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ITU-D Regional Development Forum for the EUR and CIS Region: "NGN and Broadband,

Opportunities and Challenges"Chişinău, Moldova; 24-26 August 2009

IP Multimedia systems and IP enabled services

John Visser, P.Eng.

Chairman, ITU-T TSAG

+1 613 276 6096

jvisser@rogers.com

Chişinău, Moldova; 24-26 August 2009

Abstract

Building on the NGN Overview presentation, this presentation will describe the key aspects of the IMS (IP Multimedia Subsystem), examine how it functions and provide some examples of the services and service features supported by this infrastructure.

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Chişinău, Moldova; 24-26 August 2009

Outline

Introduction

Key Aspects: Separation and Models

How the IMS Functions

Services and Features

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Chişinău, Moldova; 24-26 August 2009

Introduction I

What is the IP Multimedia Subsystem?

An architectural framework for delivering IP multimedia services in the 3GPP environment

Part of the 3GPP (and 3GPP2: MMD) vision for evolving mobile networks beyond GSM

Original formulation (Rel-5) an approach to delivering "Internet services" over GPRS

Updated by 3GPP, 3GPP2, TISPAN through including support of other access network technologies, e.g., Wireless LAN, CDMA2000, fixed line, xDSL, etc.

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Chişinău, Moldova; 24-26 August 2009

Introduction II

What is the IP Multimedia Subsystem?

To ease integration with the Internet, uses IETF protocols wherever possible, e.g., SIP

Not intended to standardize applications but rather aid the access of multimedia and voice applications from wireless and wirelineterminals, i.e., convergence of fixed and mobile

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Chişinău, Moldova; 24-26 August 2009

NGN: Separation of Services and Transport

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NGN transport

NGN services

e.g., voice telephony services (audio, fax, etc.)

e.g., Data services (WWW, e-mail, etc.)

e.g., Video services (TV, movie, etc.)

CO-CS, CO-PS and CLPS layer technologies

Rec. Y.2011 General principles and general reference model for Next Generation Networkswww.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Y.2011-200410-I!!PDF-E&type=items

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Chişinău, Moldova; 24-26 August 2009

NGN Basic Reference Model

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User plane

Control plane

Management plane

NGN service stratum

User plane

Control plane

Management plane

NGN transport stratum

Rec. Y.2011 General principles and general reference model for Next Generation Networkswww.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Y.2011-200410-I!!PDF-E&type=items

Chişinău, Moldova; 24-26 August 2009

NGN General Functional Model

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Res

ou

rces

Services

Servicecontrol functions

Transportcontrol functions

Servicemanagement functions

Transportmanagement functions

Infrastructural, application, middleware and baseware services

NGNservice

NGNtransport

Transfer functional area

Resources

Rec. Y.2011 General principles and general reference model for Next Generation Networkswww.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Y.2011-200410-I!!PDF-E&type=items

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Chişinău, Moldova; 24-26 August 2009

Structures:NGN Architecture

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Rec. Y.2012 Functional requirements and architecture of the NGNwww.itu.int/rec/T-REC-Y/recommendation.asp?lang=en&parent=T-REC-Y.2012

Chişinău, Moldova; 24-26 August 2009

Structures:applying NGN Components

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Rec. Y.2012 Functional requirements and architecture of the NGNwww.itu.int/rec/T-REC-Y/recommendation.asp?lang=en&parent=T-REC-Y.2012

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Chişinău, Moldova; 24-26 August 2009

NGN: Relationship of Users,Devices and Locations

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Network

Device mobility domain

User/servicemobility domain

Points of attachment (POA)

Telecommunications objects (mobile with transient binding to POA)

Transient binding (mobile with transient binding to device/service)

Rec. Y.2011 General principles and general reference model for Next Generation Networkswww.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-Y.2011-200410-I!!PDF-E&type=items

Chişinău, Moldova; 24-26 August 2009

Services

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Third Party Provided Applications

Network Operator Provided Applications

Service Enablers and Delivery Platforms (IMS)

Core IP NetworkBasic Services(QoS, mobility, ...)

