Functional Architecture for NGN-Based Personalized IPTV Services-LVV

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IEEE TRANSACTIONS ON BROADCASTING, VOL. 55, NO. 2, JUNE 2009 329

Functional Architecture for NGN-BasedPersonalized IPTV Services

Gyu Myoung Lee, Member, IEEE, Chae Sub Lee, Woo Seop Rhee, Member, IEEE, andJun Kyun Choi, Senior Member, IEEE

AbstractIPTV is one of the most highly visible services toemerge as part of the development of next generation network(NGN). IPTV services over manageable broadband link froma provider will be one of the ultimate goals of the broadbandrevolution using NGN. In this paper, we analyze IPTV archi-tecture developed by ITU-T and provide functional architecturefor NGN-based IPTV services according to functional mappingbetween IPTV and NGN. For this, we provide the detailed func-tional architecture and relevant operations with other functionalblocks and present the harmonized architecture between IPTVand NGN for NGN-based IPTV services with the alignment withexisting NGN architecture. As challenging architectural issues, we

also introduce personalized IPTV services based on Web-basedopen platform in NGN environment and illustrate functionalarchitecture and service examples for Web-based personalizedIPTV services.

Index TermsFunctional architecture, IPTV, NGN.

I. INTRODUCTION

THE concept of next generation network (NGN) [1] in In-

ternational Telecommunication Union Telecommunica-

tion Standardization Sector (ITU-T) takes into consideration

telecommunication industry needs such as convergence of ser-vices, optimization of the operating networks, and the extraor-

dinary expansion of digital traffic toward multimedia services.

From NGN point of view, IPTV is defined as multimedia ser-

vices over broadband IP-based networks, managed to support

the required level of quality of service (QoS)/ quality of experi-

ence (QoE), security, interactivity and reliability, etc [2], [3]. It

means that NGN should be the best tool supporting the reliable

and secure delivery of multimedia contents including video,

Manuscript received May 01, 2008; revised October 30, 2008. First publishedMay 05, 2009; current version published May 22, 2009. This work was partly

supported by the IT R&D program of MKE/IITA [2008-F015-02, Research onUbiquitous Mobility Management Methods for Higher Service Availability, andA1100-0801-3015, Development of Open-IPTV Technologies for Wired andWireless Networks].

G. M. Lee is with the Institut TELECOM SudParis, 91011 Evry, France, onleave from the Information and Communications University, Yuseong-gu, Dae-

jeon 305732, Republic of Korea (e-mail: [email protected]).C. S. Lee is with the Electronics and Telecommunications Research Institute,

Yuseong-gu, Daejeon 305700, Republic of Korea (e-mail: [email protected]).

W. S. Rhee is with the Hanbat National University, Yuseong-gu, Daejeon305719, Republic of Korea (e-mail: [email protected]).

J. K. Choi is with the Information and Communications University,Yuseong-gu, Daejeon 305732, Republic of Korea (e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TBC.2009.2020450

which is a very crucial issue for IPTV services. As the IPTV

service requires not only the broadband multimedia streaming

but also the security and reliability with a certain level of quality,

there are certain limitations to support those capabilities in cur-

rent best effort based IP network such as the Internet. Therefore,

NGN with adjustment for IPTV characteristics would be a suit-

able way to provide new emerging services over heterogeneous

networking environment. In this sense, IPTV will have the prin-

cipal role of accelerating deployment and business of NGN.

ITU-T Study Group (SG) 13 [4] has been developing Recom-

mendations on NGN from standardization point of view. Iden-tifying additional requirements and functions for relevant capa-

bilities of IPTV services are key study items of NGN release

2 [5] development in SG 13. IPTV study in ITU-T was ini-

tiated by the Focus Group (FG) on IPTV (FG-IPTV) which

produced 19 deliverables [6] on IPTV, widely covered most

of important subject areas and handed over to the appropriate

study groups via SG 13 for the development of Recommenda-

tions. The ongoing work has been carried out under the umbrella

of IPTV-global standards initiative (GSI) [7]. IPTV-GSI is the

center for the speedy preparation of standards based on docu-

ments produced by FG-IPTV.

Similar with ITU-T, the European TelecommunicationStandards Institute (ETSI) Telecoms and Internet Converged

Services and Protocols for Advanced Networks (TISPAN) has

developed several specifications for IPTV in NGN release 2 [8],

[9]. The Alliance for Telecommunications Industry Solutions

(ATIS) IPTV Interoperability Forum (IIF) and Open IPTV

Forum also produced relevant specifications [10][13] on IPTV

architecture. The above standardization bodies are commonly

considering the IP multimedia subsystem (IMS) [14] as a

key platform for IPTV [15], [16]. Cable operators have also

considered standards for providing IP services over cable [17].

IPTV services over manageable broadband link from a

provider will be the ultimate goal of the broadband revolution

using NGN. So, we focus on NGN-based IPTV services and itsarchitectural aspects. For this, we analyze IPTV architectures

[18] developed by ITU-T and provide functional architecture

for NGN-based IPTV services according to functional mapping

between IPTV and NGN. We introduce the detailed functional

architecture of IPTV harmonized with NGN and relevant oper-

ations with functional blocks based on FG-IPTV deliverables

of ITU-T.

Taking into consideration continuous evolution of services

and user requirements, Personalized IPTV Services [19] en-

able users to access and consume what they want, when and

where they want in a personalized way. These will be the key

solutions for value-added services over IP based network using

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rich contents and emergence of Web 2.0, providing open plat-

form and new business model for IPTV services in the near

future. Therefore, as a conclusion, we introduce personalized

IPTV services using Web-based open platform [20], [21] over

NGN environment with corresponding functional architecture.

