ETSI EN 302 878-3 V1.1.1 (2011-11)
Access, Terminals, Transmission and Multiplexing (ATTM); Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 3: Downstream Radio Frequency Interface; DOCSIS 3.0
Access, Terminals, Transmission and Multiplexing (ATTM); Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 3: Downstream Radio Frequency Interface; DOCSIS 3.0
DEN/ATTM-003006-3
Dostop, priključki, prenos in multipleksiranje (ATTM) - Tretja generacija prenosnih sistemov za storitve interaktivne kabelske televizije - IP-kabelski modemi - 3. del: Navzdolnji radiofrekvenčni vmesnik - DOCSIS 3.0
Ta dokument dovolj podrobno opredeljuje zahtevane radiofrekvenčne lastnosti navzdolnjih oddajnikov v sistemih zaključevanja kabelskih modemov (CMTS) in robnih kvadraturnih amplitudnih modulatorjih (EQAM) v skladu s standardom DOCSIS 3.0, da prodajalcem omogoča izdelavo naprav, ki ustrezajo potrebam kabelskih operaterjev po svetu. Poleg opredelitve zahtev za napravo DOCSIS 3.0 se lahko ta dokument uporablja tudi za druge naprave, kot so:
modulator EQAM, ki se ne uporablja za storitve DOCSIS 3.0, ali
integrirani sistem CMTS z več navzdolnjimi kanali na radiofrekvenčna vrata, ki je v skladu s prejšnjimi različicami standarda DOCSIS 3.0.
Med praksami načrtovanja kabelskega spektra, sprejetimi za različna omrežja po svetu, obstajajo razlike. Zato sta za tehnologijo fizične plasti vključeni dve enakovredni možnosti, pri čemer ni treba, da sta interoperabilni. Ena možnost temelji na navzdolnji večprogramski televizijski distribuciji, ki se uporablja v Severni Ameriki in pri kateri imajo kanali pasovno širino 6 MHz. Druga možnost temelji na ustrezni evropski večprogramski televizijski distribuciji. Obe možnosti imata enak status, čeprav struktura dokumenta ne odraža njune enakovrednosti. Prva možnost je opredeljena v točkah 5, 6 in 7, druga pa z zamenjavo vsebine omenjenih točk z dodatkom A. Skladno s tem [4] in [2] veljata le za prvo možnost,standard EN 300 429 [8] pa le za drugo. Skladnost s tem dokumentom pomeni skladnost z eno opisano izvedbo in ne z obema. Interoperabilnost opreme, izdelane v skladu s prvo možnostjo, z opremo, izdelano v skladu z drugo možnostjo, ni zahtevana.
Naprava, skladna z vmesnikom DRFI, je lahko naprava s samo enim kanalom, lahko pa je naprava z več kanali, ki lahko izdela en navzdolnji radiofrekvenčni nosilni signal ali več hkrati na enih radiofrekvenčnih izhodnih vratih. EQAM je lahko modul modularnega sistema zaključevanja kabelskih modemov (M-CMTS) ter se uporablja za zagotavljanje hitre podatkovne storitve ali služi kot sestavni del sistema digitalnega videa ali videa na zahtevo (VoD), ki naročnikom zagotavlja visokokakovostni digitalni video. Te specifikacije so izdelane za omogočanje uporabe modulatorja EQAM brez omejitev v posameznem načinu zagotavljanja storitev ali sočasno v obeh načinih zagotavljanja storitev. »Sočasno« pri začetnih izvedbah pomeni, da se lahko po nekaterih kanalih prenašajo podatki z visoko hitrostjo, po drugih pa digitalni video, če imajo radiofrekvenčna izhodna vrata več kanalov QAM. Ta dokument omogoča prihodnje načine uporabe, pri katerih se lahko pasovna širina posameznega kanala QAM v istem transportnem toku MPEG razdeli med podatke z visoko hitrostjo in digitalni video. To pomeni, da bo modulator EQAM sprejel vhodni signal prek povezave Ethernet, vhodne podatke integriral v transportni tok MPEG, moduliral enega izmed številnih radiofrekvenčnih nosilnih signalov glede na te specifikacije ter ga poslal v izhodni priključek, ki je v skupni rabi z vsemi modulatorji. Verjetno bi se en radiofrekvenčni kanal modulatorja EQAM lahko uporabljal sočasno za podatke in video. Radiofrekvenčni kanal modulatorja EQAM se lahko uporablja za podatke in video, ker navzdolnji kanali za digitalni video in podatke DOCSIS temeljijo na dodatku B priporočila ITU-T J.83 [4] za kabelska omrežja v Severni Ameriki in standardu EN 300 429 [8] za kabelska omrežja v Evropi. Pri navzdolnjih kanalih v skladu z dodatkom B priporočila ITU-T J.83 [4] je običajno edina razlika med radiofrekvenčnim kanalom modulatorja EQAM, ki deluje v video načinu, in radiofrekvenčnim kanalom modulatorja EQAM, ki deluje v načinu podatkov DOCSIS, globina prepletanja (glejte točki 6.3.1 in 6.3.3).
General Information
Standards Content (Sample)
Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
European Standard
Access, Terminals, Transmission and Multiplexing (ATTM);
Third Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems;
Part 3: Downstream Radio Frequency Interface;
DOCSIS 3.0
2 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
Reference
DEN/ATTM-003006-3
Keywords
access, broadband, cable, data, IP, IPCable,
modem
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3 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope and purpose . . 6
1.1 Scope . 6
1.2 Purpose of Document . 6
1.3 Use of References in the present document . 7
1.4 Requirements . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 10
4 Void . 11
5 Functional Assumptions . 11
5.1 Broadband Access Network . 11
5.2 Equipment Assumptions . 11
5.2.1 Frequency Plan . 11
5.2.2 Compatibility with Other Services . 11
5.2.3 Fault Isolation Impact on Other Users . 12
5.3 Downstream Plant Assumptions . 12
5.3.1 Transmission Levels . 12
5.3.2 Frequency Inversion . 12
5.3.3 Analog and Digital Channel Line-up . 12
5.3.4 Analog Protection Goal . 12
6 Physical Media Dependent Sublayer Specification . 13
6.1 Scope . 13
6.2 EdgeQAM (EQAM) differences from CMTS . 13
6.3 Downstream . 14
6.3.1 Downstream Protocol . 14
6.3.2 Spectrum Format . 14
6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 14
6.3.4 Downstream Frequency Plan . 15
6.3.5 DRFI Output Electrical . 15
6.3.5.1 CMTS or EQAM Output Electrical . 16
6.3.5.1.1 Power per Channel CMTS or EQAM . 17
6.3.5.1.2 Independence of individual channel within the multiple channels on a single RF port . 18
6.3.5.1.3 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 20
6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 24
6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 25
6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 25
6.3.6 CMTS or EQAM Clock Generation . 25
6.3.6.1 CMTS Clock Generation . 25
6.3.6.2 EQAM Clock Generation . 25
6.3.6.3 Downstream Symbol Rate . 25
6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 26
6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 26
6.3.9 Timestamp Jitter . 26
7 Downstream Transmission Convergence Sublayer . 27
7.1 Introduction . 27
7.2 MPEG Packet Format . 27
7.3 MPEG Header for DOCSIS Data-Over-Cable . 27
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4 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
7.4 MPEG Payload for DOCSIS Data-Over-Cable . 28
7.4.1 stuff_byte . 28
7.4.2 pointer_field . 28
7.5 Interaction with the MAC Sublayer . 28
7.6 Interaction with the Physical Layer . 29
Annex A (normative): Additions and Modifications for European Specification . 30
A.1 Scope and purpose . 30
A.2 Void . 30
A.3 Terms and definitions . 30
A.4 Acronyms and abbreviations . 30
A.5 Functional Assumptions . 30
A.5.1 Broadband Access Network . 30
A.5.2 Equipment Assumptions . 31
A.5.2.1 Frequency Plan . 31
A.5.2.2 Compatibility with Other Services . 31
A.5.2.3 Fault Isolation Impact on Other Users . 31
A.5.3 Downstream Plant Assumptions . 31
A.5.3.1 Transmission Levels . 31
A.5.3.2 Frequency Inversion . 31
A.5.3.3 Analog and Digital Channel Line-up . 32
A.5.3.4 Analog Protection Goal . 32
A.6 Physical Media Dependent Sublayer Specification . 32
A.6.1 Scope . 32
A.6.2 EdgeQAM (EQAM) differences from CMTS . 32
A.6.3 Downstream . 32
A.6.3.1 Downstream Protocol . 32
A.6.3.2 Spectrum Format . 32
A.6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 32
A.6.3.4 Downstream Frequency Plan . 33
A.6.3.5 DRFI Output Electrical . 33
A.6.3.5.1 CMTS or EQAM Output Electrical . 33
A.6.3.5.1.1 Output Electrical per RF Port . 33
A.6.3.5.1.2 Power per Channel CMTS or EQAM . 34
A.6.3.5.1.3 Independence of individual channel within the multiple channels on a single RF port . 35
A.6.3.5.1.4 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 37
A.6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 41
A.6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 41
A.6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 41
A.6.3.6 CMTS or EQAM Clock Generation . 42
A.6.3.6.1 CMTS Clock Generation . 42
A.6.3.6.2 EQAM Clock Generation . 42
A.6.3.6.3 Downstream Symbol Rate . 42
A.6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 42
A.6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 43
A.6.3.9 Timestamp Jitter . 43
A.7 Downstream Transmission Convergence Sublayer . 43
A.7.1 Introduction . 43
A.7.2 MPEG Packet Format . 43
A.7.3 MPEG Header for DOCSIS Data-Over-Cable . 43
A.7.4 MPEG Payload for DOCSIS Data-Over-Cable . 43
A.7.5 Interaction with the MAC Sublayer . 43
A.7.6 Interaction with the Physical Layer . 43
Annex B (normative): DOCS-DRF-MIB . 44
History . 59
ETSI
5 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
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 draft European Standard (EN) has been produced by ETSI Technical Committee Access, Terminals, Transmission
and Multiplexing (ATTM), and is now submitted for the Public Enquiry phase of the ETSI standards Two-step
Approval Procedure.
The present document is part 3 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.7].
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa
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6 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
1 Scope and purpose
1.1 Scope
The present document defines the RF characteristics required in the downstream transmitter(s) of DOCSIS 3.0 CMTSs
and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators around the
world.
In addition to defining these requirements for a DOCSIS 3.0 device, the present document could also be applicable to
other devices such as:
• an Edge QAM (EQAM) not being used for DOCSIS 3.0 services; or
• an integrated Cable Modem Termination System [CMTS] with multiple downstream channels per RF port
previous to DOCSIS 3.0.
There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore
two options for physical layer technology are included, which have equal priority and are not required to be
interoperable. One technology option is based on the downstream multi-program television distribution that is deployed
in North America using 6 MHz channelling. The other technology option is based on the corresponding European
multi-program television distribution. Both options have the same status, notwithstanding that the document structure
does not reflect this equal priority. The first of these options is defined in clauses 5, 6 and 7, whereas the second is
defined by replacing the content of those clauses with the content of annex A. Correspondingly, [4] and [2] apply only
to the first option, and EN 300 429 [8] only to the second. Compliance with the present document requires compliance
with the one or the other of these implementations, not with both. It is not required that equipment built to one option
shall interoperate with equipment built to the other.
A DRFI-compliant device may be a single-channel only device, or it may be a multiple-channel device capable of
generating one or multiple downstream RF carriers simultaneously on one RF output port. An EQAM may be a module
of a modular cable modem termination system (M-CMTS) and be used for delivering a high-speed data service or it
may serve as a component of a digital video or Video-on-Demand (VoD) system, delivering high quality digital video
to subscribers. These specifications are crafted to enable an EQAM to be used without restriction in either or both
service delivery scenarios simultaneously. "Simultaneous" in the early deployments means that if a RF output port has
multiple QAM channels, some channel(s) may be delivering high-speed data while some other channel(s) may be
delivering digital video. The present document enables future uses, wherein a single QAM channel may share
bandwidth between high-speed data and digital video in the same MPEG transport stream.
Conceptually, an EQAM will accept input via an Ethernet link, integrate the incoming data into an MPEG transport
stream, modulate one of a plurality of RF carriers, per these specifications, and deliver the carrier to a single RF output
connector shared in common with all modulators. Conceivably, a single EQAM RF channel could be used for data and
video simultaneously. The reason that an EQAM RF channel can be used for either is that both digital video and
DOCSIS data downstream channels are based on ITU-T Recommendation J.83 [4], annex B for cable networks in North
America and EN 300 429 [8] for cable networks deployed in Europe. On downstream channels complying to ITU-T
Recommendation J.83 [4], annex B, typically, the only difference between an EQAM RF channel operating in a video
mode and an EQAM RF channel operating in DOCSIS data mode is the interleaver depth (see clauses 6.3.1 and 6.3.3).
