used for computer networks. It is television over the Internet. It will become an alternative to tradi- tional cable and satellite delivery methods. How it works.
T
elevision distribution has become the largest technology infrastructure deployed after telephone and electric power networks. Television has dramatically changed the way we live, work, learn, and do business. Regular television is being delivered through radio frequency broadcast and cable television (CATV). Up to now, delivering television over a broadband network has been costly and bandwidth intensive. In an Internet Protocol television (IPTV) system, digital television service is delivered using the architecture and networking methods of the Internet Protocol suite over a packet-switched network infrastructure, which may include delivery by a broadband connection. IPTV describes a system capable of receiving and displaying a video stream encoded as a series of Internet Protocol packets. Thus, IPTV involves receiving television content by the viewer through the means used for computer networks. It is television over the Internet. It will become an alternative to traditional cable and satellite delivery methods.
How it works IPTV delivers a low-speed broadband TV connection (2.2 Mb/s) through telephone wires (copper network). Video content may originate from multiple sources: precompressed video content from a satellite, MPEG-formatted movie files from a local video on demand (VoD) server, or a direct feed from broadcasters, among others. The video streams are received by the local office, where the local content (such as TV stations and advertising) is added to the mix. The local office is equipped with receiving TV and high definition TV (HDTV) satellite signals. The local office is responsible for sending the video streams to the consumer. The number of video streams sent
©TV IMAGE COURTESY OF PKEPNERIV/WIKIMEDIA COMMONS
simultaneously by the local office to the consumer varies by the network, but it is hardly more than four due to bandwidth limitation. The consumer or end user has a set-top box that accepts signals and converts them into usable information. A user may request a channel change by sending a request for a video channel.
IPTV: An alternative to traditional cable and satellite television Digital Object Identifier 10.1109/MPOT.2011.940903
Matthew N.O. Sadiku and Sudarshan R. Nelatury
Date of publication: 27 July 2011
44
0278-6648/11/$26.00 © 2011 IEEE
IEEE POTENTIALS
IPTV is different from cable TV delivery. On cable TV, the consumer is receiving the entire range of channels all the time. This requires huge amounts of bandwidth. IPTV delivery is different in that it delivers the single channel that the consumer requires. For residential users, IPTV may be provided in conjunction with other internet services such as VoD and voice over IP (VoIP), well beyond traditional cable TV services. In businesses, IPTV may be used to deliver video streams over corporate local area networks. Delivering TV services over the Internet is not particularly different from any other streaming, except for one thing: everyone has to receive the streams at the same time. The contents of IPTV are composed of different media including voice, video, audio, and text, which require different treatment. Quality of service (QoS) and quality of experience (QoE) have been identified as critical requirements of IPTV services for consumers. IPTV may be regarded as providing multimedia services delivered over IP networks to provide the required level of QoS/QoE, security, and reliability. QoE describes the overall system performance from an end user’s expectations, while QoS represents a measure of performance from the network perspective. The relationship between the two is the issue of mapping the requirements of the end user and the service to the transport parameters and mechanisms. Figure 1 depicts the meaning and scope of IPTV, while Fig. 2 portrays several IPTV services. The IPTV architecture should be capable of monitoring video quality and may support the ability to dynamically adjust QoS/QoE metrics. Table 1 presents the differences between terrestrial broadcast TV and IPTV. Table 2 presents the advantages and disadvantages of IPTV.
Challenges and standards The advances in broadband Internet access and video technologies have made it possible for IPTV to be the next killer application for modern Internet carriers. The first IPTV service was provided in Japan in 2002; shortly after, it became available in Korea. The current quality of IPTV in the United States does not yet approach that of cable TV. In 2005, IPTV service reached about 4 million homes. By early 2010, there were more than 25 million IPTV users in the world. The phone companies will most likely embrace IPTV technology because it will open up a new market for them. JULY/AUGUST 2011
TV
Video
Audio
Text
Graphics
Data
Multimedia Service
IP-Based Network
QoS/QoE
Security
Reliability
Interactivity
Fig. 1 Definition and scope of IPTV.
• Consumer
FTTx
xDSL
• Consumer
Core Networks
IPTV Content
IP
GMPLS
Carrier Ethernet
802.11n WLAN
• Consumer
• Consumer
MPLS
Multicast
Fig. 2 Services of IPTV.
