3. Session key distribution from S to P-CSCF

1. REGISTER & Authentication vector distribution


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)


3GPP/3GPP2 IMS/MMD Differences


IMS in 3GPP/PP2

3GPP GPRSCore Network

3GPP2 Packet DataNetwork

IP MultimediaSubsystem

3GPP RAN 3GPP2 RAN

SGSN GGSN

P-CSCF S-CSCF

PDSN MIP HA

I-CSCF App Svr

RNC Node-B BSC BTS

Core Network

Radio Access Network (RAN)

IP MultimediaSubsystem

P-CSCF S-CSCF

I-CSCF App Svr

Specific to cdma2000Specific to WCDMA

Harmonized between 3GPP and 3GPP2

Notes:

3GPP Network 3GPP2 Network


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


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


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.


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



• 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.



• 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.



• 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.


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)


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


New Projects in 3GPP2 MMD

• Security Enhancements

• Policy Enhancements

• Roaming

• MMD Rev C (under discussion)

• WLAN/HRPD VoIP/VoIP handoffs (current)


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.


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.


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.


Bonus Material


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.


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:[email protected]


Multimedia stack


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)


SIP Trapezoid

CallingUserAgent

CalledUserAgent

OutboundSIP Proxy

InboundSIP Proxy

LocationService

DNSServer

Media Flow

Signaling Flow


Sample SIP Call FlowUser Agent A SIP Proxy A SIP Proxy B User Agent B

INVITE

100 Trying

180 Ringing

ACK

200 OK

BYE

INVITE

INVITE100 Trying

100 Trying

180 Ringing180 Ringing

200 OK200 OK

200 OK

ACKACK

Conversation

BYEBYE

200 OK200 OK


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.


Example INVITE messageINVITE sip:[email protected] SIP/2.0Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7Max-Forwards: 70Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>, <sip:scscf1.home1.net;lr>P-Preferred-Identity: "John Doe" <sip:[email protected]>P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11Privacy: noneFrom: <sip:[email protected]>; tag=171828To: < sip:[email protected] >Call-ID: cb03a0s09a2sdfglkj490333 Cseq: 127 INVITERequire: precondition, sec-agreeProxy-Require: sec-agreeSupported: 100relSecurity-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi=87654321; port1=7531Contact: <sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp>Content-Type: application/sdp Content-Length: (…)v=0o=- 2987933615 2987933615 IN IP6 5555::aaa:bbb:ccc:ddds=-c=IN IP6 5555::aaa:bbb:ccc:ddd t=907165275 0m=video 3400 RTP/AVP 98 99<…SDP parameters skipped…>m=audio 3456 RTP/AVP 97 96 0 15<…More SDP parameters skipped…>


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.


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.


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.


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


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)


SIP Applications

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


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


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.


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.