DOCSIS data runs in a low latency mode using a shallow interleaver depth at the cost of some burst protection.
DOCSIS data can do this because if a transmission error occurs, the higher layer protocols will request re-transmission
of the missing data. For video, the sequence of frames in the program is both time sensitive and order sensitive and
cannot be re-transmitted. For this reason, video uses a deeper interleaver depth to provide more extensive burst
protection and deliver more of the program content without loss. The penalty video pays is in latency. The entire
program content is delayed by a few milliseconds, typically, and is invisible to the viewers of the program. The
conflicting demands for interleaver depth are what prevent a single EQAM RF channel from being used optimally for
video and DOCSIS data simultaneously. A traditional integrated CMTS, however, is used solely for DOCSIS data.
1.2 Purpose of Document
The purpose of the present document is to define the RF characteristics required in the downstream transmitter(s) of
CMTSs and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators
around the world.
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7 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
1.3 Use of References in the present document
The present document will not attempt to wholly replicate the normative references provided in the document.
However, it will use extracted portions of said documents where it adds clarity to the present document. For fuller
understanding of the present document, the most recent versions of [4] annex B or EN 300 429 [8], respectively, as well
as ES 202 488-2 [1] should be available for reference.
1.4 Requirements
Throughout the present document, the words that are used to define the significance of particular requirements are
capitalized. These words are:
"MUST" This word means that the item is an absolute requirement of this specification.
"MUST NOT" This phrase means that the item is an absolute prohibition of this specification.
"SHOULD" This word means that there may exist valid reasons in particular circumstances to
ignore this item, but the full implications should be understood and the case carefully
weighed before choosing a different course.
"SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances
when the listed behaviour is acceptable or even useful, but the full implications should
be understood and the case carefully weighed before implementing any behaviour
described with this label.
"MAY" This word means that this item is truly optional. One vendor may choose to include the
item because a particular marketplace requires it or because it enhances the product,
for example; another vendor may omit the same item.
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.
[1] ETSI ES 202 488-2: "Access and Terminals (AT); Second Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems; Part 2: Radio frequency interface
specification".
[2] CEA-542-B (July 2003): "Cable Television Channel Identification Plan".
[3] ANSI/SCTE 02 (2006): "Specification for "F" Port, Female Indoor".
[4] ITU-T Recommendation J.83 (April 1997 - Annex B): "Digital multi-programme systems for
television, sound and data services for cable distribution".
[5] ISO/IEC 13818-1 (2000): "Information Technology - Generic Coding Of Moving Pictures and
Associated Audio Systems Recommendation H.222.0".
[6] Cable Television Laboratories, Inc. CM-SP-RFIv2.0-C02-090422 (April 2009): "Data-Over-Cable
Service Interface Specifications - DOCSIS 2.0 - Radio Frequency Interface Specification".
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8 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
[7] IEC 61169-24 (2002): "Radio-frequency connectors - Part 24: Sectional specification - Radio
frequency coaxial connectors with screw coupling, typically for use in 75 ohm cable networks
(type F)".
[8] ETSI EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for cable systems".
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.
[i.1] Cable Television Laboratories, Inc. SP-CMTS-NSII01-960702 (July 1996): "Data Over Cable
Interface Specifications - Cable Modem Termination System - Network Side Interface
Specification".
[i.2] Cable Television Laboratories, Inc. CM-SP-M-OSSI-I08-081209 (December 2008): "Data-Over-
Cable Service Interface Specifications - Modular Headend Architecture - M-CMTS Operations
Support System Interface Specification".
[i.3] Cable Television Laboratories, Inc. CM-SP-CMCI-C01-081104 (November 2008): "Data-Over-
Cable Service Interface Specifications - Cable Modem to Customer Premise Equipment Interface".
[i.4] Cable Television Laboratories, Inc. CM-SP-DEPI-I08-100611 (June 2010): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - Downstream External PHY
Interface Specification".
[i.5] Cable Television Laboratories, Inc. CM-SP-DTI-I05-081209 (December 2008): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - DOCSIS Timing Interface
Specification".
[i.6] Cable Television Laboratories, Inc. CM-SP-ERMI-I03-081107 (November 2008): "Data-Over-
Cable-Service-Interface Specifications - Modular Headend Architecture - Edge Resource Manager
Interface Specification".
[i.7] ETSI EN 302 878-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Third
Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems;
Part 1: General; DOCSIS 3.0".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
ceiling (ceil): returns the first integer that is greater than or equal to a given value
Cable Modem (CM): modulator-demodulator at subscriber locations intended for use in conveying data
communications on a cable television system
Customer Premises Equipment (CPE): equipment at the end user's premises; may be provided by the service provider
Carrier-to-Noise Ratio (C/N or CNR): ratio of signal power to noise power in a defined measurement bandwidth. For
digital modulation, CNR = Es/No, the energy-per symbol to noise-density ratio; the signal power is measured in the
occupied bandwidth, and the noise power is normalized to the modulation-rate bandwidth. For analog NTSC video
modulation, the noise measurement bandwidth is 4 MHz.
deciBels (dB): ratio of two power levels expressed mathematically as dB = 10log10(POUT/PIN)
deciBel-milliVolt (dBmV): unit of RF power expressed in decibels relative to 1 millivolt over 75 Ω, where dBmV =
20log10(value in mV/1 mV)
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9 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
encompassed spectrum: spectrum ranging from the lower band-edge of the lowest active channel frequency to the
upper band-edge of the highest active channel frequency on an RF output port
Electronic Industries Alliance (EIA): voluntary body of manufacturers which, among other activities, prepares and
publishes standards
EdgeQAM Modulator (EQAM): head end or hub device that receives packets of digital video or data. It re-packetizes
the video or data into an MPEG transport stream and digitally modulates the digital transport stream onto a downstream
RF carrier using quadrature amplitude modulation (QAM).
Forward Error Correction (FEC): class of methods for controlling errors in a communication system. FEC sends
parity information with the data which can be used by the receiver to check and correct the data.
gap channel: channel within the encompassed spectrum which is not active; this occurs with non-contiguous channel
frequency assignments on an RF output port
GigaHertz (GHz): unit of frequency; 1,000,000,000 or 109 Hz
Hertz (Hz): unit of frequency; formerly cycles per second
Harmonic Related Carriers (HRC): method of spacing channels on a cable television system with all carriers related
to a common reference
Hybrid Fibre/Coax system (HFC): broadband bidirectional shared-media transmission system using optical fibre
trunks between the head-end and the fibre nodes, and coaxial cable distribution from the fibre nodes to the customer
locations
Incremental Related Carriers (IRC): method of spacing NTSC television channels on a cable television system in
which all channels are offset up 12,5 kHz with respect to the [2] standard channel plan except for channels 5 and 6
kiloHertz (kHz): unit of frequency; 1,000 or 103 Hz; formerly kilocycles per second
Media Access Control (MAC): used to refer to the layer 2 element of the system which would include DOCSIS
framing and signalling
MegaHertz (MHz): unit of frequency; 1,000,000 or 106 Hz; formerly megacycles per second
Modulation Error Ratio (MER): ratio of the average symbol power to average error power
M/N: relationship of integer numbers M,N that represents the ratio of the downstream symbol clock rate to the DOCSIS
master clock rate
non-contiguous channel assignment: encompassed spectrum on an RF output port contains gap channels (inactive
channels)
National Television Systems Committee (NTSC): committee which defined the analog, colour television, broadcast
standards in North America. The standards television 525-line video format for North American television transmission
is named after this committee.
NGNA LLC: company formed by cable operators to define a next-generation network architecture for future cable
industry market and business requirements
Physical Media Dependent sublayer (PMD): sublayer of the Physical layer which is concerned with transmitting bits
or groups of bits over particular types of transmission link between open systems and which entails electrical,
mechanical and handshaking procedures
QAM channel (QAM ch): analog RF channel that uses Quadrature Amplitude Modulation (QAM) to convey
information
Quadrature Amplitude Modulation (QAM): modulation technique in which an analog signal's amplitude and phase
vary to convey information, such as digital data
Radio Frequency (RF): portion of the electromagnetic spectrum from a few kilohertz to just below the frequency of
infrared light
Radio Frequency Interface (RFI): term encompassing the downstream and the upstream radio frequency interfaces
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10 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
Root Mean Square (RMS): square root of the mean value squared a function
self-aggregation: method used to compute the headend noise floor by summing measured noise from a single device
over a specified output frequency range
Standard Channel Plan (STD): method of spacing NTSC television channels on a cable television system defined
in [3]
Upstream Channel Descriptor (UCD): MAC Management Message used to communicate the characteristics of the
upstream physical layer to the cable modems
Video on Demand (VoD): system that enables individuals to select and watch video content over a network through an
interactive television system
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CM Cable Modem
CMCI Cable Modem CPE Interface
CMTS Cable Modem Termination System
CNR Carrier-to-Noise Ratio
CPE Customer Premises Equipment
CW Continuous Wave
dBc Decibels relative to carrier power
DEPI Downstream External-PHY Interface
DOCSIS® Data-Over-Cable Service Interface Specifications
DRFI Downstream Radio Frequency Interface
DTI DOCSIS Timing Interface
EIA Electronic Industries Alliance
EQAM EdgeQAM Modulator
ERMI Edge Resource Manager Interface
FCC Federal Communications Commission
FEC Forward Error Correction
HFC Hybrid Fibre/Coax system
HRC Harmonic Related Carriers
IRC Incremental Related Carriers
ISO International Standards Organization
ITU International Telecommunications Union
ITU-T Telecommunication Standardization Sector of the ITU
MAC Media Access Control
M-CMTS Modular Cable Modem Termination System
MER Modulation Error Ratio
MPEG Moving Picture Experts Group
-3
Ms Millisecond. 10 second
NGNA Next Generation Network Architecture, see NGNA LLC
-9
Ns Nanosecond. 10 second
NTSC National Television Systems Committee
OSSI Operations System Support Interface
PHY Physical Layer
PID Package Identifier
PMD Physical Media Dependent sublayer
ppm Parts per Million
PUSI Payload Unit Start Indicator
Q Quadrature modulation component
QAM Quadrature Amplitude Modulation
RF Radio Frequency
RFI Radio Frequency Interface
RMS Root Mean Square
S-CDMA Synchronous Code Division Multiple Access
STD Standard Channel Plan
UCD Upstream Channel Descriptor
ETSI
11 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
VoD Video on Demand
4 Void
5 Functional Assumptions
This clause describes the characteristics of a cable television plant, assumed to be for the purpose of operating a
data-over-cable system. It is not a description of EQAM or CMTS parameters. The data-over-cable system MUST be
interoperable within the environment described in this clause.
Whenever there is a reference in this clause to frequency plans or compatibility with other services, or conflicts with
any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analog signals
in 6 MHz channels does not imply that such signals are physically present.
5.1 Broadband Access Network
A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid
fibre/coax (HFC) network. The generic term "cable network" is used here to cover all cases.
A cable network uses a shared-medium, "tree-and-branch" architecture, with analog transmission. The key functional
characteristics assumed in the present document are the following:
• Two-way transmission.
• A maximum optical/electrical spacing between the DRFI-compliant device and the most distant CM of
100 miles in each direction, although typical maximum separation may be 10 miles to 15 miles.
• A maximum differential optical/electrical spacing between the DRFI-compliant device and the closest and
most distant modems of 100 miles in each direction, although this would typically be limited to 15 miles.
At a propagation velocity in fibre of approximately 1,5 ns/ft, 100 miles of fibre in each direction results in a round-trip
delay of approximately 1,6 ms. For further information, see ES 202 488-2 [1], annex R.
5.2 Equipment Assumptions
5.2.1 Frequency Plan
In the downstream direction, the cable system is assumed to have a pass band with a lower edge between 50 MHz and
54 MHz and an upper edge that is implementation-dependent but is typically in the range of 300 MHz to 870 MHz.
Within that pass band, NTSC analog television signals in 6-MHz channels are assumed present on the Standard (STD),
HRC, or IRC frequency plans of [2], as well as other narrowband and wideband digital signals.
5.2.2 Compatibility with Other Services
The CM and EQAM or CMTS MUST coexist with the other services on the cable network, for example:
1) they MUST be interoperable in the cable spectrum assigned for EQAM or CMTS-CM interoperation, while
the balance of the cable spectrum is occupied by any combination of television and other signals; and
2) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in
spectrum outside of that allocated to the EQAM or CMTS. The latter is understood as:
- no measurable degradation (highest level of compatibility);
- no degradation below the perceptible level of impairments for all services (standard or medium level of
compatibility); or
ETSI
12 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
- no degradation below the minimal standards accepted by the industry (for example, FCC for analog
video services) or other service provider (minimal level of compatibility).