The intention of introducing this functional architecture is to

discuss the challenges to the development of viable and feasiblenetworking platform model for IPTV services.

The remainder of the paper is organized as follows. In

Section II, we explain concepts and architectural considerations

of NGN and IPTV services based on ITU-T recommendations

and deliverables, and discuss impact of NGN on IPTV services.

Then, in Section III, we describe the detailed functional archi-

tecture for IPTV services. We compare functional architecture

between IPTV and NGN and present an NGN-based IPTV

architecture in alignment with NGN in Section IV. Finally,

in Section V, we introduce personalized IPTV services over

NGN and illustrate functional architecture of Web-based open

platform and service examples.

II. NGN AND IPTV SERVICES IN ITU-T

A. The Concept and Architecture of NGN

ITU-T defines the NGN as a packet-based network able

to provide telecommunication services and able to make use

of multiple broadband, QoS-enabled transport technologies,

in which service-related functions are independent from un-

derlying transport-related technologies. It enables unfettered

access for users to networks, competing service providers

and/or services of their choice. It supports generalized mobilitywhich will allow consistent and ubiquitous provision of services

to users [1].

The NGN functional architecture shall incorporate the fol-

lowing principles [22]:

Support for multiple access technologies: The NGN

functional architecture shall offer the configuration flexi-

bility needed to support multiple access technologies.

Distributed control: This will enable adaptation to the

distributed processing nature of packet-based networks

and support location transparency for distributed com-

puting.

Open control: The network control interface should beopen to support service creation, service updating, and in-

corporation of service logic provision by third parties.

Independent service provisioning: The service pro-

visioning process should be separated from transport

network operation by using the above-mentioned dis-

tributed, open control mechanism.

Support for services in a converged network: This is

needed to generate flexible and easy-to-use multimedia

services, by tapping the technical potential of the con-

verged, fixed/mobile functional architecture of the NGN.

Enhanced security and protection: This is the basic prin-

ciple of an open architecture. It is imperative to protect the

network infrastructure by providing mechanisms for secu-rity and survivability in the relevant layers.

Functional entity characteristics: Functional entities

should incorporate the following principles:

Functional entities may not be distributed over multiple

physical units but may have multiple instances.

Functional entities have no direct relationship with the

layered architecture. However, similar entities may be

located in different logical layers.Along with new architectural principles the NGN will bring

an additional level of complexity beyond that of existing net-

works. In particular, support for multiple access technologies

and mobility results in the need to support a wide variety of net-

work configurations.

The NGN architecture supports the delivery of services iden-

tified in the NGN release 1 scope [23], as well as the require-

ments identified in the NGN release 1 [24]. NGN provides mul-

timedia services including conversational services, and content

delivery services, such as video streaming and broadcasting.

Fig. 1 shows an overview of the NGN functional architecture

that divides into service stratum functions and transport stratum

functions according to [25].Several functions in both the service stratum and the trans-

port stratum are needed to support various NGN services, as il-

lustrated in Fig. 1. The delivery of services/applications to the

end-user is provided by utilizing the application support func-

tions and service support functions, and related control func-

tions. The NGN supports a reference point to the applications

functional group called application network interface (ANI),

which provides a channel for interactions and exchanges be-

tween applications and NGN. The ANI offers capabilities and

resources needed for the realization of applications. The trans-

port stratum provides IP connectivity services to NGN users

under the control of transport control functions, including net-work attachment control functions (NACFs) [26] and resource

admission and control functions (RACFs) [27].

Currently, NGN release 2 [5] featuring mobility and

streaming capabilities is being developed. NGN release 2

identifies IPTV as one of service components and incorporates

additional requirements and functional capabilities for IPTV.

B. Overview of IPTV Services

In order to introduce IPTV services, we explain content valuechain, domain model and several types of IPTV services.

1) IPTV Content Value Chain: When considering the life

cycle of contents, the value chain should be the most important

fundamental framework for identifying IPTV services. Top part

of Fig. 2 shows an IPTV Content Value Chain Model taking

into consideration broadcast services and on-demand services

[13]:

Content Production: producing and editing the actual

content (movies, drama series, sports events, news reports

etc.)

Content Aggregation: bundling content into catalogue of-

fers and bouquets, ready for delivery.

Content Delivery: transporting the aggregated contents tothe consumer.



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LEE et al.: FUNCTIONAL ARCHITECTURE FOR NGN-BASED PERSONALIZED IPTV SERVICES 331

Fig. 1. NGN architecture overview (illustration from [22]).

Fig. 2. Content value chain and IPTV domains.1

Content Reconstitution: converting the content into a

format suitable for rendering on the end-user device(s).

Each role in the value chain has historically been bound to

a type of stakeholder or technical component. Content Produc-

tion, for example, is linked to production firms and to the pro-

duction teams of TV stations.

2) Domain Model for IPTV Services: Fig. 2 shows the do-

main and content value chains that are involved in the provi-

sioning of IPTV services. Four domains of IPTV service provi-

sioning are defined as follows [10], [11], [18]:

1Although considered as two separate entities, the Service Provider and theNetwork Provider may in fact be one organizational entity.

Content Provider: The entity that owns or is licensed to

sell content or content assets.

