Service Delivery Platforms for Fixed Mobile Convergence · PDF fileService Delivery Platforms for Fixed Mobile Convergence (FMC)-An Overview of the ETSI TISPAN NGN and the ... IMS

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T. Magedanz (TU Berlin / Fraunhofer FOKUS) - 2006

Prof. Dr. Thomas Magedanz

Technical University of Berlin / Fraunhofer FOKUS

([email protected])

Service Delivery Platforms for Fixed Mobile Convergence (FMC)

- An Overview of the ETSI TISPAN NGN and theIP Multimedia Subsystem (IMS)

Tutorial @ SATNAC, Stellenbosch, South Africa, September 4th, 2006

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Abstract

This tutorial provides a technical overview of the architecture,components and protocols of the emerging ETSI TISPAN Next Generation Network (NGN) and the 3GPP IP Multimedia Subsystem (IMS) / 3 GPP2 Multimedia Domain (MMD) which provides the technological basis for the provision of seamless IP based multimedia services on top of converging networks. This tutorial looks at the driving forces for the NGN / IMS architecture definition, introduces the key signalling and control protocols of all IP networks (i.e., SIP and Diameter) forming the basis for NGN/IMS component interactions, and explains the key NGN/IMS elements and their interactions.Special attention will be given to the NGN/IMS application server options, namely CAMEL, OSA/Parlay and SIP AS.The tutorial ends with an overview of the FOKUS IMS play ground (www.fokus.fraunhofer.de/ims).

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The Presenter

Prof. Dr. Thomas MagedanzThomas Magedanz (PhD) is professor in the electrical engineeringand computer sciences faculty at the Technical University of Berlin, Germany, leading the chair for next generation networks (Architektur der Vermittlungsknoten – AV). In addition, he is director of the “3G beyond” division at the Fraunhofer Institute FOKUS, which also provides the national 3G beyond test and development centre in Germany. He is senior member of the IEEE, editorial board member of several journals, and the author of more than 120 technical papers/articles. He is the author of two books on IN standards and IN evolution. Based on his 15 years of experience in the teaching complex IT and telecommunication technologies to different customer segments inan easy to digest way, Dr. Thomas Magedanz is a globally recognised technology coach. He regularly provides strategic andtechnology briefings for major operators and telecom vendors, aswell he acts often as invited tutorial speaker at major telecom conferences and workshops around the world.

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Contact

Prof. Dr.-Ing. habil Thomas Magedanz

TUB Chair Next Generation Networks / Director FOKUS 3Gb Division

[email protected]+49 171 172 70 70+49 30 3463 7229 Kaiserin Augusta-Allee 31

14513 Berlin, Germany

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Overview

• Market Drivers for FMC• NGN and related Standard Bodies• The IMS as universal SDP• IMS Core Layer• IMS Applications Layer• IMS Introduction Strategies and Deployment Issues• The FOKUS Open IMS Playground as market driven NGN R&D Testbed• Q&A

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Evolution towards Converged Networks

ConvergedNGN

HomeNetworks

CableNetworks

FixedNetworks

PSTN

ISDN

DSL

FMCGSM

MobileNetworks

AnalogueGPRS UMTS HSDPA

UMA

WiFi WiMax

Internet

FTP email WWWIMP2P

PortalsIPTVVoIP

SMS WAP

TriplePlay

Web2.0

ContentSharing

VoD

Broadcast

iTV

IT

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Convergence of Networks, Services, Applications

MobileNetwork

FixedNetwork

HomeNetworkEnterprise

Network

Fixed MobileConvergence

Mobile Enterprise Home Entertainment

Business

Connection

(IP Centre

x)

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Fixed Mobile Convergence

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The traditional Telco Value Chain is changing

The industry structure changes. New players have successfully entered thescene. Equipment and handset manufacturers additionally drive the market.

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Triple Play brings new Players in the Market

• Among traditional networkoperators (CATV / Telco) newplayers (i.e. equipmentmanufacturers and serviceproviders) have joined the racefor multimedia / triple playrevenues.

• Purpose of value creation aroundbasic communication services ismostly to maintaincompetitiveness and profitability

• Increasing competitive pressuredrives the transformation of theTelco industry.

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Time

Revenue

Community Support is one of the most

promising solutions to boost profits in NGNs

Declining voice

revenues

Looking for new NGN applications

Voice over IP (VoIP) IP CentrexMessaging/

PresenceHome

EntertainmentMultimedia Conference

…

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War is not on networks, it is on services !

• Network access becomes a commodity

• „Always on“ is getting real• Market entry barriers for services vanish

• Content and Services as overlay

• Value Chain splits horizontally• Clear & present threats for operators

• losing VAS revenues

• losing subscriber ownership

• losing control over the Mobile Value Chain

?

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Pre-FMC = 3GPP Virtual Home Environment

Virtual Home Environment: VHESystem Concept forPersonalized Service

portability across Network and Terminals boundaries

portabilityacross terminal

boundaries

portabilityacross network

boundaries

Call Forwarding: 08:00-18:00 -> ..18:00-08:00 -> ..

Lotto by WAPFootball by VRestaurantxx

Personal ServiceEnvironment

Xxzz

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IP domainCircuit-Switched domain

TraditionalCS

Co-existence All IPWorld

UniformService Delivery Platform

Network Convergence

Seamless Services Data ServicesVoice Services

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Overview


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Multi-Service, Multi-Access networks

All IP

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Internet Control vs. Telecommunications Control

CentralControl

USER USER

CentralControl

CentralControl

SW SW SWSW SW SW

UNI NNI NNI UNI

ITU Intelligent Network Control: POTS, ISDN, BISDN, FR, ATM, H.323, MEGACO/H.248, GSM

Services supported by interfaces and central controllers

User has little control

USER USER

ElectiveServer

ElectiveServer

Internet

“Dumb Network”

R

R

R

User has control of all applications and choice of servers

All services enabled by protocols: From ftp to web

No single point of failure

R

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Next Generation Network 3 Tier Architecture

• Enhanced services for the next generation network will be enabled by a tiered architecture where “Application Servers” will provide an independent service layer for the execution of enhanced services and content

• Session / Call Control based on advanced signaling protocols (i.e. SIP) is performed in Softswitches, or “Session Servers”

• Transport of signaling and content (incl. Voice) data will be done by Routers in the classical IP fashion. Dedicated nodes, i.e. “Media Gateways” and “Media Servers” are in charge for processing content data controlled by the Call Servers.

SessionServers

Media ServersRouters

ApplicationServer

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Next Generation All IP Reference Architecture

SessionControl

Function

SessionControl

Function

ApplicationServer

Function

MediaGatewayFunction

SIP SIP

SignalingGatewayFunction

•Basic call control•Signaling•Resource Management•CDR Generation

•IVR•Conferencing•Facsimile•Speech Recognition•Text-to-Speech

•Service Execution•Service Management•Service Creation

Bearer dataTransfer

SS7/IP SignalingConversion

SIP

SIP

SubscriptionServer

Function

DiameterDiameter

AAA: User and Appl Profiles

Connection / call control functions

Application control functions

SIP

RTP MediaServer

Function

SIP

Note that there are many other IETF protocols used as well, e.g. SDP, Megaco, SCTP, RTCP, MSRP, XCAP, etc.

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The NGN Definition

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NGN Global standards cooperation

Internet Engineering Task ForceInternet Engineering Task ForceDefines SIP, SDP and other protocols underlying IMS

IMS is driving some of the work in IETF

3rd Generation Partnership Project3rd Generation Partnership Project3rd Generation Partnership Project23rd Generation Partnership Project2Define IMS network elements and infrastructure

Harmonization effort has kept definitions as similar as possible

Open Mobile AllianceOpen Mobile AllianceDefining IMS services, e.g. Instant Messaging, Push-to-TalkNot strictly mobile oriented, driving wireline services also

The Parlay GroupThe Parlay GroupIntegral to IMS architecture, define standard API frameworks

American National Standards InstituteAmerican National Standards InstituteT1.679 covers interworking between ANSI ISUP and SIP

International Telecommunication UnionInternational Telecommunication UnionQ.1912.SIP covers interworking between ITU-T ISUP and SIP

H.248 for media control

ToolsTools

Services

Services

LegacyLegacy

TISPA

N

TISPA

N –– ETS

I bo

dy o

n N

ext G

en

eratio

n N

etw

ork

ETSI b

od

y o

n N

ext G

en

eratio

n N

etw

ork

Ag

ree

me

nt o

n re

use

of 3

GP

P/3

GP

P2

IMS

in co

mp

reh

en

sive

NG

N p

lan

s

Allia

nce fo

r Teleco

mm

un

icatio

ns In

du

stry So

lutio

ns

Allia

nce fo

r Teleco

mm

un

icatio

ns In

du

stry So

lutio

ns

Ne

arin

g a

gre

em

en

t to u

se 3

GP

P/3

GP

P2

IMS

CJK

Ch

ina Ja

pan

Ko

rea

CJK

Ch

ina Ja

pan

Ko

rea

Sta

rting

Focu

s Gro

up

on

NG

N

ITUITU

-- T NG

N Fo

cus G

rou

pT N

GN

Focu

s Gro

up

Lev

era

gin

g IM

S in

wire

line

Wireline &Wireline &

ConvergedConverged

NGN NGN

Architectures

Architectures

Archite

cture

Archite

cture

Wireless

Driven

Wireless

Driven

Building the NGN through Cooperation between many Standards players (incl. DSL, MSF, TMF …): leading to convergence

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3GPP IP Multimedia Subsystem (IMS)• The IMS was originally standardised by 3GPP as part of UMTS Release 5

– Basic VoIP, IM, Presence support on top of GPRS– Adaptations to “real word” have been made in Release 6 (QoS, PoC support)– Release 7 will look at unified IMS for all IP access networks (DSL, WLAN, etc.)

• The IMS is based on the IP world protocols, namely – SIP (Session Initiation Protocol) for Session Control, and – Diameter for AAA (Authentication, Authorisation & Accounting)– plus many others, i.e. SDP, RTP, RTCP, MGCP, etc.

• Key components of the IMS architecture are– Extended AAA Server (Home Subscriber System – as evolution of the HLR)– SIP servers / soft switches– Media Servers & Media Gateways– and Application Servers

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IMS 3GPP Evolution

• IMS brainstroming started in Release 4, without real specs.• IMS Release 5 is the first complete specification of IMS finished in

2003 (but based on some unrealistic assumptions;-( )• Key features of IMS Release 5:

– IMS Architecture: IMS Architecture, network entities, reference points (interfaces) between the network entities.

– User Identities: Public/Private User Identity, usage of the SIP-URI and TEL-URI, ISIM, the use of the USIM instead of the ISIM.

– IMS Session Control: IMS Registration, IMS Session Routing, Session-Modification and Teardown, SIP Signaling Compression.

– IMS Service Control: invocation/control of IMS Application Servers based on Filter Criteria in the CSCF. IM-SSF and there-use of CAMEL Services. Interconnect with the OSA-GW and the use of OSA services.

– QoS Mechanisms: QoS Preconditions, QoS/Media Authorization based on the PDF.

– Security Mechanisms: IMS User Authentication, Message Integrity Protection, IMS Network Domain Security.

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IMS 3GPP Release 6

• Release 6 adapted IMS to the real world (i.e. lack of IMS SIM cards, IPv6 deployment, competing PoC standards), etc.) and was finished end of 2005

• Key Features defined in Rel-6 IMS:– IMS Interworking: IMS Interworking to the CS-Domain (more details for CS and

PSTN), Interworking with SIP Clients in the Internet (IPv4/v6 Interworking), WLAN access to the IMS (not completed)

– IMS Session Control: multiple registrations, routing of group identities.– Security Mechanisms: confidentiality protection of SIP messages, use of public

key infrastructure, Ut-interface security, early IMS security– IMS Services: Presence, Instant Messaging, Conferencing, group management.

