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					                                 The DVB-compliant

                                    White Paper

                                         Dirk Jaeger                 (
                                         Klaus-Dieter Schunke      (
                                         Volker Leisse                (

                                         EuroCableLabs - Centre of Competence
                                         located at Braunschweig Technical University

With support of the

I n t e r o p e r a bi l i t y
C o n s o r ti u m

                                      January 2000
                                  EuroModem White Paper

Executive Summary
The introduction of bi-directional data communications on CATV networks is one of the
biggest current challenges towards the “multimedia society”. European cable networks consist
of 40 million connected households. Analysts predict that about 50% of the household will
perform broadband data communications over cable networks by using cable modem
technology. Thus, in the near future a market of about 20 million cable modems will arise in
Europe. A similar development is envisioned for Asia and other parts of the world.
For several years many companies have developed proprietary systems offering very different
levels of data communication. The lack of compatibility gave rise to international
organisations in order to develop a standardised system that pushes the market introduction.
Today, two different solutions exist in parallel: on the one hand, the European development
“EuroModem” that bases on the ETSI (European Telecommunications Standards Institute)
standard EN/ETS 300 800 developed by the Digital Video Broadcasting (DVB) Project and
the Digital Audio-Visual Council (DAVIC) and, on the other hand, the North American
solution “DOCSIS” of which development was driven by the CableLabs in North America.
EuroCableLabs (ECL) is the technical organisation of large European cable operators in the
European Cable Communications Association (ECCA). Institute for Communications
Technology at Braunschweig Technical University which acts as its Centre of Competence is
deeply involved in all activities regarding research and development of future technologies for
CATV network systems, organises and co-ordinates ECL-related work and consults ECL
members in future technology strategies. In DVB, the Institute chairs the Technical Module
and is represented in several experts groups such as the Return Channel Group and the
Multimedia Home Platform.
In recent publications it occurred quite frequently that the lack of detailed information led to
misinterpretations and wrong conclusions. Therefore, cable operators became unsure in their
efforts to make an objective decision regarding EuroModem. Thus, the Centre of Competence
of EuroCableLabs was asked many times by cable operators, manufacturers, vendors and
consultancies to prepare this white paper in order to deliver information about EuroModem in
a comprehensive form. The aim of the white paper is to describe the communication system
of EuroModem and its background.
The most outstanding feature of EuroModem is its ability to be seamlessly integrated in the
common DVB system environment. This scenario enables cable operators to offer the full
range of services on top of one single platform. This integrated system approach is not
realised by any other cable communications system. DOCSIS, for instance, has the only goal
“... to allow transparent bi-directional transfer of Internet protocol (IP) traffic, between the
cable system headend and customer locations ... “ [DOCSIS 1999]. A comparison of
EuroModem and DOCSIS, which can be found in the subsequent sections, yields the result
that the performance of the two systems is very similar. As an example might serve the
upstream transmission efficiency of TCP/IP acknowledgements that - according to field
measurements - constitute 87 percent of the number of all WorldWideWeb packets. These
packets are 40 Bytes in size and, hence, ideally fit into one single fixed-sized DVB cell as
well as into one single DOCSIS packet of variable length.
In summary, EuroModem, the European solution for broadband, bi-directional
communication on cable, is now in the stage of wide-range market introduction. It completes
the integrated, universal broadcast and communication system which EuroCableLabs is going
to establish based on DVB standards, the leading standards of the digital broadcast revolution
all over the world.

                                        page 2 of 8 pages
                                   EuroModem White Paper

The Digital Video Broadcasting (DVB) Project has driven the introduction of digital services
via all transmission media (e.g. cable, satellite, terrestrial, and micro-wave systems) within the
last years world wide. The standards developed and adopted by DVB are covering all aspects
of digital broadcasting technologies as well as uni-directional and bi-directional data
communications. Hence, it is a declared goal of the DVB Project to establish a universal
platform for all delivery media. Not only the ‘     data-over-cable’ aspect should be considered
for the introduction of cable-modem technology, but also the cable-network infrastructure, the
system environment, and service aspects.