Service Provider: A general reference to an operator that

provides telecommunication services to customers and

other users either on a tariff or contract basis. A service

provider can optionally operate a network. A service

provider can optionally be a customer of another service

provider.

Network Provider: The organization that maintains and

operates the network components required for IPTV func-

tionality. A network provider can optionally also act as ser-vice provider.



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Fig. 3. NGN for supporting IPTV services.

End-user: The actual user of the products or services. An

end-user can optionally be a subscriber.

There are several reference points (RPs) between logical do-

mains [12], [13], [18]:

RP 1: logical reference point between end-user and net-

work provider (user to network RP).

RP 2: logical reference point between network provider

and service provider (transport and control RP).

RP 3: logical reference point between service provider and

content provider (content provider RP).

RP 4: logical reference point between end user and service

provider (service platform RP).

RP 5: logical reference point between network provider

and content provider (out of scope).

RP 6: logical reference point between end-user and contentprovider. A direct logical information flow may be set up

for rights management, protection, etc.

3) Several Types of IPTV Services: IPTV services are clas-

sified as the follows [28]:

Broadcast type services (linear TV): comprise a one-way

transmission of content from one point (the source) to two

or more points (the receivers), whereas the end-user has

no control over the content or timing of what he receives,

apart from the ability to select a particular channel.

On-demand type service: is content prepared and deliv-

ered by the content provider for retrieval, which is received

and stored by the service provider. If necessary, trans-coding can be performed to accommodate the storage de-

vice characteristics. The end-user can then select and re-

trieve such contents from this storage at any time, ac-

cording to the constraints provided by the content protec-

tion metadata.

Other type services: include advertising service, public

interest service, tele-services, portal services, hosting ser-

vices, IPTV interactive service, presence services, time-

shifting and place-shifting service, session mobility ser-

vice, supplementary content, etc.

C. Impact of NGN for IPTV Services

ITU-T has developed three IPTV architectures that enableservice providers to deliver IPTV services [18]:

Non-NGN IPTV functional Architecture (Non-NGN

IPTV): The Non-NGN IPTV architecture is based on ex-

isting network components and protocols/interfaces. This

approach is a representation of typical existing networks

providing IPTV services.

NGN-based non-IMS IPTV Functional Architecture

(NGN-Non-IMS IPTV): The NGN Non-IMS IPTV ar-

chitecture utilizes components of the NGN framework

reference architecture as identified in [22] to support the

provision of IPTV services, in conjunction with other

NGN services if required.

NGN IMS-based IPTV Functional Architecture (NGN-

IMS-IPTV): The NGN-IMS based IPTV architecture uti-

lizes components of the NGN architecture including the

IMS component to support the provision of IPTV services,in conjunction with other IMS services if required. Key

benefits of using this architecture are as follows [29]:

Access-independent service delivery of a centralized

subscriber database

Open interfaces to application servers

Per-session dynamic QoS for an optimized QoE

Multimedia communications supporting other services

(e.g., quad-play services).

In this paper, we focus on IPTV services from the NGN per-

spective including IMS component. Specifically, NGN can pro-

vide enhanced capabilities for managing IP and broadband ser-

vices regardless of fixed or wireless environment, which is cru-cial for support of fixed mobile convergence (FMC) as shown

in Fig. 3. NGN can facilitate the interworking with legacy net-

works (e.g., IPv4/IPv6, mobile/wireless, broadcasting, PSTN,

etc) and accommodate various kinds of end-user devices (e.g.,

TV, personal computer (PC), phone, and wireless device in-

cluding IPTV set-top box (STB)).

Most of service providers consider IPTV as a key gate to the

triple-play service businesses (including voice, video, and data

service) using rich contents; TV programs from broadcasting

sources, On-demand video storage and user created video, etc.

A combination of voice, data and video services over broadband

links and from a provider is seen as the ultimate goal of the

broadband revolution. Therefore, NGN adjustment with IPTVcharacteristics is a suitable way for supporting new emerging



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Fig. 4. IPTV architectural overview.2 (illustration from [18]).

services over heterogeneous networking environment. We ex-pect that IPTV will have the principal role in accelerating both

deployment and business of NGN.

III. FUNCTIONAL ARCHITECTURE FOR IPTV SERVICES

A. Overall Functional Architecture for IPTV

In this section, we introduce IPTV architectures based on

[18]. To design functional architecture for IPTV, we consider the

principal functional groups for IPTV. These functional groups

provide a more detailed breakdown of the IPTV domains that

are discussed in Section II. The functional groups in the archi-tecture are derived by grouping related functions.

Fig. 4 shows an overview of the IPTV functional architec-

ture. The following points give a description of each functional

group. The related functions in each functional group are further

decomposed as shown in Fig. 5.

End-User Functions: perform mediation between the

end-user and the IPTV infrastructure.

Application Functions: enable the End-User Functions to

select and purchase or rent a content item.

Service Control Functions: provide the functions to re-

quest and release network and service resources required

to support the IPTV services.

Content Delivery Functions: receive content from theApplication Functions, store, process, and deliver it to the

End-User Functions using the capabilities of the NetworkFunctions, under control of the Service Control Functions.

Network Functions: provide IP layer connectivity be-

tween the IPTV service components and the End-User

functions.

Management Functions: perform overall system man-

agement (i.e., operations, administration, maintenance and

provisioning (OAM&P)).

Content Provider Functions: provided by the entity that

owns or is licensed to provide content or content assets.

