ETSI TR 102 881 V1.1.1 (2010-06)

Access, Terminals, Transmission and Multiplexing (ATTM); Cable Network Handbook

DTR/ATTM-003009

General Information

• Status: Published
• Publication Date: 29-Jun-2010
• Technical Committee: ATTM AT3 - Integrated broadband cable and television networks
• Current Stage: 12 - Completion
• Due Date: 23-Jun-2010
• Completion Date: 30-Jun-2010

Standards Content (Sample)

ETSI TR 102 881 V1.1.1 (2010-06)
Technical Report


Access, Terminals, Transmission and Multiplexing (ATTM);
Cable Network Handbook

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2 ETSI TR 102 881 V1.1.1 (2010-06)



Reference
DTR/ATTM-003009
Keywords
broadband, cable, IPCable
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© European Telecommunications Standards Institute 2010.
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3 ETSI TR 102 881 V1.1.1 (2010-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Symbols and abbreviations . 7
3.1 Symbols . 7
3.2 Abbreviations . 7
4 Network of the Cable operator . 8
4.1 History of the CATV network . 8
4.2 HFC Network . 10
4.2.1 Architecture . 10
4.2.2 Components . 11
4.2.3 Tree-and-branch topology . 11
4.2.4 Star topology . 12
4.3 Backbone network . 14
4.4 Home network . 15
4.4.1 Network Interface Unit . 15
4.4.2 Distribution of video signals . 15
4.4.3 Distribution of data signals . 15
4.4.4 Examples of poor in-home installations. 15
5 Physical layer . 16
5.1 Radio-frequency carrier and spectrum . 16
5.1.1 Downstream frequencies . 17
5.1.2 Upstream frequencies . 17
5.2 Analogue transmission . 17
5.2.1 AM modulation . 17
5.2.2 FM modulation . 17
5.3 Digital transmission based on QAM modulation . 17
5.4 Noise and interference . 18
5.4.1 Upstream noise and interference . 18
5.4.2 Downstream noise and interference . 19
6 Services . 19
6.1 Data services . 19
6.1.1 EuroDOCSIS protocol . 19
6.2 Telephony services . 20
6.2.1 Telephony over cable . 20
6.2.2 IP telephony based on EuroPacketCable . 20
6.3 Audio and Video Services . 21
6.3.1 Compression . 21
6.3.2 FM radio . 22
6.3.3 Broadcast TV . 22
6.3.3.1 Cable television headend . 22
6.3.3.2 Analogue TV . 24
6.3.3.3 Digital TV based on DVB-C . 24
6.3.4 IPTV . 25
6.3.5 Interactive TV . 25
6.3.6 Video on Demand . 26
6.3.7 Encryption and conditional access . 26
ETSI

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4 ETSI TR 102 881 V1.1.1 (2010-06)
Annex A: Bibliography . 27
History . 28

ETSI

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5 ETSI TR 102 881 V1.1.1 (2010-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
Introduction
The core expertise within ETSI responsible for European Standards covering Integrated Broadband Cable and
Television Networks (ATTM-AT3) has received requests from industry to produce a cable network handbook in order
to assist decision makers, both technical and regulatory people.
The current document is a cable handbook produced in cooperation with Excentis and Cable Europe in order to provide
the reader with a high level technical understanding of the CATV and Broadband Cable Networks.
ETSI

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6 ETSI TR 102 881 V1.1.1 (2010-06)
1 Scope
The present document is a technical report providing general overview of the Integrated Broadband Cable and
Television Networks and is intended as a handbook for engineers and non-engineers to familiarize themselves with the
Cable Network infrastructure, architecture, components and protocols including high level description of its
transmission principles
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
Not applicable.
[i.1] ETSI ES 201 488 (all parts): "Access and Terminals (AT); Data Over Cable Systems".
NOTE: EuroDOCSIS 1.1 is ES 201 488 (parts 1, 2, 3).
[i.2] ISO/IEC 13818:"Information technology - Generic coding of moving pictures and associated
audio information".
[i.3] ETSI ES 202 488 (all parts): "Access and Terminals (AT); Second Generation Transmission
Systems for Interactive Cable Television Services - IP Cable Modems".
NOTE: EuroDOCSIS 2.0 is ES 202 488 (parts 1, 2, 3).
[i.4] ETSI TS 102 639 (all parts): "Access and Terminals, Transmission and Multiplexing (ATTM);
Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable
Modems".
NOTE: EuroDOCSIS 3.0 is TS 102 639 (parts 1, 2, 3, 4, 5).
[i.5] ETSI TS 101 909-4: "Digital Broadband Cable Access to the Public Telecommunications
Network; IP Multimedia Time Critical Services; Part 4: Network Call Signalling Protocol [Partial
Endorsement of ITU-T Recommendation J.162 (11/2005), modified]".
[i.6] ISO/IEC 14496-10: "Information technology -- Coding of audio-visual objects --
Part 10: Advanced Video Coding".
ETSI