The specification DVB-RCC (return channel for cable) covers all aspects for bi-directional
communications over CATV networks including the physical layer, the medium access
control layer, mid layer interfaces, Quality of Service (QoS) and security aspects. Its first
version was already standardised by ETSI (EN/ETS 300 800) in July 1998 as well as by ITU
(ITU-T J.112 annex A). This version was further developed by the DVB Project with strong
support of EuroCableLabs and manufacturers. The benefit of this evolution is the guaranty for
a fully backward and forward compatibility of the standard. This means that the performance
of those cable modems which comply with the latest DVB version will not be reduced if ‘  old-
fashioned’DVB-compliant cable modems are operated at one single system.

In addition to the support of the standardisation procedure, EuroCableLabs set up a technical
experts group of several EuroCableLabs members, the EuroModem Consortium, which has
established a technical specification based on the standard EN/ETS 300 800. The EuroModem
specification mainly defines technical parameters for a cable-modem user terminal, but it also
contains aspects with regard to the Interactive Network Adapter (INA) installed in the
headend as well as recommendations for operation, administration, maintenance, and

Integrated system solution for cable
The new cable modem technology is an integrated part of the already existing digital
broadcast environment that is based on sets of DVB standards such as DVB-C, DVB-S, and
DVB-T. These standards define modulation and error protection for cable, satellite and
terrestrial, respectively, as well as topics such as the transmission of service information, data
broadcasting, and the Multimedia Home Platform. The big challenge for EuroModem was to
perfectly fit in the cable environment and to contribute to the establishment of an integrated
system solution for full service provision. This approach has the goal to enable the delivery of
all types of services including broadcasting services (TV, audio, etc.), data communication
services (Internet, e-commerce, etc.), and voice services (cable telephony, voice over IP, etc.)
on top of one single platform. All service types can be merged and transmitted from the
headend to the subscribers through one single channel. On the other hand it is possible to
distribute one service over all available broadband channels including already existing
ordinary DVB broadcast channels. The flexibility to mix broadcast and communications
services gives the operator the possibility to optimise the usage of available transmission
capacity for each channel.

The integrated system of DVB is not only the most flexible solution but it is clear that
”...Solutions which make use of one integrated set of standards like DVB, are in the long term
run cheaper, more stable and easier to support.” (Bert Meijerink, winner of the ECCA Award

                                         page 3 of 8 pages
                                                EuroModem White Paper

The Independent Network Adapter (INA) is the central unit of the integrated system. It
controls each user terminal over a signalling channel that can either be included in the high
data-rate downstream channel (in-band mode) or individually be transmitted over an
additional channel (out-of-band mode) with small bandwidth and the robust modulation
scheme QPSK. The out-of-band mode guaranties an additional degree of freedom which is
very important for interactive set-top boxes such as the EuroBox which is another part of the
integrated system.

   Broadcast content
    from backone        Integrated
       network         network and          Broadcast content

                        hardware            Broadcast content
                                                                     Out-of-band signaling
 Data connection to
 backbone network       Integrated
                       maintenance                              Integrated Network
                          system                                   Adapter (INA)
                       Integration of        connection
                       service types                                  In-band signaling

                                            Broadcast content

                                        Contributions via DVB-T and DVB-S support a simple re-modulation

                  Figure 1: Reference structure for the integrated system approach

The diagram above shows the integrated system approach that will be implemented in full
DVB-compliant cable networks. EuroModem and EuroBox connect the multimedia user
terminal to the cable network. The EuroBox is an interactive set-top box used for displaying
TV content and for enabling customers to carry out bi-directional communications. The
EuroModem is connected to a PC and is mainly used for data communications. The INA
dynamically manages all activities on the downstream and on the upstream channels in order
to ensure communication in the most efficient way. All services are managed and co-
ordinated in the headend by an integrated network and billing system. The effort for
maintaining the system is reduced to a minimum, because all applications are running on top
of one single hardware platform.

Step into the market
In May 1999 the final version of the EuroModem specification was published. It was
approved unanimously by EuroCableLabs. This was the starting point for the broad market
introduction. A tendering procedure was opened in May 1999 by sending out a detailed notice
to the European Union office in Luxembourg for official publication. Cable-modem vendors
indicated their interest to participate in the tender. 24 vendors were selected and invited to
send their system proposals to the EuroModem Consortium. After evaluation a short list of 13
vendors was published. In a first round (before end of 1999) 50.000 EuroModems have been
ordered by cable operators such as CasTel, Casema, Deutsche Telekom, Palet, Tele Danmark.
The European market will remarkably grow within the next few years especially considering

                                                          page 4 of 8 pages
                                           EuroModem White Paper

the market opportunities in Eastern Europe. More than 20.000 EuroModems are already
ordered by organisations located in Far East. Further orders of up to 500.000 pieces are
expected until the end of 2000. EuroBoxes are already in the market in high amounts. They
were ordered, for instance, by Media Kabel, Media One, NTL, Time Warner, etc. In general,
due to the successful introduction of DVB digital broadcast services the market penetration of
DVB-compliant set-top boxes with integrated modem functionality is expected to exceed by
far the demand of stand-alone cable modems.