B. End-User Functions

1) IPTV Terminal Functions (ITF): The ITF are responsible

for collecting control commands from the end-user, and inter-

acting with the Application Functions to obtain service infor-

mation (e.g., electronic program guide (EPG)), content licenses,

and keys for decryption. They interact with the Content Delivery

Functions to receive the IPTV services. They also provide the

capability for content reception, decryption, and decoding.

2The rectangular blocks represent functional blocks in the IPTV architec-ture. The rounded rectangular areas represent the particular grouping of func-tions. The solid lines represent direct relationships between either Functions

or Functional Blocks. The dotted lines represent logical associations betweenEnd-User Functions and either Functions or Functional Blocks located outsidethe End-User Functions.



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Fig. 5. Detailed IPTV functional architecture (illustration from [18]).

Application Client Functions: exchange information

with the Application Functions to support IPTV and other

interactive applications.

Service and application discovery & selection client

functional block

On-demand client functional block

Linear TV client functional block

Other client functional blocks

Service and Content Protection (SCP) Client

Functions: interact with SCP functions to provide service

protection and content protection and verifies the usage

rights and decrypts and optionally watermark the content.

Content protection client functional block Service protection client functional block

Content Delivery Client Functions: receive and control

the delivery of the content from the Content Delivery and

Storage Functions. After receiving the content, the Con-

tent Delivery Client Functions can optionally use the SCP

Client Functions to decrypt and decode the content, and

can also optionally support playback control.

Multicast content delivery client functional block

Unicast content delivery client functional block

Error recovery client functional block (option)

Control Client Functional Block: allows the ITF to ini-

tiate service requests to IPTV Service Control Functional

Block, in order to prepare for the connection to the Con-tent Delivery Functions.



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2) Home Network Functions (HNF): The HNF provide the

connectivity between the external network and each IPTV ter-

minal device. All data, content, and control traffic must pass

through the Home Network Functions in order to enter or exit

the end-users IPTV terminal device.

Delivery Network Gateway Functional Block: provides

IP connectivity between the external network and the IPTVterminal device. It manages the IP connectivity, obtains

IP addresses and configurations for the HNF and IPTV

terminal devices.

C. Application Functions

1) IPTV Application Functions (IAF): The IAF enable the

IPTV Terminal Functions to select and purchase, if necessary,

content.

Service and application discovery & selection functional

block

Linear TV application functional block

On-demand application functional block

Other application functional blocksApplication Profile Functional Block: stores the profiles for

the IPTV applications. The profiles can optionally include end-

user setting, global setting (e.g., language preference), linear

TV setting, video on demand (VoD) settings, personal video

recorder settings and IPTV service actions data, etc.

Content Preparation Functions: control the preparation and

aggregation of the contents such as VoD programs, TV channel

streams, metadata, and EPG data, as received from the content

provider functions.

Content management functional block

Metadata processing functional block

Content processing control functional block Content pre-processing functional block

Service & Content Protection (SCP) Functions: controls the

protection of the services and content.

Content protection functional block for control of access

to contents

Service protection functional block for authentication and

authorization of access to services

Application Provisioning Functional Block: adds or with-

draws applications and manages the life-cycle of IPTV

applications.

D. Service Control Functions

IPTV Service Control Functional Block: provides the func-

tions to handle service initiation, modification and termination

requests, perform service access control, establish and maintain

the network and system resources required to support the IPTV

services requested by the ITF.

Provides registration, authentication and authorization

functions for the End-User Functions.

Processes requests from IAF and forwards them to the

Content Delivery Functions in order that the Content De-

livery Functions select the most appropriate Content De-

livery & Storage Functions, for delivering content to the

End-User Functions.

Requests the Content Delivery Functions or ApplicationFunctions to collect charging information.

Service User Profile Functional Block: used for storing ser-

vice profiles and generating responses to queries for service pro-

files.

E. Content Delivery Functions

The Content Delivery Functions receive perform cache and

storage functionalities and deliver the content according to therequest from the End-User Functions. The content delivery

functions can optionally process the content.

Content Distribution & Location Control Functions

(CD&LCF): control the Content Delivery & Storage Functions

to optimize content distribution, selection and deliver content

to the ITF.

Distribution control functional block

Location control functional block

Content Delivery & Storage Functions (CD&SF): store and

cache the content process it under the control of Content Prepa-

ration Functions and distribute it among instances of Content

Delivery & Storage Functions based on the policy of Content

Distribution & Location Control Functions. Content delivery control functional block

Cache & storage functional block

Distribution functional block

Error recovery functional block (option)

Content processing functional block

Unicast delivery functional block

Multicast delivery functional block

F. Network Functions

The Network Functions are shared across all services deliv-

ered by IP to the End-User Functions. They provide the IP layer

connectivity in order to support IPTV services. Authentication & IP Allocation Functional Block: pro-

vides the functionality to authenticate the Delivery Net-

work Gateway Functional Block, which connects to the

Network Functions, as well as allocation of IP address to

the Delivery Network Gateway Functional Block and op-

tionally to the IPTV Terminal Functions.

Resource Control Functional Block: provides control of

the resources, which have been allocated for the delivery

of the IPTV services through the Access Network, Edge

and Core Transport Functions.

Access Network Functions: (1) aggregating and for-

warding the IPTV traffic sent by the End-User Functionsinto the edge of the core network and (2) forwarding the

IPTV traffic from the edge of the core network towards

the End-User Functions.

Edge Functions: forwarding the IPTV traffic aggregated

by the Access Network Functions towards the core net-

work, and also to forward the IPTV traffic from the core

network to the End-User Functions.