5.2.3 Fault Isolation Impact on Other Users
As downstream transmissions are on a shared-media, point-to-multipoint system, fault-isolation procedures should take
into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the
data-over-cable, video and other services.
For the interpretation of harmful impact, see clause 5.2.2.
5.3 Downstream Plant Assumptions
The present document has been developed with the downstream plant assumptions of this clause.
5.3.1 Transmission Levels
The nominal power level of the downstream RF signal(s) within a 6-MHz channel (average power) is targeted to be in
the range: -10 dBc to -6 dBc, relative to analog video carrier level (peak power) and will normally not exceed analog
video carrier level.
5.3.2 Frequency Inversion
There will be no frequency inversion in the transmission path in either the downstream or the upstream directions (i.e. a
positive change in frequency at the input to the cable network will result in a positive change in frequency at the
output).
5.3.3 Analog and Digital Channel Line-up
In developing the present document, it was assumed that a maximum of 119 digital channels would be deployed in a
headend. For the purposes of calculating CNR, protection for analog channels, it was assumed that analog channels are
placed at lower frequencies in the channel line-up, versus digital channels.
5.3.4 Analog Protection Goal
One of the goals of the present document is to provide the minimum intended analog channel CNR protection of 60 dB
for systems deploying up to 119 DRFI-compliant QAM channels.
The present document assumes that the transmitted power level of the digital channels will be 6 dB below the peak
envelope power of the visual signal of analog channels, which is the typical condition for 256-QAM transmission. It is
further assumed that the channel lineup will place analog channels at lower frequencies versus digital channels, and in
systems deploying modulators capable of generating nine or more QAM channels on a single RF output port analog
channels will be placed at centre frequencies below 600 MHz. An adjustment of 10*log (6 MHz / 4 MHz) is used to
account for the difference in noise bandwidth of digital channels versus analog channels. With the assumptions above,
for a 119-QAM channel system, the specification in Item 5 of table 6-5 equates to an analog CNR protection of 60 dB.
With more QAM channels the analog protection is less. With the stated assumptions, the analog protection is:
Analog Protection (dB) = 80,76 - 10*log (Number of QAM Channels).
For example, in a 143-QAM channel system, with the assumptions above, the specification equates to an analog CNR
protection of 59,2 dB.
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13 Draft ETSI EN 302 878-3 V1.1.0 (2011-04)
6 Physical Media Dependent Sublayer Specification
6.1 Scope
This clause applies to the first technology option referred to in clause 1. For the second option, refer to annex A.
The present document defines the electrical characteristics of the Downstream Radio Frequency Interface (DRFI) of a
cable modem termination system (CMTS) or an edgeQAM (EQAM). It is the intent of this specification to define an
interoperable DRFI-compliant device, such that any implementation of a CM can work with any EQAM or CMTS. It is
not the intent of this specification to imply any specific implementation. Figure 6-1 shows the M-CMTS structure and
interfaces.
Whenever a reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation,
the latter shall take precedence.
Figure 6-1: Logical View of Modular CMTS and Interfaces
The CMTS Network Side Interface [i.1], Modular CMTS Operation Support System Interf
...
Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
European Standard
Access, Terminals, Transmission and Multiplexing (ATTM);
Third Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems;
Part 3: Downstream Radio Frequency Interface;
DOCSIS 3.0
2 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
Reference
DEN/ATTM-003006-3
Keywords
access, broadband, cable, data, IP, IPCable,
modem
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ETSI
3 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
Contents
Intellectual Property Rights . 6
Foreword . 6
1 Scope and purpose . . 7
1.1 Scope . 7
1.2 Purpose of Document . 7
1.3 Use of References in the present document . 8
1.4 Requirements . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 9
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 11
4 Void . 12
5 Functional Assumptions . 12
5.1 Broadband Access Network . 12
5.2 Equipment Assumptions . 12
5.2.1 Frequency Plan . 12
5.2.2 Compatibility with Other Services . 12
5.2.3 Fault Isolation Impact on Other Users . 13
5.3 Downstream Plant Assumptions . 13
5.3.1 Transmission Levels . 13
5.3.2 Frequency Inversion . 13
5.3.3 Analog and Digital Channel Line-up . 13
5.3.4 Analog Protection Goal . 13
6 Physical Media Dependent Sublayer Specification . 14
6.1 Scope . 14
6.2 EdgeQAM (EQAM) differences from CMTS . 14
6.3 Downstream . 15
6.3.1 Downstream Protocol . 15
6.3.2 Spectrum Format . 15
6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 15
6.3.4 Downstream Frequency Plan . 16
6.3.5 DRFI Output Electrical . 16
6.3.5.1 CMTS or EQAM Output Electrical . 17
6.3.5.1.1 Power per Channel CMTS or EQAM . 18
6.3.5.1.2 Independence of individual channel within the multiple channels on a single RF port . 19
6.3.5.1.3 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 21
6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 25
6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 26
6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 26
6.3.6 CMTS or EQAM Clock Generation . 26
6.3.6.1 CMTS Clock Generation . 26
6.3.6.2 EQAM Clock Generation . 26
6.3.6.3 Downstream Symbol Rate . 26
6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 27
6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 27
6.3.9 Timestamp Jitter . 27
7 Downstream Transmission Convergence Sublayer . 28
7.1 Introduction . 28
7.2 MPEG Packet Format . 28
7.3 MPEG Header for DOCSIS Data-Over-Cable . 28
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4 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
7.4 MPEG Payload for DOCSIS Data-Over-Cable . 29
7.4.1 stuff_byte . 29
7.4.2 pointer_field . 29
7.5 Interaction with the MAC Sublayer . 29
7.6 Interaction with the Physical Layer . 30
Annex A (normative): Additions and Modifications for European Specification . 31
A.1 Scope and purpose . 31
A.2 Void . 31
A.3 Terms and definitions . 31
A.4 Acronyms and abbreviations . 31
A.5 Functional Assumptions . 31
A.5.1 Broadband Access Network . 31
A.5.2 Equipment Assumptions . 32
A.5.2.1 Frequency Plan . 32
A.5.2.2 Compatibility with Other Services . 32
A.5.2.3 Fault Isolation Impact on Other Users . 32
A.5.3 Downstream Plant Assumptions . 32
A.5.3.1 Transmission Levels . 32
A.5.3.2 Frequency Inversion . 32
A.5.3.3 Analog and Digital Channel Line-up . 33
A.5.3.4 Analog Protection Goal . 33
A.6 Physical Media Dependent Sublayer Specification . 33
A.6.1 Scope . 33
A.6.2 EdgeQAM (EQAM) differences from CMTS . 33
A.6.3 Downstream . 33
A.6.3.1 Downstream Protocol . 33
A.6.3.2 Spectrum Format . 33
A.6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 33
A.6.3.4 Downstream Frequency Plan . 34
A.6.3.5 DRFI Output Electrical . 34
A.6.3.5.1 CMTS or EQAM Output Electrical . 34
A.6.3.5.1.1 Output Electrical per RF Port . 34
A.6.3.5.1.2 Power per Channel CMTS or EQAM . 35
A.6.3.5.1.3 Independence of individual channel within the multiple channels on a single RF port . 36
A.6.3.5.1.4 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 38
A.6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 42
A.6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 42
A.6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 42
A.6.3.6 CMTS or EQAM Clock Generation . 43
A.6.3.6.1 CMTS Clock Generation . 43
A.6.3.6.2 EQAM Clock Generation . 43
A.6.3.6.3 Downstream Symbol Rate . 43
A.6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 43
A.6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 44
A.6.3.9 Timestamp Jitter . 44
A.7 Downstream Transmission Convergence Sublayer . 44
A.7.1 Introduction . 44
A.7.2 MPEG Packet Format . 44
A.7.3 MPEG Header for DOCSIS Data-Over-Cable . 44
A.7.4 MPEG Payload for DOCSIS Data-Over-Cable . 44
A.7.5 Interaction with the MAC Sublayer . 44
A.7.6 Interaction with the Physical Layer . 44
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5 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
Annex B (normative): DOCS-DRF-MIB . 45
History . 60
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6 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
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://ipr.etsi.org).
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 final draft European Standard (EN) has been produced by ETSI Technical Committee Access, Terminals,
Transmission and Multiplexing (ATTM), and is now submitted for the Vote phase of the ETSI standards Two-step
Approval Procedure.
The present document is part 3 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.7].
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 6 months after doa
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7 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
1 Scope and purpose
1.1 Scope
The present document defines the RF characteristics required in the downstream transmitter(s) of DOCSIS 3.0 CMTSs
and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators around the
world.
In addition to defining these requirements for a DOCSIS 3.0 device, the present document could also be applicable to
other devices such as:
• an Edge QAM (EQAM) not being used for DOCSIS 3.0 services; or
• an integrated Cable Modem Termination System (CMTS) with multiple downstream channels per RF port
previous to DOCSIS 3.0.
There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore
two options for physical layer technology are included, which have equal priority and are not required to be
interoperable. One technology option is based on the downstream multi-program television distribution that is deployed
in North America using 6 MHz channelling. The other technology option is based on the corresponding European
multi-program television distribution. Both options have the same status, notwithstanding that the document structure
does not reflect this equal priority. The first of these options is defined in clauses 5, 6 and 7, whereas the second is
defined by replacing the content of those clauses with the content of annex A. Correspondingly, [4] and [2] apply only
to the first option, and EN 300 429 [8] only to the second. Compliance with the present document requires compliance
with the one or the other of these implementations, not with both. It is not required that equipment built to one option
will interoperate with equipment built to the other.
A DRFI-compliant device may be a single-channel only device, or it may be a multiple-channel device capable of
generating one or multiple downstream RF carriers simultaneously on one RF output port. An EQAM may be a module
of a modular cable modem termination system (M-CMTS) and be used for delivering a high-speed data service or it
may serve as a component of a digital video or Video-on-Demand (VoD) system, delivering high quality digital video
to subscribers. These specifications are crafted to enable an EQAM to be used without restriction in either or both
service delivery scenarios simultaneously. "Simultaneous" in the early deployments means that if a RF output port has
multiple QAM channels, some channel(s) may be delivering high-speed data while some other channel(s) may be
delivering digital video. The present document enables future uses, wherein a single QAM channel may share
bandwidth between high-speed data and digital video in the same MPEG transport stream.
Conceptually, an EQAM will accept input via an Ethernet link, integrate the incoming data into an MPEG transport
stream, modulate one of a plurality of RF carriers, per these specifications, and deliver the carrier to a single RF output
connector shared in common with all modulators. Conceivably, a single EQAM RF channel could be used for data and
video simultaneously. The reason that an EQAM RF channel can be used for either is that both digital video and
DOCSIS data downstream channels are based on ITU-T Recommendation J.83 [4], annex B for cable networks in North
America and EN 300 429 [8] for cable networks deployed in Europe. On downstream channels complying to ITU-T
Recommendation J.83 [4], annex B, typically, the only difference between an EQAM RF channel operating in a video
mode and an EQAM RF channel operating in DOCSIS data mode is the interleaver depth (see clauses 6.3.1 and 6.3.3).
DOCSIS data runs in a low latency mode using a shallow interleaver depth at the cost of some burst protection.
DOCSIS data can do this because if a transmission error occurs, the higher layer protocols will request re-transmission
of the missing data. For video, the sequence of frames in the program is both time sensitive and order sensitive and
cannot be re-transmitted. For this reason, video uses a deeper interleaver depth to provide more extensive burst
protection and deliver more of the program content without loss. The penalty video pays is in latency. The entire
program content is delayed by a few milliseconds, typically, and is invisible to the viewers of the program. The
conflicting demands for interleaver depth are what prevent a single EQAM RF channel from being used optimally for
video and DOCSIS data simultaneously. A traditional integrated CMTS, however, is used solely for DOCSIS data.
1.2 Purpose of Document
The purpose of the present document is to define the RF characteristics required in the downstream transmitter(s) of
CMTSs and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators
around the world.
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8 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
1.3 Use of References in the present document
The present document will not attempt to wholly replicate the normative references provided in the document.
However, it will use extracted portions of said documents where it adds clarity to the present document. For fuller
understanding of the present document, the most recent versions of [4] annex B or EN 300 429 [8], respectively, as well
as ES 202 488-2 [1] should be available for reference.
1.4 Requirements
Throughout the present document, the words that are used to define the significance of particular requirements are
capitalized. These words are:
"MUST" This word means that the item is an absolute requirement of this specification.
"MUST NOT" This phrase means that the item is an absolute prohibition of this specification.
"SHOULD" This word means that there may exist valid reasons in particular circumstances to
ignore this item, but the full implications should be understood and the case carefully
weighed before choosing a different course.
"SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances
when the listed behaviour is acceptable or even useful, but the full implications should
be understood and the case carefully weighed before implementing any behaviour
described with this label.
"MAY" This word means that this item is truly optional. One vendor may choose to include the
item because a particular marketplace requires it or because it enhances the product,
for example; another vendor may omit the same item.
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.
[1] ETSI ES 202 488-2: "Access and Terminals (AT); Second Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems; Part 2: Radio frequency interface
specification".
[2] CEA-542-C (February 2009): "Cable Television Channel Identification Plan".
[3] ANSI/SCTE 02 (2006): "Specification for "F" Port, Female, Indoor".
[4] ITU-T Recommendation J.83 (2007), Annex B: "Digital multi-programme systems for television,
sound and data services for cable distribution".
[5] ISO/IEC 13818-1 (2007): "Information technology -- Generic coding of moving pictures and
associated audio information: Systems".
[6] Cable Television Laboratories, Inc. CM-SP-RFIv2.0-C02-090422 (April 2009): "Data-Over-Cable
Service Interface Specifications - DOCSIS 2.0 - Radio Frequency Interface Specification".
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9 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
[7] IEC 61169-24 (2009): "Radio-frequency connectors - Part 24: Sectional specification - Radio
frequency coaxial connectors with screw coupling, typically for use in 75 ohm cable networks
(type F)".
[8] ETSI EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for cable systems".
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.
[i.1] Cable Television Laboratories, Inc. SP-CMTS-NSII01-960702 (July 1996): "Data Over Cable
Interface Specifications - Cable Modem Termination System - Network Side Interface
Specification".
[i.2] Cable Television Laboratories, Inc. CM-SP-M-OSSI-I08-081209 (December 2008): "Data-Over-
Cable Service Interface Specifications - Modular Headend Architecture - M-CMTS Operations
Support System Interface Specification".
[i.3] Cable Television Laboratories, Inc. CM-SP-CMCI-C01-081104 (November 2008): "Data-Over-
Cable Service Interface Specifications - Cable Modem to Customer Premise Equipment Interface".
[i.4] Cable Television Laboratories, Inc. CM-SP-DEPI-I08-100611 (June 2010): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - Downstream External PHY
Interface Specification".
[i.5] Cable Television Laboratories, Inc. CM-SP-DTI-I05-081209 (December 2008): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - DOCSIS Timing Interface
Specification".
[i.6] Cable Television Laboratories, Inc. CM-SP-ERMI-I03-081107 (November 2008): "Data-Over-
Cable-Service-Interface Specifications - Modular Headend Architecture - Edge Resource Manager
Interface Specification".
[i.7] ETSI EN 302 878-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Third
Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems;
Part 1: General; DOCSIS 3.0".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Cable Modem (CM): modulator-demodulator at subscriber locations intended for use in conveying data
communications on a cable television system
Carrier-to-Noise Ratio (C/N or CNR): ratio of signal power to noise power in a defined measurement bandwidth. For
digital modulation, CNR = Es/No, the energy-per symbol to noise-density ratio; the signal power is measured in the
occupied bandwidth, and the noise power is normalized to the modulation-rate bandwidth. For analog NTSC video
modulation, the noise measurement bandwidth is 4 MHz.
ceiling (ceil): returns the first integer that is greater than or equal to a given value
Customer Premises Equipment (CPE): equipment at the end user's premises; may be provided by the service provider
deciBels (dB): ratio of two power levels expressed mathematically as dB = 10log10(POUT/PIN)
deciBel-milliVolt (dBmV): unit of RF power expressed in decibels relative to 1 millivolt over 75 Ω, where
dBmV = 20log10(value in mV/1 mV)
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10 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
encompassed spectrum: spectrum ranging from the lower band-edge of the lowest active channel frequency to the
upper band-edge of the highest active channel frequency on an RF output port
Electronic Industries Alliance (EIA): voluntary body of manufacturers which, among other activities, prepares and
publishes standards
EdgeQAM Modulator (EQAM): head end or hub device that receives packets of digital video or data. It re-packetizes
the video or data into an MPEG transport stream and digitally modulates the digital transport stream onto a downstream
RF carrier using quadrature amplitude modulation (QAM).
Forward Error Correction (FEC): class of methods for controlling errors in a communication system. FEC sends
parity information with the data which can be used by the receiver to check and correct the data.
gap channel: channel within the encompassed spectrum which is not active; this occurs with non-contiguous channel
frequency assignments on an RF output port
GigaHertz (GHz): unit of frequency; 1,000,000,000 or 109 Hz
Harmonic Related Carriers (HRC): method of spacing channels on a cable television system with all carriers related
to a common reference
Hertz (Hz): unit of frequency; formerly cycles per second
Hybrid Fibre/Coaxial system (HFC): broadband bidirectional shared-media transmission system using optical fibre
trunks between the head-end and the fibre nodes, and coaxial cable distribution from the fibre nodes to the customer
locations
Incremental Related Carriers (IRC): method of spacing NTSC television channels on a cable television system in
which all channels are offset up 12,5 kHz with respect to the [2] standard channel plan except for channels 5 and 6
kiloHertz (kHz): unit of frequency; 1,000 or 103 Hz; formerly kilocycles per second
Media Access Control (MAC): used to refer to the layer 2 element of the system which would include DOCSIS
framing and signalling
MegaHertz (MHz): unit of frequency; 1,000,000 or 106 Hz; formerly megacycles per second
Modulation Error Ratio (MER): ratio of the average symbol power to average error power
M/N: relationship of integer numbers M,N that represents the ratio of the downstream symbol clock rate to the DOCSIS
master clock rate
non-contiguous channel assignment: encompassed spectrum on an RF output port contains gap channels (inactive
channels)
National Television Systems Committee (NTSC): committee which defined the analog, colour television, broadcast
standards in North America. The standards television 525-line video format for North American television transmission
is named after this committee.
NGNA LLC: company formed by cable operators to define a next-generation network architecture for future cable
industry market and business requirements
Physical Media Dependent sublayer (PMD): sublayer of the Physical layer which is concerned with transmitting bits
or groups of bits over particular types of transmission link between open systems and which entails electrical,
mechanical and handshaking procedures
QAM channel (QAM ch): analog RF channel that uses Quadrature Amplitude Modulation (QAM) to convey
information
Quadrature Amplitude Modulation (QAM): modulation technique in which an analog signal's amplitude and phase
vary to convey information, such as digital data
Radio Frequency (RF): portion of the electromagnetic spectrum from a few kilohertz to just below the frequency of
infrared light
Radio Frequency Interface (RFI): term encompassing the downstream and the upstream radio frequency interfaces
ETSI
11 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
Root Mean Square (RMS): square root of the mean value squared a function
self-aggregation: method used to compute the headend noise floor by summing measured noise from a single device
over a specified output frequency range
Standard Channel Plan (STD): method of spacing NTSC television channels on a cable television system defined
in [3]
Upstream Channel Descriptor (UCD): MAC Management Message used to communicate the characteristics of the
upstream physical layer to the cable modems
Video on Demand (VoD): system that enables individuals to select and watch video content over a network through an
interactive television system
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CM Cable Modem
CMCI Cable Modem CPE Interface
CMTS Cable Modem Termination System
CNR Carrier-to-Noise Ratio
CPE Customer Premises Equipment
CW Continuous Wave
dBc Decibels relative to carrier power
DEPI Downstream External-PHY Interface
DOCSIS® Data-Over-Cable Service Interface Specifications
DRFI Downstream Radio Frequency Interface
DTI DOCSIS Timing Interface
EIA Electronic Industries Alliance
EQAM EdgeQAM Modulator
ERMI Edge Resource Manager Interface
FCC Federal Communications Commission
FEC Forward Error Correction
HFC Hybrid Fibre/Coaxial system
HRC Harmonic Related Carriers
IRC Incremental Related Carriers
ISO International Standards Organization
ITU International Telecommunications Union
ITU-T Telecommunication Standardization Sector of the ITU
MAC Media Access Control
M-CMTS Modular Cable Modem Termination System
MER Modulation Error Ratio
MPEG Moving Picture Experts Group
-3
Ms Millisecond. 10 second
NGNA Next Generation Network Architecture, see NGNA LLC
-9
Ns Nanosecond. 10 second
NTSC National Television Systems Committee
OSSI Operations System Support Interface
PHY Physical Layer
PID Package Identifier
PMD Physical Media Dependent sublayer
ppm Parts per Million
PUSI Payload Unit Start Indicator
Q Quadrature modulation component
QAM Quadrature Amplitude Modulation
RF Radio Frequency
RFI Radio Frequency Interface
RMS Root Mean Square
ETSI
12 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
S-CDMA Synchronous Code Division Multiple Access
STD Standard Channel Plan
UCD Upstream Channel Descriptor
VoD Video on Demand
4 Void
5 Functional Assumptions
This clause describes the characteristics of a cable television plant, assumed to be for the purpose of operating a
data-over-cable system. It is not a description of EQAM or CMTS parameters. The data-over-cable system MUST be
interoperable within the environment described in this clause.
Whenever there is a reference in this clause to frequency plans or compatibility with other services, or conflicts with
any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analog signals
in 6 MHz channels does not imply that such signals are physically present.
5.1 Broadband Access Network
A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid
fibre/coaxial (HFC) network. The generic term "cable network" is used here to cover all cases.
A cable network uses a shared-medium, "tree-and-branch" architecture, with analog transmission. The key functional
characteristics assumed in the present document are the following:
• Two-way transmission.
• A maximum optical/electrical spacing between the DRFI-compliant device and the most distant CM of
100 miles in each direction, although typical maximum separation may be 10 miles to 15 miles.
• A maximum differential optical/electrical spacing between the DRFI-compliant device and the closest and
most distant modems of 100 miles in each direction, although this would typically be limited to 15 miles.
At a propagation velocity in fibre of approximately 1,5 ns/ft, 100 miles of fibre in each direction results in a round-trip
delay of approximately 1,6 ms. For further information, see ES 202 488-2 [1], annex R.
5.2 Equipment Assumptions
5.2.1 Frequency Plan
In the downstream direction, the cable system is assumed to have a pass band with a lower edge between 50 MHz and
54 MHz and an upper edge that is implementation-dependent but is typically in the range of 300 MHz to 870 MHz.
Within that pass band, NTSC analog television signals in 6-MHz channels are assumed present on the Standard (STD),
HRC, or IRC frequency plans of [2], as well as other narrowband and wideband digital signals.
5.2.2 Compatibility with Other Services
The CM and EQAM or CMTS MUST coexist with the other services on the cable network, for example:
1) they MUST be interoperable in the cable spectrum assigned for EQAM or CMTS-CM interoperation, while
the balance of the cable spectrum is occupied by any combination of television and other signals; and
2) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in
spectrum outside of that allocated to the EQAM or CMTS. The latter is understood as:
- no measurable degradation (highest level of compatibility);
ETSI
13 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
- no degradation below the perceptible level of impairments for all services (standard or medium level of
compatibility); or
- no degradation below the minimal standards accepted by the industry (for example, FCC for analog
video services) or other service provider (minimal level of compatibility).
5.2.3 Fault Isolation Impact on Other Users
As downstream transmissions are on a shared-media, point-to-multipoint system, fault-isolation procedures should take
into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the
data-over-cable, video and other services.
For the interpretation of harmful impact, see clause 5.2.2.
5.3 Downstream Plant Assumptions
The present document has been developed with the downstream plant assumptions of this clause.
5.3.1 Transmission Levels
The nominal power level of the downstream RF signal(s) within a 6-MHz channel (average power) is targeted to be in
the range: -10 dBc to -6 dBc, relative to analog video carrier level (peak power) and will normally not exceed analog
video carrier level.
5.3.2 Frequency Inversion
There will be no frequency inversion in the transmission path in either the downstream or the upstream directions (i.e. a
positive change in frequency at the input to the cable network will result in a positive change in frequency at the
output).
5.3.3 Analog and Digital Channel Line-up
In developing the present document, it was assumed that a maximum of 119 digital channels would be deployed in a
headend. For the purposes of calculating CNR, protection for analog channels, it was assumed that analog channels are
placed at lower frequencies in the channel line-up, versus digital channels.
5.3.4 Analog Protection Goal
One of the goals of the present document is to provide the minimum intended analog channel CNR protection of 60 dB
for systems deploying up to 119 DRFI-compliant QAM channels.
The present document assumes that the transmitted power level of the digital channels will be 6 dB below the peak
envelope power of the visual signal of analog channels, which is the typical condition for 256-QAM transmission. It is
further assumed that the channel lineup will place analog channels at lower frequencies versus digital channels, and in
systems deploying modulators capable of generating nine or more QAM channels on a single RF output port analog
channels will be placed at centre frequencies below 600 MHz. An adjustment of 10*log (6 MHz / 4 MHz) is used to
account for the difference in noise bandwidth of digital channels versus analog channels. With the assumptions above,
for a 119-QAM channel system, the specification in Item 5 of table 6-5 equates to an analog CNR protection of 60 dB.
