Satellite Digital Multimedia Broadcast (S-DMB) is a satellite-based supplementary network for a terrestrial UMTS network, with the purpose of delivering multimedia content to mobile devices. This system is capable of providing real-time streaming TV programs, multimedia services, as well as non-real-time push and store multimedia content to mobile users.

The S-DMB system operates by utilizing a high-power geostationary satellite in conjunction with a network of medium and low-power terrestrial repeaters. These repeaters serve as gap-fillers to ensure urban indoor coverage and can be strategically located alongside mobile base stations. To enhance reception, the satellite and terrestrial repeaters synchronize their signals, allowing mobile handsets to combine incoming signals effectively.

S-DMB utilizes the satellite band allocated for IMT-2000, specifically in the 2170-2200 MHz frequency range. Within this spectrum, S-DMB can deliver approximately 18 channels at a rate of 128 kbps within a 15 MHz bandwidth. Importantly, this system has been designed to be fully compatible with the UMTS Multimedia Broadcast/Multicast Service (MBMS), simplifying its integration into UMTS terminals.