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S-CSCF

IMS Layers: Transport, Session Control, Apps

P-CSCF S-CSCF

HSS(AAA)

I-CSCF

MediaGateway

SGW, MGCF, MGF

ApplicationServer IMS enabler

Group Mgt

Access Networks(WLAN, UMTS, DSL)

PDF

Interworking withLegacy Networks(GSM, ISDN, DVB)Underlying IP Core Network

IMS Core System

IMS Service Framework

MediaServer

MFRC + MFRP

IMS enablerPresence

Note: IMS Charging Architecture is not reflected on this slides = Diameter Interfaces to many entities

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IMS Major Components

• The IMS is an Overlay Session/Service Control architecture on top of the packet domain (GPRS, UMTS, WLAN, DSL) based on IP technologies and IETF protocols(e.g. SIP, Diameter):

– IMS Core• S-CSCF (Serving Call Session Control Function) the IS anker point in the home

network• I-CSCF (Interrogating Call Session Control Function) providing topology hiding• P-CSCF (Proxy Call Session Control Function) Entrypoint into IMS world• MS (Media Server) – Media Server hosting special resources• MGF (Media Gateway) for Interworking with legacy networks• PDF (Policy Decision Function) for QoS Control using Polícies (COPS)

– IMS Application Layer• HSS (Home Subscriber System) for maintaining subscriber and AS profiles• AS (Application Server Function) for hosting applications• IMS enablers (e.g. Presence, Group Mgt.) are specific ASs with generic functions

– And the IMS end system (IMS Client) plays an important role real multimedia / IMS services

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3GPP2 Multimedia Domain (MMD)• 3GPP2 MMD is a reference architecture model for cdma2000 family

based wireless core network• Main specifications:

- “All-IP Core Network Multimedia Domain: Overview”– http://3gpp2.org/Public_html/specs/X.S0013-000-0_v1.0_022604.pdf

- “IP Network Architecture Model for cdma2000 Spread Spectrum Systems”http://3gpp2.org/Public_html/specs/S.R0037-– http://3gpp2.org/Public_html/specs/S.R0037-0_v3.0_111303.pdf

• based on IP protocols, elements and principles• Main protocols are (IETF’s) SIP, DIAMETER and Mobile IP• Consists of:

– Packet Data Subsystem (PDS): supports general packet data service– IP Multimedia Subsystem (IMS): provides multimedia session capabilities

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MS

AccessNetwork

PDS

IMS

PSTN

Internet

MMD Core Network Architecture Model

IMS&PDS

AS

CSCF

PDF

MRFCMGCF

MRFPIM-MGW

AAA

DB‘s

AccessGateway

MIP HABorderRouter

BearerSignaling

Signaling&Bearer

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3GPP2 vs. 3GPP

Through a Position Server and Position Determining Entity (PDE)

Through Sh interfaceLocation information

Not defined yetDefined between PDF & GGSNGo interface May change even during a sessionAllocated prior to registration Anchored GGSN/PDSN

P-CSCF and PDSN (Packet Data Service Node == GGSN) may be in different network

P-CSCF and GGSN are in the same network

P-CSCF location

Configuration and security stored in the IMS terminal or in R-UIM (Removable User Identity Module)

Defined a UCC (USIM or ISIM)Smart card

Not defined, since there is no CAMELBetween HSS and IM-SSF (CAMEL)Si interface

No support of PDP contextThrough PDP context activation and DHCP

P-CSCF discoveryEVRC and SMVAMRSpeech codec

Database only, separated AAADatabase and AAAHSSIPv6IPv4 and IPv6IP versionMobile IPGPRS tunnelingMobility management

3GPP23GPPFeature

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ETSI TISPAN

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Target NGN

NGN Infrastructure Evolution (CS PS)

PSTNPSTNEmulationSubsystem

PSTNSimulation

Full PSTN Feature Transparency=> Secondary NGN objective

SIP (IMS) Services & Architecture=> Primary NGN objective

IMS“SIP” services

Evolution to NGN

“Perfect Simulation”

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ETSI TISPAN NGN Releases

Release 1: A tough Job under significant market pressure

• Release 1 bringing Multimedia services0 Terminology, Strategy, QoS, Security, NNA & Identification, ENUM1 Requirements, General architecture, Early services and protocols2 Detailed architecture, Specific services and protocols, 3GPP interface endorsements, testing 3 Operations Support Systems, Congestion control, NGN user data, Single sign-on, PSTN/ISDN

emulation• Release 2 optimizing access resources usage

– According to user subscription profile and service use– Corporate users specific requirements …

• Release 3– Full mobility, Streaming Subsystem, TV Broadcasting Subsystem?

2006

Release 3

2007 2008

Release 1 Release 2

200920052004 2010

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TISPAN NGN Functional Entities

R e so u rc e a n d A d m issio n C o n tro l F u nc tio ns

R A C F

N etw o rk A c c e ssA tta c h m e n t F u n ctio n s

N A A F

O th er M ultim ed ia C o m p o n e n ts …

S trea m in g S e rv ic es

A p p lica t io n F u n c tio n s

C o re tra n sp o rt F u n c tio n s

A c c e ss T ra n sp o rt F u n c tio n s

N G N T e rm in a ls

C u sto m e rN e tw o rk s

U se rP ro file

F u n ctio n s

Other N

etworks

L e g a c yT e rm in a ls

G W

P S T N / IS D N E m u la tio n

IP M u ltim e d ia C o m p o n e n t

N N IT r a n sp o r t S tra tu m

S er v ic e S tra tu m

U N I

E d ge F u n c tio n s

A c c e ss F u n c tio ns

S e rv ic e an d

C o n tro l F u n c tio n s

C u s to m er a n d T e rm in a l F u n c tio n s

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Overall TISPAN NGN Architecture

NGN as a modular system for independance of subsystems evolution• Transfer Functions• Network Attachment Subsystem (NASS)• Resource Admission and COntrol Subsystem (RACS)• PSTN / ISDN Emulation Subsystem (PES) • IP Multimedia Subsystem (IMS)• NGN Common Functions• Applications (out of scope)

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RACS in a Nushell

• QoS handling: checks resource availability and allocates resources• Has no service knowledge, only session knowledge• Provides admission control and gate control functionalities (including the

control of Media Gateways, Access Gateways, NATs and Firewalls)• Interface to transport layer

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NASS in a Nutshell

• NASS Target: Hide access technology from control structure• Dynamic provision of IP addresses, authentication, authorization of network

access and access network configuration• Location information, location management and user privacy preferences

(e.g. for emergency services)

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IMS Architecture in the NGN settingO

ther IP Netw

orks

IP Transport (Access and Core)

T-MGF

I-BGF

AS

UPSF

P-CSCF

I/S-CSCF

BGCF

SLF

ChargingFunct ions

IWF

« Core IM S »

M w

M w /M k/M m

M r

M g

M j

M i

M p M nGm

Gq

ISCCx Dx

DhSh

Ic

Rf /Ro

Rf /RoIb

Ia

Id

PSTN/ISD

N

SGFMRFC MGCF

MRFP

Resource and Adm ission Con t rol Subsyst em

Network Attachment Subsystem

If

Ie

M wIBCF

M k

M k

UE

Ut

NetworkInterconnections

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TISPAN PES - Functional Architecture

Other IP N

etworks

IP Transport (Access and Core)

T-MGF

I-BGF

UPSF

BGCF

ChargingFunct ions

IWFIMS-based PES

Mw

Mx

Mr

MgMj

Mi

Mp Mn

Gm

Gq'

ISC/MaCx Dx

DhSh

Ic

Rf/Ro

Rf/Ro

Ib

Iw

Gq'

PSTN/ISD

N

SGFMRFC MGCF

MRFP

Resource and Admission Control Subsystem

Ie

Mw IBCFMx

Mk

Other types of service logic

PSTN/ISDN Emulation logic

Application ServersRf/Ro

MG

ZZ

ZZ

AGCF

Gq'

P1Mw

P3

Ut

Ut

Network Attachment Subsystem

e2e2

MxP-CSCF

VGW

Ut

I/S-CSCF

SLF

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3GPP R6 and TISPAN R1 NGN: R6 comparison

• Network Attachment System– 3GPP: GPRS entities + HLR (PS part)– TISPAN: NASS entities

• Resource Admission Control– 3GPP: PDF and GGSN– TISPAN: RACS entities +

RCEF and BGF entities

• MM Session Control– 3GPP: IMS (R6)– TISPAN (R1) IMS (R6)

• TISPAN Documentation:– http://portal.etsi.org/docbox/tispan/Open/NGN-R1/Stable_Drafts/

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Overview


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100%

1st ServicePOC

100%

Serv

ice

Infr

astr

uctu

re

2nd ServiceSe

rvic

eIn

fras

truc

ture

example

Vertical Solutions

SDP Infrastructure Economics

1st ServicePOC

60%

40%

• Horizontal solution can reuse infrastructure for more services to come• About 50% CAPEX Savings from 2nd service on• Carrier grade scalability of the infrastructure provided by “IMS”??

Serv

ice

Infr

astr

uctu

re

2nd Service

10%

40%

Serv

ice

Infr

astr

uctu

re

example

Horizontal Solution

Cost Savings

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AAAServer

Evolution of Service Delivery Platforms

Web/ApplicationServer

IN / CAMEL Services

ApplicationServer

OSA / Parlay Interface

INAP/CAPInterface

OSA/Parlay/JAIN Gateway

IN Platform

StoredProgram Control

Services

Parlay X

PSTNGSMGPRS/UMTSVoIP

SIP App.Server

= Services

MultimediaServices

SIP

3rd PartyApplication

Services(Enterprises / Content)

Diameter

SIP Server

NGN / IMS

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NGN / IMS Idea: Try to get Control of IP Services

The IP network allows free communication between endpointsNGNB / IMS tries to control services on an IP networkIt is a trial to provide a better Internet!

A B

Server

IP

A B

Server

Controlby

IMS

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IMS Architecture Principles

• Horizontal Architecture defining a dock for applications

• Defines service enabler capabilities• Build on existing IETF and telco SDP

standards• Provides compared to standard

internet• Better security, Service based QoS,

flexible charging and single sign onGGSNSGSN

ArchitectureArchitecture

Presence

Apps

GLMS

RAN

HSS IMS

• IMS does NOT standardise specific services, but enablers• BUT supports inherently multimedia over IP, VoIP, IM, presence (SIP)• IMS enables the flexibility in providing IP-based applications !!

Network

IMSand

Service Enablers

Applications

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Infrastructure Functionality

GGSNSGSN

ArchitectureArchitecture

Presence

PoC

GLMS

RAN

HSS IMS

Network

IMSand

Enabling Services

Applications

• Implementing generic functionality in the infrastructure is mosteconomical !!

SIP Session-/Service Control Single-Sign-On User-AuthenticationSubscription Handling QoS/Media AuthorizationSignaling CompressionCharging Support and CorrelationRouting/Addressing Support Regulatory Service Support (e.g. LI) PresenceGroup List ManagementConferencing SupportPSTN Interworking SupportCS-Roaming Support… and more

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IMS enabling Control of GPRS / IP servicesIMS Core Idea: - Define an IP Multimedia Overlay-Network over GPRS (for Session control

based on Internet protocols!)- Data (Media) transport (as well as signaling transport) via GPRS- Provide control (QoS, security, Charging) for IP services and person-to-

person communication

Circuit Switched Net (GSM)

Packet Net (GPRS)

IP MultimediaSystem (IMS)Signalling (SIP)

Transport (RTP)

Note that IMS is for fixed networks applicable too

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IMS Motivation – Flexible Service ProvisionProvision of service enablers- Presence and Group server are considered key for the future- Example: Push to Talk, but more generally community services

Packet Net (GPRS)

IP MultimediaSystem (IMS)Signalling (SIP)

Transport (RTP)

Call / Session ServerPresence ServerMessaging Server

Application Server

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Overview


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IMS

UTRAN

SGSN GGSNUE

PS Domain

IMS ArchitectureI-CSCF

Go Gi

I-CSCF

P-CSCF S-CSCFMw

HSS

Cx

Cx

Other IP/IMS networks

Mm

The PS domain provides the IP bearer to access to the IMS, i.e.

a PDP context.

The HSS holds the IMS service profile of the subscribers.

S-CSCF interconnects to externalIP networks and other IMS networks.If THIG is used by the operator to hide its internal configuration, the connection to external networks goes through an I-CSCF.