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7 ETSI TR 102 881 V1.1.1 (2010-06)
3 Symbols and abbreviations
3.1 Symbols
For the purposes of the present document, the following symbols the following apply:
Gbps Gigabit per second
GHz GigaHertz
kbps kilobit per second
kHz kiloHertz
MHz MegaHertz
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AM Amplitude Modulation
ANC Announcement Controller
ANP Announcement Player
ANS Announcement Server
AS Authorization Server
ATV Analogue TeleVision
CA Call Agent or Conditional Access
CATV Cable TeleVision / Community Antenna TeleVision
CM Cable Modem
CMS Call Management Server
CMTS Cable Modem Termination System
CPE Customer Premise Equipment
CSA Common Scrambling Algorithm
DC District Center
DHCP Dynamic Host Configuration Protocol
DNS Domain Name Server
DOCSIS Data Over Cable Service Interface Specification
DS DownStream
DTV Digital TeleVision
DVB Digital Video Broadcasting
ETSI European Telecommunications Standardisation Institute
EuroDOCSIS European Data over Cable System Interface Specification
FA Final Amplifier
FDM Frequency Domain Multiplexing
FDMA Frequency Division Multiple Access
FM Frequency Modulation
GA Group Amplifier
GC Gate Controller
HDTV High-Definition Television
HE HeadEnd
HFC Hybrid Fibre Coax
HTTP HyperText Transfer Protocol
IP Internet Protocol
IPTV IP Television
ISO International Standardisation Organisation
KDC Key Distribution Center
LC Local Center
MAC Media Access Control
Mbps Megabit per second
MG Media Gateway
MGC Media Gateway Controller
MPEG Moving Pictures Expert Group
MPLS Multi Protocol Label Switching
ETSI

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8 ETSI TR 102 881 V1.1.1 (2010-06)
MTA Multimedia Terminal Adapter
MTP Multi-TaP
MUX Multiplexing
NIU Network Interface Unit
NOC Network Operating Center
NTU Network Termination Unit
ON Optical Node
OSS Operating Support System
PAL Phase Alternating Line
PSI Program Specific Information
PSTN Public Switched Telephone Network
QAM Quadrature Amplitude Modulation
QoS Quality of Service
RC Regional Center
RF RadioFrequency
SDH Synchronous Digital Hierarchy
SDTV Standard-definition Television
SECAM SEquentiel Couleur A Mémoire
SG Signalling Gateway
SI Service Information
SONET Synchronous Optical NETwork
SS7 Signalling System 7
STB Set-Top Box
TDMA Time Division Multiple Access
TFTP Trivial File Transfer Protocol
TGS Ticket Granting Server
ToIP Telephony over IP
US UpStream
UTP Unshielded Twisted Pair
VoD Video on Demand
4 Network of the Cable operator
4.1 History of the CATV network
The CATV (Community Antenna TeleVision) network was originally set up to deliver one-way, analogue broadcast TV
transmission (unidirectional from headend to subscriber) services (Figure 1). A headend (HE) has in the cable network
operator's terminology two meanings: the first one refers to the equipment for receiving television signals for processing
and distribution over a cable television system, the second one describes facilities in which the equipment is installed
that converts the received signals into ones that are distributed in the CATV or HFC (see clause 4.2) network.
ETSI

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9 ETSI TR 102 881 V1.1.1 (2010-06)

Figure 1: The CATV network (HE=headend)
Signals were captured using terrestrial and satellite antennas and distributed using a coaxial network within the local
community. The earliest deployments started in the thirties. Until the nineties, there were thousands of small networks
all over Europe most of these are now consolidated into larger cable operators.
Amplifiers are used to compensate for the attenuation of the coaxial cables. Although the attenuation for two types of
cable for in-home use is depicted in Figure 2, it shows the general frequency-dependent trend of the attenuation of
coaxial cables. This frequency dependency is normally compensated for by equalisation filters in the amplifiers.
However the length of the cables between the amplifiers may not be too long in order that the input signal at the
amplifier is above the noise level. This shows that extending the frequency spectrum above 1 GHz would necessitate the
reduction of the distance between the amplifiers which would require a complete re-implementation of the CATV/HFC
network. This brings us to the conclusion that the frequency spectrum of the CATV and HFC network is limited at
present to below 1 GHz.
The amplifiers and tap values were chosen such that each house gets an equal TV signal. A huge number of houses (e.g.
between 50 000 and 1,6 million) can be served by one headend.
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10 ETSI TR 102 881 V1.1.1 (2010-06)




