Digital multimedia broadcasting


Digital multimedia broadcasting is a digital radio transmission technology developed in South Korea as part of the national IT project for sending multimedia such as TV, radio and datacasting to mobile devices such as mobile phones, laptops and GPS navigation systems. This technology, sometimes known as mobile TV, should not be confused with Digital Audio Broadcasting which was developed as a research project for the European Union. DMB was developed in South Korea as the next generation digital technology to replace FM radio, but the technological foundations were laid by Prof. Dr. Gert Siegle and Dr. Hamed Amor at Robert Bosch GmbH in Germany. The world's first official mobile TV service started in South Korea in May 2005, although trials were available much earlier. It can operate via satellite or terrestrial transmission. DMB has also some similarities with the main competing mobile TV standard, DVB-H.

S-DMB

T-DMB

T-DMB is made for terrestrial transmissions on band III and L frequencies. DMB is unavailable in the United States because those frequencies are allocated for television broadcasting and military applications. USA is adopting ATSC-M/H for free broadcasts to mobiles, and Qualcomm's proprietary MediaFLO system was used there. In Japan, 1seg is the standard, using ISDB.
T-DMB uses MPEG-4 Part 10 for the video and MPEG-4 Part 3 BSAC or HE-AAC v2 for the audio. The audio and video is encapsulated in an MPEG transport stream. The stream is forward error corrected by Reed Solomon encoding and the parity word is 16 bytes long. There is convolutional interleaving made on this stream, then the stream is broadcast in data stream mode on DAB. In order to diminish the channel effects such as fading and shadowing, the DMB modem uses OFDM-DQPSK modulation. A single-chip T-DMB receiver is also provided by an MPEG transport stream demultiplexer. DMB has several applicable devices such as mobile phone, portable TV, PDA and telematics devices for automobiles.
T-DMB is an standard. As of December 14, 2007, ITU formally approved T-DMB as the global standard, along with three other standards, like DVB-H, 1seg, and MediaFLO.

Smart DMB

Smart DMB started in January 2013 in South Korea. Smart DMB has a VOD service and quality has been improved from 240p to 480p. Smart DMB is built in many Korean smartphones starting with the Galaxy Grand in January 2013.

HD DMB

HD DMB started in August 2016 in South Korea. HD DMB has been improved from 240p to 720p. It uses HEVC.5 codec. There are currently 6 HD DMB stations in Seoul. Smartphones integrated Qualcomm Snapdragon 801 or higher received firmware upgrade to support HD DMB.

Countries using DMB

Currently, DMB is being put into use in a number of countries, although mainly used in South Korea. Also see list of Countries using DAB/DMB.

South Korea

In 2005, South Korea became the world's first country to start S-DMB and T-DMB service on May 1 and December 1, respectively. In December 2006, T-DMB service in South Korea consists of, 7 TV channels, 12 radio channels, and 8 data channels. These are broadcast on six multiplexes in the VHF band on TV channels 8 and 12. In October 2007, South Korea added broadcasting channel MBCNET to the DMB channel. But in 2010, this channel changed tnN go. In 2009 there were eight DMB video channels in Seoul, and six in other metropolitan cities. As of April 2013, S-DMB service in South Korea consists of 15 TV channels, 2 radio channels and 6 data channels.
South Korea has had Full T-DMB services including JSS, DLS, BWS, and TPEG since 2006.
S-DMB service in South Korea is provided on a subscription basis through TU Media and is accessible throughout the country. T-DMB service is provided free of charge, but access is limited to selected regions.
Around one million receivers have been sold. 14 million DMB receivers were sold including T-DMB and S-DMB in South Korea, and 40% of the new cell phones have the capability to see DMB.
Receivers are integrated in car navigation systems, mobile phones, portable media players, laptop computers and digital cameras. In mid-August 2007, Iriver, a multimedia and micro-technology company released their "NV", which utilizes South Korea's DMB service.
Since the advent of smartphones DMBs have been made available on phones with receivers through smartphone applications, most of which come pre-installed in phones made and sold in Korea.

Other countries

Some T-DMB trials are currently available or planned around Europe and other countries:
T-DMB works flawlessly in vehicles traveling up to 300 km/h. In tunnels or underground areas, both television and radio broadcast is still available, though DMB may skip occasionally. In South Korea, some long distance buses adopted T-DMB instead of satellite TV such as Sky TV. It works quite well even though the resolution is 240p, lower than satellite. In comparison, satellite is usually 480p or higher.