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Feature Articles: Latest Trends of Multimedia Broadcasting Technologies for Mobile Terminals

Service and Technology Overview of Multimedia Broadcasting for Mobile Terminals

Tomoyuki Ohya, Masayuki Ishikawa, Hideo Suzuki^†, Junichi Kishigami, Kenji Yamada, and Katsuhiko Kawazoe

Abstract

This article briefly explains the multimedia broadcasting service for mobile terminals planned to start in Japan in spring 2012, after the frequency band currently used for terrestrial analog broadcasting became available in July 2011, and the technology that will support it. This service is based on the ISDB-Tmm (integrated services digital broadcasting, terrestrial mobile multimedia) system. Part of the system will use technology from NTT’s research and development.

†	NTT Cyber Solutions Laboratories Yokosuka-shi, 239-0847 Japan

1. Introduction

Multimedia broadcasting for mobile terminals is scheduled to begin in Japan in spring 2012 using the ISDB-Tmm (integrated services digital broadcasting, terrestrial mobile multimedia) system^* in the frequency band from 207.5 MHz to 222 MHz that became available after terrestrial analog television (TV) broadcasting ended in July 2011 [1].

*	ISDB-Tmm system: A multimedia broadcasting system for mobile terminals and specifications for multimedia broadcasting for mobile devices. It supports stored content in addition to the viewing of realtime video.

The ISDB-Tmm broadcasting system is an expansion of the ISDB-T (T: terrestrial) system [2], [3] being used for terrestrial digital TV broadcasting and provides a service that combines two media, communications and broadcasting, which have different characteristics. As major features, the system makes use of the excellent mobile reception of terrestrial digital TV and offers extended capabilities such as improved video quality, the transfer of various kinds of large files such as video and voice, and interworking with communication functions. The main divisions in the system configuration are the broadcasting system and the information system. This article describes the planned application of technology that arose from NTT’s research and development (Fig. 1).

Fig. 1. Multimedia broadcasting concept and system configuration.

In September 2010, the Ministry of Internal Affairs and Communications authorized Multimedia Broadcasting (mmbi) [4] as a consignment broadcaster (explained below) using a framework that separates hardware and software in the implementation of multimedia broadcasting in the form of consignment broadcasting and consigned content broadcasting [5]. mmbi then established Japan Mobilecasting, Inc. [6] in January 2011 and transferred the license to operate as a consignment broadcaster in February of that year (Fig. 2).

Fig. 2. Consignment broadcasters and content consigning companies.

A broadcasting content consigner creates and organizes the programming, performs authentication, and handles charges and settlement as well as the broadcasting work for delivering the program; a consignment broadcaster broadcasts the data received from the consigner nationwide.

Of the frequency band opened up by the ending of analog broadcasting (90–222 MHz), 33 segments for nationwide broadcasting (207.5–222 MHz) are planned for use by Japan Mobilecasting, and mmbi is planning to enter the consignment broadcasting business (Fig. 3).

Fig. 3.Segment use.

2. Services provided by multimedia broadcastings

Services that are provided by multimedia broadcasting are broadly classified as those provided by realtime systems and those provided by stored content systems (Fig. 4).

Fig. 4. Services provided by multimedia broadcasting.

2.1 Realtime broadcasting

Realtime broadcasting services involve program viewing at the time of the broadcast. That is to say, realtime broadcasting can be regarded as corresponding to the one-segment broadcasting (One-Seg) offered for cell phones and mobile terminals, but multimedia broadcasting extends that service in the ways described below.

(1) Improved quality

The quality of video in multimedia broadcasting supplements the One-Seg specification with three additional schemes (Table 1). ISDB-TMM uses 13 segments in contrast with One-Seg. Thus, even video that contains fast motion can be viewed clearly, and viewing with sufficient image quality is possible on large-screen tablets and smart phones and even on larger external displays that have HDMI (high-definition multimedia interface) as well as on conventional cell phones. For good audio quality, HE-AAC (high-efficiency advanced audio coding) and HE-AACv2 are provided in addition to the MPEG-2 AAC used for One-Seg. In the future, MPEG Surround will also be available as soon as the environment for it is prepared.

table 1.Image quality comparison.

(2) Improved interworking with other media

One-Seg broadcasting also provided functions for interworking with various media, initiated by a TV program. Nevertheless, that system was focused on TV, and the interworking with other media was not necessarily active. In multimedia broadcasting, on the other hand, communication-derived content offered via a communication function is handled with relative freedom by the receiver. Multimedia broadcasting also inherently involves two different types of broadcasting system (realtime and stored). Because of those and other such factors, the system is being extended in the direction of improved interworking with One-Seg, multimedia broadcasting (both realtime and stored), and communication-derived content, etc., assuming that the receiving cell phones, which were originally planned to be the multimedia broadcasting receivers, will be equipped with those functions. In other words, the communication function can be considered to be a standard function of multimedia broadcasting receivers. To take fullest advantage of that feature, the system is being configured to deliver broadcast content and communication-derived content through seamless interworking.

