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Intelligent Features for IMS-based IPTV Nguyen Tai Hung, Nguyen Huu Thanh
Department of Communication Engineering
Hanoi University of Technology
Hanoi, Vietnam
{hungtai-fet; thanhnh}@mail.hut.edu.vn
Abstract— IMS has been widely recognized as the control and
signaling framework for delivering of the rich communication and
multimedia services to the broadband users. Amongst others, it is
deployable as the service (middleware) platform for the interactive
and personalized IPTV services. The goal of this paper is to provide
an investigation of the advanced use cases in practical perspective.
The work has been done at Hanoi University of Technology (HUT)
in the scope of its initiatives for NGN research program. Major use-
cases, or we called intelligent features, are the advanced electronic
service guide, video on demand (VoD), (IPTV) session continuity,
and parental control. Development prototypes for each of the use
cases are depicted.
Keywords - IMS; IMS IPTV; enhanced EPG; Parental
Control; Blending Service, Intelligent Features;
I. INTRODUCTION
IP Multimedia Subsystem (IMS) is the control platform for the
next generation network (NGN) architecture currently planned
for mobile and fixed multimedia services, standardized by the
3rd Generation Partnership Project (3GPP) [1]. IMS promises
a scalable integrated platform that enables new services and
provides for the blending of telecommunication and Internet
services. Thus, we have chance of using IMS to provide a
highly integrated solution for seamless, networked-based
media transportation over any end-user device.
Since IPTV has been developed and deployed for some time
and has gone through numbers of generation with different
middleware technologies. When penetrating the comercial
market, it is now facing the challenges which demand that
IPTV be equipped with more intelligent, personalized and
interactive features in a standardized and interoperable way.
This paper will explore, in experimental perspective, the
possibility of using the IMS framework as the service control
plane to provide the interactive and personalized video
services to the broadband wired and wireless users.
The paper1 begins with a concise description of the novel IMS
based IPTV architecture as well as the setup for an academic
IMS test-bed. The main part of the paper will be reserved for
presentation of the designated use cases those have been
developed in our test-bed environment. Six use cases have
been explored and selected for implementation as listed below.
1 This research is conducted under the governmental research project
“Research and development of service platform for multimedia and value-
added services for 3G/4G wireless networks and broadband Internet”
supported by NAFOSTED
• Video on Demand: A standard feature that allows user to
request the desired content (a movie, a song or a video
clip) any time they wish.
• Parental Control/Authorization: An intelligent feature that
allows the parent to control their children access to
(IPTV) broadcast channels and/or on-demand contents by
time slot or by identity.
• Enhanced electronic program guide (EPG): Another
feature that provides the (IPTV) viewers with
personalized and time-based program guide.
• Blending services [8]: An feature that allows the
composition of telephony/messaging session with video
session.
II. PREVIOUS WORKS
In fact, IMS IPTV is not a new research topic; there are dozen
of researches on the issue. For example, on [11] Bruno
Chatras et al. investigate how to incorporate IMS components
in to IPTV service platforms to provide a flexible framework
for novel differentiated services. Traditional
telecommunication networks are optimized to have dedicated
network functions at certain locations, taking cost, quality of
service, reliability and other technical circumstances into
account. Load sharing of spread network functions are
difficult to realize. With the IP Multimedia Subsystem (IMS),
a totally different approach is feasible. It is based on the IP
protocol carrying bearer and signaling/control traffic. While
bearer traffic functions still need to be optimized with respect
to best location, the signaling and control functions of the
network could be spread somewhat arbitrarily over the
network due to the fact that relatively low traffic between the
functions does not significantly impact the optimization result
of the total network. This is an additional degree of freedom
for assigning such kind of equipment to given locations. It
opens up new possibilities for scaling the equipment for total
network capacity needs and gives a chance to distribute
redundancy geographically, which influences network
reliability in a positive way. Moreover, the distributed IMS
architecture based on SIP proxy mechanisms provide better
means for redundancy and scalability as compared to ”classic
soft switches” that still follow a nodal architecture. An
important aspect that IMS addresses is its capabilities for
blending and orchestration of services; these issues within
IMS are addressed in [12]. This is particularly attractive for
operators that deploy the so-called blending services, instead
of the bundled services, to a large number of young new
2010 Australasian Telecommunication Networks and Applications Conference
978-1-4244-8172-9/10/$26.00 ©2010 IEEE 130
generation viewers. Being different from the most of the
published papers that does the investigation of IMS IPTV
from architecturing and functional perspectives, our paper
focuses on the exploration of the IMS IPTV new advantages
of highly interaction, personalization and service orchestration
in terms of the viewer’s use cases.
