차세대 DMB 기술 IEEE 논문지에 등재

DMB 2010.02.23 12:39

2년전 부터 준비 했던 차세대 DMB 개발에 관한 논문이 SCI급 논문지인 IEEE (미국 전기전자 공학자협회 )transc. on

broadcasting 지의 2010년 3월호에 실리게 되었다. 홀가분 !!

신고

영문 디지털 휴대 방송 현황 자료

DMB 2009.12.21 10:57

KAIST IBT Policy program for senior officals

이슈 리포트 2009 년 12월호에 발표한 자료

------------------------------

( 이글의 전제나 인용 가능하나 출처를 확실히 명기 하여 주시고 가능한 사전에 쪽지 나 메일로 연락 바람 )

Mobile Broadcasting Standards

Introduction

Following the great technical advances in IT, nearly every aspect of our lives has been changed. In particular, in the fields of communication and broadcasting, widespread broadband networks and digitalization are the technologies at the forefront of enriching our quality of life. With the current trend of these up-to-date technologies and convergence, many industries have started generating brand-new services that were impossible before.

Mobile broadcasting is the transmission of a TV program or video for use on a range of wireless devices such as mobile phone, PDAs, car navigation displays, and so on. The program can be transmitted in broadcast mode to every viewer in a coverage area or be uni-cast so as to be delivered based on user demand. Broadcast transmissions can be sent via a terrestrial medium, high-powered satellites, or the Internet. Mobile broadcasting services have already been started in some parts of the world, albeit in a limited area and to only a targeted audience; meanwhile a number of carriers and technology companies have been working on a roll-out of mobile broadcasting services throughout the world.

Different standards

There are several broadcasting systems that can provide multimedia in a mobile environment. These broadcasting systems include T-DMB (Terrestrial Digital Multimedia Broadcasting), S-DMB (Satellite Digital Multimedia Broadcasting), DVB-H (Digital Video Broadcasting –Handheld), and MediaFLO.

Very recently, ATSC–M/H (Advanced Television Systems Committee - Mobile/Handheld) was added into this category.

DMB

In 2005, Korea commenced S-DMB and T-DMB services for the first time in the world. T-DMB technologies and services are now standardized as a part of Korea's TTA (Telecommunication Technologies Association) standards, and are also registered as European ETSI (European Telecommunications Standards Institute) standards. As of December 14th, 2007, ITU formally approved T-DMB as a global standard, along with three other mobile broadcasting standards, DVB-H, One Seg, and MediaFLO.

T-DMB is currently the world's most successful mobile TV standard, with over 30 million devices sold. Countries in Europe and Asia have implemented commercial services.

Since DMB is based on the globally used Digital Audio Broadcasting (DAB) core standard, DMB devices are always backward compatible and can receive not only DMB multimedia services but also DAB audio services. On the broadcaster side, this means that the conventional DAB transmission system can be used for DMB transmission by simply adding a DMB video encoder to the existing DAB system.

As the first country to commercially launch mobile broadcasting, Korea is one of the most successful markets in the world, with almost 27 million devices in use. Of these devices, the most popular are mobile phones followed by navigation systems and PDAs.

DMB functionality has now become largely standard in mobile handsets, with all three of the country's mobile carriers, LG, KT, and SK Telecoms, offering handset options that enable users to access only a free-to-air terrestrial DMB platform as well as their own pay-TV services.

There are 6 DMB broadcasters providing 7 video, 13 audio, and 9 data broadcasting services. TPEG (Transport Protocol Experts Group) is a popular data broadcasting service, giving the consumer traffic and travel information. New interactive services, so called DMB2.0, are also growing in popularity, adding value to broadcasting services.

Presently, T-DMB services are provided in Ghana, Indonesia, and Norway, as well as in Korea on a commercial basis.

An Advanced Terrestrial DMB (AT-DMB) system is also being developed in Korea. The aim of AT-DMB development is to provide better resolution video service on large size displays (over 24 inches), or additional data broadcasting services with increased data, which is up to double that of conventional T-DMB. The AT-DMB system uses a hierarchical modulation technique to increase data capacity, while maintaining backward compatibility with conventional T-DMB receivers. It is expected that a field trial of AT-DMB broadcasting will be launched in Korea by 2010. An AT-DMB system can be used to provide large screen TV service in the home as well as in mobile situations. In the future, full scale High Definition (HD) terrestrial digital TV broadcasting services with H.264 video compression technology will prevail, using either the ATSC or DVB-T terrestrial digital TV standard. In the meantime, AT-DMB service can meet the demands of digital TV service in mobile as well as home use. In this sense, AT-DMB service may provide a good interim solution for developing countries that might introduce full scale HD broadcasting in the future.