With more QAM channels the analog protection is less. With the stated assumptions, the analog protection is:
Analog Protection (dB) = 80,76 - 10*log (Number of QAM Channels).
For example, in a 143-QAM channel system, with the assumptions above, the specification equates to an analog CNR
protection of 59,2 dB.
ETSI
14 Final draft ETSI EN 302 878-3 V1.1.0 (2011-09)
6 Physical Media Dependent Sublayer Specification
6.1 Scope
This clause applies to the first technology option referred to in clause 1. For the second option, refer to annex A.
The present document defines the electrical characteristics of the Downstream Radio Frequency Interface (DRFI) of a
cable modem termination system (CMTS) or an edgeQAM (EQAM). It is the intent of this specification to define an
interoperable DRFI-compliant device, such that any implementation of a CM can work with any EQAM or CMTS. It is
not the intent of this specification to imply any specific implementation. Figure 6-1 shows the M-CMTS structure and
interfaces.
Whenever a reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation,
the latter shall take precedence.
Figure 6-1: Logical View of Modular CMTS and Interfaces
The CMTS Network Side Interface [i.
...
European Standard
Access, Terminals, Transmission and Multiplexing (ATTM);
Third Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems;
Part 3: Downstream Radio Frequency Interface;
DOCSIS 3.0
2 ETSI EN 302 878-3 V1.1.1 (2011-11)
Reference
DEN/ATTM-003006-3
Keywords
access, broadband, cable, data, IP, IPCable,
modem
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© European Telecommunications Standards Institute 2011.
All rights reserved.
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DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM
3GPP and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and
of the 3GPP Organizational Partners.
GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI
3 ETSI EN 302 878-3 V1.1.1 (2011-11)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope and purpose . . 6
1.1 Scope . 6
1.2 Purpose of Document . 6
1.3 Use of References in the present document . 7
1.4 Requirements . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 10
4 Void . 11
5 Functional Assumptions . 11
5.1 Broadband Access Network . 11
5.2 Equipment Assumptions . 11
5.2.1 Frequency Plan . 11
5.2.2 Compatibility with Other Services . 11
5.2.3 Fault Isolation Impact on Other Users . 12
5.3 Downstream Plant Assumptions . 12
5.3.1 Transmission Levels . 12
5.3.2 Frequency Inversion . 12
5.3.3 Analog and Digital Channel Line-up . 12
5.3.4 Analog Protection Goal . 12
6 Physical Media Dependent Sublayer Specification . 13
6.1 Scope . 13
6.2 EdgeQAM (EQAM) differences from CMTS . 13
6.3 Downstream . 14
6.3.1 Downstream Protocol . 14
6.3.2 Spectrum Format . 14
6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 14
6.3.4 Downstream Frequency Plan . 15
6.3.5 DRFI Output Electrical . 15
6.3.5.1 CMTS or EQAM Output Electrical . 16
6.3.5.1.1 Power per Channel CMTS or EQAM . 17
6.3.5.1.2 Independence of individual channel within the multiple channels on a single RF port . 18
6.3.5.1.3 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 20
6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 24
6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 25
6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 25
6.3.6 CMTS or EQAM Clock Generation . 25
6.3.6.1 CMTS Clock Generation . 25
6.3.6.2 EQAM Clock Generation . 25
6.3.6.3 Downstream Symbol Rate . 25
6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 26
6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 26
6.3.9 Timestamp Jitter . 26
7 Downstream Transmission Convergence Sublayer . 27
7.1 Introduction . 27
7.2 MPEG Packet Format . 27
7.3 MPEG Header for DOCSIS Data-Over-Cable . 27
7.4 MPEG Payload for DOCSIS Data-Over-Cable . 28
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4 ETSI EN 302 878-3 V1.1.1 (2011-11)
7.4.1 stuff_byte . 28
7.4.2 pointer_field . 28
7.5 Interaction with the MAC Sublayer . 28
7.6 Interaction with the Physical Layer . 29
Annex A (normative): Additions and Modifications for European Specification . 30
A.1 Scope and purpose . 30
A.2 Void . 30
A.3 Terms and definitions . 30
A.4 Acronyms and abbreviations . 30
A.5 Functional Assumptions . 30
A.5.1 Broadband Access Network . 30
A.5.2 Equipment Assumptions . 31
A.5.2.1 Frequency Plan . 31
A.5.2.2 Compatibility with Other Services . 31
A.5.2.3 Fault Isolation Impact on Other Users . 31
A.5.3 Downstream Plant Assumptions . 31
A.5.3.1 Transmission Levels . 31
A.5.3.2 Frequency Inversion . 31
A.5.3.3 Analog and Digital Channel Line-up . 32
A.5.3.4 Analog Protection Goal . 32
A.6 Physical Media Dependent Sublayer Specification . 32
A.6.1 Scope . 32
A.6.2 EdgeQAM (EQAM) differences from CMTS . 32
A.6.3 Downstream . 32
A.6.3.1 Downstream Protocol . 32
A.6.3.2 Spectrum Format . 32
A.6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 32
A.6.3.4 Downstream Frequency Plan . 33
A.6.3.5 DRFI Output Electrical . 33
A.6.3.5.1 CMTS or EQAM Output Electrical . 33
A.6.3.5.1.1 Output Electrical per RF Port . 33
A.6.3.5.1.2 Power per Channel CMTS or EQAM . 34
A.6.3.5.1.3 Independence of individual channel within the multiple channels on a single RF port . 35
A.6.3.5.1.4 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 37
A.6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 41
A.6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 41
A.6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 41
A.6.3.6 CMTS or EQAM Clock Generation . 42
A.6.3.6.1 CMTS Clock Generation . 42
A.6.3.6.2 EQAM Clock Generation . 42
A.6.3.6.3 Downstream Symbol Rate . 42
A.6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 42
A.6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 43
A.6.3.9 Timestamp Jitter . 43
A.7 Downstream Transmission Convergence Sublayer . 43
A.7.1 Introduction . 43
A.7.2 MPEG Packet Format . 43
A.7.3 MPEG Header for DOCSIS Data-Over-Cable . 43
A.7.4 MPEG Payload for DOCSIS Data-Over-Cable . 43
A.7.5 Interaction with the MAC Sublayer . 43
A.7.6 Interaction with the Physical Layer . 43
Annex B (normative): DOCS-DRF-MIB . 44
History . 59
ETSI
5 ETSI EN 302 878-3 V1.1.1 (2011-11)
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://ipr.etsi.org).
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 European Standard (EN) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
The present document is part 3 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.7].
National transposition dates
Date of adoption of this EN: 14 November 2011
Date of latest announcement of this EN (doa): 29 February 2012
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 August 2012
Date of withdrawal of any conflicting National Standard (dow): 31 August 2012
ETSI
6 ETSI EN 302 878-3 V1.1.1 (2011-11)
1 Scope and purpose
1.1 Scope
The present document defines the RF characteristics required in the downstream transmitter(s) of DOCSIS 3.0 CMTSs
and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators around the
world.
In addition to defining these requirements for a DOCSIS 3.0 device, the present document could also be applicable to
other devices such as:
• an Edge QAM (EQAM) not being used for DOCSIS 3.0 services; or
• an integrated Cable Modem Termination System (CMTS) with multiple downstream channels per RF port
previous to DOCSIS 3.0.
There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore
two options for physical layer technology are included, which have equal priority and are not required to be
interoperable. One technology option is based on the downstream multi-program television distribution that is deployed
in North America using 6 MHz channelling. The other technology option is based on the corresponding European
multi-program television distribution. Both options have the same status, notwithstanding that the document structure
does not reflect this equal priority. The first of these options is defined in clauses 5, 6 and 7, whereas the second is
defined by replacing the content of those clauses with the content of annex A. Correspondingly, [4] and [2] apply only
to the first option, and EN 300 429 [8] only to the second. Compliance with the present document requires compliance
with the one or the other of these implementations, not with both. It is not required that equipment built to one option
will interoperate with equipment built to the other.
A DRFI-compliant device may be a single-channel only device, or it may be a multiple-channel device capable of
generating one or multiple downstream RF carriers simultaneously on one RF output port. An EQAM may be a module
of a modular cable modem termination system (M-CMTS) and be used for delivering a high-speed data service or it
may serve as a component of a digital video or Video-on-Demand (VoD) system, delivering high quality digital video
to subscribers. These specifications are crafted to enable an EQAM to be used without restriction in either or both
service delivery scenarios simultaneously. "Simultaneous" in the early deployments means that if a RF output port has
multiple QAM channels, some channel(s) may be delivering high-speed data while some other channel(s) may be
delivering digital video. The present document enables future uses, wherein a single QAM channel may share
bandwidth between high-speed data and digital video in the same MPEG transport stream.
Conceptually, an EQAM will accept input via an Ethernet link, integrate the incoming data into an MPEG transport
stream, modulate one of a plurality of RF carriers, per these specifications, and deliver the carrier to a single RF output
connector shared in common with all modulators. Conceivably, a single EQAM RF channel could be used for data and
video simultaneously. The reason that an EQAM RF channel can be used for either is that both digital video and
DOCSIS data downstream channels are based on ITU-T Recommendation J.83 [4], annex B for cable networks in North
America and EN 300 429 [8] for cable networks deployed in Europe. On downstream channels complying to ITU-T
Recommendation J.83 [4], annex B, typically, the only difference between an EQAM RF channel operating in a video
mode and an EQAM RF channel operating in DOCSIS data mode is the interleaver depth (see clauses 6.3.1 and 6.3.3).
DOCSIS data runs in a low latency mode using a shallow interleaver depth at the cost of some burst protection.
DOCSIS data can do this because if a transmission error occurs, the higher layer protocols will request re-transmission
of the missing data. For video, the sequence of frames in the program is both time sensitive and order sensitive and
cannot be re-transmitted. For this reason, video uses a deeper interleaver depth to provide more extensive burst
protection and deliver more of the program content without loss. The penalty video pays is in latency. The entire
program content is delayed by a few milliseconds, typically, and is invisible to the viewers of the program. The
conflicting demands for interleaver depth are what prevent a single EQAM RF channel from being used optimally for
video and DOCSIS data simultaneously. A traditional integrated CMTS, however, is used solely for DOCSIS data.
1.2 Purpose of Document
The purpose of the present document is to define the RF characteristics required in the downstream transmitter(s) of
CMTSs and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators
around the world.
ETSI
7 ETSI EN 302 878-3 V1.1.1 (2011-11)
1.3 Use of References in the present document
The present document will not attempt to wholly replicate the normative references provided in the document.
However, it will use extracted portions of said documents where it adds clarity to the present document. For fuller
understanding of the present document, the most recent versions of [4] annex B or EN 300 429 [8], respectively, as well
as ES 202 488-2 [1] should be available for reference.
1.4 Requirements
Throughout the present document, the words that are used to define the significance of particular requirements are
capitalized. These words are:
"MUST" This word means that the item is an absolute requirement of this specification.
"MUST NOT" This phrase means that the item is an absolute prohibition of this specification.
"SHOULD" This word means that there may exist valid reasons in particular circumstances to
ignore this item, but the full implications should be understood and the case carefully
weighed before choosing a different course.
"SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances
when the listed behaviour is acceptable or even useful, but the full implications should
be understood and the case carefully weighed before implementing any behaviour
described with this label.
"MAY" This word means that this item is truly optional. One vendor may choose to include the
item because a particular marketplace requires it or because it enhances the product,
for example; another vendor may omit the same item.
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.
[1] ETSI ES 202 488-2: "Access and Terminals (AT); Second Generation Transmission Systems for
Interactive Cable Television Services - IP Cable Modems; Part 2: Radio frequency interface
specification".
[2] CEA-542-C (February 2009): "Cable Television Channel Identification Plan".
[3] ANSI/SCTE 02 (2006): "Specification for "F" Port, Female, Indoor".
[4] ITU-T Recommendation J.83 (2007), Annex B: "Digital multi-programme systems for television,
sound and data services for cable distribution".
[5] ISO/IEC 13818-1 (2007): "Information technology -- Generic coding of moving pictures and
associated audio information: Systems".
[6] Cable Television Laboratories, Inc. CM-SP-RFIv2.0-C02-090422 (April 2009): "Data-Over-Cable
Service Interface Specifications - DOCSIS 2.0 - Radio Frequency Interface Specification".
ETSI
8 ETSI EN 302 878-3 V1.1.1 (2011-11)
[7] IEC 61169-24 (2009): "Radio-frequency connectors - Part 24: Sectional specification - Radio
frequency coaxial connectors with screw coupling, typically for use in 75 ohm cable networks
(type F)".
