ETSI TR 102 614 V1.1.1 (2010-06)

Environmental Engineering (EE); Reverse powering of access network unit by end-user equipment: A4 interface

DTR/EE-02038

General Information

• Status: Published
• Publication Date: 17-Jun-2010
• Technical Committee: EE 2 - EE Power Supply
• Current Stage: 12 - Completion
• Due Date: 21-Jun-2010
• Completion Date: 18-Jun-2010
• Mandate: M/462

Standards Content (Sample)

ETSI TR 102 614 V1.1.1 (2010-06)
Technical Report



Environmental Engineering (EE);
Reverse powering of access network unit
by end-user equipment: A4 interface

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2 ETSI TR 102 614 V1.1.1 (2010-06)



Reference
DTR/EE-02038
Keywords
access, network, REV
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3 ETSI TR 102 614 V1.1.1 (2010-06)
Contents
Intellectual Property Rights . 4
Foreword . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Abbreviations . 6
4 Power interfaces between the Network Termination and the Optical Network Unit or remote DSL
unit . 7
4.1 Back feeding or Reverse Powering Architecture. 7
4.2 Backfeeding or Reverse Powering Architecture Options . 8
4.3 A4 interface at the pair interface arrival . 8
4.4 ANU Power consumption . 9
4.5 Back-up options . 9
5 Progressive installation issue. 11
6 Failure detection, alarms, reparation and control monitoring . 11
7 Reliability, dependability and contract between operator and customer . 11
8 Regulatory aspects . 12
Annex A: Backfeeding Power as a function of output voltage and pairs size and length . 13
Annex B: Backfeeding principle in overlay of PSTN +DSL . 15
Annex C: Safety consideration for remote feeding . 16
History . 19

ETSI

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4 ETSI TR 102 614 V1.1.1 (2010-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Environmental Engineering (EE).
Introduction
To build increased Broadband access networks, one solution is the GPON using FTTC or FFTB or any other common
equipment with optical fibre input and copper pairs close to a cluster of customers. Today, the power supply is obtained
by local electrical mains connection or by remote power distribution on pairs from a central office. But, sometimes,
there is not enough copper or the length of the copper is too long to allow remote powering over the telecom networks
and connection to the local electrical mains is not possible or too expensive. Thus, it is advisable to extent the range of
possible powering solutions by using a solution called reverse powering or back feeding.
ETSI ATTM TM6 is developing a Technical Report to consider powering options for remote DSL nodes
(TR 102 629 [i.21]) which requires powering interface standardization.
Thepresent document introduces a possible revision for complement to EN 302 099 [i.3].
In that solution, the line termination equipment supplies the power to the ONU or ONT through the final distribution
copper line to the home. This is under consideration in ITU-T SG15 [i.22] in the GPON powering issue. In that case,
there is an injection of power in the pair at the level of one client or one client group network termination (individual or
building). At first sight, this seems strange to require from a customer to provide power for common equipment to
several customers, but this concept is already used for common radio equipment linked to a cluster of customers.
Sharing the power can be seen as equivalent to share WIFI resources in an ad'hoc network architectures.
Alternatively, one can think about a combination of power sources located at the curb and at the customer premises
such that subscribers are only powering the services they use.
ETSI

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5 ETSI TR 102 614 V1.1.1 (2010-06)
1 Scope
The present document scope is the back feeding or reverse powering architecture that can supply power to access
network unit such as ONU or ONT or remote DSL unit from the customer through its final distribution access copper
pair.
As a minimum, the present document defines a power interfaces over the customer copper pair to the access network
unit (remote DSL unit or ONU such as FTTC or FTTB cabinet) defined in TR 102 629 [i.21].
Other important issues are under discussion in the present document: overlay of PSTN on the same pair and back-up
(autonomy, locations, environments and safety), reliability and monitoring aspects are also addressed.
Other issues about local laws, unbundling rules, and cost are out of the scope.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 300 019-1-4: "Environmental Engineering (EE); Environmental conditions and
environmental tests for telecommunications equipment; Part 1-4: Classification of environmental
conditions; Stationary use at non-weatherprotected locations".
[i.2] ETSI EN 300 132-2: "Environmental Engineering (EE); Power supply interface at the input to
telecommunications equipment; Part 2: Operated by direct current (dc)".
[i.3] ETSI EN 302 099: "Environmental Engineering (EE); Powering of equipment in access network".
[i.4] IEC EN 60896-21: "Stationary lead-acid batteries - Part 21: Valve regulated types - Methods of
test".
[i.5] IEC EN 60950-22: "Information technology equipment -Safety - Equipment to be installed
outdoors".
[i.6] IEC EN 50272-2: "Safety requirements for secondary batteries and battery installations -
Part 2: Stationary batteries".
[i.7] ETSI TS 102 533: "Environmental Engineering (EE) Measurement Methods and limits for Energy
Consumption in Broadband Telecommunication Networks Equipment".
ETSI

