workshop ims chalmers 2007

8/9/2019 Workshop IMS Chalmers 2007

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GHEODE

J. Antonio Portilla-Figueras

Associate Professor

Signal Theory and Communication Department

University of Alcala.

3GPP IMS:Control Plane for Multimedia Sessions

and Fixed Mobile Convergence


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GHEODE 2

Index

Introduction: Telecommunication network evolution

Next Generation Network (NGN) and IP Multimedia Subsystem

(IMS)

Architecture and Technical Issues of the IMS

IMS Services and Applications

Market and Economic Issues

Regulatory Requirements


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GHEODE 3

Introduction (1):

Drivers of the evolution of telecommunication networks

Demand for new services by users Videoconference

VoIP

Rich Media

Streaming

Technological advances Mobile Access (GSM, UMTS, WiFi)

Fixed Access (xDSL, Cable, PLC)

Trunk Networks (DWDM, SoftSwitching)

Mixtures of both, typically market

issues The more they offer the more you want The evolution of the networks

is pushed by several factors.


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GHEODE 4

Introduction (2):

Service Evolution

In the past 20 years customer services have evolved in threeinterrelated lines 1)Operator Service Briefcase

2)Service Bundling, Charging, Customer Aware Network Services.

3)Traffic Migration

Let give a short explanation about these three points:

1) Operator Service Briefcase


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GHEODE 5

Introduction (2a):

Service Evolution contd

2) Service Bundling: the trend is that operators offer packages ofunified services

More than 50 % of the world users would say yes to bundling services

[Cambridge-2005]

7

2

7

5

40

9

26

8

2

4

2

8

4

7

9

6

4

2

29

5

9

4

0%

0%

20%

0%

40%

50%

60%

70%

80%

90%

00%

orld

verage

merica

merica

urope

candinavian

urope &

ussia

Bundeling Service Acceptance

Strongly

gree

Disagree

Neutral

Agree

StronglyAgree


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GHEODE 6

Introduction (2b):

Service Evolution contd

3) Traffic Migration, [Visser-200 ]

There is a clear trend in traffic migration from fixed

access to mobile (wireless)

Intention of Access [Cambridge-2005]

Primary Phone De

ice for Year 2007

66

4

obile Phone

Fi

ed Phone

In

erne

(!

oIP) phone


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GHEODE 7

Introduction (3)

Telecommunicaton Network Evolution

The oldWorld

The new

world

[Zuidweg-2005]


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IMS and NGN (1)

The NGN is:

A Next Generation Network (NGN) is a packet-based network able to provide

services including Telecommunication Services and able to make use of

multiple broadband, QoS-enabled transport technologies and in which

service-related functions are independent from underlying transport-related

technologies. (Adapted from ITU-T [ITU_1-200 ] )

The IMSis IP Multimedia Subsystem (IMS) is a standarized access independent IP

based architecture that interworks with existing voice and data networks for

both fixed and mobile users. (Adapted from 3GPP [3GPP_1-200 ])

The NGI is

It is an initiative to empower the current Internet using IPv protocol to obtain

high speed networks fulfilling QoS and reliable communication services(Adapted from the Internet2 Network [I2-200 ])


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GHEODE9

IMS and NGN (2)

Evolution towards a unified service delivery plattform


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GHEODE10

IMS and NGN ( )

Why IMS?[Gilles-200 ][Schmidt-200 ]

Continuity of the current business model for the deployment

of IP based services.

Gets greater average revenue per user.

Reduces the churning propensity.

Network administration savings.

A end-to-end open architecture.

Core network independent from the access.

Integrated mobility and nomadicy.


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Architecture and Technical Issues of the IMS (1)

IMS and layering architecture [Poiselk-200 ][3GPP_1-200 ]


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The previous architecture has been designed considering a

layering approach defined by 3GPP.

There is another architecture, defined by the ETSI TISPAN with

the NGN as the starting point .

The transport and bearer services are separated from the IMS

signalling network and session management services

This leads to a minimum interdependency between layers and

independency between access and core network.

Same applications can run on UE using different types of

access.

Next we are going to study the main elements of the 3GPP IMS

architecture


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GHEODE 13


The CSCF is at the heart of the network. It is subdivided into three

responsiblity areas

Proxy (P-CSCF). This is the first contact point of the users withinthe IMS. All SIP traffic to or from UE goes via the P-CSCF. It behaves

like a proxy validating the request, forwarding them to the destination

and forwarding the response. Interrogation (I-CSCF). Is the contact point within an operators

network for all connections destined to a subscriber of that network

operator.

