DVB-SH is a physical layer standard for delivering IP based media content and data to handheld terminals such as mobile phones or PDAs, based on a hybrid satellite/terrestrial downlink and for example a GPRS uplink. The DVB Project published the DVB-SH standard in February 2007. The DVB-SH system was designed for frequencies below 3 GHz, supporting UHF band, L Band or S-band. It complements and improves the existing DVB-H physical layer standard. Like its sister specification, it is based on DVB IP Datacast delivery, electronic service guides and service purchase and protection standards.
Standard description
Architecture
There are two physical layers, what increases de system configuration options. Depending on the transmitted signal modulation we can find two kind of architectures: SH-A and SH-B.
SH-A Architecture
Both terrestrial and satellite layers use Orthogonal frequency-division multiplexing this modulation solves the multipath problem, where the same token can be received multiple times with a delay due to bounces. Use OFDM in both transmitters enables creating single-frequency networks, that increases spectral efficiency but forces the terrestrial signal being identical to the transmitted by the satellite. For this reason, is permitted to implement Multi-frequency network where terrestrial and satellite components can broadcast through different channels with the same modulation.
SH-B Architecture
Terrestrial component uses OFDM but satellite uses Time-division multiplexing. Both components have to broadcast in different frequencies to avoid interference. It is not possible creating SFN but increases satellite´s signal transmission performance because TDM works better with these kinds of transmissions.
Comparison with DVB-H
The DVB-SH incorporates a number of enhancements when compared to DVB-H:
Recently, results from BMCO forum shows a radio improvement of at least 5.5 dB on signal requirements between DVB-H and DVB-SH in the UHF frequencies. The improvements to signal requirements translates to better in-building penetration, better in-car coverage and extension of outdoor coverage. DVB-SH chipsets are being developed now by DiBcom and NXP Semiconductors, and are expected to be available in beginning of 2008. Initial specifications show that the chipsets supports both UHF and S-Band and are compatible with DVB-H. DiBcom has announced a DVB-SH chip with availability in 2008 Q3. . The chip "has dual RF tuners supporting VHF, UHF, L-Band and S-Band frequencies".
, one of the biggest satellite operators in the United States, in 2007 announced a nationwide deployment of an hybrid satellite/terrestrial network in DVB-SH with Alcatel-Lucent and Expway. ICO G1 satellite carrying DVB-SH technology on board was launched on April 14, 2008. It is the world's first DVB-SH satellite in orbit. EutelsatW2A satellite carrying a Solaris Mobile DVB-SH S band payload was launched on 3 April 2009. It will cover Western Europe. S-band payload was scheduled to enter into service in May 2009 but this not occurred due to an anomaly currently being investigated. On 1 July 2009, Solaris Mobile filed the insurance claim. The technical findings indicate that the company should be able to offer some, but not all of the services it was planning to offer. Inmarsat's S band satellite programme, called EuropaSat, will deliver mobile multimedia broadcast, mobile two-way broadband telecommunications and next-generation MSS services across all member states of the European Union and as far east as Moscow and Ankara by means of a hybrid satellite/terrestrial network. It will be built by Thales Alenia Space and launched in early 2011 by ILS.
