Digital Multimedia Broadcasting

Digital Multimedia Broadcasting ( DMB) [ dɪdʒɪtəl mʌltimi ˌ ː ː d ˌ diə bɹɔ kɑ ː stɪŋ ] is a digital transmission system. With DMB mobile devices, such as mobile phones, via satellite (S- DMB) or terrestrial (T -DMB ) are supplied with data. T -DMB is based on the radio standard DAB, which has been extended to audiovisual content.

DMB as a transmission technique was developed by Robert Bosch GmbH and the Heinrich Hertz Institute, but later mainly adapted from Asian mobile operators and marketed as a commercial product. In Europe, DMB is hardly been used commercially but has been tested in several projects.

Technology

Technically extended T -DMB, DAB to audiovisual content. For video it comes H.264, BSAC audio or AAC and to a limited extent local interactive content, the Binary Format for Scenes ( BIFS ) for the course. An additional error correction ensures high transmission security in mobile applications. It is, according to the error protection, a net data rate of up to 1.5 Mbit / s ( typically 1 Mbit / s ) is possible, which is sufficient for transmission of three to four TV programs plus audio programs and data services in a DAB ensemble.

The specification of DAB / DMB closes with different modes of use in a range of 30 MHz to 3 GHz.

DMB extended DAB, DMB which inherits the full functionality of DAB. Thus, it is also mixed operation of conventional DAB services and formats possible with new DMB video services. All recipients can see to which services are, and can decide whether he can use it or whether it needs to ignore them. So you can an ensemble, for example, with three DAB audio programs ( MPEG-1 Audio Layer 2 encoding) and a DMB - specific video service ( MPEG transport stream with H.264 video and AAC / BSAC audio) and additional data services such as for example, MOT -BWS and IP-based delivery of multimedia services in the Enhanced package fashion fill, which are already specified in the DAB standard.

IP-based services may also be transmitted via the DAB ensemble. Since DMB miterbt the full DAB functionality, a DMB ensemble (specifically a DAB ensemble or DAB / DMB mixed ensemble) to transfer capable IP-based delivery of multimedia services in the packet Enhanced Mode. One example is BT Lifetime in England. BT Lifetime is based - such as DAB and DMB - on the European and global standard EUREKA 147 for transmitting digital radio, video, and multimedia content. However, an additional decoder for decoding software is required, which also supports the Internet Protocol. Conversely, BT Lifetime receivers are today without an additional software- upgrade not DMB - capable; partly a conversion will not be possible. However, DAB audio services can be received and decoded. The project Digital Extended Broadcasting contrast, a standardized interface for DAB, DVB -H and UMTS / MBMS is to be specified by an IP -based solution for DAB. If this interface can be implemented, it could, however, are only supported by new devices. New and old equipment can receive the previous programs but still, so that a smooth transition would be guaranteed. DxB was rejected in WorldDAB and an introduction is thus not directly be expected. Efforts to harmonize and combination of different standards ( eg on the basis of universal receivers ) but there are still. According to the company, the Japanese electronics manufacturer Sharp has developed the first dual- receiver that can receive DVB -H and DMB signals. The production is expected to be taken up in July 2007.

Another type of time slicing is possible and provided the basic standard of DAB with a view to reducing current consumption of the receiver corresponding signaling parameters. To avoid conceptual confusion, the term micro time slicing was created recently. This is based on short bursts of a few milliseconds long, the switch is substantially dependent on the data rate of the service. So far, this feature has not yet been used in DMB because one has so far felt the energy efficiency of the DMB method to be sufficient.

The DAB coverage in Germany is about 80 %, with the existing offer has been accepted by around 200,000-300,000 ( 10/ 2006) users. DMB as an extension of DAB could increase customer acceptance and thus justify the investments in DAB. It would be conceivable, among other things, a use in the car, as on DAB now traffic data ( TMC, TPEG -ML ) are transmitted. DMB receiver can decode also usually DAB. DAB will continue to remain as a pure audio service, and today's DAB receiver can still be used.