2.2 File-based broadcasting

Service provision by file-based broadcasting differs from realtime broadcasting in that the time scheduling and duration of viewing or use of the content is not the same as the scheduling and duration of the broadcast. That is to say, as the term file-based indicates, the service assumes that the receivers receive and temporarily store the broadcast content before it is actually viewed or used.

Thus, good content viewing or use can be expected even in locations that have poor reception of broadcast waves, such as underground areas or inside buildings. The content that is received and stored is in the form of ordinary files that are widely used by personal computers, so e-books, games, and various other types of content that cannot be handled by conventional broadcasting can be provided as well as video and audio. Because services can be premised on the receiver having a communication function, as mentioned above, services that are highly aware of interworking with the communication function are being planned.

2.2.1 Transmission technology

A major feature of file-based broadcasting is that any file can be delivered in a broadcast. To implement that feature, the protocol stack shown in Fig. 5 and IP (Internet protocol) transmission technology are used. This transmission system has an application-layer forward error correction (AL-FEC) function that provides powerful error correction that can handle data loss over an extended time period—something that is difficult for the FEC function of the radio physical layer.

Fig. 5. Multimedia broadcasting protocol stack.

2.2.2 Stored content complementation technology

Although multimedia broadcasting uses powerful error correction to overcome errors in the received data caused by deterioration of broadcast reception conditions, if the limits of that function are exceeded (e.g., the receiver remains outside the broadcasting area), then the error correction function cannot produce the correct content. Nevertheless, content reception can be completed even though the broadcast has ended because the missing content can be received via the receiver’s communication function (Fig. 6).

Fig. 6. Stored content complementation technology.

2.2.3 EPG/ECG metadata technology

File-based broadcasting differs from the conventional TV broadcasting service in that there is no concept of channels or scheduled times. On the other hand, file-based broadcasting requires content status management, for example, prior to broadcasting, during storage, and of viewable (usable) content, which is not required by the previous form of TV broadcasting. Another requirement is a function for managing content with respect to the receiver’s storage capacity and allowing the user to easily understand the storage status. The solution is electronic program guide & electronic content guide (EPG/ECG) metadata. This includes various types of information about individual programs and other items of content in the XML (extensible markup language) format that can be used by the receiver to present the user with information about content in a way that is easy to understand. It also provides a basis for recommending new content according to the user’s prior content viewing (usage history).

2.2.4 Content protection and access control technology

Multimedia broadcasting differs from the One-Seg service in that it assumes a charged broadcasting model. In other words, it must be possible to permit content viewing (use) by users who pay a charge, but restrict viewing by users who do not pay the charge. Content protection and access control technology fulfills that requirement.

The main feature of the content protection and access control technology for multimedia broadcasting, as shown in Fig. 7, is delivery of the content by broadcasting and delivery of the license for viewing (using) the content via the communication channel. Another feature is the use of a stronger encryption algorithm than is used for previous digital broadcasting.

Fig. 7. Content protection and access control.

3. Conclusion

Multimedia broadcasting takes advantage of the many excellent features of the current terrestrial digital TV and further improves content quality, offers a file-based broadcasting service, and achieves content diversification through interworking with the communications function. An even greater variety of functional extensions is planned for the future. The other Feature Articles in this set introduce metadata technologies in multimedia broadcasting for mobile terminals [7], access control in multimedia broadcasting for mobile terminals [8], and storage-based broadcasting in multimedia broadcasting for mobile terminals [9].