Public Internet

Applications Accessed via Internet

Any Access Network with Any Device

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Chişinău, Moldova; 24-26 August 2009

3GPP Network Reference Model

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Basic parts of the mobile system:• Core Network (CN)• Access Network (AN: BSS, RNS)• Mobile Station (MS) / User

Equipment (UE)

3GPP TS 23.002 V9.0.0 (2009-06):Figure 1: Basic Configuration of a PLMN supporting CS and PS services (using GPRS) and interfaceswww.3gpp.org/ftp/Specs/archive/23_series/23.002/23002-900.zip

BSS

BSC

RNS

RNC

CN

Node B Node B

IuCS IuPS

Iur

Iub

USIM

ME

MS

Cu

Uu

MSC server SGSN

Gs

GGSN GMSC

server

Gn HSS

(HLR,AuC)

Gr

Gc C

D

E

EIR

F Gf

Gi PSTN

IuCS IuPS

VLR B

Gp

VLR G

BTS BTS

Um

RNC

Abis

SIM

SIM-ME i/f or

MSC server

B

PSTN

cell

CS-MGW CS-MGW

CS-

MGW

Nb

Mc Mc

Nb

PSTN PSTN

Nc

Mc

A Gb

Nc

PDF Go

Gq Go*

CRF Gx

Rx

PCRF

Chişinău, Moldova; 24-26 August 2009

Functional Entities I

Entities common to the PS and CS domain:

• Home Subscriber Server (HSS)

• Home Location Register (HLR)

• Authentication Centre (AuC)

• Visitor Location Register (VLR)

• Equipment Identity Register (EIR)

• SMS Gateway MSC (SMS-GMSC)

• SMS Interworking MSC (SMS-IWMSC)

• Subscription Locator Function (SLF)

• Border Gateway (BG)

Entities of the CS domain:

• Mobile-services Switching Centre (MSC)

• MSC Server

• Circuit Switched - Media Gateway Function (CS-MGW)

• Gateway MSC (GMSC)

• Gateway MSC Server (GMSCServer)

• Interworking Function (IWF)

Entities of the GPRS PS domain:

• Serving GPRS Support Node (SGSN)

• Gateway GPRS Support Node (GGSN)

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Chişinău, Moldova; 24-26 August 2009

Functional Entities II

Entities of the EPC PS Domain:

• MME

• Gateways

• Serving GW

• PDN GW

• SGSN

• Trusted and Untrusted Non-3GPP

• ePDG

• 3GPP AAA Server

• 3GPP AAA Proxy

Access Network (AN) entities:

• Base Station System (BSS)

• Base Station Controller (BSC)

• Base Transceiver Station (BTS)

• Radio Network System (RNS)

• Radio Network Controller (RNC)

• Node B

• Access Network elements for E-UTRAN

• E-UTRAN Node B (eNB)

• Evolved UTRAN

• Mobile Station (MS)

• User Equipment (UE)

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Chişinău, Moldova; 24-26 August 2009

IM Subsystem entities

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3GPP TS 23.002 V9.0.0 (2009-06):Figure 6: Configuration of IM Subsystem entitieswww.3gpp.org/ftp/Specs/archive/23_series/23.002/23002-900.zip

E-CSCF

P-CSCF

S-CSCF MGCF

HSS

Cx

IP Multimedia Networks

IMS-

MGW

CS Network

Mn

Mb

Mg

Mm

MRFP

Mb

Mr

Mb

Legacy mobile

signalling Networks

I-CSCF

Mw

Mw

Gm

BGCF Mj Mi

BGCF

Mk Mk C, D,

Gc, Gr

UE

Mb

Mb

Mb

MRFC

SLF

Dx

Mp

CS

CS

Rx

Mm

LRF

Ml

Le

BGCF

Mi

LCS

Client

Cx

Dx

Sh

Ut

Mw

ISC

IBCF Mx

Mx

Mx

Ma

Dh

TrGW Izi

Ici Ix

Mg

MRB ISC

Cr

Rc

I4

AS

E-SCC AS

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Chişinău, Moldova; 24-26 August 2009

IMS Entities

IP Multimedia (IM) Core Network (CN) Subsystem entities

• Call Session Control Function (CSCF)

• Media Gateway Control Function (MGCF)

• IP Multimedia Subsystem - Media Gateway Function (IMS-MGW)

• Multimedia Resource Function Controller (MRFC)

• Multimedia Resource Function Processor (MRFP)

• Media Resource Broker (MRB)

IP Multimedia (IM) Core Network (CN) Subsystem entities (continued)

• Breakout Gateway Control Function (BGCF)

• Application Server (AS)

• Interconnection Border Control Function (IBCF)

• Transition Gateway (TrGW)

• Location Retrieval Function (LRF)

• Service Centralization and Continuity Application Server (SCC AS)

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Chişinău, Moldova; 24-26 August 2009

How the IMS Functions

SIP is like SS7: signalling to set up calls, between IMS and UMTS

INVITE, OK, ACK, BYE, ACK to initiate and terminate media transmission (greatly simplified!)