Guarantee of equipment interoperability is essential for the introduction of any standardised
system. In the complete DVB world the lean approach of self-certification has been
successfully applied to all kinds of DVB-compliant equipment. It is based on interoperability
tests which are carried out by manufacturers themselves. This decentralised test model is also
used for the EuroModem. In addition an independent organisation verifies the individual
interoperability tests and reports to a Review Board which consists of members of the
DVB/DAVIC Interoperability Consortium. The work is carried out by the Institute for
Communications Technology at Braunschweig Technical University. Initially, these activities
were funded by the European Commission. The organisation chart of all contributing parties
is shown in the figure below. Interoperability tests as well as verifications are carried out on
the base of the “System Implementation Conformance Statement” (SICS) document and the
Interoperability Test Specification for DVB-compliant equipment. In addition, the
EuroModem is tested in accordance to the EuroModem “Conformance Test Form” (CTF)
which is annexed to the EuroModem specification.

DVB/DAVIC                                           Verification of
I n t e r o p e r a bi l i t y
C o n s o r ti u m                              Interoperability Tests

        Interoperability Tests

                                                                         EuroModem Specification

                                 Development of Baseline Specification

                     Figure 2: Organisation chart of EuroModem interoperability

Technical aspects
The definition of the technical parameters of the EuroModem system is guided by the
principle that “...the solutions provided ... are a part of a wider set of alternatives to implement
interactive services for DVB systems.” [DVB-RCCL 1999]

                                                 page 5 of 8 pages
                                 EuroModem White Paper

Two different modem types are realised:
       • The class A modem as a basic type of cable modem mainly used for PC inter-
       • The class B modem which allows the connection of telephony devices to the
          modem through a common telephony interface.
The following bullet points present the most important aspects in order to assess the
performance of such a system:

Physical layer:
       • Several data rates available in downstream direction up to 51 Mbps by using 16,
           32, 64, 128 or 256 QAM
       • Flexible downstream channel bandwidth configuration (e.g. 6, 7, or 8 MHz)
       • Signalling either in broadband downstream channel (in-band mode) or in separate
           narrowband downstream channel (out-of-band mode)
       • Spectrum allocation: 110 - 862 MHz for downstream and 5 - 65 MHz for upstream
       • Powerful error protection for upstream and downstream by using Reed-Solomon
       • Several data rates available in upstream direction up to 6.178 Mbps by using the
           very robust QPSK modulation scheme

Medium Access Control (MAC) layer:
      • Very flexible access mechanisms in order to support efficiently all kinds of traffic
         scenarios, e.g.: fixed rate access for establishing an ISDN-like connection,
                           continuous piggybacking for VoIP sessions,
                           reservation mode plus piggybacking and minislots for WWW,
                           contention access for e-mail and low data-rate applications
      • Support of dynamic Quality of Service (QoS)
      • Flexible support of various user terminals (e.g. cable modem, set-top box) by
         incorporating in-band and out-of-band mode into one single headend system
      • High-level control interface to upper layers provides easily manageable services to
         individual applications
      • This standardised application interface ensures transparency of lower layers for
         different service providers
      • ‘ Direct IP’guarantees highly efficient transport of IP traffic
      • Performance enhancement by using header suppression (e.g. compressing the large
         VoIP protocol overhead gains efficiency)
      • Additional support of Ethernet bridging and PPP connection between modem and
      • Optimised MAC components for handling timing-critical services such as
         telephony, VoIP and video conferencing
      • Security:          Public key exchange using Diffie-Helman algorithm,
                           Hashing with HMAC - SHA1,
                           Encryption algorithm uses DES with 40 or 56 bit

The high performance has been verified by in-depth computer simulations and laboratory
tests. It is future proofed due to upgrading EN/ETS 300 800 which is already considered by
the EuroModem specification.

                                       page 6 of 8 pages
                                   EuroModem White Paper

Comparison with competing systems
The performance of the EuroModem system can be verified by a comparison with its main
competing standardised techniques - the different DOCSIS versions.

