ETSI TS 101 548 V1.2.1 (2014-11)

Access, Terminals, Transmission and Multiplexing (ATTM); European Requirements for Reverse Powering of Remote Access Equipment

RTS/ATTM-0631

General Information

• Status: Published
• Publication Date: 05-Nov-2014
• Technical Committee: ATTM TM6 - Wireline Access Network Systems
• Current Stage: 12 - Completion
• Due Date: 19-Nov-2014
• Completion Date: 06-Nov-2014

Standards Content (Sample)

ETSI TS 101 548 V1.2.1 (2014-11)






TECHNICAL SPECIFICATION
Access, Terminals, Transmission and Multiplexing (ATTM);
European Requirements for Reverse Powering
of Remote Access Equipment

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2 ETSI TS 101 548 V1.2.1 (2014-11)



Reference
RTS/ATTM-0631
Keywords
VDSL2
ETSI
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3 ETSI TS 101 548 V1.2.1 (2014-11)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definitions, symbols and abbreviations . 6
3.1 Definitions . 6
3.2 Symbols . 6
3.3 Abbreviations . 6
4 Introduction to Reverse Power Feed . 8
4.1 Introduction . 8
5 Reverse Power Feed Architecture . 9
5.1 Introduction . 9
5.2 Reverse Power Feed and POTS Co-Existence . 9
5.2.1 Background . 9
5.2.2 POTS Adapters . 10
5.2.2.1 POTS Adapter - E (POTSA-E) . 10
5.2.2.2 POTS Adapter - C (POTSA-C) . 10
5.2.2.3 POTS Adapter - D (POTSA-D) . 10
5.3 Reverse Power Feed Architecture without POTS on the same pair (RPFA-NOP). 11
5.4 Reverse Power Feed Architecture with Baseband POTS from the Exchange (RPFA-EXP). 12
5.5 Reverse Power Feed Architecture with Baseband POTS from the Exchange Sharing the in-premises
Wiring (RPFA-EXPSW) . 14
5.6 Reverse Power Feed Architecture with Derived POTS (RPFA-DRP) . 15
5.7 Reverse Power Feed Architecture with Derived POTS Sharing the in-premises Wiring (RPFA-DRPSW) . 16
6 Reverse Power Feed Start-Up Protocol . 17
6.1 Introduction . 17
6.2 Communications-based Start-up (CBSU) Protocol . 18
6.3 CBSU Protocol Specific Transmission Parameters . 20
7 Reverse Power Feed Power Supply Characteristics . 21
7.1 RPF Range Options and Classes . 21
7.2 RPF Safety Requirements . 24
7.2.1 Background . 24
7.2.2 Unintended consequences . 25
7.3 Electrical reference model . 25
7.4 Zero touch DPU . 26
Annex A (informative): Reverse power backup systems . 27
A.1 Case 1 battery backup in the CPE . 27
A.2 Case 2 battery backup in the DPU and CPE . 27
Annex B (normative): General POTS requirements . 28
Annex C (informative): Bibliography . 29
History . 30

ETSI

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4 ETSI TS 101 548 V1.2.1 (2014-11)
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 Technical Specification (TS) has been produced by ETSI Technical Committee Access, Terminals, Transmission
and Multiplexing (ATTM).
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "may not", "need", "need not", "will",
"will not", "can" and "cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms
for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
As various Operators consider the deployment of fibre-fed remote nodes that contain xDSL DSLAM equipment, it is
necessary to consider the means of powering such remotely located equipment. One such method, known as "reverse
power feed", transmits the power from the customer premises to the fibre-fed remote node using the distribution-side
copper network. The present document defines a reverse power feed transmission standard which allows Operators to
source suitably compliant equipment for inclusion in their networks. The reverse power feed methodology can be used
to power a remote node hosting any metallic transmission system (e.g. FAST [i.6], VDSL2 [i.7], etc.).
ETSI