30

25


20

15 RG-59

RG-6

10

5


0
0 200 400 600 800 1000 1200

Frequency [MHz]

Figure 2: Frequency dependence of the attenuation of two types of coaxial cables
Since the end of the nineties, most of the CATV networks have been converted for bi-directional operation into a
Hybrid Fibre Coax (HFC) architecture.
4.2 HFC Network
4.2.1 Architecture
Hybrid Fibre Coax (HFC) access networks are composed of optical fibre and coaxial cables (Figure 3).
Typically, optical fibre rings radiate from the regional headend to optical nodes where the signals are transferred to
coaxial cables and then carried to the customer location. A headend may serve many tens of thousands of customer
premises, with substantial resilience in the access network resulting in the need for network power at many roadside
locations. Optical nodes typically serve between several hundred to some thousands of homes.

Broadband
Bidirectional
amplifier
ON 2
Optical
HE 1
CM NIU
Fiber Ring
Node 1
ON n
Residential
Customer
Fiber par t
Coax par t

Figure 3: HFC network
ETSI
Attenuation [dB/100m]

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11 ETSI TR 102 881 V1.1.1 (2010-06)
4.2.2 Components
If we have a closer look at the HFC network from the optical node to the home, we can distinguish different
components (see Figure 5).
Two optical fibres arrive in the optical node (in practice 4 for redundancy reasons), one with the upstream signal and
one with the downstream signal.
In the fibres, digital and analogue information is transmitted over the optical fibre through modulation of a sine carrier.
Simply said, light is sent all the time and it is the fluctuation of the light that tells the receiver what information the
sender is transmitting.
In the optical node two conversions are executed: the optical signal is converted to an electrical signal by a
photodetector (o/e conversion) and the diplex filter only puts the downstream signal on the coaxial cable; the upstream
signal on the coaxial input of the optical node is also filtered by the other part of the diplex filter and is sent as input to
the laser (electrical to optical - e/o conversion) to modulate the light signal in the upstream fibre.
Behind the optical node towards the homes, the coaxial distribution plant delivers all downstream signals to the homes
and transports the upstream signals coming from the homes back to the optical node.
Individual components are shown in Figure 4.

Fibre
Coaxial cable
Splitter Amplifier Tap

Figure 4: HFC network components
Two topologies for the coaxial part of the HFC network are in use in Europe: the tree-and-branch and the star
architecture.
4.2.3 Tree-and-branch topology
Tree-and-branch is the most typical architecture for the coaxial distribution plant (Figure 5). The main trunk cable is
split in branches though splitters. Splitters are bi-directional passive components used to split and combine signals over
different paths.
ETSI

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12 ETSI TR 102 881 V1.1.1 (2010-06)

� � �
� �
DS o/e

x
r
e
l e
t
l
p i
i
f
d
o/e
US
� � �
�
Optical node

Figure 5: Tree-and-branch HFC network topology
At regular intervals, bi-directional amplifiers amplify both the up- and downstream signals.
To connect the houses taps and "drop" coaxial cables connected to the taps are used. A tap provides basically the same
function as a splitter, i.e. dividing and combining signals, but while a splitter is a symmetrical component (equal
distribution of the signals), a tap is asymmetrical. Taps are also bi-directional, but it has one input port and a number of
output ports, of which one is the main output. The tap takes a small "portion" of the downstream signals on the branch
cable and sends it to the house. Upstream signals from the house are inserted in the branch cable through the tap. The
main output of the tap receives the biggest portion of the signals. Figure 6 shows a picture of an outdoor tap with the
input and main output taps and 4 taps connected to 4 drop cables attached to the front of 4 houses.

Figure 6: Outdoor tap
4.2.4 Star topology
An alternative topology is the star configuration as shown in Figure 7. Splitters with multiple outputs or multi-taps
(mtp) are used to connect several houses. This star topology is typical for the networks in the Netherlands. A specific
terminology is also shown on Figure 7.
ETSI

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13 ETSI TR 102 881 V1.1.1 (2010-06)

RC
fibre
FA
RC
ATV
GA FA
Radio
GA FA coax
RC
fibre
STP
DTV
mtp STB
GA FA
fibre
DC
LC
Terrestial
RC
I
CM
GA FA
Satellite RC+ MAIN
Optical Voice
HE
Internet BACK-UP
node
Transit GA evFA
Peering
RC+
HE FA
RC
coax
Fiber
RC Regional Center
LC  Local Center
DC District Center
GA  Group Amplifier
FA  Final Amplifier

Figure 7: HFC-network based on a star topology
Figure 8 shows pictures of the centers and amplifiers in a real-life star-topology network.