Core Transport Functions: forwarding IPTV traffic

throughout the core network.

Multicast Transport Functions

Multicast control point functional block for the selection

of the individual multicast streams (McCPF)

Multicast replication functional block for replicatingmulticast stream (McRF)



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Unicast Transport Functions: the transport of unicast

content streams from the Unicast Delivery Functional

Block to the End-User Functions.

G. Management Functions

The Management Functions handle overall system status

monitoring and configuration. This set of functions can option-ally be deployed in a centralized or a distributed manner.

Application management functional block

Content delivery management functional block

Service control management functional block

End user device management functional block

Transport management functional block

H. Content Provider Functions

The Content Provider Functions provide many different types

of sources to the Content Preparation Functions. The physical

interfaces and content formats can optionally be different de-

pending on the type of the sources. It can optionally includefunctions for access control based on rating of the content.

Content Protection Metadata Sources: the usage rules

and rights for protected IPTV content.

Metadata Sources: an entity that provides content

provider metadata associated with the IPTV content.

Content Sources: an entity that provides IPTV content.

I. Physical Configuration for Protocol Operation

According to decomposition of each functional group, Fig. 5

shows detailed IPTV functional architecture. The IPTV archi-

tecture needs to allow for IPTV network, service and applica-

tion components to exist at different physical and logical pointsin a network. The specified protocols are operating with align-

ment of physical configuration and functional modules in IPTV

architecture.

Content provider has content sources and service provider

has streaming server and transaction servers. Transaction

servers of the service provider are composed of servers for

digital rights management (DRM), customer relationship

management (CRM), billing, profile management, identity

management, web or IPTV portal, etc.

In network provider domain, IPTV functional elements can

be mapped into a physical network hierarchy specifically for

linear TV. There are three types of network nodes [17], [18],[30];

Super Head End (SHE)the locations for acquisition

and aggregation of region-independent (national-level)

linear/broadcast TV programming. SHEs are also the

central points for on-demand content insertion.

Video Hub Office (VHO)the video distribution points

within a demographic market area. National content is re-

ceived from each SHE. Local content is acquired and en-

coded. Insertion of local content is also performed in the

VHO. IPTV services are provided from the VHO via the

aggregation/access network.

Video Serving Office (VSO)the VSO (typically a Cen-

tral Office) hosts or connects all access systems for inter-connection to consumers. In addition, the VSO contains

Fig. 6. Functional mapping between IPTV and NGN architecture.

aggregation equipment to enable efficient and reliable in-

terconnection to the VHO.

The access network functions must be located between the

video serving office (VSO) and end-user, the IP multicast

replication functions can also be optionally located in the VSO.

Various access networks may provide passive optical network

(PON), wireless, and Ethernet interfaces for delivery of IPTV

content to the residential subscriber.

The end user comprises the IPTV terminal and delivery net-

work gateway (DNG)/STB. DNG provides traffic management

and routing between the access network and the home network.

IV. NGN-BASED IPTV ARCHITECTURE

A. Comparison of Functional Architecture Between IPTV

and NGN

It is useful to relate the IPTV architecture to the general

NGN framework architecture and other networks to clarify the

similarities and differences, as well as provide a reference for

the more detailed description of IPTV specific components.

The NGN-based architecture means the IPTV architecture

in accordance with [22] for providing IPTV services. There-fore, functionalities for IPTV services have a correspondence

relationship with the NGN architecture. The NGN components

described in [22] were shown in Fig. 1.

Fig. 6 shows functional mapping between IPTV and NGN ar-

chitectures according to the relationships between the functions

of these two architectures:

Application Functions may be included in Application

Support Functions & Service Support Functions of NGN

Service Control Functions may be included in the Service

Control Functions (i.e., IPTV service component) of NGN

Content Delivery Functions may interact with both Service

Stratum and Transport Stratum of NGN

Network Functions may be included in Transport Stratumof NGN



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Fig. 7. IPTV functional architecture in alignment with NGN3 (illustration from [18]).

End-User Functions may be included in End-User Func-tions of NGN

Management Functions may be included in Management

Functions of NGN

Content Provider Functions may reside outside the NGN

Content Delivery Functions may reside outside the NGN

in cases like a 3rd party service provider.

Application Functions may reside outside the NGN in

cases like a 3rd party service provider.

IPTV Service Control Functional Block corresponds to

NGN Service Control Functions. However, NGN Service

Control Functions may include other functionalities.

B. Harmonized Architecture Between IPTV and NGN

Based on the functional mapping between NGN and IPTV

functions (see Fig. 6), we show the IPTV functional architec-

ture in alignment with NGN in Fig. 7. It presents the functional

architecture for NGN-based IPTV services.

The NGN-based IPTV architecture is based on the NGN ar-

chitecture defined in [22] and uses the components and func-

tions of the NGN. The non-NGN-based IPTV architecture does

not necessarily require these components and functions and uses

conventional and/or legacy network technologies for the de-

livery of IPTV services. The main differences are the following:

3There are two NGN-based IPTV architectures; NGN-IMS-IPTV and NGN-non-IMS-IPTV. This diagram represents NGN-IMS-based IPTV architecture.

The NGN-based IPTV architecture uses NACF to providefunctions such as authentication and IP configuration.

The NGN-based IPTV architecture uses RACF to provide

resource and admission control functions.

The NGN-based IPTV architecture uses Service Control

Functions defined in [22] to provide service control func-

tions.