Gi

Traffic PlaneControl Plane

CSCFs are the IMS entities responsible of the call control: there are 3 types of CSCFs depending on their role:• P-CSCF (Proxy CSCF)• S-CSCF (Serving CSCF)• I-CSCF (Interrogating CSCF)

50


IMS

UTRAN

SGSN GGSNUE

PS Domain

IMS Architecture (cont.)I-CSCF

Go Gi

I-CSCF

P-CSCF S-CSCFMw

HSS

Cx

Cx

Other IP/IMS network

Mm

SGWMGCF

BGCF

IMS-MGW

Legacy/PSTN

Mk

Mi

Mg

Mj

MnGi

MRF

Gi

Mr

PDFGo

Gq Those entities are responsible for

interworking betweenIMS and CS

domain/PSTN

In Release 6, the PDF can be separated fromthe P-CSCF. Those twoentities are thenconnected through the Gq interface.

The MRF is usedfor multiparty call

control

Traffic PlaneControl Plane

AS AS are connected via ISC interface (extended

SIP) to S-CSF

ISC

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User Equipment (UE)

• Contains the SIP user agent• Establishes a GPRS PDP context for

– Signaling (either dedicated or a general one)– Media transport

• Contains ISIM for authentication– Public and private user id– User Network address– Security algorithms and keys– At least a USIM

• Correlate between session control and QoS reservation

52


Call State Control Function (CSCF)

• Call State Control Function (CSCF)- Call set-up/termination and state/event management

- Address Analysis, translation, modification if required, addressportability, mapping of alias addresses

- provide service trigger mechanisms (service capabilities features) towards Application & services network (VHE/OSA)

- Interacts with HSS in the home domain to receive profile information for the user and

- Interact with MRF in order to support multi-party and other services

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Proxy Call Session Control Function (P-CSCF)

• First contact point for the UE (outbound proxy)– Forward registration to I-CSCF– Forward requests to S-CSCF (or I-CSCF)– Forward replies and incoming requests to UE

• Maintain security association with UE• Responsible for compression• Correlation between SIP and QoS• Enforce local policies• Possibly support routing to local service infrastructure

– Emergency call handling• Discovered through DHCP or during GPRS PDP establishment

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Interrogating CSCF (I-CSCF)

• Contact point within an operator– Discovered through DNS

• Assign S-CSCF to a user by contacting the HSS• May act as a THIG (Topology Hiding Inter-Network Gateway)

– Always on the path (RR and Service-Route) of any messageleaving the network

– Encrypt all entries added by the hiding network in outgoing messages

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Serving Call Session Control Function (S-CSCF)

• Acts as a registrar• Acts as a SIP proxy (forward messages ..)• Allocated to a user during registration• Always on the path of the user‘s SIP messages (use Service-Route

and RR)• Enforces service policies based on the user‘s subscription profile• Collects session information for billing• Interacts with application service platform• Acts as user agent when required (Notifications about de-

registrations and re-authentications, call termination)

56


Home Subscription Server (HSS)

• Contains user profile information indicating– Private and public identities of the user– Authentication information– Which services and medias the user is eligible for using– Filtering criteria for choosing appropriate AS

• Assist I-CSCF in choosing the appropriate S-CSCF• Maintain subscription information about the user• Enforce provider policies• Connected through Cx interface to S-CSCF and I-CSCF (DIAMETER)• Connected also to AS

– Provide user service information• Allow multiple instances by using SLF (Subscription Location

Function)

Page 29

57


Application Server (AS)

• Services include third party CC, personalized routing ....

• Services are offered by home, visited or third party provider

• S-CSCF forwards requests to AS base (possible received from HSS)

• Results of AS sent back to S-CSCF• AS can act as UA, redirect or proxy• CAMEL and OSA optional

S-CSCF

AS

ISC

1

2 3

4

58


Breakout Gateway Control Function (BGCF)

• Select PSTN/CS domain to forward call to– If the BGCF determines that the breakout is to occur in the same network

in which the BGCF is located within, then the BGCF shall select a MGCF which will be responsible for the interworking with the PSTN/CS Domain.

– If the break out is in another network, the BGCF will forward this session signalling to another BGCF in the selected network.

• How to choose an MGCF is not specified– Configuration– TRIP or similar

Page 30

59


Media Gateway Control Function (MGCF)

• Gateway to PSTN networks- Performs protocol conversion between the Legacy (e.g. ISUP,

R1/R2 etc.) and the IM domain call control protocols.

- Controls the parts of the call state that pertain to connection control for media channels in a MGW.

- MGCF selects the CSCF depending on the routing number for incoming calls from legacy networks.

– Establish bearer with appropriate code– Possibly translate codec– Act as UA (but no registration required)

60


Media Gateway Function (MGW)

• Media Gateway Function (MGW)

– This component is PSTN/PLMN transport termination point for a defined network and interfaces UTRAN with the core network over Iu.

– A MGW may terminate bearer channels from a switched circuit network and media streams from a packet network (e.g., RTP streams in an IP network). Over Iu MGW may support media conversion, bearer control and payload processing (e.g. codec, echo canceller, conference bridge).

- Interacts with MGCF, MSC server and GMSC server for resource control.

- Owns and handles resources such as codecs, echo cancellers etc.

Page 31

61


Media Resource Function (MRF)

• Provide conferencing and announcement services

• Multimedia Resource Control Function (MRFC)– Interpret information from S-CSCF and AS

•Conference booking and floor control from AS for example

– Control MRPF• Multimedia Resource Processor Function (MRPF)

– Establish bearers based on MRFC requests– Media mixing and distribution– Media streaming for announcements

• Use H.248 (MEGACO) between the two components

MRFC

MRFP

SIP

H.248

Media

62


IMS Application Layer Gateway (ALG)

• This component is defined for interworking between IPv4 and IPv6• The IMS ALG provides the necessary application function for the

SIP/SDP protocol stack in order to establish communication between IPv6 and IPv4 SIP applications.– The IMS ALG receives an incoming SIP message from CSCF nodes or

from an external IPv4 SIP network. – It then changes the appropriate SIP/SDP parameters, translating the IPv6

addresses to IPv4 addresses and vice versa. – The IMS ALG needs to modify the SIP message bodies and headers that

have IP address association indicated. – The IMS ALG will request NA(P)T-PT to provide the bindings data between

the different IP addresses (IPv6 to IPv4 and vice versa) upon session initiation, and will release the bindings at session release.

• Note: In contrast to NAPT, which are mapping IPv4/v6 applicationindependent, an ALG operates applications specific, here SIP/IMSspecific.

Page 32

63


IMS Border Control Concepts (Rel 7)• Based on operator preference, border control functions may be applied between

– two IM Core Network subsystem networks or – between an IM CN subsystem network and other SIP based multimedia network.

• These BC functions include:– Controlling transport plane functions;– Supporting functions to allow establishing communication between disparate

address realms' SIP applications;– Providing network configuration hiding to restrict the following information from

being passed outside of an operator's network: exact number of S-CSCFs, capabilities of S-CSCFs, or capacity of the network, etc;

– Screening SIP signalling information based on source/destination and operator policy (e.g. remove information that is of local significance to an operator);

– Generation of CDRs;– Selecting the appropriate signalling interconnect.

• In case border control concepts are to be applied in an IMS network, the IBCF acts as an entry point for this network (instead of the I-CSCF), and also acts as an exit point for this network.

– In this case the IBCF and I-CSCF may be co-located as a single physical node.

64


SIP Signaling in IMS – The three SIP Servers

P-CSCF

I-CSCF

S-CSCF

REG REG REG

200 OK 200 OK 200 OK

Visited network Home network

P-CSCF - Proxy CSCF. The terminals point of contact to the IMS (in the visited network). Point where IMS interacts with bearer network for QoS.

I-CSCF - Interrogating-CSCF. Responsible for finding the right S-CSCF at registration. May also perform hiding of the S-CSCF network architecture.

S-CSCF - Serving-CSCF. Anker point for IMS subscribers. Performs authentication, registration and provides access for any application servers for that subscriber. Remains in all IMS signaling for that subscriber

Page 33

65


Principle of IMS as GPRS Overlay

S-CSCF I-CSCF

GGSNSGSN P-CSCFUTRAN

SIP signalling

User data

„Home“IMS Network

„Visited“Domain

Note: Depending on GPRS Roaming Architecture and GGSN Location„P-CSCF“ may be in Visited or Home Network

66


IMS-Session: Home Networks are always involved

IP backbone

Access

Caller

Access

CalledValue added

services

Home

ISC

S-CSCF

Bearer Servicesoriented

WireLine


WLan

Home

ISC

S-CSCF


WireLine

TA?

WLan

FW?TA?GPRS

Value addedservices

UTRANFW?

TA?UTRANGPRS

Video/Audio/Signaling Video/Audio/Signaling

signaling signaling

Page 34

67


IMS: Separation of Signaling and Media transport

A’s visited networkUser A

User B

B’s visited network

A’s home network

B’s home network

Optional

Required onregistration,optional on

session establish


session establish

GPRS

mobile to mobile session

P-CSCF

P-CSCF

I-CSCF

I-CSCFI-CSCF

I-CSCF

S-CSCF

S-CSCFValue added

services

Value addedservices

IMS

GPRS

IMS

GPRS

GGSN

GGSN

68


IMS: Separation of Signaling and Media transport

A’s visited networkUser A

User B

B’s visited network

A’s home network

B’s home network

Optional


session establish


session establish

GPRS

mobile to mobile session

P-CSCF

P-CSCF

I-CSCF

I-CSCFI-CSCF

I-CSCF

S-CSCF

S-CSCFValue added

services

Value addedservices

SGSN

SGSN

IMS

IMS

GPRS

GGSN

GGSN

Page 35

69


IMS User Identity ConceptEach IMS User has at least one private and one or more public User Identities

• IMS Private User Identity:– belongs to the IMS operator– is not used for routing of SIP messages– uses the format defined in RFC 2486

• Example: [email protected]“– is stored on the ISIM card (in the mobile phone) and in the HSS (in the IMS User

Profile)

• IMS Public User Identity:– is public and may be subject to Number Portability– is used for routing of SIP messages– may use the SIP-URI format defined in RFC 3261 and/or the TEL-URI format defined

in RFC 2806• Example SIP-URI: “sip:[email protected]“• Example TEL-URI: “tel:+491231234567”

– At least one Public User Identity is stored on the ISIM card– All Public User Identities are stored in the HSS

70


Relationship between Private d Public UID

• One Private UID may be mapped to several Public UIDs• One Public UID may be shared by several Private UID within (!) one

subscription

Private User Identity-1

Private User Identity-2

Public User Identity-1



Service Profile - 1

Service Profile - 2

IMS Subscription

Page 36

71


Public Service Identities (PSIs)

• Similar to public user identities, but allocated to services (ASs) ratherthan users

• Used to identify specific applications Servers (enablers), such as presence or group list servers

• Typically take the form of a SIP URI or TEL URI– sip: [email protected], [email protected], [email protected]– tel: +49-900-123-456

• PSIs are treated as PUIs, i.e. easy routing of SIP requests to ASs (as end user systems also called „service routing“

• Public Service Identities are not authenticated– i.e., there is no corresponding private user (service) identity

72


How the IMS differs from RFC 3261 SIP Servers• The IMS was designed based on RFC 3261 (the CSCF is basically also a SIP Server)

… but includes much more!• Additional functions were added to the IMS:

– Subscriber Management, Service Control, Single-Sign-On User Authentication, – QoS/Media Authorization, Charging and Charging Correlation, – Resource Management, Interworking, Compression, Conferencing Support, Regulatory – Service Support, etc.

• Most of the IMS functions were taken from the IETF or were afterwards defined in theIETF:

– Update (RFC331), Preconditions (RFC3312), PRACK (RFC3262), Offer/Answer (RFC 3264), QoS/Media Authorization (RFC 3313), Event Notification (RFC 3265),

– Tel-URIs (RFC 2806), 3GPP P-Headers (RFC3455), Service-Route (RFC3608),– Asserted ID (RFC3325), DNS-Support (RFC 3263), SigComp (RFC3320, RFC3485, RFC 3486), – ENUM (RFC2916, RFC2915), SIP Refer (RFC3515), Digest AKA (RFC 3310), – Path-Header (RFC 3327), Security-Mechanism-Agreement (RFC3329), etc.

• A Service Infrastructure Network could also be built up starting with a standard RFC 3261 SIP Server.

• When extended to support the same Support Functions, then such a solution becomessimilar to the IMS.