S-DMB (Satelite-DMB) is a hybrid version of Digital Multimedia Broadcasting. S-DMB uses the S Band (2.6 GHz) of IMT-2000 and delivers around 18 channels at 128 kbps in a 15 MHz band. It incorporates a high power geostationary satellite, MBSat 1. For outdoor and light indoor coverage, terrestrial repeater (low power gap-filler) systems are deployed all over in urban areas.

As of November 2009, S-DMB service in Korea consists of 15 TV channels, 19 radio channels, and 3 data channels with a subscription basis through TU Media, and is accessible throughout the country.

DVB-H

DVB-H (Digital Video Broadcasting - Handheld) is one of four ITU approved mobile broadcasting formats. DVB-H technology is a superset of the DVB-T (Digital Video Broadcasting - Terrestrial) system for digital terrestrial television, with additional features to meet the specific requirements of handheld, battery-powered receivers. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. From March 2008, DVB-H has been officially endorsed by the European Union as the "preferred technology for terrestrial mobile broadcasting". The major competitors of this technology are T-DMB and the 3G cellular system based MBMS mobile-TV standard.

As of November 2009, 12 countries including Finland, Italy, and Switzerland have already started commercial operation of DVB-H service.

Across Europe, DVB-H mobile TV services are typically priced at around 15 Euros a month.

DVB-H is largely based on the DVB-T specification for European digital terrestrial television, adding to it a number of features designed to take into account the limited battery life of small handheld devices, and the particular environments in which such receivers must operate. The use of a technique called time-slicing, where bursts of data are received periodically, allows the receiver to power off when it is inactive, leading to significant power savings. DVB-H also employs additional forward error correction to further improve the already excellent mobile performance of DVB-T.

DVB-SH (Satellite services to Handhelds) now and DVB-H2 in the future are possible enhancements to DVB-H, providing improved spectral efficiency and better modulation flexibility.

The DVB-SH specification is designed to enable the delivery of mobile TV services in the S-band over hybrid satellite/terrestrial networks. The DVB-IPDC systems layer specifications cover such aspects as Electronic Program Guides (EPG), Content Download Protocols, and Service Purchase and Protection.

One Seg

One Seg is a mobile terrestrial digital audio/video and data broadcasting service in Japan and Brazil. Service began commercially on April 1st, 2006, in Japan. In Brazil, the broadcast started in late 2007 in just a few cities, with a slight difference from Japanese One Seg: a 30 frame/s transmission, while in Japan they use a 15 frame/s transmission.

ISDB-T, the terrestrial digital broadcast system developed in Japan, and used in Japan and Brazil, is designed so that each channel is divided into 13 segments. An HDTV broadcast signal occupies 12 segments, leaving the remaining (13th) segment for mobile receivers. Thus, the name "1seg", or "One Seg", was given.

However, it was reported that mobile reception is rather difficult, especially in a moving vehicle/train, as the signal quality deteriorates quickly even at speeds of around 20 km/h.

This leaves the majority of the target audience for this service unable to receive it. In-car or vehicle reception requires the use of a diversity antenna and increases the receiver's complexity and price.

MediaFlo

MediaFLO is Qualcomm (USA) company's technology to transmit data to portable devices such as cell phones and PDAs, for the use of mobile TV. Broadcast data includes real-time audio and video streams, individual, non-realtime video and audio "clips", as well as Internet Protocol datacast applications, such as stock market quotes, sports scores, and weather reports.

The "F-L-O" in MediaFLO stands for Forward Link Only, meaning that the data transmission path is one-way, from the transmitting tower to the device. The MediaFLO system transmits data on a frequency separate from the frequencies used by current cellular networks. In the United States, the MediaFLO system uses a frequency spectrum of 716-722 MHz, which was previously allocated to UHF TV channel 55.

On December 1st, 2005 Verizon Wireless and Qualcomm announced a partnership for the launch of the MediaFLO network in the USA, and Verizon launched the service commercially as part of its VCAST offering on March 1st, 2007, marketing the MediaFLO-specific technology/service as "VCAST TV". A similar announcement was made by AT&T Mobility in February 2007. AT&T Mobility launched their MediaFLO service on May 4th, 2008. However the number of subscribers is still very limited.