Use

Central Europe

Frequency allocations for DMB in Germany from 2006 in Band III and L-band occurs. Until recently, the maximum transmit power to 1 kW for the band was restricted III and 4 kW for the L-band, in southern Germany, the transmitting power was tentatively raised to up to 10 kW in Band III and 6 kW L-band. In contrast to Korea, where the VHF frequency range is used, should be used here primarily the L-band. However, the project MI FRIENDS of the Bavarian State Media Authority also runs in band III, since this is also suitable.

The only commercial DMB service in Germany was Watcha of MFD Mobiles Fernsehen Germany. According to a press release by the ALM Mobile Television Germany GmbH (MFG ) returns their licenses for DMB mobile television. In a letter to the state media institutions, the company said, to stop distributing the programs of ProSiebenSat.1 Mobile and MTV Mobile. In her message, the ALM recognized " Unfortunately, the DMB format could not prevail among the customers. The expectations have not been fulfilled. "

Samsung, LG and Perstel 2005 had shown at the IFA 2005, approximately 18 different DMB receiver models. Since all state media authorities had advertised and licensed DMB licenses, the legal foundations for Mobile TV in the DMB standard was set for a coverage of approximately 80 percent of the population.

Watcha had been a technical reach of more than 13 million people broadcast, ARD, ZDF, N24, ProSiebenSat.1 Mobile and MTV Music. It was also aired with bigFM a radio program that was underlaid with rapidly changing still images. The customer could choose between two phones that are necessary as a terminal for receiving mobile TV: Samsung SGH- P900 (supported only L band) and LG V9000. This can also receive the free DAB radio programs, as DMB devices are backward compatible.

There is also an MP3 player "D2 " from Cowon with DMB reception and multimedia receiver " IRIVER B20 " with 2.4-inch TFT display and a housing that is not much bigger, weighing about 75 g. Here is a VHF-FM tuner, DAB and DMB receiver (Digital Multimedia Broadcasting) an internal memory for audio and video files via the USB2 interface ( same battery charger) are installed, also accessible is.

In Cologne " WDR - Mobile TV " with WDR - TV 320 x ran from 2006 to 2010, the DMB test program live in MPEG4 QVGA 240 pixels, 30 fps recoded at 384 Kbit / s It was broadcast on VHF channel 12 from Cologne- tower at the Media Park with 10 kW in a DMB / DXB- multiplex (1/4 of a terrestrial television channel ), also (acquired ARD television program 1:1) The first in the same format. Since 2011, only " Eins Live " run where the current radio program with a freeze - loop with regularly changing content is played (eg, music, news and current temperatures), " WDR - Mobile TV " ( WDR2 ) with the latest news text and still images, and " WDR - DMB test " with cartoons ( Kiraka ) or changing stills and 60 min video loop of 2007 receiving result in portable and mobile operation. unlike the (same VHF channel ) DAB reception can be found at DMB at the same critical points (ground floor in the house, narrow city streets ) less sound interference and hardly dropouts.

Should be tested to the most comprehensive model projects with which the operating payment-financed mobile broadcasting ( audio and video services ), owned the project MI FRIENDS the Bavarian Regulatory Authority for Commercial Broadcasting in Munich. Italy, Austria, Liechtenstein and Switzerland to take over the MI FRIENDS subprojects Lake and South Tyrol / Transalp also participate in the project of the BLM.

In the first test region of Munich were during the Football World Cup 2006 with MI FRIENDS total of 12 DMB and 19 DAB stations with DMB receivers available through releases in each 1.5 MHz wide frequency blocks LC and LG ( UHF), 11C, 11D, 12A and 12D (VHF ). Aired were, inter alia, the ARD program, ZDF and the FSO.

Also within the scope of the project MI FRIENDS four channels were broadcast after the World Cup in Regensburg. These were Rmobil ( a television with a strong local connection for mobile use ), Rmix ( a nationwide program ), Rockantenne2go ( a radio program with image support) and GongFM (also a radio program with picture support). The goal here was the testing of additional services, personalized content and interactivity.

Two other test areas were the Bodensee region ( a nichtverwirklichtes Project ), in which the use should be tested in leisure activities, as well as South Tyrol, which was chosen as a test region with tourist use and for testing in topographical problem areas.