Page 37

73

User Registration and Authentication

UE SGSN HLR GGSN CSCF‘s HSS IMS-AS

GPRS Attach

PDP Context Activation

IMS Registration and User Authentication

IMS Service Access

Bearer LevelAuthentication

IP Transport setup

IMSRegistration

IMSService Access

74


UE Procedures for IMS Access

• Connect to the IP-CAN (IP Core Access Network) and acquire the necessary IP address, which includes, or is followed by, the P-CSCF discovery procedure

• Register to the IM subsystem as defined by the IMS registration procedures• If an UE explicitly deactivates the IP-CAN bearer that is being used for IMS

signalling, it shall first de-register from the IMS (while there is no IMS session in progress)

• If an UE explicitly deactivates the IP-CAN bearer that is being used for IMS signalling while an IMS session is in progress, the UE must first release the session and de-register from the IMS and then deactivate the IP-CAN bearers

• If an UE acquires a new IP address e.g. by changing the IP address according to, the UE shall re- register in the IMS by executing the IMS registration

• In order to be able to deliver an incoming IMS session, the IP-CAN bearer that is being used for IMS signalling need to remain active as long as the UE is registered in the IM CN subsystem

Page 38

75


Step 0: User RegistrationIMS Terminal P-CSCF I-CSCF HSS S-CSCF

(1) REGISTER(2) REGISTER

(3) Diameter UAR

(5) REGISTER

(4) Diameter UAA

(6) Diameter MAR

(7) Diameter MAA(8) 401 Unauthorized(9) 401 Unauthorized

(10) 401 Unauthorized


(13) Diameter UAR

(15) REGISTER(14) Diameter UAA

(16) Diameter SAR

(17) Diameter SAA(18) 200 OK

(19) 200 OK(20) 200 OK

76


Step 0: User RegistrationIMS Terminal P-CSCF I-CSCF HSS S-CSCF


(3) Diameter UAR

(5) REGISTER

(4) Diameter UAA

(6) Diameter MAR(7) Diameter MAA

(8) 401 Unauthorized(9) 401 Unauthorized

(10) 401 Unauthorized


(13) Diameter UAR

(15) REGISTER(14) Diameter UAA

(16) Diameter SAR

(17) Diameter SAA(18) 200 OK

(19) 200 OK(20) 200 OK

Request User information

to assign S-CSCF

S-CSCF selectionaccording to capabilities

HSS generates authentication

vectors

S-CSCF sends challenge

P-CSCF reads andremoves keys forsecure channel

with terminal

Calculatesresponse

to challenge

S-CSCFchecks answer

to challenge

Updates HSS

User-Profiledownloaded

Will further assert user’s identity as related to terminal

UE is registered

DNS query ofRequest-URI

Page 39

77


IMS Session Setup & Control

• This happens after User Registration (and Authentication!)• Why do we need the IMS Session Setup ?

1. Capability Negotiation (e.g. negotiation of session components, codecs, port numbers, addresses, etc.)

2. Network Resource Reservation and the support of QoS Preconditions• Additional Functions performed by the IMS during the IMS Session

Setup:– Routing to the Terminating IMS (= the IMS of the B-Party)– Routing / Breakout to the PSTN / CS-Domain when the B-Party is not in

the IMS, but in the PSTN / CS-Domain– Service Control / Invocation of Application Servers to trigger the

execution of Originating- and/or Terminating IMS Services– Integrity/Confidentiality Protection of SIP Messages– QoS/Media Authorization– SIP Signaling Compression

78


IMS QoS Support

• The actual Network QoS for IMS services is provided by the Access Network (e.g. based on UMTS QoS) and the IMS network infrastructure(e.g. based on Diff-Serv support in routers and switches).

• The IMS provides a correlation and control mechanism based on the use of the Policy-Decision-Function (PDF).

• Key functions of the PDF:– acts as Policy Decision Point (PDP):

• the GGSN is the corresponding Policy Enforcement Point (PEP).– authorizes and controls the resource usage for each bearer (e.g. GPRS/UMTS

PDP-Context):• this prevents the misuse of Network QoS and the theft of service.• this allows to limit the resource consumption.

– exchanges Charging Correlation Identifiers with the GGSN (ICID, GPRS Charging ID):• this allows the correlation of charging information generated in the PS-

Domain (SGSN, GGSN) and in the IMS (e.g. CSCF, AS).

Page 40

79

T. Magedanz (TU Berlin / Fraunhofer FOKUS) - 2006IMS Session Control – Complex Scenario

User A Registered

UE-A GGSN P-CSCF S-CSCF I-CSCF S-CSCF P-CSCF GGSN UE-B

User B Registered

INVITE

180 Ringing

200 OK

ACK

S

12

SS3

PRACKRR

RRB B

GoGo

200 OK

O Go

OGo200 OK

1 RR Resource Reservation

Service Control

Token generation

2 Resource Authorization 3 Same as 1,2

BO

Verify binding Open gate

Media Transport (RTP)

183 PR

200 OK

80


IMS Session Binding and QoS Bearer Control

• The Media/QoS Authorisation is performed on a per-session basisusing the Go-interface and an IMS Authorisation Token used for theIMS Session Binding.– enables the IMS to: authorise/open/close/modify the IMS Bearer Path (e.g.

for Voice/Video Traffic).• IMS Application Servers are not involved in the IMS Session Binding

Procedure.

Page 41

81


Session Initiation - 1

IMS Terminal #1 P-CSCF I-CSCF HSS S-CSCF(1) INVITE

(7) Diameter LIR

Originating VisitedNetwork

S-CSCF

Originating HomeNetwork

(3) INVITE

(5) INVITE

Evaluation of initial filter criteria

(2) 100 Trying(4) 100 Trying

(8) Diameter LIA

(6) 100 Trying

Terminating Home Network

P-CSCF IMS Terminal #2

Terminating VisitedNetwork

(9) INVITE

(11) INVITE

(10) 100 Trying


(12) 100 Trying(13) INVITE

(14) 100 TryingPre-alert user

(15) 183 Session Progress(16) 183 Session

Progress(17) 183 Session Progress(18) 183 Session


Progress

82



IMS Terminal #1 P-CSCF I-CSCF HSS S-CSCF(1) INVITE

(7) Diameter LIR


S-CSCF


(3) INVITE

(5) INVITE


(2) 100 Trying(4) 100 Trying

(8) Diameter LIA

(6) 100 Trying




(9) INVITE

(11) INVITE

(10) 100 Trying


(12) 100 Trying(13) INVITE

(14) 100 TryingPre-alert user

(15) 183 Session Progress(16) 183 Session



Progress

Provisional responsesto avoid retransmissions

DNS query onRequest-URI

Locating S-CSCF where the called-party

is registered

AS Servicesfor caller

AS Servicesfor callee

Local registrar look-up for callee’s address

Callee is reachable, begin resource reservation

Authorize QoSresources (PDF)


Page 42

83



IMS Terminal #1 P-CSCF I-CSCF HSS S-CSCF


S-CSCF


(20) 183 Session Progress




Alert user

(39) 200 OK(40) 200 OK

(21) PRACK

Res

ourc

eR

eser

vatio

n

(22) PRACK

(23) PRACK

(24) PRACK(25) PRACK

(26) 200 OK

Resource

Reservation

(27) 200 OK(28) 200 OK

(29) 200 OK(30) 200 OK

(31) UPDATE(32) UPDATE


(35) UPDATE

(36) 200 OK

(37) 200 OK(38) 200 OK

84





S-CSCF


(20) 183 Session Progress




Alert user

(39) 200 OK(40) 200 OK

(21) PRACK

Res

ourc

eR

eser

vatio

n

(22) PRACK

(23) PRACK


(26) 200 OK

Resource

Reservation

(27) 200 OK(28) 200 OK

(29) 200 OK(30) 200 OK



(35) UPDATE

(36) 200 OK

(37) 200 OK(38) 200 OK


PDP contextactivation

PDP contextactivation

QoS useenabled

QoS useenabled

Terminating LegOriginating Leg

Page 43

85





S-CSCF

Originating HomeNetwork Terminating Home Network





(51) PRACK(52) 200 OK

(53) 200 OK(54) 200 OK

(55) 200 OK(56) 200 OK

Alert user(41) 180 Ringing

(42) 180 Ringing(43) 180 Ringing


(46) 180 Ringing

Acceptsession

(58) 200 OK(57) 200 OK

(59) 200 OK

(61) 200 OK(62) 200 OK

(60) 200 OK

(63) ACK(64) ACK

(65) ACK(66) ACK

(67) ACK


86





S-CSCF

Originating HomeNetwork Terminating Home Network





(51) PRACK(52) 200 OK

(53) 200 OK(54) 200 OK

(55) 200 OK(56) 200 OK

Alert user(41) 180 Ringing



(46) 180 Ringing

Acceptsession

(58) 200 OK(57) 200 OK

(59) 200 OK

(61) 200 OK(62) 200 OK

(60) 200 OK

(63) ACK(64) ACK

(65) ACK(66) ACK

(67) ACK

Phone startsringing

Aknoledgesphone ring

Answer the call

Starts media flow

Starts media flow


Page 44

87


IMS Online / Offline Carging

• The IMS architecture supports both online and offline chargingcapabilities.

• Online charging– is a charging process where IMS entities, such as an application server

(AS), interact with the online charging system.– the online charging system in turn interacts in real time with the user's

account and controls or monitors the charges related to service usage.• Offline charging

– is a charging process where charging information is mainly collected afterthe session and the charging system does not affect in real time theservice being used

– a user typically receives a bill on a monthly basis, which shows thechargeable items during a particular period.

• Due to the different nature of charging models different architecturesolutions are required.

88


IMS Charging Architectures

Page 45

89


Offline Accounting Principles

• Charging Trigger Function (CTF)– watches for accountable events– sends them

• Charging Data Function (CDF)– construct CDRs from events

received via Rf reference point– events may be of several types

• Charging Gateway Function (CGF)– collect, validate and (persistantly)

store CDRs (in files)– forward batch files to Billing

domain

CN Domain

Service element

Sub- system

Billing Domai

Rf Ga Bx

C

T

F

C

D

F

C

G

F

3GPP network

90


Rel. 6 – IMS Offline Charging Architecture

• Focus is IMS related (bearertraffic excluded for IMS spec.)

• Compared to Rel. 5– CCF splitted into CDF and

CGF – Ga added

• First rules on what events to trigger Rf commands arespecified for– P/I/S –CSCF– BGCF– SIP AS– MGCF– MRFC

Billing Domain Billing Domain

BGCFBGCF

MGCF MGCF

MRFC MRFC

SIP ASSIP AS

CDF CDF

CGF CGF

P - CSCF S - CSCF P - CSCF I - CSCF

S - CSCF

Rf Ga

Bi

Page 46

91


Offline Charging Example

Offline Charging is basedon the Diameter messages

- Account Request (ACR)- Account Answer (ASR)

Start: open a new CDRInterim: adds further infoStop: closes the CDREvent: unreleted session

CDR

92


Online Accounting Principles• Charging Trigger Function

– Sends events for authorization to OCF– Must delay resource usage until permission is

granted– Must support quota supervision during resource

usage/consumption

• Online Charging Function has 2 modules– Session based Charging

• charges network / user sessions (e.g. voice calls, GPRS PDP contexts or IMS sessions)

– Event based Charging• event-based online charging (also referred

to as “content charging”) in conjunction with any application server (e.g. SIP) or service NE

• Account Balance Management Function• Rating function (for data volume, session

time & service events)

CN Domain

Service element

Sub- system

Ro

C

T

F

3GPP network

CAP

O

C

F

ABMF

RF

OCS

Rc

Re

Page 47

93


Rel. 6 – IMS Online Charging Architecture

Billing Domain Billing Domain

BGCFBGCF

MGCFMGCF

MRFCMRFC

SIP ASSIP AS

OCS OCS

P -CSCFS -CSCFP -CSCFI -CSCF

S -CSCF IMS - GWF

Ro

ISC

• Specification for IMS (no bearer included)

• IMS Gateway Functionas new element– either part of OCS or– Stand-alone solution

(e.g. SIP AS) • Triggering behaviour

not specified

94


Online Charging Example

Online Charging is basedon the Diameter messages

- Credit Control Request(CCR)

- Credit Control Answer(CSR)

The IMS-GWF requests unitsfrom the Online CharingServer (OCS) to provide a service (e.g. a session or a subsription, or any otherservice)

Page 48

95


IMS Diameter Base Protocol Extensions

Base

Pro

toco

lE

xten

sion

s

Rf application defined in 3GPP TS32.299 uses the accounting portion of the base protocol and its server is stateless.Ro application defined in 3GPP TS32.299 extends Diameter Credit Control Application (DCCA) RFC4006, which uses both stateful and stateless part of auth-portion in the base protocol.

