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The 5th PSU-UNS International Conference on Engineering and
Technology (ICET-2011), Phuket, May 2-3, 2011 Prince of Songkla University, Faculty of Engineering
Hat Yai, Songkhla, Thailand 90112
Li Xuan¹, Liu Jing¹, Sungchol Cho¹, Jin Xianshu¹,
S. Kamolphiwong², T.Ang-Chuan²,T. Sribuddee³, Ta Bahung⁴, Quincy Wu⁵, Basuki Suhardiman
6, Sunyoung Han*
¹Department of Computer Science and Engineering Konkuk University, 1 Hwayang, Gwangjin, Seoul 143-701, Korea
²Department of Computer Engineering, Faculty of Engineering, Prince of Songkla University, Thailand
³UniNet-ThaiREN, Thailand
⁴National Agency for Science and Technology Information, Vietnam
⁵National Chi Nan University, Taiwan 6Bandung Institute of Technology, Indonesia
{lxahtena, jing8100, cschol, hyunsook}@cclab.konkuk.ac.kr
Abstract: IPTV becomes one of the most popular
multimedia applications in recent years. It supports not
only the traditional voice and data services but also the
new service types such as VoD, broadcast TV, live TV
and so on. However, because of limited network resource
and users’ increasing requirement about QoS, it is
difficult to guarantee QoS of multimedia IPTV. So in this
paper, we study on the overlay multicast-based IPTV and
design a scheme and test bed based on multi-channel and
overlay network for improving QoS of IPTV.
Key Words: Multi-channel / Overlay / QoS of IPTV /
Multicast
1. INTRODUCTION
With the rapid development of Internet, the general
Internet services (such as Web service, FTP service,
video and audio download, etc.) cannot satisfy people's
demand any more. The multimedia service with higher
quality is required more and more. The Internet Protocol
Television (IPTV) becomes one of the most popular
multimedia applications in recent years[1][2]. It can
deliver the multimedia data to thousands of consumers at
the same time over IP-based network. The IPTV supports
not only the traditional voice and data services but also
the new services such as Video on Demand(VoD),
broadcast TV, live TV and so on. However, because of
limited bandwidth, unstable network and different
compression coding standards, the qulity of these kinds
of multimedia services cannot be guaranteed when they
are transmitted. So in order to guarantee the required
*Corresponding author
level of the QoS of theses multimedia services, IPTV is
facing many challenges[3].
In this paper, we mainly study on the overlay
multicast-based IPTV and design a scheme based on
multi-channel and overlay network for improving IPTV
transmission quality. Then we design the whole testbed
for this scheme and do the experiments with Thailand,
Vietnam, Indonesia and Taiwan.
The rest of this paper is structured as follows. The
overlay multicast for IPTV and some related work are
introduced in section 2. Section 3 analyses the decline of
the IPTV quality and presents the scheme based on
multi-channel and overlay network. Then section 4
presents the whole testbed architecture and the
experimental process. Finally, we summarize our work
and outline items for future work in section 5.
2. RELATED WORK
2.1. Multicast for IPTV
As we know, the delivery of multimedia data of IPTV
will push network infrastructures to the limit and require
very high levels of QoS [4][5]. There are two dominant
technologies for the delivery of packetized IPTV to
multiple recipients over Internet: peer-to-peer technology
and IP multicast tree technology. The use of packet-
switched IP multicast trees to deliver the content is a
well-established technology. It's the most efficient
delivery mechanism to support a tremendous number of
users at one time.
A Scheme Based on Multi-channel and
Overlay Technology for Improving IPTV
Transmission Quality
373
2.2 Overlay network technology
An overlay network is a virtual network of nodes and
logical links that is built on top of an existing network
with the purpose to implement some special network
services. In our research, it is responsible for handling
stream transmission of IPTV applications and operated
in an organized and coherent way. We do the experiment
on the overlay network named Trans-Eurasia
Information Network 3(TEIN3). TEIN3 is a huge
network with high speed for scientific research. Our
testbed contains Korea, Thailand, Vietnam, Indonesia
and Taiwan five countries who are connected by TEIN3.
2.3 Compression method for multimedia data
In order to guarantee QoS of IPTV service and satisfy
consumers' requirements for various multimedia data, we
need different video compression methods to support
high quality IPTV services.