[8] ETSI EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
modulation for cable systems".
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.
[i.1] Cable Television Laboratories, Inc. SP-CMTS-NSII01-960702 (July 1996): "Data Over Cable
Interface Specifications - Cable Modem Termination System - Network Side Interface
Specification".
[i.2] Cable Television Laboratories, Inc. CM-SP-M-OSSI-I08-081209 (December 2008): "Data-Over-
Cable Service Interface Specifications - Modular Headend Architecture - M-CMTS Operations
Support System Interface Specification".
[i.3] Cable Television Laboratories, Inc. CM-SP-CMCI-C01-081104 (November 2008): "Data-Over-
Cable Service Interface Specifications - Cable Modem to Customer Premise Equipment Interface".
[i.4] Cable Television Laboratories, Inc. CM-SP-DEPI-I08-100611 (June 2010): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - Downstream External PHY
Interface Specification".
[i.5] Cable Television Laboratories, Inc. CM-SP-DTI-I05-081209 (December 2008): "Data-Over-Cable
Service Interface Specifications - Modular Headend Architecture - DOCSIS Timing Interface
Specification".
[i.6] Cable Television Laboratories, Inc. CM-SP-ERMI-I03-081107 (November 2008): "Data-Over-
Cable-Service-Interface Specifications - Modular Headend Architecture - Edge Resource Manager
Interface Specification".
[i.7] ETSI EN 302 878-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Third
Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems;
Part 1: General; DOCSIS 3.0".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Cable Modem (CM): modulator-demodulator at subscriber locations intended for use in conveying data
communications on a cable television system
Carrier-to-Noise Ratio (C/N or CNR): ratio of signal power to noise power in a defined measurement bandwidth. For
digital modulation, CNR = Es/No, the energy-per symbol to noise-density ratio; the signal power is measured in the
occupied bandwidth, and the noise power is normalized to the modulation-rate bandwidth. For analog NTSC video
modulation, the noise measurement bandwidth is 4 MHz.
ceiling (ceil): returns the first integer that is greater than or equal to a given value
Customer Premises Equipment (CPE): equipment at the end user's premises; may be provided by the service provider
deciBels (dB): ratio of two power levels expressed mathematically as dB = 10log10(POUT/PIN)
deciBel-milliVolt (dBmV): unit of RF power expressed in decibels relative to 1 millivolt over 75 Ω, where
dBmV = 20log10(value in mV/1 mV)
ETSI
9 ETSI EN 302 878-3 V1.1.1 (2011-11)
encompassed spectrum: spectrum ranging from the lower band-edge of the lowest active channel frequency to the
upper band-edge of the highest active channel frequency on an RF output port
Electronic Industries Alliance (EIA): voluntary body of manufacturers which, among other activities, prepares and
publishes standards
EdgeQAM Modulator (EQAM): head end or hub device that receives packets of digital video or data. It re-packetizes
the video or data into an MPEG transport stream and digitally modulates the digital transport stream onto a downstream
RF carrier using quadrature amplitude modulation (QAM).
Forward Error Correction (FEC): class of methods for controlling errors in a communication system. FEC sends
parity information with the data which can be used by the receiver to check and correct the data.
gap channel: channel within the encompassed spectrum which is not active; this occurs with non-contiguous channel
frequency assignments on an RF output port
GigaHertz (GHz): unit of frequency; 1,000,000,000 or 109 Hz
Harmonic Related Carriers (HRC): method of spacing channels on a cable television system with all carriers related
to a common reference
Hertz (Hz): unit of frequency; formerly cycles per second
Hybrid Fibre/Coaxial system (HFC): broadband bidirectional shared-media transmission system using optical fibre
trunks between the head-end and the fibre nodes, and coaxial cable distribution from the fibre nodes to the customer
locations
Incremental Related Carriers (IRC): method of spacing NTSC television channels on a cable television system in
which all channels are offset up 12,5 kHz with respect to the [2] standard channel plan except for channels 5 and 6
kiloHertz (kHz): unit of frequency; 1,000 or 103 Hz; formerly kilocycles per second
Media Access Control (MAC): used to refer to the layer 2 element of the system which would include DOCSIS
framing and signalling
MegaHertz (MHz): unit of frequency; 1,000,000 or 106 Hz; formerly megacycles per second
Modulation Error Ratio (MER): ratio of the average symbol power to average error power
M/N: relationship of integer numbers M,N that represents the ratio of the downstream symbol clock rate to the DOCSIS
master clock rate
non-contiguous channel assignment: encompassed spectrum on an RF output port contains gap channels (inactive
channels)
National Television Systems Committee (NTSC): committee which defined the analog, colour television, broadcast
standards in North America. The standards television 525-line video format for North American television transmission
is named after this committee.
NGNA LLC: company formed by cable operators to define a next-generation network architecture for future cable
industry market and business requirements
Physical Media Dependent sublayer (PMD): sublayer of the Physical layer which is concerned with transmitting bits
or groups of bits over particular types of transmission link between open systems and which entails electrical,
mechanical and handshaking procedures
QAM channel (QAM ch): analog RF channel that uses Quadrature Amplitude Modulation (QAM) to convey
information
Quadrature Amplitude Modulation (QAM): modulation technique in which an analog signal's amplitude and phase
vary to convey information, such as digital data
Radio Frequency (RF): portion of the electromagnetic spectrum from a few kilohertz to just below the frequency of
infrared light
Radio Frequency Interface (RFI): term encompassing the downstream and the upstream radio frequency interfaces
ETSI
10 ETSI EN 302 878-3 V1.1.1 (2011-11)
Root Mean Square (RMS): square root of the mean value squared a function
self-aggregation: method used to compute the headend noise floor by summing measured noise from a single device
over a specified output frequency range
Standard Channel Plan (STD): method of spacing NTSC television channels on a cable television system defined
in [3]
Upstream Channel Descriptor (UCD): MAC Management Message used to communicate the characteristics of the
upstream physical layer to the cable modems
Video on Demand (VoD): system that enables individuals to select and watch video content over a network through an
interactive television system
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CM Cable Modem
CMCI Cable Modem CPE Interface
CMTS Cable Modem Termination System
CNR Carrier-to-Noise Ratio
CPE Customer Premises Equipment
CW Continuous Wave
dBc Decibels relative to carrier power
DEPI Downstream External-PHY Interface
DOCSIS® Data-Over-Cable Service Interface Specifications
DRFI Downstream Radio Frequency Interface
DTI DOCSIS Timing Interface
EIA Electronic Industries Alliance
EQAM EdgeQAM Modulator
ERMI Edge Resource Manager Interface
FCC Federal Communications Commission
FEC Forward Error Correction
HFC Hybrid Fibre/Coaxial system
HRC Harmonic Related Carriers
IRC Incremental Related Carriers
ISO International Standards Organization
ITU International Telecommunications Union
ITU-T Telecommunication Standardization Sector of the ITU
MAC Media Access Control
M-CMTS Modular Cable Modem Termination System
MER Modulation Error Ratio
MPEG Moving Picture Experts Group
-3
Ms Millisecond. 10 second
NGNA Next Generation Network Architecture, see NGNA LLC
-9
Ns Nanosecond. 10 second
NTSC National Television Systems Committee
OSSI Operations System Support Interface
PHY Physical Layer
PID Package Identifier
PMD Physical Media Dependent sublayer
ppm Parts per Million
PUSI Payload Unit Start Indicator
Q Quadrature modulation component
QAM Quadrature Amplitude Modulation
RF Radio Frequency
RFI Radio Frequency Interface
RMS Root Mean Square
ETSI
11 ETSI EN 302 878-3 V1.1.1 (2011-11)
S-CDMA Synchronous Code Division Multiple Access
STD Standard Channel Plan
UCD Upstream Channel Descriptor
VoD Video on Demand
4 Void
5 Functional Assumptions
This clause describes the characteristics of a cable television plant, assumed to be for the purpose of operating a
data-over-cable system. It is not a description of EQAM or CMTS parameters. The data-over-cable system MUST be
interoperable within the environment described in this clause.
Whenever there is a reference in this clause to frequency plans or compatibility with other services, or conflicts with
any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analog signals
in 6 MHz channels does not imply that such signals are physically present.
5.1 Broadband Access Network
A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid
fibre/coaxial (HFC) network. The generic term "cable network" is used here to cover all cases.
A cable network uses a shared-medium, "tree-and-branch" architecture, with analog transmission. The key functional
characteristics assumed in the present document are the following:
• Two-way transmission.
• A maximum optical/electrical spacing between the DRFI-compliant device and the most distant CM of
100 miles in each direction, although typical maximum separation may be 10 miles to 15 miles.
• A maximum differential optical/electrical spacing between the DRFI-compliant device and the closest and
most distant modems of 100 miles in each direction, although this would typically be limited to 15 miles.
At a propagation velocity in fibre of approximately 1,5 ns/ft, 100 miles of fibre in each direction results in a round-trip
delay of approximately 1,6 ms. For further information, see ES 202 488-2 [1], annex R.
5.2 Equipment Assumptions
5.2.1 Frequency Plan
In the downstream direction, the cable system is assumed to have a pass band with a lower edge between 50 MHz and
54 MHz and an upper edge that is implementation-dependent but is typically in the range of 300 MHz to 870 MHz.
Within that pass band, NTSC analog television signals in 6-MHz channels are assumed present on the Standard (STD),
HRC, or IRC frequency plans of [2], as well as other narrowband and wideband digital signals.
5.2.2 Compatibility with Other Services
The CM and EQAM or CMTS MUST coexist with the other services on the cable network, for example:
1) they MUST be interoperable in the cable spectrum assigned for EQAM or CMTS-CM interoperation, while
the balance of the cable spectrum is occupied by any combination of television and other signals; and
2) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in
spectrum outside of that allocated to the EQAM or CMTS.
ETSI
12 ETSI EN 302 878-3 V1.1.1 (2011-11)
Harmful interference is understood as:
- any measurable degradation (highest level of compatibility); or
- any degradation above the perceptible level of impairments for any service (standard or medium level of
compatibility); or
- any degradation above the minimal standards accepted by the industry (for example, FCC for analog
video services) or other service provider (minimal level of compatibility).
5.2.3 Fault Isolation Impact on Other Users
As downstream transmissions are on a shared-media, point-to-multipoint system, fault-isolation procedures should take
into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the
data-over-cable, video and other services.
For the interpretation of harmful impact, see clause 5.2.2.
5.3 Downstream Plant Assumptions
The present document has been developed with the downstream plant assumptions of this clause.
5.3.1 Transmission Levels
The nominal power level of the downstream RF signal(s) within a 6-MHz channel (average power) is targeted to be in
the range: -10 dBc to -6 dBc, relative to analog video carrier level (peak power) and will normally not exceed analog
video carrier level.
5.3.2 Frequency Inversion
There will be no frequency inversion in the transmission path in either the downstream or the upstream directions (i.e. a
positive change in frequency at the input to the cable network will result in a positive change in frequency at the
output).
5.3.3 Analog and Digital Channel Line-up
In developing the present document, it was assumed that a maximum of 119 digital channels would be deployed in a
headend. For the purposes of calculating CNR, protection for analog channels, it was assumed that analog channels are
placed at lower frequencies in the channel line-up, versus digital channels.
5.3.4 Analog Protection Goal
One of the goals of the present document is to provide the minimum intended analog channel CNR protection of 60 dB
for systems deploying up to 119 DRFI-compliant QAM channels.
The present document assumes that the transmitted power level of the digital channels will be 6 dB below the peak
envelope power of the visual signal of analog channels, which is the typical condition for 256-QAM transmission. It is
further assumed that the channel lineup will place analog channels at lower frequencies versus digital channels, and in
systems deploying modulators capable of generating nine or more QAM channels on a single RF output port analog
channels will be placed at centre frequencies below 600 MHz. An adjustment of 10*log (6 MHz / 4 MHz) is used to
account for the difference in noise bandwidth of digital channels versus analog channels. With the assumptions above,
for a 119-QAM channel system, the specification in Item 5 of table 6-5 equates to an analog CNR protection of 60 dB.
With more QAM channels the analog protection is less. With the stated assumptions, the analog protection is:
Analog Protection (dB) = 80,76 - 10*log (Number of QAM Channels).
For example, in a 143-QAM channel system, with the assumptions above, the specification equates to an analog CNR
protection of 59,2 dB.
ETSI
13 ETSI EN 302 878-3 V1.1.1 (2011-11)
6 Physical Media Dependent Sublayer Specification
6.1 Scope
This clause applies to the first technology option referred to in clause 1. For the second option, refer to annex A.