The NGN-IMS-based IPTV architecture (see Fig. 7) uses

Core IMS Functions such as IPTV Service Control Functional

Block and associated functions such as Service User Profile

Functional Block defined in [31] to provide service control

functions. The core IMS Functions offer a session control

mechanism, and provide functions for authentication and au-thorization of IPTV Terminal Functions based on user profile,

as well as functions for the interaction with RACF for resource

reservation. The core IMS Functions also provide interaction

between IPTV Terminal Functions, IPTV Application Func-

tions and Content Delivery Functions. The core IMS Functions

can be used for Service Discovery. Functions such as charging

and roaming can also be supported by IMS mechanisms.

The NGN-non-IMS-based IPTV architecture uses Service

Control Functions other than core IMS Functions to provide

service control functions.

The key advantages of NGN-based IPTV architecture are

to realize personalized value-added services and use more

efficiently network resources using tight integration with NGNfunctionalities such as NACF, RACF and IMS, etc.



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Fig. 8. Procedural flows for Linear TV and VoD services in NGN-IMS-IPTV architecture.

C. Procedural Flows for IPTV Services

This section provides detailed descriptions of the procedural

flows for linear TV and VoD services in NGN-IMS-IPTV archi-

tecture as shown in Fig. 8 [18].

First, the ITF acquire service parameters which include the

content identifier, logical uniform resource locator (URL),

bandwidth, codec information for VoD, and a logical channel

identifier for linear TV. Then, the ITF initiate a service request

to the core IMS functions. The core IMS functions optionally

determine the location of the ITF, for example by querying the

NACF.

Next, for linear TV services, the core IMS functions forwardthe request to the Linear TV application with ITF location and

logical channel identifier(s). The linear TV application passes

the ITF location and the logical channel identifier(s) to the con-

tent delivery control function. The content delivery control func-

tion determines the multicast addresses and which CD&SF uses

to output the required channels and has multicast network paths

to the IPTV terminal based on the association between logical

channel identifiers and multicast addresses. It returns the corre-

sponding multicast addresses to the linear TV application. The

linear TV application returns the multicast network parameters

to the core IMS.

For VoD services, the core IMS functions send a network re-

source request to the RACF. The RACF performs network re-

source reservation and sends the response to the core IMS func-tions. The core IMS functions send the service request with



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content identifier, logical URL to the on-demand IPTV appli-

cation functional block. The on-demand application functional

block performs service authorization. The on-demand IPTV ap-

plication functional block sends the request to the CD&LCF via

core IMS functions in order to select the CD&SF. The core IMS

Functions forward the request to the CD&LCF. The CD&LCF

selects a suitable CD&SF based on some criteria (e.g., the stateof the CD&SFs and the knowledge of distributed content among

the CD&SF etc). The CD&LCF resolves the logical URL of

content into the physical URL of an allocated CD&SF, and re-

sponds the URL of selected CD&SF to on-demand application

functional block via core IMS functions. The core IMS func-

tions forward the response to the on-demand application func-

tional block. The on-demand application functional block sends

the content resource request to the selected CD&SF via core

IMS functions in order to allocate content resources. The core

IMS functions forward the content resource request to the se-

lected CD&SF. The CD&SF performs content resource alloca-

tion and sends the response to the core IMS functions. The core

IMS functions forward the response to the on-demand appli-cation functional block. The on-demand application functional

block sends the service response to the core IMS functions.

After that, the core IMS functions send a network resource

request to the RACF. The RACF performs network resource

allocation and sends the response to the core IMS functions. The

core IMS functions send the service response to the ITF.

Finally, for linear TV services, the ITF receives a list of one or

more logical channels and their multicast addresses and main-

tains this mapping for the duration of the multicastsession. After

that, the ITF initiate channel control request by initialing a mul-

ticast join request and receives the multicast stream. When the

user exits the linear TV application (i.e., they stop watchingTV), the ITF will request the session be ended and will release

any requested resources. For VoD services, the ITF connect to

the identified CD&SF to receive the content.

V. CHALLENGING ISSUES FOR NGN-BASED IPTV SERVICES

A. Personalized IPTV Services

The challenge to a successful IPTV service lies not only in

the underlying transport networks but also in the need for ser-

vice applications and their platforms to adapt to new business

models, and changing service trends and environments. IPTVservice is growing the number of service providers, users, and

content, while enlarging its area of services at the same time.

The potential of a growing quantity of IPTV services will re-

sult in enormous expansion of options for users. Under these

circumstances, spotting what the user may like or want to enjoy

becomes a key factor for successful IPTV service. Moreover, the

personalization of service allows providing more value added

services, which will make the IPTV service worthwhile. The

IPTV services will adopt more Internet and telecommunication

capabilities in step with the rapidly developing service environ-

ment. New business models will require open, flexible, and agile

platform such as Web or its more advance form, Web 2.0.

From the future trend in the end-users perspective, thevalue will be transferred from access service of traditional

Fig. 9. Personalized IPTV services using Web-based open platform.

telecom providers to content-based services such as IPTV. The

key factor underpinning the success of all end-user-oriented

services lies in the degree of users awareness. Personalized

services are identified as tailor-made to the users needs for

delivering appropriate content and services. These services are

to improve the users experience and satisfaction. In addition, as

devices evolve, the real benefits of IPTV using a multi-terminal

(including multiple functions such as camera, video recorder,

phone, TV, music player, etc) are in the merging of entertain-

ment and communications, the integration of telephone features

into television experience, and the mobility of video services

that follow the user anywhere, anytime.