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6 ETSI TR 102 614 V1.1.1 (2010-06)
[i.8] IEC TR 62102 (second edition): "Electrical safety - Classification of interfaces for equipment to be
connected to information and communications technology networks".
[i.9] IEC EN 60950-1: "Information Technology Equipment - Safety".
[i.10] Directive 2002/22/EC modified by 2007/0248 (COD): "European Directives on universal service".
[i.11] Code Of Conduct on Energy Consumption of Broadband Communication Equipment European
Commission Directorate-General, Joint Research Centre.
[i.12] 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".
[i.13] IEC TS 62367: "Safety aspects for xDSL signals on circuits connected to telecommunication
networks (DSL: Digital Subscriber Line)".
[i.14] IEC TS 60479-1: "Effects of current on human beings and livestock -Part 1: General aspects".
[i.15] IEC 60 364-4-41: "Low voltage electrical installations part 4-41 Protection for safety protection
against electrical shock".
[i.16] ETSI EN 300 253: "Environmental Engineering (EE); Earthing and bonding of telecommunication
equipment in telecommunication centres".
[i.17] IEC EN 60364-1: "Low voltage electrical installations - Part 1: Fundamentals principles,
assessment of general characteristics, definition".
[i.18] ETSI ES 202 336-1: "Environmental Engineering (EE); Monitoring and Control Interface for
Infrastructure Equipment (Power, Cooling and Building Environment Systems used in
Telecommunication Networks) Part 1: Generic Interface".
[i.19] IEC EN 60950-21: "Information technology equipment - Safety - Part 21: Remote power feeding".
[i.20] IEC TS 61201: "Use of conventional touch voltage limits - Application guide".
[i.21] ETSI TR 102 629: "Access, Terminals, Transmission and Multiplexing (ATTM); Reverse Power
Feed for Remote Nodes".
[i.22] ITU-T SG15- WD GR07 (WP 1/15): "GPON powering issue".
[i.23] IEC EN 60364-4-41: "Electrical installations of buildings - Part 4-41: Protection for safety -
Protection against electric shock".
[i.24] The New Product Safety Standard for Communication Technology Equipment
Wilfried SCHULZ - (T-Systems Enterprise Services GmbH) Goslarer Ufer 35, D-10589 Berlin,
Germany.
NOTE: For more information, please contact [e-mail]
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AC Alternating Current
ANU Access Network Unit
BBCoC Broadband Code of Conduct
CO Central Office
CPE Customer Premises Equipment (equivalent to End-User Equipment)
DC Direct Current
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Module
FTTC Fibre to the Cabinet
FTTB Fibre to the Building
ETSI

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7 ETSI TR 102 614 V1.1.1 (2010-06)
HGW Home Gate Way
G-PON Gigabit capable Passive Optical Network
LCA Life Cycle Assessment
NT Network Termination
NTE Network Termination Equipment
OF Optical Fibre
ONT Optical Network Termination
ONU Optical Network Unit
PC Personal Computer
PON Passive Optical Network
POTS Plain Old Telephony Service
PSTN Phone Subscriber Transmission Network
RFT Remote Feeding Telecommunication
SELV Safety Extra Low Voltage
VRLA Valve regulated lead acid
4 Power interfaces between the Network Termination
and the Optical Network Unit or remote DSL unit
4.1 Back feeding or Reverse Powering Architecture
A typical example of the power architecture of backfeeding (or reverse powering) is proposed on figure 1 in order to
define reverse power interface A4.
S/P
xDSL
Cu pair POTS or ISDN
(PSTN)
Power
Final distribution
P
option
Copper pair
PSU
S/P
xDSL
S AC plug
PG
OF
ONU
P
"A4"
Option 1:
P
customer battery
interface
CPE
"A"
Option 2:
interface Super-
P= reverse power
capacitor
S = standard signal interface (combining xDSL + ISDN or
or battery
POTS signal including remote powering from central
office)
S/P = Signal/Power filter
FTTx
PG = Power gathering (or combining) Interface with S/P
filter function.