The present document defines the electrical characteristics of the Downstream Radio Frequency Interface (DRFI) of a
cable modem termination system (CMTS) or an edgeQAM (EQAM). It is the intent of this specification to define an
interoperable DRFI-compliant device, such that any implementation of a CM can work with any EQAM or CMTS. It is
not the intent of this specification to imply any specific implementation. Figure 6-1 shows the M-CMTS structure and
interfaces.
Whenever a reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation,
the latter shall take precedence.
Figure 6-1: Logical View of Modular CMTS and Interfaces
The CMTS Network Side Interface [i.1], Modular CMTS Operation Support System Interface [i.3], Radio Frequency
Interface (RFI), and the Cable Modem CPE Interface [i.3] are documented in existing DOCSIS specifications (see
clause 2.2). The DOCSIS Timing Interface [i.5], Downstream External-PHY Interface [i.4], Downstream Radio
Frequency Interface (the present document), and
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Access, Terminals, Transmission and Multiplexing (ATTM) - Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems - Part 3: Downstream Radio Frequency Interface - DOCSIS 3.035.200Vmesniška in povezovalna opremaInterface and interconnection equipment35.180Terminalska in druga periferna oprema ITIT Terminal and other peripheral equipmentICS:Ta slovenski standard je istoveten z:EN 302 878-3 Version 1.1.1SIST EN 302 878-3 V1.1.1:2012en01-februar-2012SIST EN 302 878-3 V1.1.1:2012SLOVENSKI
STANDARD
European Standard SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 2
Reference DEN/ATTM-003006-3 Keywords access, broadband, cable, data, IP, IPCable, modem ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
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Important notice Individual copies of the present document can be downloaded from: http://www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Format (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current status of this and other ETSI documents is available at http://portal.etsi.org/tb/status/status.asp If you find errors in the present document, please send your comment to one of the following services: http://portal.etsi.org/chaircor/ETSI_support.asp Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 2011. All rights reserved.
DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 3 Contents Intellectual Property Rights . 5 Foreword . 5 1 Scope and purpose . 6 1.1 Scope . 6 1.2 Purpose of Document . 6 1.3 Use of References in the present document . 7 1.4 Requirements . 7 2 References . 7 2.1 Normative references . 7 2.2 Informative references . 8 3 Definitions and abbreviations . 8 3.1 Definitions . 8 3.2 Abbreviations . 10 4 Void . 11 5 Functional Assumptions . 11 5.1 Broadband Access Network . 11 5.2 Equipment Assumptions . 11 5.2.1 Frequency Plan . 11 5.2.2 Compatibility with Other Services . 11 5.2.3 Fault Isolation Impact on Other Users . 12 5.3 Downstream Plant Assumptions . 12 5.3.1 Transmission Levels . 12 5.3.2 Frequency Inversion . 12 5.3.3 Analog and Digital Channel Line-up . 12 5.3.4 Analog Protection Goal . 12 6 Physical Media Dependent Sublayer Specification . 13 6.1 Scope . 13 6.2 EdgeQAM (EQAM) differences from CMTS . 13 6.3 Downstream . 14 6.3.1 Downstream Protocol . 14 6.3.2 Spectrum Format . 14 6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 14 6.3.4 Downstream Frequency Plan . 15 6.3.5 DRFI Output Electrical . 15 6.3.5.1 CMTS or EQAM Output Electrical . 16 6.3.5.1.1 Power per Channel CMTS or EQAM . 17 6.3.5.1.2 Independence of individual channel within the multiple channels on a single RF port . 18 6.3.5.1.3 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 20 6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 24 6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 25 6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 25 6.3.6 CMTS or EQAM Clock Generation . 25 6.3.6.1 CMTS Clock Generation . 25 6.3.6.2 EQAM Clock Generation . 25 6.3.6.3 Downstream Symbol Rate . 25 6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 26 6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 26 6.3.9 Timestamp Jitter . 26 7 Downstream Transmission Convergence Sublayer . 27 7.1 Introduction . 27 7.2 MPEG Packet Format . 27 7.3 MPEG Header for DOCSIS Data-Over-Cable . 27 7.4 MPEG Payload for DOCSIS Data-Over-Cable . 28 SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 4 7.4.1 stuff_byte . 28 7.4.2 pointer_field . 28 7.5 Interaction with the MAC Sublayer . 28 7.6 Interaction with the Physical Layer . 29 Annex A (normative): Additions and Modifications for European Specification . 30 A.1 Scope and purpose . 30 A.2 Void . 30 A.3 Terms and definitions . 30 A.4 Acronyms and abbreviations . 30 A.5 Functional Assumptions . 30 A.5.1 Broadband Access Network . 30 A.5.2 Equipment Assumptions . 31 A.5.2.1 Frequency Plan . 31 A.5.2.2 Compatibility with Other Services . 31 A.5.2.3 Fault Isolation Impact on Other Users . 31 A.5.3 Downstream Plant Assumptions . 31 A.5.3.1 Transmission Levels . 31 A.5.3.2 Frequency Inversion . 31 A.5.3.3 Analog and Digital Channel Line-up . 32 A.5.3.4 Analog Protection Goal . 32 A.6 Physical Media Dependent Sublayer Specification . 32 A.6.1 Scope . 32 A.6.2 EdgeQAM (EQAM) differences from CMTS . 32 A.6.3 Downstream . 32 A.6.3.1 Downstream Protocol . 32 A.6.3.2 Spectrum Format . 32 A.6.3.3 Scaleable Interleaving to Support Video and High-Speed Data Services . 32 A.6.3.4 Downstream Frequency Plan . 33 A.6.3.5 DRFI Output Electrical . 33 A.6.3.5.1 CMTS or EQAM Output Electrical . 33 A.6.3.5.1.1 Output Electrical per RF Port . 33 A.6.3.5.1.2 Power per Channel CMTS or EQAM . 34 A.6.3.5.1.3 Independence of individual channel within the multiple channels on a single RF port . 35 A.6.3.5.1.4 Out-of-Band Noise and Spurious Requirements for CMTS or EQAM . 37 A.6.3.5.2 CMTS or EQAM Master Clock Jitter for Asynchronous Operation . 41 A.6.3.5.3 CMTS or EQAM Master Clock Jitter for Synchronous Operation . 41 A.6.3.5.4 CMTS or EQAM Master Clock Frequency Drift for Synchronous Operation. 41 A.6.3.6 CMTS or EQAM Clock Generation . 42 A.6.3.6.1 CMTS Clock Generation . 42 A.6.3.6.2 EQAM Clock Generation . 42 A.6.3.6.3 Downstream Symbol Rate . 42 A.6.3.7 Downstream Symbol Clock Jitter for Synchronous Operation . 42 A.6.3.8 Downstream Symbol Clock Drift for Synchronous Operation . 43 A.6.3.9 Timestamp Jitter . 43 A.7 Downstream Transmission Convergence Sublayer . 43 A.7.1 Introduction . 43 A.7.2 MPEG Packet Format . 43 A.7.3 MPEG Header for DOCSIS Data-Over-Cable . 43 A.7.4 MPEG Payload for DOCSIS Data-Over-Cable . 43 A.7.5 Interaction with the MAC Sublayer . 43 A.7.6 Interaction with the Physical Layer . 43 Annex B (normative): DOCS-DRF-MIB . 44 History . 59
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 5 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://ipr.etsi.org). 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 European Standard (EN) has been produced by ETSI Technical Committee Access, Terminals, Transmission and Multiplexing (ATTM). The present document is part 3 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.7].
National transposition dates Date of adoption of this EN: 14 November 2011 Date of latest announcement of this EN (doa): 29 February 2012 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
31 August 2012 Date of withdrawal of any conflicting National Standard (dow): 31 August 2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 6 1 Scope and purpose 1.1 Scope The present document defines the RF characteristics required in the downstream transmitter(s) of DOCSIS 3.0 CMTSs and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators around the world. In addition to defining these requirements for a DOCSIS 3.0 device, the present document could also be applicable to other devices such as: • an Edge QAM (EQAM) not being used for DOCSIS 3.0 services; or • an integrated Cable Modem Termination System (CMTS) with multiple downstream channels per RF port previous to DOCSIS 3.0. There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore two options for physical layer technology are included, which have equal priority and are not required to be interoperable. One technology option is based on the downstream multi-program television distribution that is deployed in North America using 6 MHz channelling. The other technology option is based on the corresponding European multi-program television distribution. Both options have the same status, notwithstanding that the document structure does not reflect this equal priority. The first of these options is defined in clauses 5, 6 and 7, whereas the second is defined by replacing the content of those clauses with the content of annex A. Correspondingly, [4] and [2] apply only to the first option, and EN 300 429 [8] only to the second. Compliance with the present document requires compliance with the one or the other of these implementations, not with both. It is not required that equipment built to one option will interoperate with equipment built to the other. A DRFI-compliant device may be a single-channel only device, or it may be a multiple-channel device capable of generating one or multiple downstream RF carriers simultaneously on one RF output port. An EQAM may be a module of a modular cable modem termination system (M-CMTS) and be used for delivering a high-speed data service or it may serve as a component of a digital video or Video-on-Demand (VoD) system, delivering high quality digital video to subscribers. These specifications are crafted to enable an EQAM to be used without restriction in either or both service delivery scenarios simultaneously. "Simultaneous" in the early deployments means that if a RF output port has multiple QAM channels, some channel(s) may be delivering high-speed data while some other channel(s) may be delivering digital video. The present document enables future uses, wherein a single QAM channel may share bandwidth between high-speed data and digital video in the same MPEG transport stream. Conceptually, an EQAM will accept input via an Ethernet link, integrate the incoming data into an MPEG transport stream, modulate one of a plurality of RF carriers, per these specifications, and deliver the carrier to a single RF output connector shared in common with all modulators. Conceivably, a single EQAM RF channel could be used for data and video simultaneously. The reason that an EQAM RF channel can be used for either is that both digital video and DOCSIS data downstream channels are based on ITU-T Recommendation J.83 [4], annex B for cable networks in North America and EN 300 429 [8] for cable networks deployed in Europe. On downstream channels complying to ITU-T Recommendation J.83 [4], annex B, typically, the only difference between an EQAM RF channel operating in a video mode and an EQAM RF channel operating in DOCSIS data mode is the interleaver depth (see clauses 6.3.1 and 6.3.3). DOCSIS data runs in a low latency mode using a shallow interleaver depth at the cost of some burst protection. DOCSIS data can do this because if a transmission error occurs, the higher layer protocols will request re-transmission of the missing data. For video, the sequence of frames in the program is both time sensitive and order sensitive and cannot be re-transmitted. For this reason, video uses a deeper interleaver depth to provide more extensive burst protection and deliver more of the program content without loss. The penalty video pays is in latency. The entire program content is delayed by a few milliseconds, typically, and is invisible to the viewers of the program. The conflicting demands for interleaver depth are what prevent a single EQAM RF channel from being used optimally for video and DOCSIS data simultaneously. A traditional integrated CMTS, however, is used solely for DOCSIS data. 1.2 Purpose of Document The purpose of the present document is to define the RF characteristics required in the downstream transmitter(s) of CMTSs and EQAMs, sufficiently enough to permit vendors to build devices that meet the needs of cable operators around the world. SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 7 1.3 Use of References in the present document The present document will not attempt to wholly replicate the normative references provided in the document. However, it will use extracted portions of said documents where it adds clarity to the present document. For fuller understanding of the present document, the most recent versions of [4] annex B or EN 300 429 [8], respectively, as well as ES 202 488-2 [1] should be available for reference. 1.4 Requirements Throughout the present document, the words that are used to define the significance of particular requirements are capitalized. These words are: "MUST" This word means that the item is an absolute requirement of this specification. "MUST NOT" This phrase means that the item is an absolute prohibition of this specification. "SHOULD" This word means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course. "SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label. "MAY" This word means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.
