DVB-T2
At the end of June 2008, the DVB Steering Board approved the DVB-T2 specification, a second generation digital terrestrial transmission system. Compared with the DVB-T standard developed over ten years ago, DVB-T2 is expected to provide an increase in capacity of 30-50% in equivalent reception conditions using existing receiving antennas.
The new specification introduces new modulation and coding techniques to enable highly efficient use of spectrum. The first commercial DVB-T2 receivers are expected to be available as early as the middle of 2009.
Baseline features
The specification is designed primarily for fixed reception to roof-top antennas and has the same frequency spectrum channel characteristics as DVB-T allowing for compatibility with Geneva 2006 Agreement.
Like DVB-T, DVB-T2 uses OFDM (orthogonal frequency division multiplex) modulation and provides a toolkit with different numbers of carriers (1k, 2k, 4k, 8k, 16k, 32k) and modulation constellations (QPSK, 16 QAM, 64 QAM, 256QAM). For error protection, DVB-T2 uses LDPC (low density parity check) and BCH (Bose-Chaudhuri-Hocquengham) coding. A new technique, known as Rotated Constellations, has been introduced to provide additional robustness in certain conditions.
An innovative feature proposed for the DVB-T2 specification, Time Frequency Slicing (TFS) creates a large multiplex by combining radio-frequency channels to make a single 'virtual' channel to allow for efficient statistical multiplexing. However, because not all details of TFS had been confirmed in time for the completion of the specification, 'hooks' have been put in place to allow for its introduction at a later stage.
DVB-T2 testing
Testing of the specification has begun in the United Kingdom. Last June, the BBC, together with the broadcast network operators Arqiva and National Grid Wireless, made the first DVB-T2 test transmission. In September, the BBC announced the successful demonstration of a live end-to-end DVB-T2 transmission using a prototype demodulator that it developed capable of receiving DVB-T2 signals. The demonstration consisted of a 36 Mbit/s multiplex carrying 3 high-definition programmes each coded at 11 Mbit/s using MPEG-4 AVC.
Adopting the new standard
At this stage, only the British communications regulator OFCOM has presented official plans to launch national DVB-T2 services. OFCOM would like to use DVB-T2 to provide 4-5 high-definition television services from a single multiplex. No other country in Europe has yet issued clear plans for the introduction of DVB-T2 services although there is clearly growing interest.