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5 ETSI TS 101 548 V1.2.1 (2014-11)
1 Scope
The present document defines architectures for reverse powering of remote network nodes from multiple CPEs. The
architectures describe how to combine reverse power feed with POTS and data transmission. Options for combining
reverse powering with battery backup are also described. The present document identifies requirements for POTS
signalling translation when operated over reverse power feed. Start-up protocols are defined that will ensure safe
connection of reverse powered systems. Management requirements for reverse power feed and power combining within
the remote network node are specified.
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 202 971: "Access and Terminals (AT); Public Switched Telephone Network (PSTN);
Harmonized specification of physical and electrical characteristics of a 2-wire analogue interface
for short line interface".
[2] CENELEC EN 60950-1: "Information Technology Equipment - Safety, Part 1: General
requirements (IEC 60950-1:2005 + Cor.:2006 + A1:2009, modified)".
[3] ETSI ES 203 021: "Access and Terminals (AT); Harmonized basic attachment requirements for
Terminals for connection to analogue interfaces of the Telephone Networks; Update of the
technical contents of TBR 021, EN 301 437, TBR 015, TBR 017".
[4] Recommendation ITU-T G.994.1: "Handshake procedures for digital subscriber line transceivers".
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] IEEE 802.3: "LAN/MAN CSMA/CD (Ethernet) Access Method".
NOTE: Available at http://standards.ieee.org/getieee802/802.3.html.
[i.2] NICC ND 1645 (V1.1.2) (2011-06): "NGA Telephony; Architecture and requirements".
NOTE: Available at http://www.niccstandards.org.uk/files/current/ND1645v1.1.2.pdf?type=pdf.
[i.3] ETSI TS 101 952-1: "Access network xDSL splitters for European deployment; Part 1: generic
specification of xDSL over POTS splitters".
[i.4] Recommendation ITU-T G.993.2: "Very high speed digital subscriber line transceivers 2
(VDSL2)".
[i.5] Recommendation ITU-T G.993.2 Amendment 5: "Short reach VDSL2 with reduced power and
enhanced data rate".
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6 ETSI TS 101 548 V1.2.1 (2014-11)
[i.6] Recommendation ITU-T G.9700 (04/14): "Fast access to subscriber terminals (FAST) - Power
spectral density specification".
[i.7] ETSI TS 101 271 (V1.2.1): "Access, Terminals, Transmission and Multiplexing (ATTM);Access
transmission systems on metallic access cables; Very High Speed digital subscriber line system
(VDSL2) [Recommendation ITU-T G.993.2 modified]".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
power splitter: device that performs a frequency splitting/combining function between the services being carried
(which can include POTS and xDSL based services) and the injected DC electrical power
service splitter: low pass filter that separates baseband POTS from xDSL frequencies
NOTE: The relevant specifications for the service splitter can be found in ETSI TS 101 952-1 [i.3].
3.2 Symbols
For the purposes of the present document, the following symbols apply:
R 2-wire analogue presented interface
U-R Reference point at CPE containing both DC power and service data
U-R2 Reference point at CPE containing the filtered service data
U-R2P Reference point at CPE containing the injected DC power
U-R2S Reference point at CPE containing the baseband POTS and the converted POTS signalling
U-O Reference point at DPU containing both DC power and service data
U-O2 Reference point at DPU containing the filtered service data
U-O2O Reference point at DPU containing the baseband POTS and the converted POTS signalling
U-O2P Reference point at DPU containing the extracted DC power
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
4PPoE 4-Pair Power over Ethernet
ACT Active
ATA Analogue Telephone Adapter
BAT Battery
CBSU Communications based Start-Up protocol
CO Central Office
CP Customer Premises
CPE Customer Premises Equipment
CPE ME CPE's Management Entity
DBPSK Differential Binary Phase Shift Keying
DC Direct Current
DN Distribution Network
DP Distribution Point
DPU Distribution Point Unit
DPU ME DPU's Management Entity
DSL Digital Subscriber Line
FTTdp Fibre To The distribution point
FTTP Fibre To The Premises
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7 ETSI TS 101 548 V1.2.1 (2014-11)
FTU FAST Transceiver Unit
NOTE: See Recommendation ITU-T G.9700 [i.6].
FTU-O FTU at the DPU
FTU-R FTU at the remote site
GPON Gigabit Passive Optical Network
HON Higher Order Node
LPF Low Pass Filter
LR Long Range
ME Management Entity
NMS Network Management System
NT Network Termination
NTE Network Termination Equipment
NTU Network Terminating Unit
OAM Operations And Maintenance
OLT Optical Line Termination
ONU Optical Network Unit
PD Powered Device
PDU Power Distribution Unit
PE Power Extraction
PHY Physical (layer)
PME-C CPE's Power Management Entity
PME-D DPU's Power Management Entity
PMT Power Management Transceiver
PoDL Power over Data Line
POTS Plain Old Telephony Service
PS Power Splitter
PSE Power Sourcing Equipment
PSU Power Supply Unit/Combiner
PWD PoWereD
RDY Ready
RFT Remote Feed Telecommunication
RPCE Reverse Power Control Entity
RPD Remote Powered Device
RPF Reverse Power Feed
RPFA-DRP Reverse Power Feed Architecture - Derived POTS
RPFA-DRPSW Reverse Power Feed Architecture - Derived POTS Sharing in-premises Wiring
RPFA-EXP Reverse Power Feed Architecture - Exchange POTS
RPFA-EXPSW Reverse Power Feed Architecture - Exchange POTS Sharing in-premises Wiring
RPFA-NOP Reverse Power Feed Architecture - No POTS
SELV Safety Extra Low Voltage
SG Service Gateway
SR Short Range
SS Service Splitter
SU Service Unit
TNV Telecommunication Network Voltage
VA Volt Ampere
VDSL Very high speed Digital Subscriber Line
VoIP Voice over Internet Protocol
VTU VDSL2 Transceiver Unit
NOTE: See Recommendation ITU-T G.993.2 [i.4].
VTU-O VTU at the ONU
VTU-R VTU at the remote site
xDSL Unspecified DSL variant
xTU-O FTU-O or VTU-O
xTU-R FTU-R or VTU-R
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8 ETSI TS 101 548 V1.2.1 (2014-11)
4 Introduction to Reverse Power Feed
4.1 Introduction
The basic architecture of a fibre-fed remote node with reverse power feed is shown below in Figure 1.

