ETSI TR 102 629 V2.1.2 (2011-03)

Access, Terminals, Transmission and Multiplexing (ATTM); Reverse Power Feed for Remote Nodes

RTR/ATTM-06023

General Information

• Status: Withdrawn
• Publication Date: 10-Mar-2011
• Withdrawal Date: 28-Nov-2019
• Technical Committee: ATTM TM6 - Wireline Access Network Systems
• Current Stage: 50 - Withdrawn
• Due Date: 11-Mar-2011
• Completion Date: 29-Nov-2019
• Mandate: M/462

Standards Content (Sample)

Technical Report
Access, Terminals, Transmission and Multiplexing (ATTM);
Reverse Power Feed for Remote Nodes

2 ETSI TR 102 629 V2.1.2 (2011-03)

Reference
RTR/ATTM-06023
Keywords
ADSL, VDSL
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ETSI
3 ETSI TR 102 629 V2.1.2 (2011-03)
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 Reverse Power Feed for Remote Nodes . 7
4.1 Reverse Power Feed Background . 7
4.2 Power Backup Situations . 8
4.2.1 Case 1 Battery Backup at the NTE . 8
4.2.2 Case 2 Battery Backup at the DP and NTE . 8
4.2.3 Case 3 Battery Backup at the DP Only . 8
4.2.4 Case 4 Battery Backup at the DP and Cabinet . 9
4.2.5 Case 5 Battery Backup at the DP and Cabinet with Forwards Powering from the CO. 9
4.3 Options for Reverse Power and Forwards Power Feed . 10
4.3.1 Reverse Power Feed to the DP. 10
4.4 Reverse Power Feed Architecture . 11
4.4a Reverse Power Feed Options. 11
4.5 U Electrical Interface . 11
R2P
4.5.1 Current standards in force . 11
4.5.2 Telecommunications cables . 12
4.5.3 Safety of personnel . 12
4.6 ONU Power Consumption . 12
4.7 Reverse Power Feed Specification . 13
4.7.1 Distribution Point Reverse Powering . 13
4.7.2 Cabinet Reverse Powering . 14
4.8 Reverse Power Feed and POTS . 15
4.8.1 Class 1 . 15
4.8.2 Class 2 . 18
4.8.3 Class 3 . 19
4.8.4 Class 4 . 19
4.8.5 POTS-only Requirements & Lifeline Support . 19
4.8.5.1 Scenario 1 - ATA in HGW . 20
4.8.5.2 Scenario 2 - ATA in NTU . 20
4.8.5.3 Scenario 3 - ATA in SU with POTS adapters . 20
4.8.5.4 Scenario 4 - POTS from exchange/cab with POTS adapters . 21
4.9 Reverse Power Feed States . 21
4.10 Concatenated Reverse Power Feed Architectures . 21
4.11 Power Sharing/Billing Model . 22
4.12 External Requirements on the Reverse Power Feed . 22
Annex A: Bibliography . 23
History . 24