Accordingly, personalized IPTV services will permit for

users to access and consume what they want, when and where

they want in a personalized way on local and/or remote personal

storage systems from both broadcast and online services. These

services are targeting and customizing content for individualusers based on the followings: user preferences, features of user

devices and/or access networks and natural environments such

as mood, location, time, etc.

Unlike the legacy Web world, where users were passive ob-

servers of Web site content, the advanced web world such as

Web 2.0 is providing dynamicity and interactivity in near real

time to the users. The emphasis of Web 2.0 is not on creating re-

tail community-type services of its own but on building an open

platform through which third-party application developers can

access and launch their own services. The open platform gen-

erates extra profits through extended management and the cre-

ation and deployment of value-added services while fully sup-porting new service requirements. Using interactive, collabora-

tive and customizable features Web 2.0 can provide rich user

experiences/interfaces and new business opportunities for IPTV

services. From standards point of view, IMS-based NGN will be

a key platform for service control capabilities in IPTV.

We expect that a new service platform, which combines

web-based open structure using Web and IMS-based NGN as

shown in the Fig. 9, will provide Personalized IPTV Services

as one of new business models for service providers/network

providers. The illustrated service platform creates new business

for IPTV services with new features. The web-based IPTV is

a platform that allows an organization to integrate its business

information, applications, and services into a web-based IPTVportal benefiting from easy navigation and access.



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Fig. 10. Example of functional architecture for Web-based open IPTV platform.

Fig. 11. Service examples of personalized IPTV using intelligent multimedia, Web and personalized networking technologies.

B. Web-Based Open Platform for IPTV Services

For the emerging personalized IPTV services, we provide an

example of functional architecture for web-based open IPTV

platform in NGN as shown in Fig. 10. The illustrated IPTV ar-

chitecture consists of the following functional components:

Contents: The contents are classified into digital broad-

casting, online content and stored content in digital video

discs (DVDs) and hard disk drives (HDDs), etc. The con-

tent domain requires functionality, which receives videocontent from producers and other sources. Afterward,

these contents are encoded and stored in an acquisition

database for VoD, etc.

Head-end: The head-end domain requires a function-

ality which receives video streams in different formats.

These video streams in different formats are then refor-

matted and encapsulated for transmission with appropriate

QoS indications to the network through content prepara-

tion. This makes them ready for delivery to end-users using

service delivery management. In addition, to support per-

sonalized IPTV services, web-based service operation andpersonalization functions are very critical.



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Network: The IMS-based NGN of the network domain

can support transport functions, and service and transport

control functions. Specifically, it supports delivery capa-

bilities, such as multicast, which is necessary for the reli-

able and timely distribution of IPTV data streams from the

service nodes to the end-user. Moreover, the core and ac-

cess network of NGN cover the optical distribution back-bone network for high capacity and the various digital sub-

scriber line access multiplexers (DSLAMs).

End-user: The device of the end-user performs func-

tional processing through web-based client, service usage

monitoring, and content decoder. The functional pro-

cessing includes setting up the connection and QoS with

the service node, decoding the video streams, channel

change functionality, user display control and connections

to user appliances such as a standard definition television

(SDTV) or a high definition television (HDTV) monitor

using Web. The end-user also has a network interface

which terminates the IPTV traffic at the home network.

C. Service Examples of Personalized IPTV

In order to provide personalized IPTV services using pro-

posed web-based open IPTV platform, intelligent multimedia,

Web and personalized networking technologies should be

tightly interacted with several functions which are illustrated in

Fig. 10. In particular emerging Web technologies which include

ontology, semantic, mash-up, and community functions, etc

can be key enablers of personalized IPTV services. Here we

introduce service examples of personalized IPTV from the

viewpoint of customer (e.g., smart client) as an end user asshown in Fig. 11 [32], [33].

The personal IPTV broadcast services provide a customer

with a wayto advertise personal contents so that other customers

can access such contents. These services make the IPTV cus-

tomer into a content provider. The service provider is respon-

sible for relaying session information between the broadcasting

customer and the receiving customers, possibly assuming some

access control functions so as to ensure that a given customer is

entitled to broadcast his/her personal contents.

The development and provisioning of IPTV services through

the use of portal sites will increase. Portal services are branded

aggregation of products and services designed to satisfy a largemajority of customers needs, such as VoD, shopping, banking,

communication, entertainment and other interactive services

with a portal menu. The portal services can target customers

by broadcasting commercials, advertisements and interactive

responsible advertising. Portal services may provide walled

garden access and/or direct Internet access.

The IPTV portal services basically operate in a similar

manner to a web service on the Internet and take advantage

of the TV screen in the same way as data broadcasts in digital

broadcasting, and control functions related to IPTV services.

These services support hyperlink functions for linking to other

parts of the same portal site or to other portal sites.

Consequently, Web-based open IPTV can provide commu-nity-based content navigation/ranking, personalized content

creation and customized content provisioning with collective

intelligence to customers.

VI. CONCLUSION

In this paper, we reviewed the basic concept and architecture

models of IPTV in relation with NGN. We explained the im-pact of NGN on IPTV services emphasizing that NGN can pro-

vide IPTV services more efficiently through managed IP and

convergence broadband capabilities. Then, we have analyzed

IPTV architecture developed by ITU-T and provided functional

architecture for NGN-based IPTV services according to func-

tional mapping between IPTV and NGN functions. For this, we

showed the detailed functional architecture and relevant opera-

tions with functional blocks and presented the harmonized ar-

chitecture between IPTV and NGN for NGN-based IPTV ser-

vices. As a conclusion, taking into consideration all this and

the emergence of advanced user requirements, we introduced a

personalized IPTV service concept combining Web-based open

platform with NGN environment and illustrated functional ar-

chitecture for Web-based personalized IPTV services and ser-

vice examples.