III. IMS-BASED IPTV ARCHITECTURE
A. Novel framework
Figure 1. IMS-based IPTV
Figure 1 shows a high-level functional IPTV network
architecture being supported by an IMS infrastructure. The
model provides multimedia services to the end user by means
of the SIP Application Server (SAS). The SAS implements the
service logics which users interact and request the movies
and/or other online contents in the personalized and intelligent
ways. Important logics have been implemented for the special
features like enhanced electronic program guide (eEPG),
interactive (parental) authorization, blending sessions, etc. The
SAS interacts with the IPTV Terminal Funtionality (IUF) that
handles the display and interactivity functions for viewers.
The IUF also performs functions such as content
encoding/decoding and buffering for both unicast and
multicast streams. The system is divided into a number of
logically separated parts, namely, the home domain, the core
network, the access/transportation network, the service/content
domain and service management.
B. IPTV User Profile
In the IMS IPTV architecture, personalization is an
important feature. To achieve personalization at the
application level (i.e. personalized EPG’s, advertisements, or
even personalized blended communication services), every
user has an IPTV profile. The relation between the IPTV
profile and the IMS profile depends on the availability of a
home IMS gateway. The home gateway is a functional block
with an attached ISIM card reader, which can be deployed in
the residential gateway or any other networked consumer
equipment. The gateway translates home signaling, whether
SIP, UPnP or perhaps pure HTTP to IMS signaling. It also
takes care of NAT traversal and secures connectivity with the
P-CSCF in the IMS domain, as well as identity, device
subscription, and management inside the home domain and
towards the IMS core.
If the household contains a home gateway, the family members can choose whether they want to have full IMS identity, which enables them to have full communication capabilities supported by IMS, or they just opt to have an IPTV profile, that will use the default IMS household identity for authentication purposes. The IPTV profile information that needs to be shared between different IMS services is stored in the IPTV XDMS database. This database is accessed using XCAP, which works over HTTP. These profiles can be shared by different users and other stakeholders within the IPTV system.
C. The Testbed
Figure 2. The HUT Next Generation Test-bed
In the scope of the joint-research project between Hanoi University of Technology and Fraunhofer Institute FOKUS Berlin - Germany, we set up a next generation network test-bed in our lab for the purpose of prototyping new multimedia and rich-feature communication services using IMS framework. The test-bed consists of all three layers: media layer for transportation of media traffic in unicast, multicast and broadcast. The core layer for signaling and session/service control makes use of the FOKUS’ open source IMS Core [3,4,5] that delivers CSCF servers and a light user profile database (HSS). Our project main focus is on the application layer in which we specified and developed prototypes for IP telephony and IP television value added services based on Sailfin platform. A Media Server was also developed at our lab using VLC (VideoLAN) media stack. Besides that we have developed a comprehensive framework and prototype of IMS IPTV Client that is based on the open source IMS Communicator. Finally, several IMS interfaces, namely, Sh, Mw, etc are implemented on our own effort. Figure 2 depicts high level view of our test-bed setup.