96


IMS Security

• Two security solutions are proposed• Full IMS security

– Standardized in Release 5 and 6 with full features– Defines security in the network and the terminals– Requires ISIM and rich features in the terminal, P-CSCF and S-CSCF

• Early IMS Security– Standardised in Release 6– Idea: Reuse GPRS authentication (and IP address) for IMS authentication– Developed for early IMS deployment without existance of all security

enablers– Not stringend as the full IMS security solution– Intended to have minimal impact on existing terminals– Offers less security but good enough for early deployment

Page 49

97


Complete IMS Security Solution

• Divided into:– Network Domain Security (already existing for GPRS)– Access Domain Security (linked to SIP and CSCFs / HSS)

• SIP Security is provided on a hop-by-hop fashion– End-to-end security is not supported !

• Terminals accept a UICC (Universal Intergraded Circuit Card) that contains an ISIM (IMS Subscriber Identity Module) application

• The ISIM stores identities (public, private), home domain, and long term security keys

• The S-CSCF authenticates the user at SIP registration time• The security mechanism is negotiated (but only IPSec is supported so far)• Authentication scheme based on the UMTS AKA (Authentication and

Key Agreement) called IMS AKA• Delegate identity enforcement to the P-CSCF• P-CSCF and UE establish an IPSec connection for integrity protection

(Release 5 onwards) and confidentiality (Release 6 onwards)

98


Complete IMS Security

GPRS DomainExisting GPRS Access

Security

SIP UAIMS Visited

IMS Home

Security Mechanism Agreement

Authentication & Key Agreement (AKA)

Network Domain Security

Integrity Protection

IMS

Secu

rity

SecureApps

SecureApps

Non-secureApps

Page 50

99


Early IMS Security

• There is no IPsec connection (UE – P-CSCF), no IMS AKA, and no HTTP Digest authenication

• Idea: Reuse / rely on GPRS authentication• Binding between public/private user identity and GPRS allocated IP address is

created in the HSS• The GGSN authenticates the GPRS usage based on the IMSI• The GGSN uses RADIUS to send the HSS the attached user´s IP address, IMSI

and MS-ISDN• The HSS binds the IMSI and MS-ISDN to the private and public user identities• The P-CSCF verifies that the source IP address in the IMS signalling IP

packets is the same as the „send by“ parameter in the Via header field of SIP REGISTER request

– If they differ, the P-CSCF adds a „received“ parameter to the record the seen IP address

• When the S-CSCF requires to authenticate the user, it checks ist IP address in the „received“ or „sent by“ parameters of the register request

100


Early IMS Security

IMS Terminal GGSN I-CSCF HSS S-CSCF(1) PDP Context

Activation Request

P-CSCF

(3) RADIUS ACA

(2) RADIUS ACR

[IP address, IMSI, MSISDN]

(18) 200 OK

(7) REGISTER “sent-by“ IP address

(4) PDP Context ActivationAccept IP address

(5) REGISTER “sent-by“ IP address

(6) GGSN prevents IP spoofing

(8) Check Source IP address against “sent-by” parameter

(9) REGISTER “sent-by“ IP address “received“ IP address (10) Diameter UAR

(11) Diameter UAA(12) REGISTER

(13) Diameter MAR

(14) Diameter MAA[IP address]

(15) Check received IP address against “sent-by” or

“received” IP address

(16) Diameter SAR

(17) Diameter SAA(19) 200 OK(20) 200 OK

Page 51

101


Media Plane Security

• IMS User plane security relies on bearer network security (e.g. UMTS/GPRS packet domain ciphering in Release 5)

• There is no end to end security for media flows• Opportunities in future releases to integrate end to end key agreement

with SIP• End to end encryption options

– Application layer (e.g. S-RTP)– Network layer (e.g. IPsec)

102


Overview


Page 52

103


SIP enables different AS Modes of Operation

Four modes of operation are distinguished:• Application Server acting as terminating UA, or redirect server• Application Server acting as originating UA• Application Server acting as a SIP proxy• Application Server performing third party call control/ B2BUA mode

CSCF

AS(Content Server)

CSCF

AS(Wake up Svr)

CSCF

AS(Call Forw.)

CSCF

AS(Click2Dial)

RTPSIP

A BA B A B

104


How does a SIP AS Provide Enhanced Services

• S-CSCF determines that a call requires enhanced service processing– Filtering may be based on calling / called party or other mechanism

(defined by filtering criteria) eg. SIP message type, header fields, etc.• Based on filtering criteria, the S-CSCF determines the address of the

Application server and relays the call to the AS function. The Application Server receives the call and invokes the appropriateservice logic taking one of the following actions:– Redirects the call to a new destination– Send the call back through the S-CSCF in order to monitor subsequent call

events (ie act as a SIP Proxy)• The Application Server (based on some other input) can also set-up

calls between other entities in the network (ie. act as a B2BUA)

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Major Service Platform Interfaces

Service Delivery Platform (Application Server)

Service Platform Trigger PointsService Platform Adaptor

SIP B2BUA Interface

HSS

S-CSCF

SPT

SP Filter criteria 2 SPT Mapping

ISC = Ext. Session Initiation Protocol

SIPSIPSIP Proxy Server

Sh = Diameter

Cx = Diameter

Note: Cloning of IN principles!

Value Added Services

106


Major Service Platform Interfaces

Service Delivery Platform (Application Server)

Service Platform Trigger PointsService Platform Adaptor

SIP B2BUA Interface

HSS

S-CSCF

SPT

SP Filter criteria 2 SPT Mapping

ISC = Ext. Session Initiation Protocol

SIPSIPSIP Proxy Server

Sh = Diameter

Cx = Diameter

Note: Cloning of IN principles!

Value Added Services

Application Data(Filter Information)User status changes

User AuthenticationUser locationUser Profile (Filter Information)

Applicationspecific servicecontrol

Detection Points:Methods / Responses,Headers, SDP info, etc

DP Criteria:AS-Specific Methods / Responses,Headers, SDP info, etc set by AS/HSS

Page 54

107


IMS Diameter Base Protocol Extensions

Base

Pro

toco

lE

xten

sion

s

Cx application defined in 3GPP TS29.229, Sh application defined in 3GPP TS29.329 use the stateless part of the auth-portion in the base protocol.Rf application defined in 3GPP TS32.299 uses the accounting portion of the base protocol and its server is stateless.Ro application defined in 3GPP TS32.299 extends Diameter Credit Control Application (DCCA) RFC4006, which uses both stateful and stateless part of auth-portion in the base protocol.

108


Cx (and Dx) Interface

• Cx - Interface supports information transfer between S-CSCF and HSS– Diameter application for user profile handling & user authentication

• to exchange location information● to authorize a user to access the IMS• to exchange authentication information• to download and handle changes in the user data stored in the server

• Dx – Interface between I-CSCF and the Subscription Locator Function (SLF) –in case of HSS look-up

– Diameter redirect agent functionality to retrieve an HSS address

• Both RPs are pecified in 3GPP TS 29.228 and TS.29.229 – TS 29.228 IM Cx and Dx interfaces; Signalling flows and message contents– TS 29.229 IM Cx and Dx interfaces based on the Diameter protocol; Protocol details– (http://www.3gpp.org/ftp/Specs/archive/2x_series/2x.xxx)

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IMS Cx Diameter Extensions

Cx Application (Described in 3GPP TS29.228, 3GPP TS29.229)Defined between I-CSCF and HSS, between S-CSCF and HSS.Uses stateless part of the auth-portion in the base protocol.Defines new commands:

Defines a series of vendor specific AVPs.

Push-Profile-Request / Push-Profile-Answer

Registration-Termination-Request / Registration-Termination-Answer

Multimedia-Auth-Request / Multimedia-Auth-Answer

Server-Assignment-Request / Server-Assignment-AnswerLocation-Info-Request / Location-Info-AnswerUser-Authorization-Request / User-Authorization-Answer

Command-Name

PPR/PPA

RTR/RTAMAR/MAA

SAR/SAALIR/LIAUAR/UAAAbbreviation

S-CSCF, HSS

S-CSCF, HSSS-CSCF, HSS

S-CSCF, HSSI-CSCF, HSSI-CSCF, HSS

Between

110


Sh Interface

• Interface between HSS and Application Server (AS)• Diameter application that allows a Diameter server and a Diameter

client:• to download and update transparent and non-transparent user data• to request and send notifications on changes on user data

• Further information on the Sh reference point is provided in – TS 29.328 IM Sh interface; Signalling flows and message contents– TS 29.329 IM Sh interface based on the Diameter protocol; Protocol details

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IMS Sh Diameter Extensions

Push-Notification-Request / Push-Notification-AnswerSubscribe-Notifications-Request / Subscribe-Notifications-AnswerProfile-Update-Request / Profile-Update-Answer

User-Data-Request / User-Data-AnswerCommand-Name

PNR/PNASNR/SNAPUR/PUAUDR/UDA

Abbreviation

Sh Application (Described in 3GPP TS29.328, 3GPP TS29.329)Defined between AS and HSSUses stateless part of the auth-portion in the base protocol.Defines new commands

Defines a series of vendor specific AVPs.

112


IMS User Profile

Page 57

113


IMS Initial Filter Criteria• The IFC is the key point for service provisioning in IMS and specified in 3GPP TS 23.218 and 29.228 • The S-CSCF downloads the IFC‘s for a particular user from HSS and has the ability to forward SIP

messages to an appropriate Application Server (SIP AS, OSA SCS)• AS application/service invocation is triggered as a result of a pattern matching on any SIP header

or body

HSS

IM User Profile(s)S-CSCF

IM User Profilesstorage

AS1

Application

ApplicationAS2

Application

ApplicationAS3

Application

Application

1 INVITE

2 INVITE 3 INVITE 4 INVITE 5 INVITE

6 INVITE

Cx - User Profile download/update

Filter Criteria 2 SPT ProcessingPrio 1 = AS1, Prio 2 = AS2, Prio 3 = AS 3, etc.

iFc 1 met iFc 3 met

114


Service Example (1) —Single AS case

Example 1: Single application server triggering

3. P

UB

LIS

H

4. 2

00 O

K

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115


Service Examples (2) — Multiple AS case

Example 2: Multiple application servers triggering

3. MESSAG

E4. M

ESSAGE

2. Filter Evaluation

6. M

ESSA

GE

7. M

ESSA

GE

5. Filter Evaluation

116


Scalability of the IMS

HSS

S-CSCF 1

SIP AS X

Sh

Cx

ISC

S-CSCF 2 S-CSCF Y

SIP AS 2SIP AS 1

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Different AS Alternatives

• CAMEL Services via Camel Support Environment (CSE): – intended for the support of existing IN Services (provides service continuation).

• OSA Services via Open Service Access Service Capability Server: – intended for the support of 3rd Party Application Providers. OSA SCS provides

access and resource control.

• IMS services on SIP-Application Server:– intended for new services. A multitude of widely known APIs (CGI, CPL, SIP

Servlets) is available.

• IMS services directly on the CSCF (similar to SIP AS):– SIP-AS co-located on the CSCF– seems to be useful for simple services. May be beneficial for the Service

Availability and the Service Performance.

118


SIP ASHSS(AAA)

Media Server

SIP

IMS Application Server Options

DiameterSIP

OSAGTW IM-SSF

App

licat

ion

Serv

erIM

S C

ore

Serv

er

P/I/S-CSCF(SIP Proxy)

SIP ServerPDF

OSAAS CAMEL

ApplicationServers

Local AS

RTP

Page 60

119


INSCP

Online &OfflineCharging (ECF, CCF)

CAMEL Reuse within IMS

CAMEL Support Env.(Application Server)

IN App 1

Service Platform Trigger PointsIM SSF (SIP2CAP)

SIP Interface

ShHSS

S-CSCF

SPT

SP

Filter criteria

ISC

SIP

SIP-Server

Sh = Diameter

Cx = Diameter

Ro + Rf = Diameter

Diameter

CAP

CAP Interface

SIP 2 CAP mapping needed!