ETSI
4 ETSI TR 102 629 V2.1.2 (2011-03)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
Introduction
As various European operators consider the deployment of fibre-fed remote nodes that contain ADSL2+/VDSL2
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. ETSI TM6 has agreed to create a new document that defines a reverse
power feed transmission standard and which allows European operators to source suitably compliant equipment for
inclusion in their networks.
ETSI
5 ETSI TR 102 629 V2.1.2 (2011-03)
1 Scope
The present document identifies the scope of a reverse power feed standard or standards that will allow operators to be
able to source suitably compliant equipment for inclusion in their networks.
The present document will identify the requirements for reverse power feed, consider the coexistence of reverse power
feed with POTS and scenarios involving the deployment of reverse power feed for cabinet and distribution point
locations.
Other issues for consideration include:
- Safety.
- Efficiency.
- Power Back-up.
- Performance monitoring (for further study).
- Reliability (for further study).
- Power-sharing (for further study).
- Billing (for further study).
Other issues such as local laws, unbundling rules and cost are considered out of 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] IEEE 802.3: "LAN/MAN CSMA/CD (Ethernet) Access Method".
NOTE: Available at http://standards.ieee.org/getieee802/802.3.html.
[i.2] IR Cooper, DW Faulkner: "Reverse Powering Over DSL". Proceedings of the 13th European
Conference on Networks and Optical Communications (NOC 2008) 1 - 3 July 2008, Krems,
Austria.
[i.3] ON Semiconductor AND8333/D: "High Power PoE Applications, On Semiconductor application
sheet", April 2008.
ETSI
6 ETSI TR 102 629 V2.1.2 (2011-03)
[i.4] ETSI TR 102 614: "Environmental Engineering (EE); Reverse powering of access network unit by
end-user equipment: A4 interface".
[i.5] 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.6] 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.7] ETSI TS 102 533: "Environmental Engineering (EE) Measurement Methods and limits for Energy
Consumption in Broadband Telecommunication Networks Equipment".
[i.8] Code Of Conduct on Energy Consumption of Broadband Communication Equipment European
Commission Directorate-General, Joint Research Centre; Final v2: 17 July 2007.
[i.9] Void.
[i.10] CENELEC EN 60950-21: "Information Technology Equipment - Safety. Part 21 Remote Power
Feeding (IEC 60950-21:2002)".
[i.11] BT contribution 08CC-020: "Remote Node Powering", ITU SG-15, Campbell, CA, 15-19
September 2008.
[i.12] BT Network Requirement 181, Signalling System AC15, Issue 06, August 1989".
NOTE: Available at http://www.btwebworld.com/sinet/BTNR_181_Volume_1.pdf.
3 Abbreviations
For the purposes of the present document, the following terms and definitions apply:
ATA Analogue Terminal Adaptor
CLASS Customer Local Access Signalling System
CO Central Office
CPE Customer Premises Equipment
DC Direct Current
DP Distribution Point
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Multiplexer
ECS Electronic Communications Services
EOC Embedded Operations Channel
FTTx Fibre To The x (where x could be cabinet, premises etc.)
HGW Home GateWay
ISDN Integrated Services Digital Network
NTE Network Termination Equipment
NTU Network Terminating Unit
ONU Optical Network Unit
PATS Publicly Available Telephone Service
PoE Power over Ethernet
POTS Plain Old Telephony Service
POTSA POTS - Analogue presentation
POTSD POTS - derived
PSTN Public Switched Telephone Network
PVC Permanent Virtual Circuit
RFT Remote Feeding Telecommunication
SELV Safety or Separation Extra Low Voltage
SG Service Gateway
SU Service Unit
VDC Voltage (Direct Current)
nd
VDSL2 2 generation Very high-speed Digital Subscriber Line
VoIP Voice over Internet Protocol
ETSI
7 ETSI TR 102 629 V2.1.2 (2011-03)
4 Reverse Power Feed for Remote Nodes
4.1 Reverse Power Feed Background
The basic architecture of a reverse power feed system is shown in figure 1.
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
POTS
D
SG
Derived Voice
Central Office Fibre-fed Remote Node Local Power Feed
(cabinet or DP located)
Home network
Figure 1: Generic Reverse Power Feed Architecture
Figure 1 shows power being injected at the NTE from a local power source (located within the home/building) which
traverses the local loop to power a fibre-fed remote node which can be located at either the 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 both with an analogue presentation (POTSA) at the NTE and also as a derived POTS service
(POTSD). 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/what is responsible for the powering of
common circuitry contained within the node. It is easy to envisage that an individual user could be responsible for the
powering of the remote line terminating/driver electronics corresponding to their particular circuit (see note). However,
it is not so easy to determine who/what is responsible for powering of say the ONU that terminates the fibre link.
NOTE: In practice even this may not be easy to implement since DSL chipsets may be of an octal channel design
and therefore all eight channels will be required to be powered in order to operate a single channel.
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.
Such situations result in the requirement for battery back-up devices and these may be located in the SG, remote node
itself or the cabinet providing that spare copper-pairs remain connected to the fibre-fed remote node. Figure 2 shows
battery backup devices have been located in the NTE and fibre-fed remote node. It is envisaged that in order to provide
high-reliability services (including lifeline POTS support) then a combination of battery back-up devices will be
distributed throughout the network.
ETSI
8 ETSI TR 102 629 V2.1.2 (2011-03)
4.2 Power Backup Situations
4.2.1 Case 1 Battery Backup at the NTE
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Fibre-fed Remote Node
(cabinet or DP located)
Figure 2: Battery Backup at NTE
Figure 2 shows the case where battery backup is placed at the NTE. The aim being that if there is a local power failure
then lifeline POTSA (or maybe POTSD) plus OAM support at the remote node can be provided by the battery backup.
4.2.2 Case 2 Battery Backup at the DP and NTE
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Fibre-fed Remote Node
(cabinet or DP located)
Figure 3: Battery Backup at the DP and NTE
Figure 3 shows the addition of another battery backup located at the DP. This gives the advantage in that equipment
located at the DP can remain powered even though no subscribers are connected and thus retaining OAM support.
4.2.3 Case 3 Battery Backup at the DP Only
Figure 4 shows the battery backup being located only at the DP. This arrangement takes away the responsibility for
backup from the subscriber - but probably means in practice that a larger capacity backup device is required when
compared to Case 2.
ETSI
9 ETSI TR 102 629 V2.1.2 (2011-03)
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Central Office Fibre-fed Remote Node
(cabinet or DP located)
Figure 4: Battery Back-up at the DP
4.2.4 Case 4 Battery Backup at the DP and Cabinet
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Fibre-fed Remote Node
(cabinet or DP located)
Figure 5: Battery Backup at the DP and Cabinet
Figure 5 shows the battery backup being located at the cabinet and the DP. This arrangement allows a smaller battery to
be located at the DP. The battery at the cabinet could be reverse power charged from the DPs.
4.2.5 Case 5 Battery Backup at the DP and Cabinet with Forwards
Powering from the CO
Power fed to remote node over
same copper pair as XDSL signal
POTS /POTS
A D
NTE
CO cabinet DP
Central Office Fibre-fed Remote Node
(cabinet or DP located)
Figure 6: Forwards Powering from the CO
ETSI
10 ETSI TR 102 629 V2.1.2 (2011-03)
Figure 6 shows another option where the battery located at the cabinet is forwards power trickle charged from the CO.
This instance relies upon there being copper cable still existing between the CO and the cabinet.
4.3 Options for Reverse Power and Forwards Power Feed
4.3.1 Reverse Power Feed to the DP
Reverse power feed to the DP is now considered in more detail. Figure 7 shows the sample lengths of 9 million
drop-wires in the UK [i.2] (note the rise above 100 m is caused by all drop-wires above 100 m being summed into a
common bin). It can be clearly seen from figure 7 that the average length of a drop-wire (in the UK) is approximately
30 m.
Over such lengths, it is not necessary to operate at high voltages in order to reduce copper losses to an acceptable level
and therefore it is possible to operate at SELV levels (60 V dc) in order to achieve a reasonably efficient reverse
powering scheme.
Sample of dropwire lengths
0.2
0.15
0.1
0.05
020 40 60 80 100
drop length x (m)
Figure 7: Sample UK Dropwire Lengths [i.2]
As a starting basis for such a powering scheme it would be possible to adopt/modify existing technology in the form of
IEEE 802.3-2005 [i.1] (commonly known as IEEE 802.3af - Power over Ethernet) technology (PoE). This specification
uses a line voltage of 36 V DC to 57 V DC (nominal voltage supply range for 48 V powered equipment) over two of the
four pairs of Cat 3/Cat 5e cable, with a current range of 10 mA to 400 mA subject to a maximum load power of
14,40 W. After cable losses, a maximum power of approximately 12,95 W is available to the remote device although
another 10 % to 25 % of this can be lost due to inefficiency of the switched mode power supplies used.
PoE technology normally operates over 2 or 4 pairs of the Cat 3/Cat 5e cable and therefore alternative coupling
arrangements will have to be made in order to operate over a single pair. However, a large percentage of homes in the
UK are fed with two-pair cable and therefore it would be possible to retain the same differential data transmission over
each pair with transformer coupling with each pair acting in common-mode as one side of the DC supply. However,
even if two pairs are used, it may be necessary to increase the existing PoE current limit beyond 400 mA in order to be
able to remotely power DSLAM equipment located at the DP when consideration is made regarding the power
requirements of existing DSLAM technologies.
Note that a future standard, commonly known as PoE+ is being drafted by the IEEE 802.3at task force to extend the
PoE using two pairs of Cat5e cable to be able to provide 24 W of power. Beyond this, proprietary solutions using up to
720 mA of current per line pair to provide 36 W of remote power feed on a single pair have also been devised [i.3].
ETSI
Fraction (x)
11 ETSI TR 102 629 V2.1.2 (2011-03)
4.4 Reverse Power Feed Architecture

