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IMS: An Architecture for Convergent Next Generation Multimedia Services. Research and Standardisation Challenges. Dr. Sorin Georgescu [email protected] Agenda. IMS Architecture Overview Standardisation Status The Service Layer View IMS and SOA

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IMS: An Architecture for Convergent Next Generation Multimedia Services. Research and Standardisation Challenges

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IMS: An Architecture for Convergent Next Generation Multimedia Services. Research and Standardisation Challenges

Dr. Sorin Georgescu

[email protected]


Agenda l.jpg

Agenda

  • IMS Architecture Overview

  • Standardisation Status

  • The Service Layer View

  • IMS and SOA

  • Research and Standardisation Challenges


Next generation networks evolution drivers l.jpg

Next Generation Networks Evolution Drivers

  • Societal and Business trends

  • Internet is becoming a major enabler of communications

  • Consumers are embracing computing, mobile and digital technology in their everyday life

  • Evolution of Business models require increased levels of personal mobility

  • Convergence

  • Converged devices (Mobile, WLAN, Internet etc.)  Connectivity

  • Converged services  Ease of use

  • Converged networks  Reliability, Security, Reduced OPEX/CAPEX

  • Converged business models  Increased margins, Avoidance of twin pitfalls risk

  • Access Technology Enhancements

  • HSPA (High Speed Packet Access) – evolved WCDMA

  • OFDMA (Orthogonal Frequency Division Multiple Access) – 3GPP LTE, WiMAX, MBWA, ADSL/VDSL, DVB-T/H etc.

  • Spatial Processing – multi-antennas Base Stations supporting advanced spatial processing


The evolution to ims multimedia applications l.jpg

Non-Interactive Multimedia

Movies

Video

Music

Ring tone

Person-to-Contentknown usability patterns

Photos

Internet

Streaming

Text/Pictures

Download

Interactive Multimedia

HTTP

Video

SMS/MMS

Active

phonebook

Person-to-Persondominates traffic growth

Image

Sharing

Text

Presence

Voice

Push-To-Talk

MMS

SMS

Voice

The Evolution to IMS Multimedia Applications


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Watch and Communicate service

  • While out in town, Bob stopped by at the Jazz festival. He made a short clip and would like to ask his friends if they are interested to go to the evening performance.

  • He checks the presence information of Alice and Dave.

  • Bob opens a Chat session and sends the clip to his friends. He asks if they are interested to go to the evening performance.

  • Dave is watching TV, therefore the chat session is diverted to his IMS enabled STB.

Communication services

Personalised content services

Group and context support


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IMS – a Standard-based Architecture for NG Services

  • IMS defines an open IP-based service infrastructure where service intelligence is located in the servers and mobile devices.

  • IMS as originally specified by 3GPP, was aiming to enable real-time multimedia services over the IP bearer in GSM and W-CDMA networks.

  • 3GPP2 defined later the MMD for CDMA2000 networks which is now aligned with IMS.

  • TISPAN provided the specifications for DSL access.

  • CableLabs provided the specifications for the cable access and now their work together with 3GPP to incorporate PC 2.0 specifications into IMS release 8.

  • Since release 6, interworking with WLAN is supported.

  • If IMS is not used:

    • Multimedia communication at best effort

    • Service orchestration can be complex

    • Service roaming can be difficult to implement

    • Provisioning and charging are service specific

    • Compliance with LI requirements can be an issue


Ims tispan architecture l.jpg

AS

Application

(SIP AS,

OSA AS,

CAMEL SE)

HSS

OSA SCS

‘IMS Data’

IM SSF

SIP AS

SLF

HLR/AuC (‘CS/PS’)

CSCF

BGCF

S-CSCF

I-CSCF

IMS Session Signalling

IMS User Plane Data

MGCF

P-CSCF

NASS

SPDF/ A-RACF

SGW

MRF

IMS GW

CS Networks

(PSTN, CS PLMN)

DSLAM

UE

BAS

PDF

MRFC

ALG

3GPP R7 / TISPAN R1

MRFP

IMS-MGW

TrGW

WLAN

PDG

WLAN WAG

UE

IPv4 PDN

(IPv4 Network)

