S-DMB, Satellite Digital Multimedia Broadcasting, uses DMB technology. However, it uses a hybrid network: in order to avoid the masking problems inherent toin satellite broadcasting, a network of ground repeaters (estimated at 15, 000 in South Korea) is linked to a geostationary satellite.
The South Korean S-DMB
Based on CDMA (Code division multiple access), Korean S-DMB uses the Ku frequency band (12.214-12.239 GHz) uploading and the S band (2.630-2.655 GHz) downloading to mobile telephones. S-DMB uses the principle of the Single Frequency Network for more effective use of the frequency spectrum: the satellite and ground repeaters broadcast on the same band. Multiple echo problems are avoided using CDMA (or OFDM - Orthogonal frequency-division multiplexing - type modulation). The signals can be synchronised by a GPS reference frequency. The data rates are high (7 Mb/s) at high vehicle speeds (up to 150 km/h or 74 mph).
South Korea's S-DMB service has been deployed since April 2005 by TU Media (SK Telecom), the service was launched in December. Unlike T-DMB, the service is paid by a monthly subscription of about 10 Euros for 14 video channels and 25 radio channels. At the end of 2005 terminals were priced at around 500 Euros.
S-DMB in Europe
Alongside the Korean S-DMB, experimentation was carried out in Europe to adapt to local conditions. The radical difference lies in the European will to broadcast S-DMB content on a 3G layer, making broadcasting compatible with existing UMTS (Universal Mobile Telecommunications System) terminals. It would also require ground repeaters to provide high enough speeds, especially inside buildings.
The frequencies used are in the IMT-2000/UMTS (1980 – 2010 MHz and 2170 – 2200 MHz) bands. These bands are adjacent to the terrestrial UMTS bands, and therefore easy to integrate into the frequency range of a UMTS terminal.
This system meets the need for a hybrid system combining the strength of a point-to-point network for its interactivity and broadcasting for its massive multimedia content.
The 3G network in Europe is dynamic and is attracting more and more subscribers, thereby significantly reducing costs of deployment and terminals.
Various experiments have been carried out in Europe:
• MAESTRO: tests carried out starting in January 2004 and now complete (an industrial consortium headed by Alcatel Alenia Space);
• MODIS: launched in 2002 leading to the building of an S-DMB mobile terminal;
• And also: SATIN, RELY etc.