Serving (S-CSCF). It is the brain of the IMS and is in the homenetwork. Peforms session control and registration services for UE. It

maintain the session state and works with the service plattforms andcharging functions.


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Architecture and Technical Issues of the IMS ( )

The Policy Decision Function (PDF) is responsible for making

policy decisions based on session and media related information

obtained from the P-CSCF. It acts as a policy decision point for

the Service Base Local Policy.

[Sheppard-200 ]


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GHEODE 15


TheH

ome Subscriber Server (H

SS) is the main data storagefor all service related data of the IMS. It includes user identities,

registration information, access parameters, and service

triggering information.

Multimedia Resource Function Controller (MRFC) is needed to

support bearer related-services, (conference announcing)

Multimedia Resource Function Processor (MRFP) providesuser-plane resources requested and instructed by the MRFC.


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GHEODE 16


The Application Server (AS) is not a pure IMS entity but

provides the value added multimedia services in the IMS. The

main functions are

The possibility to process an incoming SIP request.

The capability to originate SIP request

The capability to send accounting information

Media GatewayControlFunction (MGCF), is a gateway that

enables communication between IMS and CS users.

IPMultimedia Subsystem-Media GatewayFunction (IMS-

MGW). Provides the user-plane link between CS network and

IMS. SignallingGateway (SGW) is used to interconnect different

signalling networks, as SCTP-IP to SS .


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Architecture and Technical Issues of the IMS ( )

Protocols used in the IMS. Session Initiation Protocol (SIP). For establishing, modification and termination

of multimedia sessions between two terminals. It is the key of the IMS system.

Session Description Protocol (SDP):An application layer protocol for describing

multimedia sessions. Text base, describes the type address, ports..and indicates

them to the calling parties.

Diameter is an authentication, authorization and accounting (AAA) protocolwhich provides AAA services to a large range of access technologies.

Real Time Transport Protocol (RTP) is a protocol defined for providing e2e

delivery of real-time data. It also contains services for this type of data (payload

type, monitoring). It does not provide QoS but QoS monitoring using Real Time

Control Protocol (RTCP)

Common Open Policy Service (COPS). It supports policy control of the Quality of

Service (QoS) signalling protocols like Resource Reservation Protocol.


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GHEODE 18

IMS Services and Applications (1)

3GPP does not provide standardised services but servicecapabilities and high level requirements [Zarri-2003].

The following requirements have to be fulfilled for IP multimedia

applications [3GPP-2005].

Negotiable QoS for IP multimedia sesions

During the establishment.

During the session

For individual media components.

Negotiation of QoS between operators in roaming.

Support of variety of media types.

Within each IP multimedia session one or more IP multimedia applications

shall be supported


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GHEODE 19

IMS Services and Applications (2)

The end user services can be categorized into two main types

[GSMA-200 ].

Type (as perceived by the

users)Description Typical Services

User to User Services

These services involves 2 or more

users

Network provides and add value

providing services managing. It

can arise problems due to the

influence of 3rd parties

Voice

Videophone

Rich Media.

Advance Messaging.

Push to Talk

Gaming.

Services between Users and a

Server

Involves one or more users whocommunicate with a central server

Network may only provide an bit

pipe if 3rd party servers are used

Advance messaingGaming (User vs

Machine)

Push services.


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GHEODE20

IMS Market and Economic Issues (1)

The Service Providers [Hart-2005]

Provider Description Services Example

Traditional Wireline PSTN with mixed TDMand VoIP networks

Residential and businesstelephony, DSL .

BT, Telefonica, FranceTelecom, Magyar Telekom

Mobile Carriers 2-2.5G, 3G G? Serviceproviders

Cellular telephony, SMS,MMS, gaming,

Orange, Vodafone, EplusPannon GSM

MVNOs Brand focused vendorswhich lease cellularcarriers networks.

Pre-paid, streaming, SMS,sports news, video

BT, Walt Disney Group,Virgin

NGSP Internet based VoIPproviders without their own

access network

Broadbandcommunications, VoIP

Vonage, AT T, Euphonex

Cable Cable operators with

growing telephony andVoIP products

Broadcast TV channels,

cable modem service,Internet Telephony

ONO, Telewest, Cable

Wireless, UPC Hungary

Content and

Application provider

Media films, advertisers,multimedia contentproviders

TV programs, music,movies

Time Warner, BBC,Vivendi, Sony, NBC.