131
IV. USE CASES
A. Video on Demand
Figure 3. Requesting the on-demand contents
In our research, as depicted on Figure 3, we consider a
scenario in which an IMS user initiates a call to a specific
content (a movie, a song or other resources) locating at the
content provider through an IMS domain. The request can be
routed through different SIP servers (CSCFs); at S-CSCF a
suitable iFC is invoked to forward the request to IPTV AS, the
AS will then proxy the request to MRF (Media Server). Media
Server, after accepting the request, will send back the
successful responses (via AS) as well as the RTP streams
directly to the emulated setop box (STB). In our scenario, we
had implemented the AS based on Sailfin platform; the Media
Server was designed and implemented using VLC
(VideoLAN) RTP stack and oSIP library.
B. Remote Parental Control
A special feature, called Parental Control, had been designed
and implemented which allows the parent to control their child
from requesting and viewing classified contents. In this
scenario, as shown on the Figure 4, the child (Peter) initiates a
call to a specific content (movie and channel), the request will
be forwarded to IPTV AS through IMS Core, the AS, through
the in-house developed Sh interface, will download and check
the service registration of this user and learnt that this user
need the permission (from his parent) in order to view the
requested content. The AS then checks the status of the parent
(Alice) through Presence service and asks for her permission
(via Message method). Depending on the response from Alice,
whether she accepts or denies the request, IPTV AS will either
send back to Peter the denial response (603 Decline) or proxy
the request to Media Server which will subsequently send RTP
stream to Peter’s Client.
C. Enhanced EPG
Personalization is a key feature in the IMS IPTV solution.
In this sense, we have complemented the user profile with a
new XML-formatted [9] service profile for each IMS identity
to contain the personalized information. That leads to another
intelligent feature for IMS-based IPTV, we called Enhanced
EPG. With this feature user will be classified in to different
groups (via subscription) with different service levels.
Figure 4. IPTV Parental Control Feature
In this scenario, users in different classes, after registering
in to the IMS Core, will send Subscribe request to IPTV AS
for the EPG service. The AS then, via Sh interface, will query
the HSS to download the relevant iFC and check the registered
service profile of the requesting user, if the user belongs to the
free service package (no need access control) then AS will
build the relevant channel list and send it, through the payload
(in XML) of 200 OK Response message, back to the
requesting user. In the other hand, if the user belongs to the
group that need access control (e.g. for Premium service
packages) then the AS needs to query the HSS again to obtain
the necessary data to build the suitable channel list and sends
it back to the requesting user. Figure 5 and 6 below show the
basic message exchanges for implementation of these two
scenarios. The access control also provides the time
constrained service profile in which the requesting for
different time slots will receive different channel lists.
Figure 5. Message Flow for EPG of un-controlled access
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Figure 6. Message flow for Enhanced EPG Feature
D. Session Continuity
MN P-CSCF I-CSCF S-CSCF proxy AS
305 use proxy
INVITE(mSCTP)INVITE
INVITE(mSCTP)INVITE(mSCTP)
INVITE(mSCTP)
INVITE(mSCTP)INVITE(mSCTP)
INVITE(mSCTP)100 trying
100 trying100 trying
183 sp183 sp
183 sp183 sp
183 sp
PRACKPRACK
PRACKPRACK
MN PDP
Context Activation 200 OK200 OK
proxy PDP
Context Activation
AS PDP
Context Activation
200 OK200 OK
Visited IMS Domain 1 Home IMS Domain
REFER (AS)
200 OK
MN P-CSCF I-CSCF S-CSCF proxy AS
305 use proxy
INVITE(mSCTP)INVITE
INVITE(mSCTP)INVITE(mSCTP)
INVITE(mSCTP)
INVITE(mSCTP)INVITE(mSCTP)