IM SSF

120


3GPP CAMEL

• CAMEL = Customized Applications for Mobile Enhanced Logic• CAMEL

– Is the use of IN in mobile circuit switched and packet switched networks: GSM/GPRS

– IN-based architecture enabling to offer operator specific services (OSS) to mobile subscribers even when roaming in another network (international roaming)

• CAMEL enables inter-network GSM/GPRS service control, by reusingthe existing international signaling transport infrastructure– CAMEL Application Protocol (CAP) is based on IN Capability Sets 1 and 2– CAMEL additionally exploits Mobile Application Part (MAP)

• CAMEL Standardisation started in 1994 (as a GSM Phase 2+ Feature)• CAMEL evolves in Phases, which are part of Releases!!!

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121


CAMEL Phases

• Camel Phase 1– Basic Call Control functionalities for GSM calls

• Camel Phase 2– ApplyCharging in VPLMN : GSM calls are monitored directly in VPLMN– Announcement : access to annoucements directly from the VPLMN

• Camel Phase 3– Handling of GPRS Sessions and pdp-contexts for session control, monitoring

(location update, QoS,…) and charging (time and volume triggers)– Support of SMS-MO through CS and PS networks– Anytime interrogation and modification of customer data in HLR– Mobility management enhancements

• Camel Phase 4– Multi-leg GSM call handling– Creation of a new GSM call– PLUS: Interworking with IP Multimedia Subsystem

122


CAMEL(SCF)

S-CSCF

IM-SSF

HSS

MSC (SSF)

HLR

2G Circuit Switch Voice Network

3G IP based Voice & Data Networks

SGSN (SSF)

2.5G Packet Switch GPRS Data Network

MAP

Home Network

CAP(over IP)

CAP

MAP

SIP

CAMEL Evolution

Camel Phase 1 + 2Camel Phase 4

Camel Phase 3

IVR (IP)

Page 62

123


Home Network

CAMEL Phase 4 in IMS Domain

Visited Network

IP Multimedia

InterrogatingNetwork

CSE HSSMAP

imSSF

Cx

IP Multimedia

IP Multimedia Subsystem

GGSN

MGCFT-SGW

MGWPSTNPLMN

SIP SIP

proxyCSCF

SIPS-CSCF

CAP over

IP

SGSN

• IM-SSF provides– Triggering of CAMEL services in gsmSCF– Call State model (O-IM-BCSM / T-IM-BCSM) based on CAMEL Phase 3!

124


MOC VoIP with CAMEL interaction

S-CSCF/imSSF HSSUE CSE

Visited network Home network

Invite

If calling subsc. is not registered, dialogue with HSS is opened to obtain O-CSI

InitialDPCAP instructionsAnalysis for calls

requiring IN i.e. trigger criteria in O-CSI

P-CSCF

A

I-CSCF

Page 63

125


Parlay AS (API)


OSA / Parlay AS within IMSService Delivery Platform

(Application Server)Parlay App 1

FW

SIP Interface

ShHSS

S-CSCF

SPT

SP

Filter criteria

ISC

SIP

SIP-Server

Sh = Diameter

Cx = Diameter

Ro + Rf = Diameter

Diameter

Parlay X GWParlay App 2

Parlay X AppParlay X App

Parlay GTW

MPCC MMM PRES CHARG

126


Parlay/OSA (Open Service Access) define an API that enables operatorand 3rd party applications to make use of network functionalitythrough a set of open, standardised service interfaces

Parlay/OSA API

Gateway

Mapping to network specific protocols

App 1 App 2 App N Applications (independent of underlyingnetwork technology)

3GPPETSIParlayJAIN SPA

OSA/Parlay/JAIN: One Set of Open APIs

ISDN GSM/GPRS Internet / UMTS

Page 64

127


OSA / Parlay’s Technical Approach

• Framework Interface Set - Common Functions That Are Required to Enable Services to Work Together in a Coherent Fashion e.g.

– Authentication, Discovery, Manageability• Transport interface

– CORBA, WSDL (Web Services)• Service Interface Set(s) - Common Functions

That Deliver Whole Complex Services or Sub-components of Services e.g

– Call Control, User Interaction, Content-based Charging, Location, Presence and Availability, Messaging, Policy Management, Quality of Service …

• Resource Interfaces - Interfaces used between a Parlay Gateway and network elements

– not specified in Parlay (but hints in OSA)

ApplicationServer

Frameworkinterface

Parlay/OSA GatewayResourceinterface

Resourceinterface

Serviceinterface Th

e Par

lay/O

SA A

PI

128


Focal Points of API Standardisation (Parlay 5)

UserInteraction

Data sessioncontrol

GenericMessaging

ConnectivityManagement

AccountManagement

Contentbased charging

TerminalCapabilities

PolicyManagement

Presence &Availability

Management

Call Control

Mobility

Framework

Not

par

tof O

SA

MMMessaging

Page 65

129


Parlay – OSA – ETSI – JAIN Relationhip

ES 201 915-14TS 29.1980-14PAMES 201 915-13TS 29.1980-13Policy ManagementES 201 915-12TS 29.1980-12ChargingES 201 915-11TS 29.1980-11Account ManagementES 201 915-10N/AConnectivity ManagementES 201 915-9N/AMessagingES 201 915-8TS 29.1980-8Data Session ControlES 201 915-7TS 29.1980-7Terminal CapabilitiesES 201 915-6TS 29.1980-6MobilityES 201 915-5TS 29.1980-5User InteractionES 201 915-4TS 29.1980-4Call Control

ES 201 915-3TS 29.1980-3FrameworkES 201 915-2TS 29.1980-2Common TypesES 201 915-1TS 29.1980-1Overview

ETSI OSA API Version 1 spec.

3GPP OSA API Release 4

spec.

Parlay Version 3.1 spec.

JSR-123 v.1.0 (PAM)

JSR-098 v.1.0 (ULS)JSR-103 v.1.0 (UI)

JSR-021 v.1.1 (JCC)

JSR-024 v.1.0 (TSM, SD, SAM)JSR-119 v.1.0 (IM)

JSR-145 v.1.0 (Common)JSR-136 v.1.0 (JTSP)

JAIN SPA API spec.

130


OSA/Parlay Interfaces – Classic vs. Parlay X

Parlay X App

SIPServer SCP/CSE

XMLScript Java VB

Parlay X Gateway

“MakeACall (A,B)” “GetCallInfo”

HLR

XML Transport: Simple XML sequences

over SOAP, CORBA, HTTP, …Parlay X APIs

“Web Services” AppParlay

C++/ Java App

ClassicParlayAPIs

Parlay Gateway

XMLScript Java VB

XMLCORBAIDL, Java

CORBAIDL, Java,XML, …

createCall()routeReq(A)routeReq(B)…

XML Transport: Complex XML sequences

over SOAP, CORBA, HTTP, …

routeRes(A)routeRes(B)…

IIOP

createCall()routeReq(A)routeReq(B)…

routeRes(A)routeRes(B)…

Not reallyDemanded!

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131


NetworkResource

NetworkResource

NetworkResource

NetworkResource

Example Parlay X Web Services

Send SMS

Initiate Call Conference

ZipCodes

Whoseon-line ?

Sort inorder

Currentlocal

Weather

Airline flightcheckMake

payment

AccountStatement

NewApplication

Note: Network Operator acting as Web Service Provider

Directory

LatestScores

PublicUDDI

Registry

132


3GPP Parlay X Web Services

• Parlay X Web services havebeen adopted by 3GPP CN TSG (September 2004) for inclusionin OSA Release 6

– The documents are numbered TS 29.199-xx-600

– 3GPP TS 29.199 is structured in 14 Parts

Part 14: PresencePart 13: Address List ManagementPart 12: Multimedia ConferencePart 11: Audio callPart 10: Call handlingPart 9: Terminal locationPart 8: User statusPart 7: Account managementPart 6: PaymentPart 5: Multimedia Message Service (MMS)Part 4: Short Message Service (SMS)Part 3: Network-initiated third party callPart 2: Third party call Part 1: Common

TS 29.199 specifications

Page 67

133


The JAIN APIs

JAIN Service Logic Execution Environment (JSLEE)

JAIN Call Control (JCC) and JAIN Coordination and Transactions (JCAT)

JAIN ServiceCreation

Environment(JSCE)

Secure Telco Space

TCAP ISUP INAP SIP MAP MGCP

Untrustedthird-party

applications

JAIN Service Provider Access (JSPA)

Trusted third-party

applications

VendorIndependence

ProtocolIndependence

NetworkIndependence

OperatorIndependenceSecurity Interface

PSTNBroadbandIP SatelliteWireless

Open API

134



SIP Application Server (Servlets)

Service Platform Trigger PointsSIP Servlet Engine

SIP Interface

ShHSS

S-CSCF

SPT

SP

Filter criteria

ISC

SIP

SIP-Server

Sh = Diameter

Cx = Diameter

Ro + Rf = Diameter

Diameter

SIP Service ServletsSIP Service Servlets

Page 68

135


SIP Servlet API

• Objectives of the SIP Servlet API as specified in the JSR116 – SIP Servlet API Version 1.0

– SIP signalling – Allows applications to perform a reasonable complete set of SIPsignalling actions, including support for acting as user agent client (UAC), user agent servers (UAS), and proxy.

– Simplicity – Containers handle “non-essential” complexity such as managing network listen points, retransmissions, CSeq, Call-ID, Via headers, routes etc.

– Converged applications – It is possible for containers to support converged applications which make use of multiple protocols such as HTTP and SIP. Typical applications are web, telephony and presence.

– Third party application development – The servlet model supports third party application development. An XML deployment descriptor is used to communicate application configuration.

– Application composition – It is possible for several applications to execute on the same incoming or outgoing request or response. Each application has its own set of rules and execute independently of other applications in a well-defined and orderly manner.

– Carrier grade – Servlets store application data in container managed sessionobjects. Implementations may persist and/or replicate this data to achieve high availability.

136


SIP Servlets

(taken from ‘SIP Sevlets White paper’ by Jose Soler Lucas)

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137


SIP Servlets

#1 INVITE TM

#2 pass invitationto call processinglogic

#3 return anaction

#4a INVITE TM@cell

#4b INVITE voicemail@trash

SIP ServletContainer

Ser

vlet

SIP Servlet API

Ser

vlet

Call Screening Service

138


Servlet Control SIP.XML

• SIP.XML is xml-code that specifies the Servlet container habit and controls the Servlet invocation.

• An Eclipse Plugin enables the graphical control / modification of the SIP.XML within the SIP Servlet Execution Environment.

Servlet ContainerSIP.XML

Servlet orarchive

Servlet orarchive

Servlet orarchive

Servlet orarchive

SIP Request

Match of Criteria

Note: The SIP XMLEnables to host multipleand independent Servlets(Applications) within on one SIP AS !

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139


Converged SIP and HTTP Sessions

• In Converged Applications, SIP Servlet and HTTP Servlet share the same Servlet Context through Converged Application Helper.

• Through Listener and attributes in Context, HTTP and SIP Servlet can communication with each other.

• More than one HTTP Sessions and SIP Sessions belong to the same SipApplicationSession, which acts as bridge between HTTP and SIP world.