1) H.264[6] is an advanced video coding for generic
audiovisual services. This video format has a very broad
application range that covers all forms of digital
compressed video from low bit-rate Internet streaming
applications to HDTV broadcast and digital cinema
applications with nearly lossless coding[7]. 2) MPEG-
2[8] is widely used as the format of digital television
signals that are broadcasted over the air, cable, and direct
broadcast satellite TV systems. It also specifies the
format of movies and other programs that are distributed
on DVD and similar discs. 3) Audio Video Interleave
(AVI) is a multimedia container format introduced by
Microsoft. AVI files can contain both audio and video
data in a file container that allows synchronous audio-
with-video playback. 4) Windows Media Video (WMV)
is a video compression format for several proprietary
codecs developed by Microsoft. It was originally
designed for Internet streaming applications, and now
WMV 9 has gained adoption for physical-delivery
formats such as HD DVD and Blu-ray Disc.
2.4 Multi-channel for IPTV
Fig. 1. Multi-channel for multimedia services
As shown in Fig. 1, the multimedia service can be
designed as multiple virtual channels. Various service
contents(such as video streaming, data, wireless) can be
deliveried into different channels with different
bandwidth, which can make full use of the limited
bandwidth resource and guarantee a required QoS level
of different service contents.
2.5 Overlay multicast testbed between Korea and
Thailand[9]
Before this work, we already established a testbed
over KOREN, THaiREN and TEIN2 for the
measurement of overlay multicast traffic. We did lots of
experiments on that testbed to analyze the speed of
stream transmission and tranmission security when the
stream is forwarded to various international networks.
Fig. 2. Overlay multicast testbed between KU and PSU
As shown in Fig. 2, the stream encoding was done in
KU, and the streaming was forwarded over KOREN,
TEIN2 and THaiREN. After receiving the video
streaming, the Edge OMR delivered it to local users by
using multicast.
3. PROPOSED SCHEME BASED ON MULTI-
CHANNEL AND OVERLAY TECHNOLOGY
3.1. Overview of the scheme and architecture
For maintaining the level of multimedia service
quality and supporting multi-channel and overlay well,
we need a stable and effective network environment. So
as shown in Fig. 3, in order to obtain more exhaustive
and accurate experimental data and result, we design this
whole testbed and do the experiments with Thailand,
Vietnam, Indonesia and Taiwan.
Fig. 3. Architecture of the scheme based on overlay
network
The core network of this test bed is TEIN3, and five
high speed research networks in different countries
connect to TEIN3 to support multimedia data
transmission based on multi-channel. In this scheme,
Konkuk University in Korea establishes different
channels to transmit multimedia streams with other test
374
points in other countries. In order to support multicast
IPTV, Overlay Multicast Relay (OMR) device is set up
in every test point. It consists of server and client
terminal which are called Root and Edge in this scheme.
The Root can capture the local multimedia stream from
video server, and then transmit it by unicast through
overlay network. And the use of Edge is to receive the
multimedia stream from overlay network and implement
the local multicast.
3.2. Evaluation and analysis about QoS of IPTV
multimedia streams
In this scheme, we plan two phases for the
implementation and experiment. First one is evaluation
and analysis about QoS of IPTV multimedia streams.
Through this phase, we can get evaluation about QoS of
various multimedia data and find the problem when
transmitting streams by using multi-channel and overlay
technology.
Fig. 4. Overlay multicasting architecture in the first
phase
Fig. 4 shows us the test bed architecture of the first
phase. For more exhaustive evaluation data, various
multimedia formats should be considered in this scheme.
First we transmit multimeida streams with other 4
countries respectively, and the condition is as followings:
Table 1. QoS of IPTV based on single channel
Thailand Vietnam Indonesia Taiwan
Stream
format
AVI H.264 Live
stream
MPEG-
2
QoS Good Good Good Good
As shown in Table 1, when we transmit video stream
with just one country at one time, the QoS of IPTV is
good for different stream formats. Because it is single
channel and network resource (like bandwidth) is enough
for high quality video stream transmission.
Then a group experiment is implemented. We adopt
two single channels to transmit different video formats to
Thailand and Vietnam simultaneously, and the same
work is done with Indonesia and Taiwan simultaneously.
The former result is still good but the QoS of both live
stream and MPEG-2 goes down obviously. At last, when
we adopt four single channels to transmit different video
formats to four countries simultaneously, the QoS of
each channel arises obvious decline.