3GPP R6

BB

(IPv4/

IPv6)

PEF

GGSN

BG

IPv6 PDN

(IPv6 Network)

UE

RAN

SGSN

3GPP R5

IMS/TISPAN Architecture


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Functional Overview (1)

  • CSCF (Call Session Control Function) consists of 3 separate functions: P-CSCF, I-CSCF, S-CSCF

  • P-CSCF (Proxy-CSCF):

    • Entry point to IMS from any access network

    • Performs integrity protection

    • Local outbound stateful proxy for all SIP requests/responses, ensuring all signalling is sent via the home network

    • Includes a Policy Decision Function (PDF) that authorizes bearer resources

  • I-CSCF (Interrogating-CSCF):

    • First contact point in home network

    • Selects assigned S-CSCF

    • Performs network hiding (THIG)

  • S-CSCF (Serving-CSCF):

    • Stateful proxy that provides session control

    • Performs subscriber authentication

    • Acts as SIP registrar

    • Invokes the AS’ (Application Servers) based on IFC (Initial Filter Criteria)

  • SLF (Subscriber Location Function):

    • Look-up function used in networks where multiples HSS’ exist

  • HSS (Home Subscriber Server):

    • IMS subscriber records and service profile

    • IMS authentication data

  • MRF (Media Resource Function) consists of 2 separate functions: MRFC, MRFP

  • MRFC (Media Resource Function Controller):

    • Controls media resources in MRFP

    • Acts as SIP B2BUA

  • MRFP (Media Resource Function Processor):

    • Media stream processing (transcoding etc.)

    • Multimedia announcements

    • Incoming streams mixing


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Functional Overview (2)

  • SIP AS (Application Server):

    • Hosts IMS native applications

  • IM SSF (IP Multimedia Switching Service Function):

    • Provides interworking with CAMEL, ANSI-41, INAP or TCAP services

  • OSA SCS (Open Service Architecture Service Capability Server):

    • Provides interworking with OSA services

  • BGCF (Breakout Gateway Control Function):

    • Selects the network in which PSTN breakout is to occur and within that network selects the MGCF

  • MGCF (Media Gateway Control Function):

    • Controls media channels in IMS MGW

    • Performs conversion between ISUP/TCAP and IMS call control protocols

  • IMS MGW (IMS Media Gateway):

    • Terminates bearer channels from CS networks and PS media streams

    • Owns/handles resources (echo cancellers, codes, etc.)

  • SGW (Signaling Gateway):

    • Performs conversion at transport level (SCCP, SCTP)

  • SBC (Session Border Controller):

  • PDF/SPDF (Policy Decision Function / Serving Policy Decision Function):

  • A-RACF (Access - Resource and Admission Control Function):

  • NASS (Network Attachment Subsystem):

  • DSLAM (Digital Subscriber Line Access Multiplexer):


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IMS Service Routing – the IFCs

  • In comparison to IETF SIP Routing where the originator of SIP request may specify a preferred path in the Route header, in IMS the P-CSCF removes this path and ensures that IMS SIP Routing is followed.

  • SIP requests in IMS architecture are always routed to the Home S-CSCF, in both the originating and terminating network.

  • The S-CSCF uses subscriber’s Service Profile (downloaded during registration), to link-in the SIP AS’ which will process the SIP request.

  • The Initial Filter Criteria (IFC) within the Subscriber Profile provide a simple service logic to decide which AS shall be linked-in. These rules are of static nature i.e. they do not change on a frequent basis.

IMS AS

HSS

Home B

IMS AS

HSS

Home A

2

7

9

5

1

8

6

S-CSCF

I-CSCF

S-CSCF

4

10

Visited B

Visited A

P-CSCF

P-CSCF

3

11

IMS Service Routing = Service Profile based Routing


Service application identification icsi iari l.jpg

Appl 1

Appl 2

IARI2

IARI2

IARI1

CS 1

CS2

ICSI1

ICSI2

SIP Stack

Service/application identification – ICSI/IARI

A Communication Serviceis an aggregation of one or several media components and the service logic managing the aggregation, represented in the protocols used.