140


SIP AS vs. CAMEL vs. OSA/Parlay

• CAMEL supports:– legacy IN services in 2G and 3G networks– Services based on proven and reliable IN technology (reuse!)– But CAMEL is expensive and limited in evolution

• SIP AS supports:– Multimedia conferencing services, integrated with HTTP– Exploitation of cheaper internet technology– Easier service creation, but not yet proven for carrier grade services

• OSA is an API (!!) which could be mapped to boh CAMEL and SIP– OSA is enabling EAI in Telecoms– Proven technology (reuse of existing services in NGN)– Support implementation of different business model (walled vs. open

garden)– Best support of 3rd parties

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141


Relating OSA/Parlay vs. CAMEL vs. SIP AS

OSA/Parlay FMC Services (Apps Servers)

Seamless NGN Services (opt. by 3rd Parties)

OSA Gateway

MSC

Camel CSE

CAP

ReuseCAMEL Services

GGSNSGSN

CAP GSM /GPRS

Parlay (X) API

OSA Gateway

SIP AS

S-CSCF

Build newMM Services HSS

(AAA)

3GPP IMS

SIP CAP

WLAN / DSL WAG

PDFPDF

142


Overview

• IMS Motivation• IMS Overview• IMS Key protocols (IETF SIP and Diameter) • IMS Key components• IMS Application Server options• Sample IMS Multimedia Applications• The IMS Playground @ FOKUS• Summary• Q&A and IMS Playground Demos• References & Acronyms

Page 72

143


IMS Applications

144


IMS integrates different Communication Services

Voice

SMS

Instant Messaging

MMS

Pre-IMS Communication(“Service Islands”)

IMS Communication(“Combinational Services”)

Voice / VideoSMS

Instant Messaging

MMS

From the usage of specificindividual communication services ... ... to the integrated usage of different

communication services centeredaround presence information and

within groups ( communities)

GroupsPresencePoC

TV

Page 73

145


IMS for VoIP Supplementary Services• Example IMS Service Architecture for an IMS Voice/Video/Data telephony service:

– the SIP-AS provides Supplementary Services such as e.g. Call-Forwarding, Call-Barring, Simultaneous-Ringing, etc.

ApplicationsApp

licat

ions

146


Multimedia Call – Change of Media Scenario

• Change of Media Scenario uses basic IMS components, requests enhanced functionalities on client side (e.g. Video) and Operator dependent change of PDP-context.

• Change of Media Scenario is a seamless switch of media –No session interruption

Alice (caller) Bob (callee)

(2) INVITE (SDP=Voice)(3) 200 OK

(1) INVITE (SDP=Voice)

(4) 200 OK

P-/I-/S-CSCF

IMS

environment

Do you wantto see mynew skirt?

(7) 200 OK(5) INVITE (SDP=Voice+Video)

(8) 200 OK

(6) INVITE (SDP=Voice+Video)

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147


Multimedia Call – Rich Converged Call Scenario

• A Rich Converged Call Scenario makes use of the advantages of the peer to peer protocol SIP and the well known client-server protocol HTTP. It enables a client or an application to perform a HTTP Push with the target to provide another subscriber with personalized web content.

• A Rich Converged Call Scenario requests minor but specification compliant modification of the SIP User Agent to open the website automatically.

Alice (caller) Bob (callee)

(2) INVITE (SDP=Voice)(3) 200 OK

(1) INVITE (SDP=Voice)

(4) 200 OK

P-/I-/S-CSCF

IMS

environment

I found an excellentweb/ wap site. I will push it to you.

(7) 200 OK(5) INFO (body=http://open-ims.org)

(8) 200 OK

(6) INFO (body=http://open-ims.org)

148


Instant Messaging

• Near real-time exchange of multimedia messages in a one-to-one or one-to-many connection

• Instant Messaging is the first presence-enabled application in the mobile environment

• Different forms of IM– immediate messaging– session-based messaging– deferred delivery messaging

• Different types of IM– Text– Audio– Picture– Video

• IMS insures the interworking between different message types

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149


Immediate messaging

• User A generates a Message consisting of text or multimedia content and fills the request-URI with the address of the recipient B

• The IMS infrastructure (P/I/S-CSCF) forwards the message to the recipient

• Once user B receives the message, he replies with a 200 OK message

• Note: Each immediate message is an independent transaction and is not related to any previous requests

MESSAGE MESSAGE MESSAGE

200 OK200 OK200 OK

User A User B

150


Session-based messaging

• Before user A sends a MESSAGE, he invites user B to a message session by generating an INVITE message

• Once the session has been established, user A and B can exchange messages• Note : A session has a well-defined lifetime: a message session starts when

the participants begin the session and stops when the participants close the session

MSRP Send MSRP Send MSRP Send

MSRP 200 OK

User A User B

INVITE

200 OK

INVITE

200 OK

INVITE200 OK

:::BYE

200 OK

MSRP 200 OK MSRP 200 OK

200 OK 200 OK

P/I/S-CSCFP/I/S-CSCF

MSR

PSI

PSI

P

BYE BYE

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151


IMS for Presence, Push 2 Talk, IM• Example IMS Service Architecture for the IMS services:

– Presence, – Push-to-Talk (PTT),– Instant Messaging (IM)

ApplicationsA

pplic

atio

ns

152

• In June 2002, the mobile industry set up a new, global organization called the Open Mobile Alliance (OMA)

–www.openmobilealliance.org• The Open Mobile Architecture initiative supporters and the WAP Forum

formed the foundation for the Open Mobile Alliance• The following organizations have integrated into OMA:

– Location Interoperability Forum (LIF)– SyncML Initiative– MMS-IOP (Multimedia Messaging Interoperability Process)– Wireless Village – Mobile Gaming Interoperability (MGIF)

– Mobile Wireless Internet Forum (MWIF)

• Other industry forums focusing on interoperability and open standards are welcome to join

Open Mobile Alliance (OMA)

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OMA Service Enablers and IMS

• IMS provides the following:– Routing and reachability– Authentication and transitive trust– Signaling compression– Privacy– User profile storage– Charging, accounting– Interface to the access network

• OMA SIP-based service enablers are specifiedon top of IMS as common platform, e.g.– Presence, Group Management, etc.

Standards

OMAforApplicationEnablers

3GPPforNetworkArchitecture

154


OMA Service Enablers and IMS

OMA service enablers

IMS

PoC Messa-ging

Otherenablers

IP Transport

ISC

Regist-ration

SessionControl Charging

Page 78

155


Push to Talk over Cellular (PoC)• PoC is standardised in the Open Mobile Alliance (OMA), Rel. 1 in 2005• First specification process was initiated by the MENSA (Motorola, Ericsson,

Nokia, Siemens, AT&T Wireless) consortium in 2002, 2003• PoC is a way of communication that uses half-duplex connections

– similar to walkie-talkie functionality– allows to deliver a talk burst to a collection of users

• PoC client is (usually) in the handset as a soft client• PoC server has ambiguous functionality: It manages both the signalling and

also the media– By definition the PoC server is acting as a SIP AS, connecting to IMS CN through

the ISC interface• OMA PoC does not consider access network issues (any access network can

be used)• OMA PoC requires the XML Document Management (XDM) enabler for group

session configuration• OMA PoC may use OMA XDMS architecture for presence as a presence

enabler• Dedicated floor control messages are used to grant access to the floor to

ensure semi-duplex paradigm

156


MENSA PoC Architecture Rel. 1 (2002)

• Introduction of Group List and Management Server

• No presence functionalityrequired

• No Network-NetworkInterworking (NNI)

• No automated deviceconfiguration

Source: PoC MENSA Rel. 1.1

UE

Im

PoC

Ser

ver

ACC

ESS

GLMS

IMSCore

(CSCF/HSS)

Presence Server

Ipl

Ips

Ik

IfIf

It

(talk)

Page 79

157


UE

OMA PoC Architecture Rel. 1 (2005)

• Introduction of OMA Enablerarchitecture forPoC

• XML DocumentManagement Enabler

• Alignment of PoCArchitecture to OMA enablerconcept

• Presence Enabler• Device

Management Enabler

• NNI

Used Protocols:• SIP• RTP/RTCP• RTCP• XCAP

Source: OMA/PoC Candidate Version 1.0

DM-1

Rem

ote

PoC

Net

wor

kR

emot

e Po

CN

etw

ork

ACC

ESS

NET

WO

RK

SIP

/ IP

Cor

ePresence

Server

PoC-7

PoC-3

DMServer

XDM-3

PRS-3

PoCServer

PRS-5

IP-1

XDMC

PRS-1

PRS-2

PoC-1

Aggregation Proxy

PoC-6XDM-1

PoC-2PoC-8

PoC-4

Shared XDMS

XDM-2

XDM-4

XDMC

XDM-3

PoC-5

DMClient

Presence Source

Watcher

PoCXDMS

PoCClient

158


From PTT to Community-Support

• PoC/PTT basically defines a specific service based on genericenablers (Presence, GLMS/XDMS, FOTA)

• Infact PoC/PTT could be regarded as a specific instantiation of a groupcommunication framework

• Making money with PoC/PTT is unclear• Making money with SMS and voice calls is clear• Idea:

– Reuse PoC/PTT enablers for other communication services as wellIntegrated Presence driven IM, email, SMS, MMS, VoIP, CS-Calls,

Video calls, etc.– Provide group communication to those who really need it

well established Communities (Sports, Work, health, fun) will appreciate this!

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IMS is a perfect basis for eCommunity services

• IMS is today considered as the common platform for FMC and NGNs

• A convergent community-service can ideally be based on the IMS platform granting:– convergence and compatibility

between fixed/mobile networks– multi-media and converged

services support– providing key community service

enablers, such as• Group Management• Presence• IM / PoC• generic VoIP/MMoIP support,

etc.

All-IP Network

IMS

Cellular Networks Fixed Networks

3GPP Domain NGN Domain

IMS

160


eCommunities - sooooo many Options

Page 81

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Overview

• Market Drivers for FMC• NGN and related Standard Bodies• The IMS as universal SDP• IMS Core Layer• IMS Applications Layer• IMS Introduction Strategies and Deployment Issues• The FOKUS Open IMS Playground as market driven NGN R&D Testbed• Summary & Q&A

162


IMS Introduction Challenges

– IMS Integration Challenges• Core Network, SCE&SDP, OSS/BSS, Charging System

ChargingSystem

OSS /BSS ?

Core NetworkInfrastructure

Applications SCE and SDPInfrastructure

?

?

?

IMS

Page 82

163


Wireline IMS Introduction

164


Wireless IMS Introduction

Page 83

165


Platform for migration to next-

generation network

Platform for fixed-mobile convergence

IMS Deployment Contexts

Platform for specific

service(s)

Project timescale

Project capex

166


IMS Deployment Worldwide

Source: visiongain

Page 84

167


IMS to „unglue“ the value chain

Value AddedServices

NetworkTransport

• Tight vertical integrationof network and services

• Limited access for 3rd Parties(MVNO, Service Provider)

• Operators struggle to offerattractive service portfolio

GSM value chain

IMS value chain

NG Service NetworkProvider

NetworkTransport

Service/ApplicationProvider

• Loose vertical integration of networks, services and applications

• Standardized interfaces alloweasy integration of partners

Focus on core competenciesand economies of scaleEnriched service offerings fortarget communities

„wholesale“ „retail“

168


Flatrates enable reasonable VoIP/Internet Access

WLO

TelcoPSTNxDSL

WLAN

LANEnterprise

MNOUMTSGPRS

Internet Service ProvidersAccess Network Providers

InternetApplication

Servers

Page 85

169


IMS as enabler for providing VA Internet Service

WNO

TelcoPSTNxDSL

WLAN/WiMax

LANEnterprise

MNOUMTSGPRS


UnsecureInternet

Applications

Secure IMSApplications

IMS Value Prepositions:-Security-QoS-Flexible Charging-Plug & Play

170


MNO providing Fixed Mobile Convergence

WNO

TelcoPSTNxDSL

WLAN/WiMax

LANEnterprise

MNOUMTSGPRS


UnsecureInternet

Applications

MNO FMC IMSApplications

Partnerships

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171


NGN, IMS and SDPs

Mobile Access Networks

(GSM, GPRS)

Fixed Access Networks

(PSTN/ISDN)

Cable / TV Networks

Fixed and Mobile Internet Access

IP Core NetworkBearer Cotrol (QoS)

Seamless Applications & Content (FMC)

Service Enablers

Session Control

IntelligentNetworks/ CAMEL

VoIPSIP ServersAAA Servers

InternetWeb Servers

JavaJAIN

CORBA / C++OSA / Parlay

SOAWeb Services

IP MultimediaSystem

NGN

NGN

SDP

172

GSM

GPRSEDGE

UMTSIMS

CDMA

WiFi

Satellite

Mobile AccessMobile Access Fix Access Fix Access

PSTN Cable

xDSL

Public networkPublic network

DECT

WiFi

Mobile AccessMobile Access Fix Access Fix Access

LAN

PBX

Private networkPrivate network

IPIP--BackboneBackbone

DB

Control Layer(MSC-Server, CSCF, AAA,..)