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GHEODE21


The path towards IMS

IMS

Maturity

Name SIP

Elements

IMS /

APPs

CSCFs Data on

HSS

IMS

Clients

Date

0 Not IMS None None None None None 2000-2005

0.5 Pre-IMS Few Maybe Maybe None None 2005-200

1 Some IMS Some Some Some Some Maybe 200 -200

2 Real IMS Most Many Most Most Some 200 -2012

3 Ideal IMS All All All All All 2012->


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GHEODE22


IMS critics [Moriana-200 ]

The technology is not ready yet.

There are serious doubts about the interoperability.

It is going to be very difficult to make it all work.

There is no real customer demand for combinatorial services.

The new services are not really new.

IMS threats

Traditional vendors may take all the IMS equipment cake.

IMS is an architecture, not a service. It does not provide direct revenues.

Subscriber will expect all services to be free, as they are in Internet.

Again interoperability.

Unproven business case

Migration cost.


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GHEODE23

IMS regulatory requirements (1).

Consumer requirements

Emergency calls.

Consumer protection and privacy.

Fraud Detection.

Operations requirement.

Roaming and service provider coordination

Default service and routing options.

Competition requirements

Number portability

Service interoperability

Unbundling.

Interconnection

Billing

[Rutkowski-2005]


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GHEODE24

IMS regulatory requirements (2):IMS Billing

There are two main billing options Recurrent billing (Off Line Billing). The user receives a bill every month.

The Charging Collector Function (CCF) recovers information of all IMS

elements and constructs the Charging Data Record which generates the

invoice.

Transaction Based Billing (On Line Billing). The serving CSCF

communicates with a Session Charging Function (SCF), which controlsthe available user credit and control the IMS elements.

Several problems could arise here

Termination of sessions of another network users.

Information interchange between the Charging system of different

networks

Flat rate.


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GHEODE 25

References

[Cambridge-2005] A.T. Kearney Cambridge Study, Mobinet 2005.

[Visser-200 ]. J. Visser, Mobility and Fixed Mobile Convergence, GSC-

11, November 200

[Zuidweg] J. Zuidweg, IMS for Fixed and Mobile Convergence,

[Tf-2005] J. Relao et all, Plataformas Multimodales en Redes de

Nueva Generacin, Comunicaciones Telefonica I+D, March 2005. [ITU_1-200 ] ITU, Definition of Next Generation Network

http://www.itu.int/ITU-

T/studygroups/com13/ngn200 /working_definition.html

[3GPP_1-200 ], 3GPP TS 23.22 version . .0 Release .

[I2-200 ] Internet 2 Home Page, www.internet2.edu

[Gilles-200 ] G. Bertrand, The IP Multimedia Subsystem (IMS) An

Overview, http://www.rennes.enst-

bretagne.fr/~gbertran/files/IMS_an_overview.pdf


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References

[Schmidt-200 ] D. Schmidt, D. Kamarga, Economic Drivers for IMS-based Converged Services, Siemens Networks LLC white paper.

[Sheppard-200 ] S. Sheppard, IMS Crash Course, McGraw Hill, 200

[Moro-2005 ] D. Moro, A. Jular, S. Fernndez, Estudio de la

interconexin entre redes fijas y mviles en el plano de control mediante

los estndares IMS de 3GPP y NGN de TISPAN, Journal

Comunicaciones de Telefonica I+D, n 3 , pp 111-11 , 2005.

[Zarri-2003]M. Zarri, Future service capabilities offered by the 3GPP

system; th International Conference on 3G Mobile Communication

Technologies, 2003.

[3GPP-2005]Service Requirements for the Internet Protocol (IP)

multimedia core network subsystem (IMS). 3GPP TS 22 22 V .5.0 (00-200 ).

[GSMA-200 ] IMS Services Applications, GSM Association Official

Document: SE.35, December 200 .


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References

[Hart-2005] C. Hart, IP Multimedia Substymes (IMS) forwireline and wireless applications Venture Development

Corporation, White paper.

[Moriana-200 ] Operator Guidebook to IMS and Next

Generation Network and Services, www.morianagroup.com,

200

[Rutkowski-2005] A. Rutkowski, The NGN Global Regulatory

Ecosystem, Open Workshop Indentifying policy and regulatory

issues in Next Generation Networks, Brussels, June 2005

[Arnbak-2000] J. Arnbak, Regulation for Next Generation

Technologies and Markets, Telecommunications Policy, n 2 ,

2000.

workshop ims chalmers 2007

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