workshop ims chalmers 2007
TRANSCRIPT
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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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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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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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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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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
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2
4
2
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2
29
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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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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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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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IMS and NGN (2)
Evolution towards a unified service delivery plattform
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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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Architecture and Technical Issues of the IMS (2)
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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Architecture and Technical Issues of the IMS (3)
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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Architecture and Technical Issues of the IMS (5)
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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Architecture and Technical Issues of the IMS (5)
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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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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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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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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IMS Market and Economic Issues (2)
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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IMS Market and Economic Issues (3)
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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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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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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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.