This decline results from live stream. Because the
real-time video stream demands a high and stable
bandwidth to maintain the real-timing and uncompressed
video stream transmission, the QoS of other channels is
also influenced.
3.3. Multimedia data transmission scheme based on
multi-channel
The second phase is to utilize multi-channel and
overlay technology to implement IPTV multimedia data
transmission with four countries simultaneously.
In order to implement multicast and multi-channel
IPTV services, we need a protocol which can support
video stream transmission of various formats and real-
time QoS control. Real-time Transport Protocol (RTP) is
a good choice to do this job. RTP defines a standardized
packet format for delivering audio and video over IP
networks. This standard defines a pair of protocols, RTP
and Real-time Transport Control Protocol (RTCP). RTP
is used for transfer of multimedia data, and RTCP is used
to monitor transmission statistics and QoS, and it’s also
used to aid synchronization of multiple streams.
One of the design considerations of RTP is to support
a range of multimedia formats (such as H.264, MPEG,
MJPEG, etc.) and allow new formats to be added without
revising the RTP standard. So in this scheme, we can use
RTP to implement multi-channel. When the streaming
server in Konkuk University of Korea sends streams of
various formats including real-time streaming, the
enormous video stream is delivered to different channels
by using RTP and VLC multimedia framework.
Fig. 5. Multi-channel for IPTV stream transmission with
4 countries
As shown in Fig. 5, four different video streams are
delivered into four channels and sent to Taiwan,
Vietnam, Thailand and Indonesia respectively. Every
channel has its own destination, so the unicast is used for
stream transmission on overlay network. When streams
arrive at each test point, the Edge OMR in local area can
relay the stream by using multicast for local users.
As we know, RTCP provides out-of-band statistics
and control information for an RTP flow. The primary
function of RTCP is to provide feedback on the QoS in
media distribution by periodically sending statistics
information to participants in a streaming multimedia
session. In this scheme, because of different stream
fomats, these channels have different requirements about
bandwidth and the level of QoS. So according to the
feedback information (such as lost packet counts, jitter,
round-trip delay time, etc.) of RTCP, the stream server
can adjust encoding parameters timely to guarantee QoS
of IPTV multimedia transmission.
So this scheme can not only evaluate the performance
of multiple video streams and QoS of IPTV multimedia
data transmission, but also guarantee QoS of IPTV when
multiple video streams of different formats are
transmitted simultaneously.
375
4. EXPERIMENTS AND DISCUSSION
In this section, first we carry out the whole test bed
including multimedia stream server, the Root OMR and
Edge OMRs in other 4 countries. Table 2 shows the
device information about Root and Edge OMRs.
Table 2. Device information about Root and Edge OMRs
CPU Hard
disk
Network
interface
mem
ory
Korea
OMR
Intel(R)
Celeron(R)
2.00GHz
100G 100baseT
x-FD
2474
76
KB
Thailand
OMR
Intel(R)
Core(TM)2
Quad Q6600
2.40GHz
250G 100baseT
x-FD
3635
736
KB
Indonesia
OMR
Intel(R)
Pentium(R)D
3.00GHz
80G 100baseT
x-FD
5141
96
KB
Vietnam
OMR
Intel(R)
Pentium(R)D
3.00GHz
80G 100baseT
x-FD
5141
96
KB
Taiwan
OMR
Intel(R)
Pentium(R)D
3.00GHz
80G 100baseT
x-FD
5141
96
KB
Fig. 6 shows the actual test bed architecture for
multimedia IPTV service in this scheme. The connection
from KOREN to TEIN3 has a high bandwidth as
2.5Gbps, and other connections from other countries to
TEIN3 have the bandwidth of 622Mbps or 155Mbps. So
we choose Konkuk University in Korea as the server
point which is responsible for multimedia stream
encoding and transmission by multi-channel.
Fig. 6. The actual test bed architecture for multi-channel
IPTV service
In the first phase, we test the single channel stream
transmission with other four countries respectively. The
live streaming case between Korea and Indonesia is
shown in Fig. 7. The real-time streaming source goes
into overlay network through Root OMR. Then the Edge
OMR in Indonesia can receive this stream and transmit it
to local users by using multicast. Through this process,
we evaluate the QoS of multimedia streams of various
formats and the result shows the QoS is good enough for
users when only one stream is transmitted. But when
multiple streams are transmitted simultaneously, the QoS
of each stream gets influenced since the real-time
streaming case demands a very high and stable
bandwidth.