POTS
U
U
U
O R2S
R
management
U
O2S
Broadband
Service Power
Power
NT
Service
L2/L3 functionality
splitter splitter
splitter
splitter
POTS
U
O2P
U
R2P
Power
U
O2 combiner
Derived POTS
ONU XTU-O
Power
insertion
PSU
battery
Service
Gateway
battery
Figure 8 : Reverse Power Feed Reference Model
The reference model shown in figure 8 depicts a similar architecture to that given in the definition of the A4 interface
from [i.4]. Here the ONU or remote DSL unit is located distant from the CO (FTTx) in a cabinet, underground orpole-
top location, The FTTx equipment is common to N customers (x=Building, Curb, Pole-top, Node etc.) and is typically
powered via a 48 V dc interface [i.5] via a power gathering/combining interface from the various copper pairs
connected to the N customers connected to the remote node. A power splitter separates the signal (S) and power (P).
Note that a battery backup device is shown in figure 8 to enable the ONU to be able to communicate to the PON feeder
network even when there are no customers actively connected to the remote node.
At the CPE, the copper local loop is powered by a direct current source (also shown with battery back-up) and again
connects to the home phone pair network (defined by the standard [i.6]). The power interface at this point is UR2P
which is equivalent to the A4 interface as described by [i.4].
4.4a Reverse Power Feed Options
There shoul
...