DOCSIS 1.0-compliant equipment has serious technical disadvantages compared with
• Quasi no commercial use in Europe
• Slow commercial introduction in the USA because of no QoS support; US-based cable
   operators are waiting for DOCSIS 1.1
• Not useable for the integrated system platform (no simultaneous support of modems and
   set-top boxes)
• Problems with stable performance: Benchmark test published in Broadband Bob Report of
   13.10.99: “None of the [DOCSIS 1.0] modems could maintain a consistent performance
• It is uncertain whether the modem can be upgraded towards DOCSIS 1.1 via a simple
   software download
• The advantage of DOCSIS 1.0 is the current availability of higher volumes and the larger
   number of supporting vendors

DOCSIS 1.1-compliant equipment has very similar performance as the EuroModem if only a
data-over-cable system is considered. Taking into account the integrated system approach
DOCSIS 1.1 has technical and commercial disadvantages:
• Problems with the backward compatibility to old-fashioned DOCSIS 1.0 modems. (The
    enhanced performance of DOCSIS 1.1-compliant modems cannot be used if they are
    operated together with old modems.)
• First certifications by CableLabs U.S. planned not before spring 2000
• Useable as a stand alone cable-modem system
• Not useable for the integrated system solution
• Not optimised for European cable networks

EuroDOCSIS was developed in order to reduce the technical disadvantages of DOCSIS 1.1
for Europe. It has the task to adjust DOCSIS 1.1 to the European situation.
• It is still a proprietary system, because it is not in compliance with any standard, yet, but it
    is a mix of different annexes of ITU-T standards. In November 1999, the interim DOCSIS
    1.1 specification was submitted to ETSI. It was objected by a large number of ETSI
    members because of non-conformance with the ETSI statutes.
• European customers are labouring under a misapprehension if they think that they can buy
    DOCSIS-compliant equipment off the shelf. Parts such as tuners and filters used for
    EuroDOCSIS differ from the corresponding parts of the original DOCSIS. Thus, operators
    deploying EuroDOCSIS cannot benefit immediately from the price reduction in the
    original DOCSIS market.
• CableLabs U.S. will not certify EuroDOCSIS products.
• According to the newsletter Cable Europe (29.09.99) there is “No product available to
    date that complies with ... EuroDOCSIS”. The reason for this is that EuroDOCSIS is a
    variant of DOCSIS 1.1 which will not be available before spring 2000.
• Cable operators do not have any chance to influence the further development of the
    standard which has already started.

                                         page 7 of 8 pages
                                   EuroModem White Paper

DOCSIS 1.2 is the next step of evolution.
• There is no full backward-compatibility to DOCSIS 1.0 and 1.1 on the physical layer
• Many proprietary solutions (such as S-CDMA, FA-TDMA) which were developed by
  manufacturers (such as Terayon, Broadcom) are discussed at the moment to be included in
  the specification
• Broadcom Bob Report (13.10.99): “Last month, the DOCSIS certification board issued a
  letter to the [IEEE] 802.14 stating that it would use its own resources to develop the
  advanced PHY for DOCSIS 1.2 instead of using the 802.14 Working Group’         s

•      Goal of EuroCableLabs is the definition of an integrated system for the transmission of
       all types of services, such as broadcasting, data communications and voice, across all
       conceivable transmission media, like cable, satellite, terrestrial and micro-wave systems
•      EuroModem ideally fits into the integrated system
•      It is future proofed
•      Interoperability of the EuroModem is ensured
•      Many vendors from Europe, U.S., Israel and Far East are producing EuroModems
•      Support by large European cable operators
•      The EuroModem offers cable operators access to the world of digital services - not just
       to data-over-cable
•      The EuroModem is part of a complete service platform including EuroModem, EuroBox
       and the MHP as an open software environment
•      The rest of the world is still looking at individual components such as cable modems;
       even though the service platform concept offers various perspectives it is by now widely
•      EuroCableLabs is closely related to the globally successful DVB Project and its system
•      European cable operators and other DVB members can influence the future of
       EuroModem - not that of other systems

Shipment of EuroModems in large quantities is just about to start.

More information:
(1)   EuroCableLabs             
(2)   EuroModem                 
(3)   EuroBox                   
(4)   ECCA                      
(5)   Interoperability issues   
(6)   DVB                       

                                         page 8 of 8 pages

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