We believe that the web-based open IPTV platform is a chal-

lenging architectural issue. Personalized IPTV services will be a

key solution for value-added services over NGN, and the emer-

gence of Web 2.0 will provide an open platform and a new busi-

ness model for IPTV services in the near future.

ACKNOWLEDGMENT

The authors are grateful to Dr. Daniel Genin from National

Institute of Standards and Technology (NIST) for reviewing and

providing many helpful comments which have improved the

quality of this paper.

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[19] J. Lyu, S. Pyo, J. Lim, M. Kim, S. Lim, and S. Kim, Design of openAPIs for personalized IPTV service, in Proc. the 9th InternationalConference on Advance Communication Technology, Feb. 2007, vol.1, pp. 305310.

[20] M. Hofmanand L. R. Beaumont, Open pluggable edge services,an ar-chitecture for networked content services, IEEE Internet Computing,vol. 11, pp. 6773, Jan. 2007.

[21] S. Kim and S. Y. Lee, Web technology and standardization for Web2.0 based IPTV service, in Proc. the 10th International Conferenceon Advance Communication Technology, February 2008, vol. 3, pp.

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Gyu Myoung Lee (M02) received B.S. degree inelectronic and electrical engineering from Hong IkUniversity, Seoul, Korea, in 1999 and M.S., andPh.D. degree in school of engineering from Infor-mation Communications University (ICU), Daejeon,

Korea, in 2000 and 2007, respectively.He is currently with Institut TELECOM SudParis

as a research fellow, specializing in IPTV networksand standards development. Since 2007 he has beenworking as a research professor in ICU, Korea and asan invited researcher in Electronics and Telecommu-

nications Research Institute, Korea. He worked as a guest researcher in NationalInstituteof Standardsand Technology, USA, in 2007 andas a visiting researcherin the University of Melbourne, Australia,in 2002. His research interestsincludeubiquitous networking and IPTV services for NGN, IPv6 protocols, and trafficengineering including optical switching technologies.

Dr. Lee has activelyparticipated in standardization meetings includingITU-TSG 13, IPTV-GSI, and IETF. He received several Best Paper Awards in interna-tional and domestic conferences and served as a reviewer of IEEE journal andinternational conferences.

Chae Sub Lee received the B.Sc. (Eng.) and M.Sc(Eng.) degree from Kon-Kuk University in elec-tronics engineering, Seoul, Korea in 1983 and in1985, respectively.

He has been working in the telecoms standardiza-tion field for over 20 years. He has been actively in-volved in regional standards in ASTAP, APT, TTAand CJK in the area of network standards. He has

been involved in ITU-T standards development forthe ISDN, GII, IP-based networks and NGN. He wasmainly involved in Study Group XVIII (currently SG

13) as a rapporteur on Architecture and Interworking areas. He is a chairmanof ITU-T SG 13 on future networks including mobile and NGN. He has beenserved as one of Vice-Chairman of ITU-T IPTV Focus Group since July 2006.He shared his role as a Chairman of NGN Focus Group from June 2004 tillNovember 2005. After a career of twenty years with KT as a senior researchingengineer, he has been an invited researching staff to ETRI.

Woo Seop Rhee (M01) received B.S. degree incomputer science from Hong Ik University, Seoul,Korea, in 1983 and M.S., and Ph.D. degree in 1995and 2003, respectively, in computer science fromChungnam National University, Daejeon, Korea.

From 1983 to 2005, he was with the Electronicsand Telecommunication Research Institute (ETRI).He involved in development of TDX switchingsystem, HANbit ACE ATM switching system andOptical access system as a project leader.

In 2005, Dr. Rhee joined Hanbat National Univer-sity, Daejeon, Korea and is currently assistant professor of Multimedia engi-neering department. His research interests are concerned with broadband net-work architecture, quality of service in Internet and mobility management withmulticast. He is an active member of ITU-T SG 13 as Editor and member ofKICS in Korea and IEEE.

Jun Kyun Choi (SMXX) received the B.Sc. (Eng.)from Seoul National University in electronics engi-

neering, Seoul, Korea in 1982, and M.Sc (Eng.) andPh.D. degree in 1985 and 1988, respectively, in elec-tronics engineering from Korea AdvancedInstitute ofScience and Technology (KAIST).

From June 1986 until December 1997, he waswith the Electronics and Telecommunication Re-search Institute (ETRI). In January 1998, he joinedthe Information and Communications University(ICU), Daejeon, Korea as a Professor. He is a

Senior Member of IEEE, the executive member of The Institute of ElectronicsEngineers of Korea (IEEK), Editor Board of Member of Korea InformationProcessing Society (KIPS), Life member of Korea Institute of CommunicationScience (KICS). His research interests are concerned with broadband networkarchitecture and technologies particular emphasis on performance and protocolproblems. Secondary interests include the international standard activities onbroadband network architecture and protocol with mobility support.

Dr. Choi is an active member of ITU-T SG 13 as a Rapporteur or Editor fromJanuary 1993 on theATM, MPLS, andNGN issues. He hadalso submittedmorethan 30 drafts on IETF during last few years.

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