INVITE(mSCTP)100 trying
100 trying100 trying
183 sp183 sp
183 sp183 sp
183 sp
PRACKPRACK
PRACKPRACK
MN PDP
Context Activation 200 OK200 OK
proxy PDP
Context Activation
AS PDP
Context Activation
200 OK200 OK
Visited IMS Domain 1 Home IMS Domain
REFER (AS)
200 OK
UPDATEUPDATE
180 ringing180 ringing
180 ringing180 ringing
180 ringing
PRACKPRACK
PRACKPRACK
200 OK200 OK
200 OK200 OK
UPDATE
200 OK200 OK
200 OK200 OK
UPDATE
200 OK200 OK
200 OK200 OK
200 OK ACKACK
ACKACK
ACK
mSCTP connection between MN and proxy
TCP/UDPconnection
proxy <> AS
UPDATEUPDATE
180 ringing180 ringing
180 ringing180 ringing
180 ringing
PRACKPRACK
PRACKPRACK
200 OK200 OK
200 OK200 OK
UPDATE
200 OK200 OK
200 OK200 OK
UPDATE
200 OK200 OK
200 OK200 OK
200 OK ACKACK
ACKACK
ACK
mSCTP connection between MN and proxy
TCP/UDPconnection
proxy <> AS
Figure 7. mSCTP connection setup between MN, proxy, AS and other
components in IMS
The issue of session continuity is also studied in our test-bed,
in which we investigated a new approach [10] that allows
handing over of an on-going IPTV session between different
access heterogeneous environments. We propose a new
component in the IMS domain, namely an proxy based on
mSCTP (mobile Stream Control Transmission Protocol) that
acts as an anchor point for soft vertical handover of mobile
nodes, which have multiple physical interfaces (e.g.,
WLAN/UMTS). Principally, our approach facilitates a break-
before-make handover scheme with QoS support, in which the
mSCTP proxy can set up multiple mSCTP tunnels pre-
established via multiple networks. The mSCTP-based proxy
can support QoS provisioning and adaptation for the mobile
nodes when moving in a heterogeneous wireless environment.
The network scenario for session continuity is depicted in
Figure 10.
After registering with a network, let’s say the visited IMS
domain 1 as illustrated in Figure 7, the MN wants to initiate a
call to an IPTV Application Server. At this moment the MN
does not know the existence of an mSCTP-based proxy, thus it
sends an INVITE message with the URI of the service identity
(PSI). Since the MN supports mSCTP in the transport layer, it
would like to set up an mSCTP connection if possible. In our
implementation, instead of sending an INVITE message
informing that the expected transport protocol is TCP or UDP,
mSCTP is specified in the INVITE message on the VIA header
field. Upon receiving the INVITE message, the home S-CSCF
analyses the message and realizes that the MN requests
mSCTP. Instead of forwarding INVITE to the AS, the home S-
CSCF sends a redirect message “305 use proxy” to the MN,
which specifies the URI of the mSCTP-based proxy in the
Contact field. The MN then sends INVITE to the proxy,
requesting to build an mSCTP transport session between the
MN and the mSCTP-based proxy. When the home S-CSCF
process the redirected INVITE message from the MN, it will
also send a REFER to the proxy instructing it to establish a
session from the proxy to the AS.
Following INVITE messages are QoS provisioning steps.
These steps are much like the conventional signaling flow,
except that the proxy should set up two sessions: one between
MN and the proxy with mSCTP tunnel, and the other between
the proxy and the AS. There are three PDP contexts that
should be established for the MN, proxy and AS. The session
setup procedure in our approach is a bit more complex than
usual with 66 messages. In Figure 7, we neglect some
messages that do not play significant role in the signaling
flow. The most advantages of our approach are in the vertical
handover process. The fast handover operation just requires 12
messages in our case versus 46 messages in the conventional
approach. For the handover including QoS setup, it takes 58
messages, 12 messages more when compared to the
conventional approach. If the two mSCTP tunnels already
exist, instead of a lengthy full session establishment, only 2
SIP messages are required to switch the session forth and back
through the two legs of the mSCTP tunnels.