An IMS application is an application that uses an IMS Communication Service(s) in order to provide a specific service to the end-user. Only IMS applications other than the default application associated to the Communication Service are identified through IARIs.

  • 3GPP TS 23.228 R7 introduced the ICSI/IARI identifiers as a mechanism for UEs to provide a hint to the network on the AS’ they wish to be linked-in the signalling path.

  • The introduction of ICSI/IARI in 3GPP aims to address to a certain extent the limitations due to the use of the Service Profile routing paradigm. The ICSI/IARI are used as parameters in the IFC, therefore the AS selection process becomes more dynamic.

  • The ICSI/IARI provides a mechanism to control rating based on selected pricing model. For example, it is possible to rate differently a Messaging Communication Service when invoked from a Multimedia application then when invoked from a Gaming application.

ICSI = IMS Communication Service ID

IARI = IMS Application Reference ID

CS = Communication Service


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Service Convergence in Quadruple Play

Industry consolidation and alliances

=

Convergence at Service Provider level.

End User experience

=

Access to subscribed services from any device in the bundle

Service continuity

Common provisioning, mgmt and billing

Common service and subscriber management

Fixed Mobile Convergence

=

Converged Service Architecture

Setup of the appropriate QoS and resources


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Agenda

  • IMS Architecture Overview

  • Standardisation Status

  • The Service Layer View

  • IMS and SOA

  • Research and Standardisation Challenges


Standardisation fora l.jpg

VCC

CSI

Presence

PoC

Messaging

GLMS

Standardisation fora

Multimedia

Telephony

IP

GSM/WCDMA Access to IMS

Broadband Access to IMS

WLAN Access to IMS

PacketCable™

WiMAX

Forum

DOCSIS

DSL

Forum

Mobile

Enterprise

Residential


3gpp r7 reference model l.jpg

C

HLR/AuC* HSS*

SMS-GMSCSMS-IWMSC

R

R

Wo

Um

Wu

Uu

Wp

Wn

Ww

Mw

**

Wf

Dw

Wg

MSC

EIR

Gb, Iu

AF

PCRF

Wx

Gf

Gs

BM-SC

SMS-SC

Gi

GGSN

SGSN

IMS-MGW

Mb

SGSN

MRFP

OCS*

CGF*

IMS

TE

MT

UTRAN

P-CSCF

CSCF

PDN

Intranet/

Internet

Wd

Gd

Wy

Ga

Gmb

Gr

Iu

Rx+ (Rx/Gq)

Mb

Wz

Gn/Gp

Wa

Wa

Gm

Gx+ (Go/Gx)

Gi

3GPP AAAProxy

3GPP AAAServer

BillingSystem*

BillingSystem*

Gy

Cx

Dx

Gn

Wf

GERAN

TE

MT

WLANUE

HLR/AuC*

WLAN AccessNetwork

CDF

HSS*

SLF

D/Gr

Ga

Gc

Wi

OCS*

Wm

WAG

PDG

Note: * Elements duplicated for picture layout purposes only, they belong to the same logical entity in the architecture baseline.

** is a reference point currently missing

UE

CGF*

Traffic and signalling

Signalling

3GPP R7 Reference Model


Tispan r1 reference model l.jpg

S/T

S/T

GW

TISPAN R1 Reference Model

Application Servers

Rf

/Ro

Ut

Rf

/Ro

Other types of service logic

Charging

Ut

Functions

PSTN/ISDN Emulation logic

Network

Sh

Rf

/Ro

ISC

Dh

Attachment

UPSF

Iw

SLF

Cx

IWF

Subsystem

Dx

Ib

P3

PES

e2

Mw

e2

Mw/Mk/Mm

IBCF

Ic

I/S

-

CSCF

P2

P1

Mk

AGCF

Mi

Mk

BGCF

Mw

Mr

Mj

Gq

'