Figure 1: Generic Fibre-fed Remote Node Architecture with reverse power feed
Figure 1 shows power being injected at the NTE from a local power source (located within the home and/or building)
which traverses the local loop to power a fibre-fed remote node which can be located at either the distribution
point (DP) or cabinet using the same copper pair cable that is used to transmit the xDSL to/from the home/fibre-fed
remote node. A metallic POTS service is shown at the NTE. Voice services can also be implemented as a derived
service from the service gateway (SG).
An issue with regards to reverse powered fibre-fed nodes is that of who or what is responsible for the powering of
common circuitry contained within the node. It is easy to envisage that an individual user should be responsible for the
powering of the remote line terminating/driver electronics corresponding to his particular circuit. However, it is not so
easy to determine who or what is responsible for powering of say the ONU that terminates the fibre link.
There may be occasions where only a single user is providing power to the remote node but this may not be sufficient to
power all of the remote node electronics for proper operation. Also, there may be occasions where say a GPON feed
requests a response from the ONU (for ranging or management purposes) when no users are currently connected and
providing electrical power.
It is recognized that one single (i.e. generic) specification cannot consider all possible architectural variants, therefore
the present document has been organized as a series of architecture options and equipment shall adhere to one or more
of these options.
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9 ETSI TS 101 548 V1.2.1 (2014-11)
5 Reverse Power Feed Architecture
5.1 Introduction
There shall be compatibility with other architectures such as forwards powering of remote equipment from the CO or
the provision of local mains powering.
Service Providers may provide options for power back-up capability at the remote node and/or the customer premises. It
shall be possible to combine these power-feed options, for example when there is not enough power to operate a remote
node by reverse powering from a single customer alone. Under such circumstances it shall be possible to augment this
power with forwards power from the CO or local mains derived power.
Reverse powering shall have a power splitter (located at the customer premises and another at the remote node) to
enable power to be inserted at the customer end of a link and extracted at the remote node. The power splitter performs
a frequency splitting and combining function between the services being carried (which can include POTS and xDSL
based services) and the injected DC electrical power. The power splitter shall have an upper frequency limit for
powering of 300 Hz. In the case of POTS services being carried over the same metallic loop, and considering the
emergence of wideband POTS services for high quality voice, the cut-over frequency of the reverse power feed power
splitter should be in the order of 10 Hz or less.
Within the remote node, if it operates with multiple power-fed lines then there shall be a power extraction and combiner
unit. The purpose of this unit is to combine the multiple power feed input to produce a single power source output. A
fair power-sharing algorithm shall exist where the power load is fairly shared amongst the input power sources.
The technical specifications in the present document shall apply to each architecture described below as one of the five
options shown in Table 1.
Table 1: Architecture Options for Reverse Power Feed
Option Name Description
1 RPFA-NOP Reverse Power Feed Architecture - No POTS
2 RPFA-EXP Reverse Power Feed Architecture - Exchange POTS
3 RPFA-EXPSW Reverse Power Feed Architecture - Exchange POTS Sharing in-premises Wiring
4 RPFA-DRP Reverse Power Feed Architecture - Derived POTS
5 RPFA-DRPSW Reverse Power Feed Architecture - Derived POTS Sharing in-premises Wiring