All SIP messages are in pairs except ACK

Media do not go through IMS

IMS controls nodes controlling media flows

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Chişinău, Moldova; 24-26 August 2009

How the IMS Functions

Need IP addresses of users’ machines: SIP registrar

Users register with their SIP Proxy/SIP Registrar (DHCP)

Inviting user asks SIP Proxy/Registrar for location of party to be invited

SIP Proxies can relay INVITEs, other messages

Find other SIP Proxies through DNS lookup

More detail?Basic: Wikipedia articlehttp://en.wikipedia.org/wiki/IP_Multimedia_Subsystem

Detailed: IMS Rel-9 Stage 2 Architecture & Info Flows Spec. www.3gpp.org/ftp/Specs/archive/23_series/23.228/23228-900.zip

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Chişinău, Moldova; 24-26 August 2009

Complex?

Yes, but brings added value (other networks, content adaptation, etc.)

Scalability thanks to the potential for replication of IMS elements

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IMS and IP Networks - Simplified

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Services and Features

Services are in application end points, not in IMS

Do not want to standardize all services

Limits competition, slow response to market, etc.

Instead aim to provide an environment able to support may applications. Some features:

Subscribe to friends’ proxies: track their status

Move, initiate new INVITE to send media to new location

Multiple devices: transfer media data to another device where logged in

Call filtering by many criteria

3GPP Stage 1 22.nnn-series specifications are available at:

www.3gpp.org/ftp/Specs/html-info/22-series

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Chişinău, Moldova; 24-26 August 2009

Summary

IMS is an architectural framework for delivering

IP multimedia services in the 3GPP environment

IMS brings internet and UMTS together

Based on strong separations between control/bearer, call/session, application/service

IMS architecture appears complex with a lot of signalling, but brings significant benefits, e.g.,

Ability to handle many types of accesses

Scalability!!

Ability to handle third party service providers

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Chişinău, Moldova; 24-26 August 2009

Acronyms

AIN Acronym Intensive EnvironmentAAA Authentication, Authorization, and

AccountingAIN Acronym Intensive EnvironmentAuC Authentication CentreBG Border GatewayBSC Base Station ControllerBSS Base Station SubsystemBTS Base Transceiver StationCL ConnectionlessCO Connection OrientedCS Circuit-SwitchedCSCF Call Session Control FunctionCS-MGW Circuit Switched - Media Gateway FunctionDHCP Dynamic Host Configuration ProtocolDNS Domain Name SystemEIR Equipment Identity RegistereNB E-UTRAN Node BENUM E.164 Number MappingePDG enhanced Packet Data GatewayGGSN Gateway GPRS Support NodeGMSC Gateway MSCGPRS General Packet Radio ServiceGW GatewayHLR Home Location RegisterHSS Home Subscriber ServerI-CSCF Interrogating-CSCFIMS IP Multimedia Core Network SubsystemIMSI International Mobile Subscriber IdentifierIN Intelligent NetworkIP Internet ProtocolISIM IMS SIM

IWF Interworking FunctionMGCF Media Gateway Control Function MGF Media Gateway FunctionMME Mobility Management EntityMS Mobile StationMSC Mobile-services Switching CentreNAT Network Address TranslationNode B BTS using WCDMANP Number portabilityOSA Open Services ArchitectureP-CSCF Proxy-CSCFPDG Packet Data GatewayPDN Packet Data NetworkPS Packet-SwitchedRAB Radio Access BearerRNC Radio Network ControllerRNS Radio Network SubsystemS-CSCF Serving-CSCFSGSN Serving GPRS Support NodeSGSN Serving GPRS Support NodeSIM Subscriber Identity ModuleSIP Session Initiation ProtocolSLF Subscription Locator FunctionSMS-GMSC SMS Gateway MSCSMS-IWMSC SMS Interworking MSCSSF Service Switching FunctionUE User EquipmentUMTS Universal Mobile Telecoms SystemURL Universal Resource LocatorUSIM UMTS SIMUTRAN UMTS Terrestrial Radio Access NetworkVLR Visitor Location Register

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