The DVB-C specification was developed in 1994. It provides a toolbox of QAM modulation schemes from 16-QAM to 256-QAM for television and radio broadcasting services, as well as for data transmission. At the moment, this standard is deployed worldwide in cable systems ranging from the larger CATV networks down to smaller SMATV systems.
Responding to increased consumer demand for a broader range of (digital TV) services, many cable operators have already upgraded their networks, deploying 256-QAM modulation (thus achieving 50 Mbit/s payload per cable channel) and increasing the frequency range used for downstream transmission up to its maximum of 862 MHz. Many cable operators currently offer a rich analogue TV package alongside several hundreds of digital TV channels and an increasing amount of new, and more sophisticated (interactive and personalised) services.
Demand for more and more advanced services however is constantly growing, and cable operators are seeking ways to offer products like HDTV and VoD on a commercial scale within a relatively short timeframe, together with the required accompanying interactive services. Hybrid Fibre Coax (HFC) networks are therefore being optimised providing enhanced performance and thus allowing even higher modulation schemes than DVB-C is offering today.
A DVB-TM Study Mission (DVB TM 3811 Rev.1) addressing this challenge showed that recent technological developments in the areas of signal processing, channel coding and modulation well provide the means to significantly increase the transmission capacity of cable networks, and to allow for the broad introduction of advanced digital TV services via cable.
Consequently a process was initiated in DVB to capture a set of Commercial Requirements, and this CfT is issued to solicit technical contributions for the development of a DVB-C2 specification that will be capable of serving the cable industry for at least the upcoming 10-12 years.