References

[1]	T. Ohya, X. Morizumi, X. Nishiumi, X. Nakayama, X. Koganemaru, and X. Kamise, “ISDB-Tmm Technical Review,” J. Inst. Image Inform. TV Engnr, Vol. 34, No. 52, pp. 47–50, 2010 (in Japanese).
[2]	ARIB Standard Specification, “Transmission System for Digital Terrestrial Television Broadcasting,” ARIB STD-B31, 2001.
[3]	“ARIB Technical Report, “Operational Guidelines for Digital Terrestrial Television Broadcasting,” ARIB-TR-B14, 2002.
[4]	http://www.mmbi.co.jp/ (in Japanese).
[5]	Ministry of Internal Affairs and Communications, “Authorization of Plans for Establishing Special Base Stations Using Frequencies Between 207.5MHz and 222MHz,” Sept. 2010.
[6]	http://www.j-mobilecasting.com/ (in Japanese).
[7]	S. Fukatsu, K. Tanaka, K. Horiguchi, and M. Horii, “Metadata Technologies in Multimedia Broadcasting for Mobile Terminals,” NTT Technical Review, Vol. 9, No. 8, 2011. https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201108fa8.html
[8]	S. Ishii, K. Ito, H. Kuwano, A. Akutsu, and T. Morizumi, “Access Control in Multimedia Broadcasting for Mobile Terminals,” NTT Technical Review, Vol. 9, No. 8, 2011. https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201108fa9.html.
[9]	A. Yamada, H. Matsuoka, R. Kitahara, and J. Hagiwara, “Storage-based Broadcasting in Multimedia Broadcasting for Mobile Terminals,” NTT Technical Review, Vol. 9, No. 8, 2011. https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201108fa10.html.

	Tomoyuki Ohya Executive Research Engineer, mmbi, Inc. He received the B.E. and M.E. degrees in electronic engineering from Kyoto University in 1986 and 1988, respectively, and the M.S. degree in management of technology from Massachusetts Institute of Technology, U.S.A., in 2000. He joined NTT in 1989. In 1992, he moved to NTT DoCoMo, Inc and engaged in R&D of digital speech coding technologies for the PDC (personal digital cellular) system and IMT-2000. He moved to mmbi in 2010. His main research interest is currently multimedia signal processing and the quality-of-service architecture for fourth-generation (4G) mobile communications networks. He is a member of ASJ, IEICE, and IEEE. He received the Young Engineer’s Award from IEICE in 1995.
	Masayuki Ishikawa Director, Senior Vice President, Corporate Strategy Dept., mmbi, Inc. He received the B.S. degree in aeronautics from the University of Tokyo in 1980 and the M.S. degree in aeronautics and astronautics from Stanford University, USA, in 1985. He has been engaged in business planning in the area of broadcasting businesses. He is currently engaged in real business development of mobile broadcasting services using ISDB-Tmm.
	Hideo Suzuki Executive Research Engineer, Supervisor, NTT Cyber Solutions Laboratories. He received the B.E. and M.E. degrees in material engineering from Tohoku University, Miyagi, in 1984 and 1986, respectively. After joining NTT Communication and Information Processing Laboratories in 1986, he was engaged in R&D of optical information processing and a web-based collaborative learning system. From 2004 through 2006, he was a Senior Manager in the R&D Center of NTT EAST. In 2006, he joined NTT Network Service Systems Laboratories, where he was involved in an NGN service trial. He is currently engaged in R&D of a metadata platform system for IPTV and multimedia broadcasting services.
	Junichi Kishigami General Manager, NTT Cyber Communications Laboratory Group. He received the B.S. and M.S. degrees in physics and the Ph.D. degree in electronic engineering from Hokkaido University, Hokkaido, in 1980, 1982, and 1989, respectively. He joined Nippon Telegraph and Telephone Public Corporation (now NTT) in 1980 as a researcher and investigated the solid-state physics of thin-film heads, a key technology in the development of high-capacity magnetic storage devices. In 1989, he was responsible for the design and development of an electronic filing system for video-on-demand. From 1994 to 1999, he worked in NTT America as a vice president and general manager at the IP headquarters in the area of creating and promoting Internet business both in the USA and Japan. He coordinated Internet service providers and the backbone between the USA and Japan. He is a member of IEICE and a Distinguished Speaker of IEEE. He became General Manager of NTT Cyber Solutions Laboratories and became General Manager of NTT Cyber Communications Laboratory Group in July 2011.
	Kenji Yamada Senior Manager, R&D Produce Group, NTT Research and Development Planning Department. He received the B.S. degree in science from Yamaguchi University in 1990. He joined NTT in 1990. His main achievements are managing the introduction of an online shopping system, the video distribution system, and a comic delivery system for mobile phones.
	Katsuhiko Kawazoe Chief Producer, R&D Produce Group, NTT Research and Development Planning Department. He received the B.E. and M.E. degrees in engineering from Waseda University, Tokyo, in 1985 and 1987, respectively. Since joining NTT in 1987, he has mainly been engaged in R&D of radio communication systems, satellite communication systems, and the personal handy-phone system (PHS). His specialty is forward error correction systems. He is currently a co-chairman of the ARIB Working Group for Broadcasting Systems based on a Home Server. He is a member of IEICE and received the Young Engineer’s Award from IEICE in 1995. He moved to his current department in July 2008.

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