Papers from the DVB/DAVIC Interoperability Consortium
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Papers from the DVB/DAVIC Interoperability Consortium |
The Stage has been set for High Speed Cable Modems and Set Top Boxes |
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The cable modem is one of the new technologies, which gives an economically attractive broadband access to the Internet, and the demand has been obvious for a long time. Many barriers have been removed - for example the necessary liberalisation has already been carried out or has been planned around the world. The finalisation of open standards and the availability of products has now set the stage for roll-out.
Worldwide interest in different interactive cable standards
The last barrier concerned the standards. Although cable modems - all based upon proprietary technologies - have existed in the market for several years, the cable operators have predominantly only carried out field trials with these products. Partly because these were first generation products, and partly because they were not based on an industry standard, which is considered a prerequisite for establishing the necessary price competition.
The clarification concerning standards has benefited manufacturers in finalising products, and cable modems based on open standards are now available. A prototype of the first DAVIC/DVB cable modem was introduced in London in October 1997, and the first prototype MCNS cable modems were shown at the Western Cable Show in the USA in December 1997. Actual shipping is expected in the 3rd quarter of 1998.
A number of organisations have for some years worked hard in order to be amongst the few open standards which would survive on the market. The most important are the IEEE working group 802.14, Multimedia Cable Network Services (MCNS or DOCSIS), Digital Audio Video Council (DAVIC) and the Digital Video Broadcasting (DVB). DVB and DAVIC work closely together are are closely connected to the European Telecommunication Standards Institute (ETSI). Despite the attempt to co-operate on a broader scale, a difference of interests and of priorities have hindered an actual agreement. The exception is DVB and DAVIC, which are now fully identical with regard to their cable modem specifications.
The technologies and standards partly stem from data communication and partly from digital TV/Video. The use of the Internet has spread rapidly despite the fact that no quality guarantees exist, for example concerning delays. Therefore, the Internet is not (yet) suited to real time services like speech or video. ATM, which is more advanced, is suitable to these services. ATM enables a guarantee for limited delays, and due to this it has been developed to support both data, sound and video.
IEEE is the illustrious North American society of electronics engineers, which also standardised Ethernet and Token Ring. IEEE has made a point of conforming to the ATM standard as a supplement to the Internet standard (IP), and therefore IEEE has been supported by large companies with ATM-based products, e.g. Com21 and IBM.
MCNS was initiated by North American cable operators and media companies, who wished to speed up the elaboration of cable modem standards. MCNS is based upon North American TV standards such as NTSC. A characteristic of these TV standards is the 6 MHz channel bandwidth. Fast commercial deployment and Internet traffic have been given higher priority than ATM, which is therefore currently not supported by MCNS.
Essential parts of the DAVIC standard have existed since 1996, and the DVB standard is endorsed by ETSI as ETS 300 800. MCNS finalised its first version of its specification late 1997. Both DVB/DAVIC and MCNS standards have recently become ITU standards (International Telecommunication Union). The future of the IEEE standard is uncertain for the time being, and it was not approved as an ITU standard for the time being. Therefore, IEEE has lost ground to DAVIC/DVB and MCNS, which both fulfil the most important technical and commercial demands of the industry and the cable operators.
Because the MCNS compliant cable modems have been developed for North American conditions, MCNS holds a strong position in North America. MCNS cable modem producers include among quite many GI, 3Com, Nortel/Bay and Samsung.
In Europe the support of DVB/DAVIC is particularly strong, partly because the standard is adapted to European conditions, partly because an EU directive determines that digital TV transmission must be based upon DVB. The European Union wishes digital audio & video services to be based upon DVB/DAVIC. The European Cable Communications Association (ECCA) recommends that its members use equipment based on these standards, and many cable operators demand DVB/DAVIC compliant cable modems. Several manufacturers can now deliver DVB/DAVIC cable modems, e.g. Hughes Network Systems, SIMAC and COCOM.. Several set-top-box manufacturers have announced and/or demonstrated embedded cable modem functionality based on DVB/DAVIC, e.g. Nokia, Sagem and Thomson MultiMedia, and head-end transmission equipment is available from e.g. Alcatel, DiviCom, Hughes Network Systems, SIMAC, Thomson Broadcast Systems and COCOM.
Presumably, a variant of the MCNS standard will be used in Japan. This variant is now also an ITU standard. In Asia the cable operators are faced with the choice between the two standards, and it is yet too soon to point out the winner. It is most likely that both DAVIC/DVB and MCNS will gain substantial market share.
South America is often perceived as being closely related to North America. However, as regards TV, South America has adopted European standards, and a number of countries use PAL. Thus, for cable modems, DVB/DAVIC and MCNS are likely to share the market.
In general, most countries with PAL/SECAM cable infrastructures and/or which choose DVB for their digital TV infrastructure will also have significant advantages from chosing DVB/DAVIC for data communication.
The background for this is economy and services. DVB and DAVIC support digital TV and data communication as well as telephony. It is therefore possible to base all services on one technology if DVB/DAVIC is chosen. Some of the specific advantages are: video and voice services can be brought to the PC, data and voice services can be brought to the set-top-box, less backup equipment is required, less trans-modulation equipment is needed, technicians need only learn one technology, and measuring equipment need only be bought for this technology. It also means that central equipment will be the same for all three services.
If one wishes to offer the services digital TV, data communication and telephony and does not wish to have base them on DVB/DAVIC, the result will be a platform consisting of three technologies and three sets of equipment.
A choice of DVB/DAVIC as the standard for cable modems has a extraordinary implication: due to the fact that the cable modem receives a digital TV signal, the PC will be able to show digital TV on the monitor. That is one of the things which an MCNS cable modem cannot do. Every month a large amount of TV cards for PCs are sold, indicating that this possibility is valued by consumers.
Consequently, the battle of the standards has now been decided. There are DVB/DAVIC cable modems (and set-top-boxes) and MCNS cable modems. The stage has been set, and the cable operators as well as the end users can look forward to the advantages of cheap and fast Internet access.
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