Figure 1: back feeding or reverse powering architecture (example in order to define A4 interface)
ETSI
Distant CO
End-user terminals
or HGW

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8 ETSI TR 102 614 V1.1.1 (2010-06)
The remote cabinet (ONU or remote DSL unit or .) under consideration (more generally ANU) is generally located in
FTTB or FFTC cabinet or underground chamber. The telecom node equipment is common to N customer (x=Building,
Curb, Node, …), and is generally powered through 48 V interface A as defined in EN 300 132-2 [i.2] by a power
gathering interface PG receiving pairs from customer through a filter separating signal S and power P (S/P ). The
filter
S/P is out of the scope of the present document. The interface on the different telecom existing line should not be
filter
affected by reverse powering, so that there should be no change for the existing central office equipment or home
terminals. The voltage on the distribution line between the customer and the telecom node equipment may be different
than the POTS voltage or ISDN voltage if the distance or power load needs higher voltage to allow power transport
with an acceptable efficiency.
The pairs are powered by customer wall adapters though an S/P connected to the home phone pair network defined
filter
by ES 202 971 [i.12]. The same wall adapter may be used to power the client home gateway, often called "box".
The power interface with the pair between customer and ANU is called A4 and located in figure 1.
NOTE : With the same voltage interface as DSL over POTS or ISDN, the filter is very similar to existing one.
4.2 Backfeeding or Reverse Powering Architecture Options
There should be a compatibility with other architecture such as remote powering or mains power supply which is very
simple when the power input interface of the ANU or remote DSL is the interface A [i.2].
There may be options such as back-up in the FTTx or/and in the customer premises.
There should be also possible contributions between different power supplies for example:
• When there is not enough remote pairs, a part of the power can be provided by reverse powering, e.g. the
energy for the common parts could be provided from the CO, while the energy for the single line could be
provided by each customer.
NOTE 1: This can be useful to allow initial powering at installation with few customers, or in special area or time
where a lot of customers shut down their systems (e.g. tourist area with great variation of numbers of
permanent customers)
• When there is a mains interruption, back-up can be provided through to the CPE by the reverse powering
battery back-up. In that case the powering is not reverse and should be compliant with EN 302 099 [i.3].
NOTE 2: This should probably be limited in power for some essential service. It is out of the scope of the present
document to define these services.
4.3 A4 interface at the pair interface arrival
The A4 interface is of type TNV-1 according to TS 60479-1 [i.14] and EN 60950-1 [i.9] in Network Environment 1 as
defined in TR 62102 [i.8] (the circuits connected to telecommunication network are usually TNV-type; besides in case
of cloud to cloud lightning just above the building the possibility to have induced surges on the vertical pairs, usually
not shielded, is not reduced), i.e. the voltage is 60 V maximum and peaks are limited according to TR 62102 [i.8],
TS 62367 [i.13] and EN 60950-1 [i.9].
NOTE: There is a possibility of using other voltages beyond SELV as long as they have sufficient safety features
built in ITU-T Q2 (ISDN). Considering the risk with children, this should not be recommended for
residential use, but only for professional use (e.g. non public area in office premises). This is not
described in the present document. Earthing and grounding should be addressed in detail in respect to
EN 300 253 [i.16]
For information EN 60364-1 [i.17] and EN 60364-4-41 [i.23] safety standard should be considered.
See details of current effect on human in annex C.
The power interface A of the ANU or remote DSL equipment is 48 V [i.2], i.e. 40,5 V to 57 V in normal range. It is not
recommended to add a voltage converter (step-up) for reliability and efficiency reasons. That means limited voltage
drop and power loss in the pairs. Annex A gives maximum power values depending on line section and line length
considering A interface minimum voltage.
ETSI

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9 ETSI TR 102 614 V1.1.1 (2010-06)
15 W is the limit according to EN 60950-1 [i.9] for the power on a telecommunication network and the A4 interface is
be designed in order to limit the output current to a value that does not cause damage to the telecommunication wiring
system due to overheating, under any load condition as required by the same EN 60950-1 [i.9]. The S/P should be
filter
dimensioned for the maximum current of 250 mA at 60 V.
This give also a limit for the energy cost per user. The power should be fairly supported by customer by a method to
split almost equally the power between reverse powering lines e.g. at the combiner level.
NOTE 1: The overlay of back feeding with POTS on the pair between customer and the telecom node is possible.
There should be circuitry to avoid a power collision between the phone remote powering and low
frequency signals with the reverse powering. There are several possible solutions with detection of
80 V - 50 Hz ringing signal from central office side or phone off hook from customer phone side. There
should be no change in the operation of the terminals of a common customer installation with several
POTS or DSL telecom equipment plugs, e.
...