V. SOME EXPERIMENTAL RESULTS
This section highlights some of the various intelligent features
implemented in our test-bed prototype. Figure 8 illustrates a
personalized user portal which provides a different content
meta-data (channel list) to registered user from different
group. Figure 9 shows feature of blending services that allows
displaying the Incoming Call/Message from buddies on the
online TV screen if the watching user is not on the “Do not
133
disturb” mode. The viewer then has options of pausing the TV
session to handle the incoming call/message or reject it.
Finally, figure 10 shows our proposed architecture for the
implementation of (IP TV) session continuity.
Figure 8. Channel List for different User Categories of Enhanced EPG
feature
Figure 9. Incoming Call/Message Display
VI. CONCLUSIONS AND FUTURE DIRECTIONS
This paper presents our investigation, in experimental
perspective, of using IMS framework to provide intelligent
features for IPTV services. In particular, it focuses on the video
on demand, remote parental control, blending services, session
handover without interruption and other interactive features
which some of the use cases were discussed and presented
here-above. It shows how SIP [2, 7] signaling and IMS can be
used to provide the Interactive and Blending features for the
entertainment video services.
The initial results promise the great potential of those IMS-based TV interactive and differentiated features, which offer attractive and rich multimedia experiences to the end user. We are currently investigating and developing several other intelligent features of IMS-based TV, namely, the context-based session continuity that allows to seamlessly handover the
IPTV sessions across different screens/terminals on different access networks.
Visited IMS domain 2 - WLANVisited IMS domain 1 - UMTS
Home IMS domain
GGSN PDG
AP
P-CSCF
I-CSCF
HSS
GGSN
S-CSCF
AS
MN
mSCTPProxy
P-CSCF
Data path
Signaling path
RNC
Visited IMS domain 2 - WLANVisited IMS domain 1 - UMTS
Home IMS domain
GGSN PDG
AP
P-CSCF
I-CSCF
HSS
GGSN
S-CSCF
AS
MN
mSCTPProxy
P-CSCF
Data path
Signaling path
RNC
Figure 10. Signaling paths and data paths between MN, mSCTP proxy, AS
and IMS components
VII. ACKNOWLEDGEMENT
The authors would like to acknowledge the National
Foundation for Science and Technology Development
(NAFOSTED) of Vietnam for funding this work.
REFERENCES
[1] TS 23.328, “IP Multimedia Subsystem,” 3GPP, Release 6
[2] J. Rosenberg, et al., “SIP: Session Initiation Protocol,” RFC 3261, IETF, June 2002
[3] F. inc., XDMS: The FOKUS XML Document Management Server,
http://www.fokus.fraunhofer.de/bereichsseiten/.
[4] Open IMS Core Playfround, see http://www.openimscore.org/
[5] SIP Express Router, see http://www.iptel.org/ser
[6] UCT IMS Client, see http://uctimsclient.berlios.de
[7] M. Handley, V. Jacobson, “SDP: Session Description Protocol,” RFC 2327, IETF, April 1998
[8] Service Capability Interaction Manager, see http://en.wikipedia.org/wiki/Service_Capability_Interaction_Manager
[9] J. Rosenberg, The Extensible Markup Language (XML) Configuration Access Protocol, http://tools.ietf.org/html/draft-ietf-simple-xcap-12.
[10] Nguyen Huu Thanh, Le Thi Hang, Vu Van Yem, Ngo Quynh Thu, Nguyen Xuan Dung, “Multimedia Session Continuity with Context-Aware Capability in IMS-based Networks”, in Proceedings of IEEE Sixth International Symposium on Wireless Communication Systems 2009 (ISWCS’09), September 7 – 10, 2009, Siena-Tuscany, Italy
[11] B. Chatras, M. Said. Delivering Quadruple Play with IPTV over IMS. International Conference on Intelligence in Networks (ICIN) 2007, Bordeaux, France
[12] Beck, Andre , Bob Ensor, Jairo Esteban, 2007, "IMS and IPTV Service Blending -Lessons and Opportunities," Journal of the Institute of Telecommunications Professionals
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