All projects have been completed and evaluated. The results of the accompanying research have been published in the publication series of the Bavarian Regulatory Authority for Commercial Broadcasting. When selecting the test regions was at the forefront to get evaluation results that should be on nearly all European regions transferable. The BLM draws as a conclusion, for the normal operation, the question of funding of infrastructure and program costs yet to be solved and writes as follows: "Not least is the fact of crucial importance that a clear majority of users surveyed are not prepared for a mobile radio use in addition to pay fees. "

South Korea

In South Korea, went in the third quarter of 2005, the commercial S -DMB service (S = satellite) in operation; This service is chargeable. According to the MIC (Ministry for Information and Communication ) recorded T -DMB on April 1, 2007, approximately 1.3 million users.

In Korea, 2006, approximately 50 different DMB receiver types were available in the market. Prices were converted to 80-800 € and were divided into three main segments:

• Low Price ( USB receiver, etc.) 80-120 U.S. $
• Mid Price (mobile phones ) U.S. $ 200-500
• High Price (pure DMB receiver with touchscreen multimedia player and navigation ) U.S. $ 200-800

DMB receiver with integrated navigation, MS media player and picture-in -picture function based on WIN CE 5.0 have been offered on the market starting at $ 550. The German company Blaupunkt already offered 2007, his navigation system Lucca 5.2 with DMB in Korea.

As of June 2006, further licenses for the commercial ( funded by advertising ) were awarded operation. Currently 7 video, 13 audio and 8 data channels are offered.

In February 2008, the free, terrestrial T -DMB range with 6 channels about 10 million customers, the satellite-based system of competition with 19 paid channels about 1.3 million customers. The operator of the satellite supply needs by its own account 2.5-3 million customers to be profitable. The terrestrial DMB offer will be used according to a random sample of 1 August of 1.17 % of the owners of the corresponding device. Receivers are mainly used in mobile phones ( 48.8 %), but also in multi -function displays in cars ( 37.8 %), media players (9.4%) and USB dongles ( 3.8%).

By the end of 2009 the number of T -DMB users had risen to 20 million.

People's Republic of China

The People's Republic of China has ordered 500,000 T-DMB-E RECIPIENT at Samsung. 300,000 of them for the province of Guangdong (about 80 million inhabitants) and 200,000 for Beijing. In the People's Republic of China T -DMB is in addition to other solutions the premier choice of Chinese regulator SARFT.

Planned rollout:

• Beijing / Tianjin: DAB-/DMB-Feldversuche (two audio and one video service ) since 2005
• Guangdong: various DAB-/DMB-Feldversuche since 2005, two multiplexes with four audio and two video services to broadcast
• Shanghai: The Oriental Pearl Group launched the project Mobile TV. Field trials of DAB - IP ( see also BT Lifetime under Technology ) since 2005. DMB field trials are planned for 2006.

Assessment

DAB is provided for approximately 2.0 MHz bandwidth over which, according to the error protection, for example 1 Mbit / s can be transmitted to user data. That's enough for about three TV programs with 300 kbit / s plus audio programs and data services per ensemble, where an ensemble of only a quarter of TV channel occupies and correspondingly more programs by a combination of several ensembles is possible, eg in Munich: 12 DMB and 19 DAB stations and additional telematics and data services.

DAB / DMB is primarily designed for mobile reception and uses for power efficient decoding a process in which selectively received and decoded only the appropriate relevant carriers. The power consumption of DMB receivers is about 150 mW without time slicing. Time slicing is also provided with DAB / DMB, but was not yet used due to low power consumption in practice.

By using the modulation scheme OFDM and the simple coding ( QPSK) relatively large single-frequency networks ( Single Frequency Networks, SFN) are possible, in contrast to multi-frequency networks ( Multi Frequency Networks, MFN) allow the same frequency in neighboring cells.

The specification of DAB / DMB closes with different modes using a 30 MHz to 3 GHz. Frequency allocations for DAB are made ​​in Germany in Band III and L-band.

DAB / DMB mobility ( in the vehicle, even at high speed ) is arranged. Show reception tests of DMB on commuter trains that received correctly is also possible here. Due to the limited regulatory in Germany transmit power (1 kW to 4 kW in Band III and L-band ), it is currently only limited to receive within buildings.