45
Table 1. Comparison between terrestrial broadcast TV and IPTV. Terrestrial Broadcast TV
IPTV
Service not guaranteed
Guaranteed QoS/QoE
One way
Two way (interactive)
Simultaneous channel streams
Selected channel bundles
All content flow downstreams
Contents remain in network
No management
Managed billing
Table 2. Advantages and disadvantages of IPTV. Advantages
Disadvantages
Two-way capability lacked by traditional TV distribution technologies
It is sensitive to packet loss and delays
Point-to-point distribution allowing each viewer to view individual broadcasts
Its price is too high for average people
Ability for digital video recorders to record multiple broadcasts at once
IPTV systems currently do not support HDTV broadcasts
Ability to integrate television with other IP-based services like VoIP
Video data compressed a lot
Conclusions This article presents an overview of IPTV services and its key technologies. IPTV is a key element of the “triple play” where video, voice, and data services are bundled together. It is an emerging Internet application that provides flexibility and interactivity. Though IPTV is still in its infancy stage, it is the wave of the future for telecommunications. Watching IPTV content will be just like surfing the Internet. It is anticipated that IPTV will be used to deliver instruction to students. IPTV has an advantage over satellite, terrestrial, or cable TV systems because it has an embedded return channel. This enables a service provider to add more interactivity. IPTV services were originally targeted fixed terminals but mobility possibilities have come up. Mobile IPTV, which extends many IPTV services to mobile users.
Read more about it Owing to the growing demand from consumers for a better video experience, future IPTV services should provide two types of quality: standard definition TV (SDTV) and high definition TV (HDTV). SDTV and HDTV need a bandwidth of 1–4 Mb/s and 4–12 Mb/s, respectively. The broadcast industry intends to convert our current system to HDTV, a conversion which presumably will be completed in another five years. HDTV increases the number of scan lines on the screen and widens the aspect ratio of the screen from the standard 4:3, which is what most televisions are today, to 16:9. SDTV refers to digital television broadcast in 4:3 aspect ratio. The difference between SDTV and HDTV is that the signal on SDTV is more compressed than that of HDTV. The picture definition of SDTV is also slightly lower than on HDTV. The IPTV industry needs help from standardization bodies. Standardization of IPTV is important for its success. Standardization of next deneration networks (NGN) including IPTV services has progressed in the International Telecommunication Union (ITU). (Next generation networking is a broad term that describes some key architectural evolutions in computer networks that will be deployed over the next five to ten years.) The IPTV World Forum has been formed to meet annually and bring together all vendors and service providers to develop IPTV services. No other resource brings together this depth of information from such a diverse and skilled range of 46
experts. The Open IPTV Forum was set up in 2006 to create an architecture for future IPTV services. The consumer electronics companies have a great interest in the Open IPTV Forum. The European
Though IPTV is still in its infancy stage, it is the wave of the future for telecommunications.
Telecommunications Standards Institute (ETSI) published an IPTV standard, TISPAN (Telecommunications and Internet converged Services and Protocols for Advanced Networking), in March 2008. TISPAN is actively defining the service requirements and capabilities for customers’ home networks to be connected to the NGN. Finally, the Alliance for Telecommunications Industry Solutions (ATIS) initiated the IPTV Interoperability Forum (IIF), which develops standards to enable the interoperability, interconnection, and implementation of IPTV systems and services. IIF is recognized globally as the leading developer of requirements, standards, and specifications for IPTV.
• J. Weber and T. Newberry, IPTV Crash Course. New York: McGraw-Hill, 2007. • J. Hjelm, Why IPTV: Interactivity, Technologies and Services. Chichester, U.K.: Wiley, 2008. • J. She, et al., “IPTV over WiMAX: Key success factors, challenges, and solutions,” IEEE Commun. Mag., pp. 87– 93, Aug. 2007. • Y. Xiao, et al., “Internet protocol television (IPTV): The killer application for the next-generation internet,” IEEE Commun. Mag., pp. 126–134, Nov. 2007. • J. Maisonneuve, et al., “An overview of IPTV standards development,” IEEE Trans. Broadcast., vol. 55, no. 2, pp. 315–328, June 2009. • M. L. El-Sayeed, et al., “Comparison of transport network technologies for IPTV distribution,” Bell Labs Tech. J., vol. 11, no. 2, pp. 215–240, 2006.
About the authors Matthew N.O. Sadiku (mnsadiku@ pvamu.edu) is a professor at Prairie View A&U University in Texas. He is the author of over 30 books and more than 180 papers. His areas of interest include numerical modeling of electromagnetic problems and computer networks. Sudarshan R. Nelatury (srn3@psu. edu) is with the Department of Electrical, Computer, and Software Engineering at the School of Engineering and Engineering Technology, Pennsylvania State University, Erie, Pennsylvania. His research interests include electromagnetics and digital signal processing. IEEE POTENTIALS