ATSC-M/H

ATSC-M/H (Advanced Television Systems Committee - Mobile/Handheld) is a very recently approved mobile broadcasting standard in the USA that allows TV broadcasts to be received by mobile devices. Its official appellation is A/153.

Just as DVB-H and OneSeg are mobile TV extensions of the DVB-T and ISDB-T terrestrial digital TV standards, respectively, ATSC-M/H is a suggested extension of the available digital TV broadcasting standard, ATSC. ATSC is optimized for a fixed reception, mainly for HDTV, and uses 8VSB modulation. The ATSC transmission scheme is not robust enough against mobile reception and multipath radio interference, and is designed for highly directional fixed antennas. To overcome these issues, additional channel coding mechanisms are introduced in ATSC-M/H to protect the signal. ATSC-M/H is jointly developed by Korea's Samsung and LG electronics.

The ATSC-M/H standard defines the technical specifications necessary for broadcasters to provide new services to mobile and handheld devices using their digital television (DTV) transmissions. The new services for mobile and handheld devices are carried along with current DTV services without any adverse impact on legacy receiving equipment. ATSC-M/H was developed to support a variety of services including free-to-air, interactive services delivered in real-time, subscription-based TV, and file-based content downloads for playback at a later time. The standard can also be used for transmission of new data broadcasting services. A broadcasting trial of ATSC-M/H will be started across North America by the end of 2009.

Mobile broadcasting service by standard

T-DMB

(AT-DMB)

DVB-H

OneSeg

MediaFLO

ASTC-M/H

Transmission technology

OFDM

OFDM

BST-OFDM

OFDM

8-VSB

Transmission bandwidth (㎒)

1.536

5/6/8

0.429/0.500

/0.57

[1 segment ]

6 [5/7/8]

partial of 6 ㎒

Frequency

efficiency

0.5 ~ 1.1

[0.7 ~ 1.5]

0.6 ~ 2.5

[for 16QAM ]

0.65 ~ 1.3077

1.0 ~ 1.83

0.5 ~ 1.0

Video compression

H.264

H.264

H.264

H.264

H.264

Major service area

Korea .

Europe. China

Europe. Asia

Japan . Brazil

USA

USA

Conclusion

While though there are several existing mobile broadcasting standards, core technologies such as H.264 video compression and OFDM (Orthogonal frequency-division multiplexing) are the most common. Therefore many mobile broadcasting decoding ICs can handle the above mentioned formats.

Broadcast free-to-air and pay TV services are being rolled out as spectrum is released, and broadcasting companies and mobile phone operators are stepping up their mobile TV strategies, with mobile advertising still hotly anticipated as a major revenue-earner.

Until now, free-to-air mobile broadcasting services such as Korea's T-DMB and Japan's One Seg share more than 97% of all mobile broadcasting service subscribers. The share of DVB-H and MediaFlo services, which occupies less than 3%, is unexpectedly low, due to being subscription based services. This implies that most people expect broadcasting services to be a free public service rather than subscription based.

Along with regular mobile broadcasting services such as T-DMB, One Seg, DVB-H, and so on, 3G cellular telecommunication and mobile internet based services are also joining the mobile broadcasting service race.

It is forecasted that mobile broadcasting service subscribers will reached 140 million by 2011, from 74 million as of the second half of 2009. Revenue from mobile TV services will generate $6.5 billion in 2011.

Worldwide mobile broadcasting service subscribers

신고

2009년 1 학기 서울공대 정책대학원 강의

DMB 2009.05.28 08:13


9개 나라에서 온 석박사 과정 학생들 - 동남 및 중앙 아시아와 아랍권 학생이 대부분. 몽고와 베트남에서 온 학생은 한국인으로 착각할 정도로 닮았다.

영어 전용 강의로 첨단 정보통신 기술, 관련 정책과 산업 동향을 소개하고 있다. 지난 학기에 이어 매주마다 관악산이 변하는 모습을 눈여겨 보게 된다.







신고

DMB 기사 - 월간 중앙 2005년 6월 호 게제

DMB 2009.05.16 22:14

오늘 확인 해 보니 더 이상 링크가 존재 하지 않아 스캔한 것을 올립니다.

아직도 DMB 관련 자료를 구하는 분이 계서서...





















신고