Gm

Mg

SGF

P

-

CSCF

MGCF

MRFC

Ie

Other IP Networks

Gq

'

Gq

'

PSTN/ISDN

Mp

Mn

Resource and Admission Control Subsystem

MRFP

Z

Z

T

-

MGF

S/T

S/T

IP Transport (Access and Core)

I

-

BGF

MG

Z

Z


Wis in 3gpp release 7 02 2008 l.jpg

WIs in 3GPP release 7 (02/2008)

  • Coexistence between TISPAN and 3GPP authentication schemes study

  • SAE (System Architecture Evolution)

  • RAN LTE (Long Term Evolution)

  • MMTel (Multimedia Telephony)

  • VCC (Voice Call Continuity) between IMS VoIP and CS speech

  • CSiCS (Circuit Switched IMS Combinational Service)

  • SMS/MMS over IP

  • FBI (Fixed Broadband access to IMS)

  • IMS Emergency Calls

  • PCC (Policy Control and Charging Evolution)

  • E2E QoS

  • AIPN (All IP Network) Feasibility Study

  • Service Identification using ICSI/IARI

  • Liberty Alliance and 3GPP security interworking

  • Location Services for WLAN interworking

  • MRFP-MRFC (Mp) Interface

  • Parlay X WS:

    • Message broadcast

    • Geocoding

    • Application driven QoS

    • Device Management

    • Multimedia Streaming/Multicast Control

  • ISIM API for Java Card


Wis in 3gpp release 8 tentative 03 2009 l.jpg

WIs in 3GPP release 8 (tentative 03/2009)

  • Architecture impacts of Service Brokering

  • Enhancements for support of PacketCable 2.0 requirements

  • Multimedia Priority Service

  • Personal Network Management

  • Enhancements for support of machine to machine communication

  • Enhanced Generic Access Networks

  • HSPA FDD (Frequency Division Duplex)

  • Enhancements to SAE/LTE Architecture

  • OAM&P Studies


Agenda19 l.jpg

Agenda

  • IMS Architecture Overview

  • Standardisation Status

  • The Service Layer View

  • IMS and SOA

  • Research and Standardisation Challenges


Ims in oma service environment context l.jpg

IMS in OMA Service Environment context


Oma simple im reference model l.jpg

OMA SIMPLE IM Reference Model


Limitations of isc service orchestration model l.jpg

Limitations of ISC Service Orchestration Model

SIP-AS

SIP-AS

SIP-AS

SIP-AS

SIP-AS

SIP-AS

Req URI = A

Req URI = B

S-CSCF

S-CSCF

HSS

HSS

I-CSCF

I-CSCF

  • The application server decides whether to remain linked-in for the whole session by adding its address to the Record-Route SIP header.

  • Application Servers are unaware of the existence of other AS', and whether these will be linked-in.

  • No service or session state will be passed between application servers unless they use proprietary extensions i.e. are co-designed.

  • Response messages are routed to the AS’s in the reverse order

  • If during call handling procedure an AS retargets the SIP request by changing the Request URI, subsequent filter analysis in the S-CSCF is stopped and the S-CSCF forwards the request towards the new target without linking-in the other AS’ specified by IFC.

1

2


Scim vs service broker l.jpg

SCIM vs. Service Broker

Camel Services

AS

AS

OSA AS

AS

AS

AS

AS

OSA API

CAP

SCIM

OSA SCS

IM SSF

Service Broker

Service Broker

MAP

ISC

Si

ISC

ISC

Sh

Cx

HSS

S-CSCF

Sh

S-CSCF

  • The Service Broker architecture has been introduced as WI in IMS Release 8.

  • The objective is to provide a coherent and consistent IP multimedia service experience when multiple applications are invoked.

  • The work is handled by 3GPP SA2 (Architecture) group in TR 23.810. So far, just the some high level deployment scenarios and some uses cases have been defined.

  • Can be centralised, distributed or hybrid (as in the figure above).

  • The Service Capability Interaction Manager (SCIM) orchestrates service delivery among application servers.

