DVB-C2
Technology Overview
Large transmission capacities are required for high-definition TV (HDTV) and video on demand (VOD) as well as for TV cable networks. However, the DVB-C standard, which has been in use since 1994, sets limits here. The objective of DVB-C2 is to increase transmission capacity by more than 30 % while maintaining the same channel bandwidth.
This is achieved essentially by means of new modulation modes and an enhanced forward error correction (FEC) method that allows the use of high-efficiency video and audio codecs such as H.264 or HE AAC.
In addition to the single-carrier modes, orthogonal frequency division multiplex (OFDM) multicarrier modes are now defined in the standard. QAM orders of up to 4096 are now possible, as opposed to a maximum of 256QAM in the case of DVB-C.
In the OFDM modes, like in DVB-T/DVB-T2, pilots are used in order to adapt the receiver to the physical characteristics of the transmission medium by performing "channel estimation".
An improved error correction method, which is already being used in DVB-S2, delivers higher robustness against interference at similar signal-to-noise ratios. Therefore, reliable transmission is also achieved when using high-compression codecs.
A further increase in the transmission capacity can be achieved by applying a variable coding method and by varying the modulation modes to handle the content to be transmitted.
Deployment Scenario
The first commercial use of DVB-C2 can be expected in early 2010. Initially, DVB-C2 may primarily be used for sophisticated services and content such as HDTV and VOD, in coexistence with DVB-C. DVB-C2 cannot be expected to fully replace DVB-C over the next several years.
Key Parameters
| DVB-C2 | |
|---|---|
| Frequency | 48 MHz - 862 MHz |
| Modulation |
COFDM or single-carrier QAM, Modulation schemes: 16QAM to 4096QAM |
| FEC | LDPC + BCH or Reed-Solomon |
| Channel Bandwidth | 6 MHz, 8 MHz |
| Interleaving | bit, time and frequency interleaving |
| Encoding | H.264/AVC, MPEG-4 HE AAC v2 (AAC+) |
| Input Interface | Multiple transport stream and generic stream encapsulation |
| Modes | Variable and adaptive coding and modulation |