Fig. 7. Live streaming test architecture between Korea
and Indonesia
By using VLC framework, we can monitor each
stream bit rate and packet losting condition on real time
when playing test video. So we record each bit rate at
intervals of one minute and draw the Fig. 8. As shown in
Fig.8, from the beginning to the 10th minute, the stream
bit rates of four different videos get a similar trend. Even
the real-time streaming to Indonesia also doesn't occupy
too much bandwidth since we just record the static image
for real-time streaming. So the QoS of these four videos
can be maintained at a relatively good level. But after 10
minutes, we start moving the camera and recording
something moving. As a result, the bit rate of the real-
time streaming to Indonesia goes up obviously while the
bit rates of the other three streams get decreased.
Because the real-time stream occupies a great amount of
bandwidth unexpectedly, packet-lost of the other three
streams becomes more serious and the QoS also get
worse at the same time. So if we transmit these streams
in different channels, this kind of influence can be
reduced to minimum and the QoS of other streams can
be guaranteed well.
Fig. 8. Stream bit rate of four countries' test video
The second phase is the multi-channel test between
five countries. We use RTP based on VLC framework to
support multi-channel stream transmission. And OMR is
used for overlay multicasting. When multimedia streams
of different formats are transmitted in different channels,
the feedback information about streams can be sent back
to the stream server. Then according to this information,
the server can adjust values of stream encoding
parameters to reduce lost-packet rate and delay time.
Although the definition of real-time streaming frames
may decline, the QoS of the other streams can reach to
the requaired level while the fluency of streams also can
be guaranteed well.
376
5. CONCLUSION
This paper firstly introduces the current development
of IPTV and stduies some related technologies about
QoS of IPTV. Secondly we design and build a multi-
channel test bed with four other countries for evaluating
and improving QoS of multimedia IPTV. Finally we do
some experiments on this test bed to discuss the reasons
which result in the decline of QoS of IPTV and the
solution based on multi-channel and overlay network.
Our future work will address how to improve the
accuracy of QoS evaluation and how to make streams
from different channels be received in each local area.
We hope this scheme and test bed can do more work for
improving QoS of IPTV.
6. REFERENCES
[1] N. Degrande, K. leavens, D. De Vleeschauwer, et al.,
“Increasing the user perceived quality for IPTV
services”, IEEE Communications magazine, 2008,
46(2):94-100.
[2] U.Jennehag, T. Zhang, S. Pettersson, “Improving
transmission efficiency in H.264 based IPTV systems”,
IEEE Transactions on broadcasting, 2007, 53(1):69-78.
[3] ATIS Std. ATIS-0800007, “IPTV High Level
Architecture,”, 2007.
[4] Cisco System White Paper, “Optimizing Video
Transport in your IP Triple Play Network”,
2006[Online]. Available: www.cisco.com
[5] A. Sardell, Juniper Networks, “Video Transport on an
MPLS Backbone”, White Paper, Mar. 2005[Online].
Available: www.juniper.com
[6] T. Wiegand, G. J. Sullivan, G. Bjontegaard, et al.,
“Overview of the H.264/AVC Video Coding
Standard”, IEEE Transactions on circuits and
systems for video technology, 2003, 13(7): 560-576.
[7] D.Marpe, T. Wiegand, and G. J. Sullivan, “The
H.264/MPEG4 Advanced Video Coding Standard
and Its Applications”, IEEE Commun. Mag., vol.44,
no.8, Aug. 2006, pp.134-44.
[8] “Generic Coding of Moving Pictures and Associated
Audio Information-Part 2: Video,” ITU-T and
ISO/IEC JTC 1, ITU-T recommendation H.262 and
ISO/IEC 13818-2(MPEG-2), 1994.
[9] Jing Liu, Sungchol Cho, Sunyoung Han, Keecheon
Kim, YoungGuk Ha, Jongwon Choe, Sinchai
Kamolphiwong, Hyunseung Choo, Yongtae Shin,
Chinchol Kim, “Establishment and Traffic
Measurement of Overlay Multicast Testbed in
KOREN, THaiREN and TEIN2”, ACM Mobility
Conference, Sep, 2009, pp. 135-42.
377