HLRHSS

App1App1App1VASP

SMSCUSSD Gw

LBS

IVR

MMSC

OTA

ContentDelivery

MRF

MediaGW

Service Execution Environment

App1 App2 App3

MRFPresence

ExposureOSA

Parlay /XOMA

SDPSDP

Abstraction Layer

Internetwwwwww

GoogleGoogle

blogsblogs

PortalsPortals

SkypeSkypeicqicq

GamingGaming

33rdrd Party ASPParty ASP

Sup

ervi

sion

Pro

visi

onin

gB

illin

gC

RM

Ope

ratio

n &

Mai

nten

ance

Access Network Layer

Connectivity Layer

Control Layer

ExposureLayer

Service Execution Environment

Service CreationEnablers(incl. Content

Delivery)

Abstraction Layer

Service Delivery Platform = Horizontal Layers

IMS

Page 87

173


SDP Technology Maturity Level

Introduction Growth Maturity Decline

Limitedcommercial deployments

Limited trials and technology evaluation

IMS

OSA/Parlay IN

Commercial deployments

Market acceptanceMature technology

Massive deployments

WebServices

Growingcommercial

deployments

174


Overview


Page 88

175


Fraunhofer FOKUS Facts

– FOKUS has been founded 1988 in Berlin, Germany– 220 employees: scientists, students, technicians

originating from 30 nations

– FOKUS is THE Telecoms R&D institute within theFraunhofer Society

• Fraunhofer Society is the biggest German R&D organisation, total # of 12.000 employees)

• 60 institutes in total, 15 institutes in ICT

– FOKUS works since 17 years on convergence of IT, telecoms, internet and homeentertainment and performs applied research and development projects

• Performs strategic studies, solution concepts, system integration and prototypdevelopments

• Strong cooperation with universities & Establishment of spin offs (e.g. iptelorg.com)

– FOKUS fundung: 20% state, 80% industry R&D projects

• Key to success: Strategic Partnerships with big players (DTAG, NTT, etc)

– Main R&D Vision: „I-centric communications“ and „autonomic communications“

176


Nat. Open 3Gb Test & Development Center– Provision of a unique 3Gb Testbed covering all

three 3G beyond layers– Foundation for industrial and academic projects

• Applications development support• Applications validation• Service Platform prototyping• Infrastructure component testing• Network Technologies integration• ....

– Officially supported by

Applications

UMTSFDD/TDD

GSM /GPRS

WLANa/b/x

DVB-S/T

weitere

3Gb Network Technologies

Service Platforms& Middleware

mGov

OtherNetws

Parlay

3Gb Roaming

SIPAAAIMS

weitere

Web services

Otherplatforms

mHealth mXXX. weitereweitereOtherApps

Eng

inee

rin

g T

oo

ls,C

on

form

ance

Test

ing

, M

easu

rmen

ts, a

nd

Man

agem

ent

European 3Gb R&D Projects

National 3Gb R&D Projects

NGN Testbed @ Fraunhofer FOKUS

Parlay Playground

IMS Playground

www.fokus.fraunhofer.de/national_host

Page 89

177


IMS playground @ FOKUS

• forms a globally unique state of the art IMS infrastructure featuring all majorIMS componentsand interfaces

• is a key infrastructure of the FOKUS NGN Service Delivery Platform test and development center

• comprises– a full IMS based on own developments– additional best of bread carrier grade components from partners

• Goals:– Provision of an open IMS platform and planned interconnection to

Operator IMS test beds– Interoperability test of IMS components (S-CSCFs, Media Gateways, SIP

AS, etc.)– Environment for development of new MM applications, application

platform extensions and IMS mobility, QoS and security reasearch• Contact: www.fokus.fraunhofer.de/ims

178


OPEN IMS Playground Overview

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179


FOKUS – developed IMS Components

• IMS Core– Call Session Control Functions

• SIP proxy with 3GPP features - SER– Home Subscriber Server

• Diameter based AAA Server- FHoSS– Media Server

• Media Streaming – SEMS

• IMS Application Layer– IMS compliant SIP Clients – OSC– Application Server

• SIP Servlet AS – SIPSEE• Parlay X Gateway – OCS-X• Parlay Gateway – OCS

180

Motivation for an Open Source IMS Core

• IMS is in trial phases with telco and cable operators worldwide• R&D efforts for NGNs are gaining support• While there are already many Open Source projects established in the

plain VoIP area for – SIP clients – SIP proxies – SIP stacks – SIP (testing) tools

around the standard, there are currently practically no Open Source projects with specific focus on the IMS

• FOKUS is aiming to fill this void

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181


Open IMS Core – Components

182


Call Session Control Functions

• CSCF = SIP proxy to route and process the SIP signaling

– Proxy-CSCF • outbound proxy for User Endpoints – entry point in the IMS network• keep local registrar and firewall the core network• add important network/charging/etc information to the messages• bridge between access network (visited network) and user’s home network

– Interrogating-CSCF• entry point in the Home Network• originating/terminating party assigned Serving-CSCF retrieval• stateless forwarding of messages

– Serving-CSCF• local registrar for served users• authenticate the users • subscription server for registration status events• evaluate Initial Filter Criteria and route messages accordingly to Application Servers for service

processing

I-CSCF

S-CSCF

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183


HSS & SIP2IMS Gateway

– Home Subscriber Server• evolution of a Home Location Register to the all-IP core network• stores user profile, provisioning data• keeps registration status• keeps location information

– SIP2IMS Gateway• allows transformation of IETF SIP messages to IMS conformant messages• Translates MD5 authentication to IMS AKA authentication

HSS

184


Elements around the Open IMS Core

Functionalitly of the Open IMS Core can be verified with additonalcomponents

– IMS UE• must be capable of performing IMS AKA registration• IMS specific SIP behaviour e.g. subscription to own registration event

– SIP client• uses IETF SIP protocols without IMS extensions (e.g. Kphone, eyebeam)• attaches to IMS Core via SIP2IMS Gateway

– Application Servers • tested Service platforms for the Open IMS Playground

• SIPSEE (SIP AS)• Open Coummincation Server (Parlay Gateway) • Open Communication Server X (Parlay X Gateway)

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185

T. Magedanz (TU Berlin / Fraunhofer FOKUS) - 2006Specification Guidelines for the Open SourceIMS Core

• IETF RFCs (selection)– SIP: Session Initiation Protocol – RFC 3261– Hypertext Transfer Protocol (HTTP) Digest Authentication Using Authentication

and Key Agreement (AKA) - RFC 3310– SIP Private Header Extensions - RFC3455– Diameter Base Protocol – RFC 3588– SIP Event Package for Registration - RFC3680

• 3GPP IMS Release 6 Specifications (selection)– TS 23.228 – IMS Stage 2 (Rel.6)– TS 24.229 - IP Multimedia Call Control Protocol based on Session Initiation

Protocol (SIP) and Session Description Protocol (SDP); Stage3 (Rel.6)– TS 29.228 – Cx and Dx Interfaces, Signalling flows and message contents

(Rel.6)– TS 33.102 - 3G Security; Security architecture (Rel. 6)– TS 33.203 - Access security for IP-based services (Rel.6)

186

The Open Source IMS Core

• A version of the Open IMS Core is currently being developed and was already successfully tested with commercial IMS products. It– provides first time implementations of core IMS components

• Call Session Control Functions• Home Subscriber Server

– offers an Open Source IMS platform to make use of the ISC interface– can act as a tool for IMS services proof-of-concept – allows to test alpha/beta versions of commercial IMS products– does not intend to compete with carrier grade developments but wants to

create an Open IMS community and to accelerates IMS adoption– release of the CSCFs scheduled for end of 2006 via the BerliOS

(www.berlios.de) platform

• For further information please contact{weik,vingarzan}@fokus.fraunhofer.de

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187


Integration of Partner Components @ FOKUS IMS PG

Not

e: T

his

isno

ta c

ompl

ete

Part

ner L

ist!

XDMS Presence

Testing

188


Reference Customers

– Consulting on IMS development strategies for major vendors– Consulting on bids and gap analysis of commercial products for key

global integrator– Extensions (Interfaces/Reference Points) of commercial solutions of

various vendors– Implementation of prototypes for vendors and operators– Integration and Compliancy testing of commercial solutions– Consulting on IMS integration strategies for major German Operator– Interoperability testing for major European vendors– IMS Load- /Perfomance testing for key global hardware vendor– Application Service development for major German operator– Consulting for establishing IMS Testbeds at remote sites – Plus German and European R&D projects on Feature Interaction and

Service composition

Page 95

189


FOKUS Work Areas in IMS/NGN

Open IMS Playground

Open SourceIMS Core

IMS Application

Server&Client

IMSBenchmarking

& InteroperabilityTools

VoIP / IMSSecurity

& Reliability

IMS Data

ManagementHSS

FMC / NGNApplicationsPrototyping

Consulting forOperators& Vendors

InteroperablityTesting &

Benchmarking

R&DProjects

FMC / IMSHandover

IMS /DVBIntegrationTriple Play

190


3GPPETSIOMA IETF ITU-T

ContributionTo

Standards

FOKUS NGN/IMS R&D Focal Points

DifferentAccess Networks

(WLAN, UMTS, DSL)

Interworking withLegacy Networks(GSM, ISDN, DVB)

NGN All IPCore Network

IP MultimediaSystem (IMS)

NGN Application Servers / APIsMM Content DeliverySingle Sign On (HSS)Service Orchestration

Model Driven Architecture(MDA)

Content & Services

Development of necessary Services

Client Software

Integration of different Access Networks

QoS Provision & Security

Interworking with other networks

IMS Management + AAAIMS Conformance Tests

Scalability & Performance

www.fokus.fraunhofer.de/IMS

Page 96

191


Summary

• IMS – is an overlay service network architecture applicable to any IP network

(GPRS, UMTS, WLAN, DSL, ..) based on internet standards (IETF)– is a global standard (supported by 3GPP, 3GPP2, ETSI, OMA, IETF)– can be considered as THE universal Service Delivery Platform for NGNs

supporting also Fixed Mobile Convergence (FMC)• IMS should be mainly considered as a service enabler (i.e. no real IMS

services are standardised!)• Push to Talk / PoC can be regarded as first IMS real life proof of

concept• But biggest service potential is in Community-based services• FOKUS provides knowhow and a powerful infrastructure for testing

IMS components and prototyping IMS / NGN services

192


Any Questions?

Page 97

193


IMS ReferencesTS 23.228 Archi IP Multimedia Subsystem (IMS); Stage 2 S2TS 33.203 Security Access Security (& integrity protection) for IP-based Services”, Stage 2 S3TS 33.210 Security Netw. domain sec.; IP network layer security (sec of SIP signalling between network nodes) S3TS 23.218 Call Control IP Multimedia (IM) session handling; IM call model; Stage 2 N1TS 24.228 Call Control Signalling flows for the IMS Call Control based on SIP and SDP; Stage 3 N1TS 24.229 Call Control IP Multimedia Call Control Protocol based on SIP and SDP; Stage 3 N1TS 26.235 User plane Packet Switched Conversational Multimedia Applications; Default codecs S4TS 26.236 User plane Packet Switched Conversational Multimedia Applications; Transport protocols S4TS 29.162 Interworking Interworking between the IM CN subsystem and IP networks N3TS 29.163 Interworking Interworking between the IM CN subsystem and CS networks N3TS 23.278 Service Logic CAMEL - IP Multimedia System (IMS) interworking; Stage 2 N2TS 29.278 Service Logic CAMEL Application Part (CAP) specification for IP Multimedia Subsystems (IMS) N2TS 29.228 User data & interfaces IP Multimedia (IM) Subsystem Cx and Dx Interfaces; Signalling flows and message contents N4TS 29.229 User data & interfaces Cx and Dx interfaces (based on Diameter) Protocol details N4TS 29.328 User data & interfaces IP Multimedia Subsystem (IMS) Sh interface signalling flows and message contents N4TS 29.329 User data & interfaces Sh interface based on the Diameter protocol N4TS 22.115 Charging Charging & Billing, Stage 1 S5TS 23.815 Charging Charging implications of IMS architecture S2/S5TS 32.225 Charging Charging data description for the IMS - Rel 5 S5TS 32.260 Charging IMS Charging - Rel 6

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