Regional Center Local Center (small one)
District Center Group Amplifier Final Amplifier

Figure 8: Different facilities and equipment in case of star-type HFC network
ETSI

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14 ETSI TR 102 881 V1.1.1 (2010-06)
The HFC network is a shared medium. This means that the signals transmitted by the different customers connected to
the same segment of the optical node, will be transported on the same cables. Therefore, solutions to avoid interference
between the signals were needed (see clause 5.1). Moreover the bandwidth provided by the spectrum of the HFC
network will be shared among all customers of the coaxial segment connected to the optical node.
4.3 Backbone network
Cable network operators covering larger areas operate a number of headends interconnected via optical links, i.e. the
backbone network. The backbone uses fibre optics to transport information. Backbone technologies that are used are
Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH), and Ethernet. These technologies can
only transport digital information in contrast to the HFC network where analogue and digital signals are present. The to
be transmitted bit-stream modulates a pulse train. A "1"-bit is transmitted by sending a light pulse, a "0"-bit by not
sending a light pulse. SONET, SDH and Ethernet use what is called a baseband signal.
The backbone enables the cable operator to achieve national coverage, with content being inserted and distributed on a
national, regional or local basis as appropriate. The backbone network (network across country or between countries)
typically consists of a primary ring, which runs through all the regions where the operator offers services. In each
region, one or more secondary rings depart from the primary ring (Figure 9).
A master headend and its associated servers are located in the Network Operating Centre (NOC). In the NOC gateways
to the internet and to traditional telephony providers are installed.

Euro-DOCSIS CMTS
+Telephony equipment
+ Router
Bidirectional
amplifier
ON 2
Secondary
Secondary
Telephone
Optical
HE 1
CM
NIU
Fiber Ring
IP
Node 1
Backbone
Teleph.
Ring
Backbone
modem
ON n
Connections
Residential
Primary
Customer
Telephony
International
Backbone
Gateways Telephony Switch
Connectons
Primary
/ conversions
Gateway
IP Backbone Router
Internet
DHCP
GAMES
SMTP
Server Farm
WEB
NOC
POP

Figure 9: HFC and backbone network topology of the cable operator's network
The secondary rings interconnect a number of regional headends. From each headend, an HFC network consisting of
multiple nodes departs. A fibre ring runs through a number of optical nodes and each optical node is the starting point
of a coaxial distribution plant. A regional headend therefore contains multiple optical transmitters and receivers that are
connected over fibre to the different optical nodes in the field.
In the case where telephony is replaced by VoIP, the telephone backbone is merged to the IP backbone.
It should be stressed that this "ring" topology is the ideal case, based on local circumstances, variations exist.
Backbones of cable systems are the same as those used by the "telecom" operators.
ETSI

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15 ETSI TR 102 881 V1.1.1 (2010-06)
4.4 Home network
4.4.1 Network Interface Unit
The Network Interface Unit (NIU, also called the Network Termination Unit (NTU), terminates the signals on the drop
cable at the entrance of the home. It isolates the network of the cable operator from the in-home network. The NIU
contain filters to separate video, data and in case of telephony over cable (see clause 6.2.1) also the telephony signals.
Figure 10 shows an in-home setup with an NIU and a cable modem connected to the NIU.

Figure 10: In-home set-up with NIU and cable modem
Sometimes an amplifier is embedded in the NIU (active NIU) to bring the signal in the home to the correct level. NIUs
are not used in all countries.
4.4.2 Distribution of video signals
In the home the signals are mostly distributed through coaxial cables. Sometimes splitters and amplifiers are used to
distribute the signals to different rooms. By using amplifiers cable losses are compensated such that in each room an
acceptable signal level is obtained.
As the installation of the home networks are the responsibility of the home owner and not of the cable operator, the
quality of the in-home installation is in the hands of the home owner or electrician who installs the cables. The home
cables used are mostly of low quality. This means that they may have a large and frequency-dependent attenuation and
poor shielding. This has a large impact on the pick-up of ingress noise (see clause 5.4.2). The choice of low-quality
cables is due to the limited expertis
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