5.2 Reverse Power Feed and POTS Co-Existence
5.2.1 Background
Table 1, option 2 to option 5 involve reverse power feed co-existing with POTS - whether this is exchange based POTS
(RPFA-EXP, RPFA-EXPSW) or derived POTS (RPFA-DRP, RPFA-DRPSW).
When a POTS service is present on the same wires as reverse power feed (option 2, option 3 and option 5) the POTS
DC signalling/low frequency signalling will be translated so that it uses another part of the baseband spectrum, but the
basic analogue voice signal remains essentially untouched. At the CPE, the signalling is restored and POTS is presented
as normal.
When POTS is provided by derived voice service (option 4 and option 5), low power (L2) modes may be used to
provide the voice service even when the entire payload is not required by other services. The CPE presentation may be
either an analogue presentation via an ATA or directly to a VoIP handset.
In order to achieve co-existence between reverse power feed and POTS various adaptors are required as described in
clause 5.2.2 for use in the reverse power feed reference models.
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10 ETSI TS 101 548 V1.2.1 (2014-11)
5.2.2 POTS Adapters
The following three different types of POTS adaptor are specified for use in the reverse power feed reference models:
1) POTS Adapter - E (POTSA-E)
2) POTS Adapter - C (POTSA-C)
3) POTS Adapter - D (POTSA-D)
Where reverse power feed and POTS signals traverse the same copper wires a signalling system shall be implemented
to allow the signalling at the POTS interface based on off-hook/on-hook DC impedance, and in those jurisdictions
requiring it, line reversal for Calling Number ID alerting to be communicated across the copper pair from the DPU to
the POTS terminals. This functionality can be provided by the various POTS adaptors described below.
5.2.2.1 POTS Adapter - E (POTSA-E)
POTS Adapter - E is the single adapter located at the DPU and this adapter shall perform the following functions:
1) Translate the downstream DC and low frequency POTS signalling into an in-band or out-of-band signalling
system.
2) Translate the signals from the upstream in-band or out-of-band signalling system into DC and low frequency
POTS signalling.
POTSA-E may provide a relay by-pass when un-powered (for life-line operation) or when signalled to provide direct
access to the exchange to allow operations such as line-test to be performed.
5.2.2.2 POTS Adapter - C (POTSA-C)
POTS Adapter - C is the single adapter located at the NT module and this adapter shall perform the following functions:
1) Translate the upstream DC and low frequency POTS signalling from the POTS Terminal into an in-band or
out-of-band signalling system.
2) Translate the downstream in-band or out-of-band signalling system into POTS signalling towards the POTS
Terminal.
3) Provide sufficient current limit and DC voltage to supply one or more phone devices.
4) Provide a pre-defined rate of change of current increase when a phone device goes off-hook to allow for the
detection of phone devices going off-hook that do not have the correct POTS adapter fitted.
POTSA-C may provide relay by-pass when un-powered (for lifeline operation) or when signalled to provide direct
access to the exchange to allow operations such as line-tests to be performed.
5.2.2.3 POTS Adapter - D (POTSA-D)
POTS Adapter - D is the adapter that can be attached to every phone device connected to the in-premises wiring on the
home network. This adapter operates in the presence of reverse powering. This adapter shall perform the following
function:
1) Translate the signals from the upstream DC and low frequency POTS signalling from the POTS Terminal
into an in-band or out-of-band signalling system.
2) Translate the signals from the downstream in-band or out-of-band signalling system into POTS signalling
towards the POTS Terminal.
3) Provide sufficient current limit and DC voltage to supply a single phone device.
4) Provide a pre-defined rate of change of current increase when a phone device goes off-hook to allow for the
detection of phone devices going off-hook that do not have the correct POTS adapter fitted.
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11 ETSI TS 101 548 V1.2.1 (2014-11)
5.3 Reverse Power Feed Architecture without POTS on the
same pair (RPFA-NOP)
The functional reference model of the reverse power feed architecture without POTS on the same pair (RPFA-NOP) is
shown in Figure 2. In this option, the reference model illustrates the RPF architecture with the broadband service only
and no underlying narrowband service, neither exchange-based POTS nor derived POTS.
The xTU-O is located inside the Distribution Point Unit (DPU) at the network side of the wire pair (U-O reference
point). The xTU-R is located inside the Network termination (NT) at the customer premises side of the wire pair (U-R
reference point). Each DPU is located at a distribution point and can contain one or more xTU-O transceivers (xTU-O-I,
I = 1…N), with each transceiver connected to an NT.
At the backhaul link termination, the PHY blocks represent the physical layer of the xTU-O module towards the access
network and of the NT towards the customer premises (CP). These blocks are shown for completeness of the data flow
but are out of scope of the present document. The L2+ blocks represent the Layer 2 and above functionalities contained
in the xTU-O module and the NT. These blocks are shown for completeness of the data flow but are out of scope of the
present document.
The traffic from all DPUs is aggregated by a backhaul transmission system operating over the Distribution Network
(DN) and Higher Order Node (HON) up to the V reference point. The type of transmission system is out of scope of the
present document.
The management of a DPU is performed by the network management system (NMS), passing management information
to the DPU's management entity (DPU ME) over a management communications channel that is provided over the
backhaul transmission system. The details of the management communications channel and most of the management
functionality required for the DPU are out of scope of the present document.
As there is a need for management transactions between the DPU and the CPE for controlling the start-up of reverse
powering to the DPU when mains power is applied to the CPE and for monitoring powering in normal operations,
power management transceivers are connected to the copper drop in the DPU (PMT-I, I = 1…N) and the customer
premises (PMT) to support a management protocol. The management information is exchanged between the PMT-I and
DPU ME through the power management entity PME-D. At the customer premises, the information flow takes place
between the PMT and CPE ME through the power management entity PME-C.
The power is inserted on the li
...