  • Underspecified in TS 23.002, the SCIM has become a sort of “magic box” that would solve all issues related to service orchestration.

  • Possible types of SCIM:

    • AS Internal SCIM (figure above)

    • SIP Broker SCIM / Service Broker SCIM

    • Legacy SCIM


Parlay x web services l.jpg

Parlay X Web Services

WS-I Basic Profile: WSDL + SOAP

WS-I Secure Profile: WSDL + SOAP + WS-Security

  • Parlay X Web Services is an abstraction of Parlay WS

  • Parlay X WS GW acts as a Service Broker SCIM

  • Enablers which only support WS-I Basic Profile are enhanced with additional WS functionality such as WS-Security, WS-Policy, WS-Addressing

  • Services defined so far (17) cover: call control, messaging (SMS, MMS), payment, location, geocoding and mapping, presence etc.

  • Described in WSDL. Service discovery is based on UDDI.


Agenda25 l.jpg

Agenda

  • IMS Architecture Overview

  • Standardisation Status

  • The Service Layer View

  • IMS and SOA

  • Research and Standardisation Challenges


Soa reference model l.jpg

SOA Service Description Model

SOA Reference Model

  • What is SOA:

  • A paradigm which defines concepts and general techniques for the design, encapsulation and instantiation of reusable business functions using loosely coupled service interactions

  • SOA Reference Model:

    • Service

    • Service description

    • Interaction

    • Contract & Policy

    • Visibility

    • Execution Context

    • Real world effect


Soa orchestration l.jpg

Client

SOA Orchestration

Routing based on service identity (equivalent to PSI routing in IMS)

  • SOA Characteristics

  • Services have well defined Service Contracts

  • Services are encapsulated

  • Services share a message bus and messages exchanged are well documented

  • Services can be discovered dynamically

  • Services are loosely coupled

  • Systems of services are assembled at runtime

  • Service bus functions:

  • Supports an asynchronous message based communication protocol that uses a common format encoding scheme (SOAP/XML)

  • Routes, Translates and can Store and Forward exchanged messages

  • Supports a Discovery mechanism


Ims soa architecture l.jpg

Service Contract

SOA

UDDI

SOA AS

Schema

SOAP/XML

MLP

SIP

Service Bus

MM7

SB API

SB API

SB API

Enabler

IMS AS

GW AS

Orig. network

CSCF

IMS

JSR 281

Heterogeneous Service Bus IMS-SOA Architecture

IMS-SOA Architecture

  • Service Enablers:

  • Provide functionality which can be used by other end-user applications (ex. Location Service)

  • Unaware of the context in which they are used. Only the consumer service is aware.

  • Service Bus

  • Handles the communication between IMS Application Servers and the Service Enablers and the communication with SOA Application Servers.

  • Optimized for Server-to-Server communication

  • Besides providing support for standard open protocols (ex. SOAP), may provide support for Native Interface protocols (ex. MLP, MM7, SIP etc.)

  • Service Orchestration

  • The consumer AS that invokes the Service Enabler implements the SCIM function. An external Service Broker may be used as well.

  • IMS Service Enablers are invoked from SOA domain through the GW AS.


Agenda29 l.jpg

Agenda

  • IMS Architecture Overview

  • Standardisation Status

  • The Service Layer View

  • IMS and SOA

  • Research and Standardisation Challenges


Ims core network l.jpg

IMS Core Network

  • Coexistence of access specific authentication methods

  • Media Adaptation using UE capabilities discovery

  • Design of efficient algorithms for real-time adaptation of MBMS content

  • Access agnostic vs. access aware P-CSCF

  • QoS awareness, access agnostic control of the QoS

  • Media security


Ims service layer l.jpg

IMS Service Layer

  • Service Orchestration paradigms. The integration with SOA architecture

  • Enhancements to presence service to support device capabilities, subscription state, user preferences, context awareness, bearer state

  • Multimodal interaction

  • Payment brokerage

  • Personalised/interactive advertisement

  • QoS control over the Service Bus.


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Thank you for your attention!

[email protected]


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