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. [1] ETSI ES 202 488-2: "Access and Terminals (AT); Second Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 2: Radio frequency interface specification". [2] CEA-542-C (February 2009): "Cable Television Channel Identification Plan". [3] ANSI/SCTE 02 (2006): "Specification for "F" Port, Female, Indoor". [4] ITU-T Recommendation J.83 (2007), Annex B: "Digital multi-programme systems for television, sound and data services for cable distribution". [5] ISO/IEC 13818-1 (2007): "Information technology -- Generic coding of moving pictures and associated audio information: Systems". [6] Cable Television Laboratories, Inc. CM-SP-RFIv2.0-C02-090422 (April 2009): "Data-Over-Cable Service Interface Specifications - DOCSIS 2.0 - Radio Frequency Interface Specification". SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 8 [7] IEC 61169-24 (2009): "Radio-frequency connectors - Part 24: Sectional specification - Radio frequency coaxial connectors with screw coupling, typically for use in 75 ohm cable networks (type F)". [8] ETSI EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems". 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. [i.1] Cable Television Laboratories, Inc. SP-CMTS-NSII01-960702 (July 1996): "Data Over Cable Interface Specifications - Cable Modem Termination System - Network Side Interface Specification". [i.2] Cable Television Laboratories, Inc. CM-SP-M-OSSI-I08-081209 (December 2008): "Data-Over-Cable Service Interface Specifications - Modular Headend Architecture - M-CMTS Operations Support System Interface Specification". [i.3] Cable Television Laboratories, Inc. CM-SP-CMCI-C01-081104 (November 2008): "Data-Over-Cable Service Interface Specifications - Cable Modem to Customer Premise Equipment Interface". [i.4] Cable Television Laboratories, Inc. CM-SP-DEPI-I08-100611 (June 2010): "Data-Over-Cable Service Interface Specifications - Modular Headend Architecture - Downstream External PHY Interface Specification". [i.5] Cable Television Laboratories, Inc. CM-SP-DTI-I05-081209 (December 2008): "Data-Over-Cable Service Interface Specifications - Modular Headend Architecture - DOCSIS Timing Interface Specification". [i.6] Cable Television Laboratories, Inc. CM-SP-ERMI-I03-081107 (November 2008): "Data-Over-Cable-Service-Interface Specifications - Modular Headend Architecture - Edge Resource Manager Interface Specification". [i.7] ETSI EN 302 878-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Third Generation Transmission Systems for Interactive Cable Television Services - IP Cable Modems; Part 1: General; DOCSIS 3.0". 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: Cable Modem (CM): modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system Carrier-to-Noise Ratio (C/N or CNR): ratio of signal power to noise power in a defined measurement bandwidth. For digital modulation, CNR = Es/No, the energy-per symbol to noise-density ratio; the signal power is measured in the occupied bandwidth, and the noise power is normalized to the modulation-rate bandwidth. For analog NTSC video modulation, the noise measurement bandwidth is 4 MHz. ceiling (ceil): returns the first integer that is greater than or equal to a given value Customer Premises Equipment (CPE): equipment at the end user's premises; may be provided by the service provider deciBels (dB): ratio of two power levels expressed mathematically as dB = 10log10(POUT/PIN) deciBel-milliVolt (dBmV): unit of RF power expressed in decibels relative to 1 millivolt over 75 Ω, where
dBmV = 20log10(value in mV/1 mV) SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 9 encompassed spectrum: spectrum ranging from the lower band-edge of the lowest active channel frequency to the upper band-edge of the highest active channel frequency on an RF output port Electronic Industries Alliance (EIA): voluntary body of manufacturers which, among other activities, prepares and publishes standards EdgeQAM Modulator (EQAM): head end or hub device that receives packets of digital video or data. It re-packetizes the video or data into an MPEG transport stream and digitally modulates the digital transport stream onto a downstream RF carrier using quadrature amplitude modulation (QAM). Forward Error Correction (FEC): class of methods for controlling errors in a communication system. FEC sends parity information with the data which can be used by the receiver to check and correct the data. gap channel: channel within the encompassed spectrum which is not active; this occurs with non-contiguous channel frequency assignments on an RF output port GigaHertz (GHz): unit of frequency; 1,000,000,000 or 109 Hz Harmonic Related Carriers (HRC): method of spacing channels on a cable television system with all carriers related to a common reference Hertz (Hz): unit of frequency; formerly cycles per second Hybrid Fibre/Coaxial system (HFC): broadband bidirectional shared-media transmission system using optical fibre trunks between the head-end and the fibre nodes, and coaxial cable distribution from the fibre nodes to the customer locations Incremental Related Carriers (IRC): method of spacing NTSC television channels on a cable television system in which all channels are offset up 12,5 kHz with respect to the [2] standard channel plan except for channels 5 and 6 kiloHertz (kHz): unit of frequency; 1,000 or 103 Hz; formerly kilocycles per second Media Access Control (MAC): used to refer to the layer 2 element of the system which would include DOCSIS framing and signalling MegaHertz (MHz): unit of frequency; 1,000,000 or 106 Hz; formerly megacycles per second Modulation Error Ratio (MER): ratio of the average symbol power to average error power M/N: relationship of integer numbers M,N that represents the ratio of the downstream symbol clock rate to the DOCSIS master clock rate non-contiguous channel assignment: encompassed spectrum on an RF output port contains gap channels (inactive channels) National Television Systems Committee (NTSC): committee which defined the analog, colour television, broadcast standards in North America. The standards television 525-line video format for North American television transmission is named after this committee. NGNA LLC: company formed by cable operators to define a next-generation network architecture for future cable industry market and business requirements Physical Media Dependent sublayer (PMD): sublayer of the Physical layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical and handshaking procedures QAM channel (QAM ch): analog RF channel that uses Quadrature Amplitude Modulation (QAM) to convey information Quadrature Amplitude Modulation (QAM): modulation technique in which an analog signal's amplitude and phase vary to convey information, such as digital data Radio Frequency (RF): portion of the electromagnetic spectrum from a few kilohertz to just below the frequency of infrared light Radio Frequency Interface (RFI): term encompassing the downstream and the upstream radio frequency interfaces SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 10 Root Mean Square (RMS): square root of the mean value squared a function self-aggregation: method used to compute the headend noise floor by summing measured noise from a single device over a specified output frequency range Standard Channel Plan (STD): method of spacing NTSC television channels on a cable television system defined in [3] Upstream Channel Descriptor (UCD): MAC Management Message used to communicate the characteristics of the upstream physical layer to the cable modems Video on Demand (VoD): system that enables individuals to select and watch video content over a network through an interactive television system 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: CM Cable Modem CMCI Cable Modem CPE Interface CMTS Cable Modem Termination System CNR Carrier-to-Noise Ratio CPE Customer Premises Equipment CW Continuous Wave dBc Decibels relative to carrier power DEPI Downstream External-PHY Interface DOCSIS® Data-Over-Cable Service Interface Specifications DRFI Downstream Radio Frequency Interface DTI DOCSIS Timing Interface EIA Electronic Industries Alliance EQAM EdgeQAM Modulator ERMI Edge Resource Manager Interface FCC Federal Communications Commission FEC Forward Error Correction HFC Hybrid Fibre/Coaxial system HRC Harmonic Related Carriers IRC Incremental Related Carriers ISO International Standards Organization ITU International Telecommunications Union ITU-T Telecommunication Standardization Sector of the ITU MAC Media Access Control M-CMTS Modular Cable Modem Termination System MER Modulation Error Ratio MPEG Moving Picture Experts Group Ms Millisecond. 10-3 second NGNA Next Generation Network Architecture, see NGNA LLC Ns Nanosecond. 10-9 second NTSC National Television Systems Committee OSSI Operations System Support Interface PHY Physical Layer PID Package Identifier PMD Physical Media Dependent sublayer ppm Parts per Million PUSI Payload Unit Start Indicator Q Quadrature modulation component QAM Quadrature Amplitude Modulation RF Radio Frequency RFI Radio Frequency Interface RMS Root Mean Square SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 11 S-CDMA Synchronous Code Division Multiple Access STD Standard Channel Plan UCD Upstream Channel Descriptor VoD Video on Demand 4 Void
5 Functional Assumptions This clause describes the characteristics of a cable television plant, assumed to be for the purpose of operating a data-over-cable system. It is not a description of EQAM or CMTS parameters. The data-over-cable system MUST be interoperable within the environment described in this clause. Whenever there is a reference in this clause to frequency plans or compatibility with other services, or conflicts with any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analog signals in 6 MHz channels does not imply that such signals are physically present. 5.1 Broadband Access Network A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid fibre/coaxial (HFC) network. The generic term "cable network" is used here to cover all cases. A cable network uses a shared-medium, "tree-and-branch" architecture, with analog transmission. The key functional characteristics assumed in the present document are the following: • Two-way transmission. • A maximum optical/electrical spacing between the DRFI-compliant device and the most distant CM of 100 miles in each direction, although typical maximum separation may be 10 miles to 15 miles. • A maximum differential optical/electrical spacing between the DRFI-compliant device and the closest and most distant modems of 100 miles in each direction, although this would typically be limited to 15 miles. At a propagation velocity in fibre of approximately 1,5 ns/ft, 100 miles of fibre in each direction results in a round-trip delay of approximately 1,6 ms. For further information, see ES 202 488-2 [1], annex R. 5.2 Equipment Assumptions 5.2.1 Frequency Plan In the downstream direction, the cable system is assumed to have a pass band with a lower edge between 50 MHz and 54 MHz and an upper edge that is implementation-dependent but is typically in the range of 300 MHz to 870 MHz. Within that pass band, NTSC analog television signals in 6-MHz channels are assumed present on the Standard (STD), HRC, or IRC frequency plans of [2], as well as other narrowband and wideband digital signals. 5.2.2 Compatibility with Other Services The CM and EQAM or CMTS MUST coexist with the other services on the cable network, for example: 1) they MUST be interoperable in the cable spectrum assigned for EQAM or CMTS-CM interoperation, while the balance of the cable spectrum is occupied by any combination of television and other signals; and 2) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in spectrum outside of that allocated to the EQAM or CMTS.
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 12 Harmful interference is understood as: - any measurable degradation (highest level of compatibility); or - any degradation above the perceptible level of impairments for any service (standard or medium level of compatibility); or - any degradation above the minimal standards accepted by the industry (for example, FCC for analog video services) or other service provider (minimal level of compatibility). 5.2.3 Fault Isolation Impact on Other Users As downstream transmissions are on a shared-media, point-to-multipoint system, fault-isolation procedures should take into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the data-over-cable, video and other services. For the interpretation of harmful impact, see clause 5.2.2. 5.3 Downstream Plant Assumptions The present document has been developed with the downstream plant assumptions of this clause. 5.3.1 Transmission Levels The nominal power level of the downstream RF signal(s) within a 6-MHz channel (average power) is targeted to be in the range: -10 dBc to -6 dBc, relative to analog video carrier level (peak power) and will normally not exceed analog video carrier level. 5.3.2 Frequency Inversion There will be no frequency inversion in the transmission path in either the downstream or the upstream directions (i.e. a positive change in frequency at the input to the cable network will result in a positive change in frequency at the output). 5.3.3 Analog and Digital Channel Line-up In developing the present document, it was assumed that a maximum of 119 digital channels would be deployed in a headend. For the purposes of calculating CNR, protection for analog channels, it was assumed that analog channels are placed at lower frequencies in the channel line-up, versus digital channels. 5.3.4 Analog Protection Goal
One of the goals of the present document is to provide the minimum intended analog channel CNR protection of 60 dB for systems deploying up to 119 DRFI-compliant QAM channels. The present document assumes that the transmitted power level of the digital channels will be 6 dB below the peak envelope power of the visual signal of analog channels, which is the typical condition for 256-QAM transmission. It is further assumed that the channel lineup will place analog channels at lower frequencies versus digital channels, and in systems deploying modulators capable of generating nine or more QAM channels on a single RF output port analog channels will be placed at centre frequencies below 600 MHz. An adjustment of 10*log10 (6 MHz / 4 MHz) is used to account for the difference in noise bandwidth of digital channels versus analog channels. With the assumptions above, for a 119-QAM channel system, the specification in Item 5 of table 6-5 equates to an analog CNR protection of 60 dB. With more QAM channels the analog protection is less. With the stated assumptions, the analog protection is:
Analog Protection (dB) = 80,76 - 10*log10(Number of QAM Channels). For example, in a 143-QAM channel system, with the assumptions above, the specification equates to an analog CNR protection of 59,2 dB. SIST EN 302 878-3 V1.1.1:2012
ETSI ETSI EN 302 878-3 V1.1.1 (2011-11) 13 6 Physical Media Dependent Sublayer Specification 6.1 Scope This clause applies to the first technology option referred to in clause 1. For the second option, refer to annex A. The present document defines the electrical characteristics of the Downstream Radio Frequency Interface (DRFI) of a cable modem termination system (CMTS) or an edgeQAM (EQAM). It is the intent of this specification to define an interoperable DRFI-compliant device, such that any implementation of a CM can work with any EQAM or CMTS. It is not the intent of this specification to imply any specific implementation. Figure 6-1 shows the M-CMTS structure and interfaces. Whenever a reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation, the latter shall take precedence.
Figure 6-1: Logical View of Modular CMTS and Interfaces The CMTS Network Side Interface [i.1], Modular CMTS Operation Support System Interface [i.3], Radio Frequency Interface (RFI), and the Cable Modem CPE Interface [i.3] are documented in existing DOCSIS specifications (see clause 2.2). The DOCSIS Timing Interface [i.5], Downstream External-PHY Interface [i.4], Downstream Radio Frequency Interface (the present document), and Edge Resource Manager Interface [i.6] require new specifications specific to the M-CMTS in a Next Generation Network Architecture (NGNA) environment. 6.2 EdgeQAM (EQAM) di
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