ETSI TR 105 174-4 V1.1.1 (2009-10)

Access, Terminals, Transmission and Multiplexing (ATTM); Broadband Deployment - Energy Efficiency and Key Performance Indicators; Part 4: Access networks

DTR/ATTM-02005-3

General Information

• Status: Published
• Publication Date: 07-Oct-2009
• Technical Committee: ATTM AT2 - Infrastructure, Physical Networks & Communication Systems
• Current Stage: 12 - Completion
• Due Date: 09-Oct-2009
• Completion Date: 08-Oct-2009

Standards Content (Sample)

Technical Report
Access, Terminals, Transmission and Multiplexing (ATTM);
Broadband Deployment - Energy Efficiency
and Key Performance Indicators;
Part 4: Access networks
2 ETSI TR 105 174-4 V1.1.1 (2009-10)

Reference
DTR/ATTM-020005-3
Keywords
access, cable, optical, site engineering
ETSI
650 Route des Lucioles
F-06921 Sophia Antipolis Cedex - FRANCE

Tel.: [phone]  Fax: [phone]

Siret N° 348 623 562 00017 - NAF 742 C
Association à but non lucratif enregistrée à la
Sous-Préfecture de Grasse (06) N° 7803/88

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 2009.
All rights reserved.
TM TM TM TM
DECT , PLUGTESTS , UMTS , TIPHON , the TIPHON logo and the ETSI logo are Trade Marks of ETSI registered
for the benefit of its Members.
TM
3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.
LTE™ is a Trade Mark of ETSI currently being 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 TR 105 174-4 V1.1.1 (2009-10)
Contents
Intellectual Property Rights . 5
Foreword . 5
Introduction . 5
1 Scope . 7
2 References . 7
2.1 Normative references . 7
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 10
4 Overview of access network solutions . 12
4.1 Customer access point . 12
4.2 Principal access technologies . 13
4.2.1 Metallic Loop . 13
4.2.2 Other metallic-based solutions . 13
4.2.3 Wireless access . 14
4.2.3.1 General . 14
4.2.3.2 Bluetooth . 14
4.2.3.3 ZigBee . 14
4.2.3.4 WiFi . 14
4.2.3.5 WiMax . 15
4.2.3.6 GSM, GPRS, UMTS and 4G . 15
4.2.3.7 Fixed wireless links . 16
4.2.4 Optical Fibre . 17
4.2.4.1 General discussion . 17
4.2.4.2 Fibre To The Cabinet (FTTC) . 17
4.2.4.3 Fibre to the Building (FTTB) . 19
4.2.4.4 Fibre to the Home (FTTH) . 19
4.2.5 Other access technologies . 19
5 Energy efficiency standards and metrics . 19
5.1 Summary of pre-existing work . 19
5.2 Power requirement metrics and KPI . 20
5.2.1 Background . 20
5.2.2 Suggested metrics . 20
5.2.3 KPI figures . 21
5.3 Power requirements metrics applied to access network solutions . 21
5.3.1 Metallic loop . 21
5.3.2 Other metallic-based access solutions. 22
5.3.3 Wireless access . 22
5.3.3.1 General discussion . 22
5.3.3.2 Bluetooth and Zigbee . 22
5.3.3.3 WiFi . 22
5.3.3.4 WiMax . 22
5.3.3.5 Fixed wireless links . 23
5.3.4 GSM, GPRS, UMTS and 4G . 23
5.3.5 Optical fibre solutions . 23
5.3.5.1 FTTC . 23
5.3.5.2 FTTB . 23
5.3.5.3 FTTH . 24
5.3.6 Summary of power requirement metrics . 24
5.3.6.1 Determination of parameters . 24
5.3.6.1.1 Transmission rate/bitrate . 24
5.3.6.1.2 Distance . 24
ETSI
4 ETSI TR 105 174-4 V1.1.1 (2009-10)
5.3.6.1.3 Power requirements . 25
5.3.6.2 Network Configuration Issues . 25
5.3.6.3 Applicability. 25
5.3.6.4 Further development . 26
5.4 Energy Efficiency Key Performance Indicators (KPIs) . 26
5.5 Customer premises networks . 27
6 Increasing the energy efficiency of access networks. 28
6.1 Network Architecture and deployment . 28
6.2 Technology overview . 28
6.3 Targets and actions needed . 29
6.4 Energy saving measures . 30
6.4.1 FTTC . 30
6.4.2 FTTB . 30
6.4.3 CPE and Home equipment . 30
7 Overall Conclusions . 30
Annex A: Table of EEF and NPC values . 32
History . 33

ETSI
5 ETSI TR 105 174-4 V1.1.1 (2009-10)
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).
The present document is part 4 of a multi-part deliverable. Full details of the entire series can be found in part 1 [i.22].
Introduction
The increasing interaction between the different elements of the Information Communication Technology (ICT) sector
(hardware, middleware, software, services, etc.) supports the concept of convergence in which:
• a variety of multi-service packages can be delivered over a common infrastructure;
• a variety of infrastructures is able to deliver these packages.
• a single multi-service-package may be delivered over several different infrastructures.
As a result of this convergence, the development of new services, applications and content there is an increasing
demand for bandwidth, reliability, quality and performance. The consequent increase in the demand for energy which
implications for cost and, in some cases, availability. It is therefore important to maximize the energy efficiency of
network equipment at all levels.
New technologies and infrastructure strategies are expected to enable operators to decrease the energy consumption, for
a given level of service, of their existing and future infrastructures thus decreasing their costs. This requires a common
understanding among market participants that only standards can produce.
The present document is Part 4 of a multi-part set which has been produced by ETSI Technical Committee Access,
Terminals, Transmission and Multiplexing (ATTM) in close collaboration with CENELEC via the Co-ordination Group
on Installations and Cabling (CGIC). The document set offers a contribution to the required standardization process by
establishing an initial basis for work on ICT networks and transmission engineering, with active collaboration from a
number of other ETSI and CENELEC Technical Bodies. When complete, the documents will contain information that
has been jointly evolved to present developments in installations and transmission implementation, and describing their
progress towards energy efficiency in next generation networks (NGN).
ETSI
6 ETSI TR 105 174-4 V1.1.1 (2009-10)
The present document analyses the work on Access Networks whilst details of each of the other parts of the document
set can be found in Part 1. Clearly the energy efficiencies of Operator Sites, Data Centres, the Core Networks and
Customer Network Infrastructures are also important in maximizing the end-to-end energy efficiency of broadband
communications and these issues will be covered in other parts of the document set. However, Access Networks differ
from the other network components in that they are likely to include a very large number of locations each consuming a
relatively low amount of energy. Not only do such small installations tend to be inefficient in their power utilization but
when multiplied by their number, their total energy usage becomes considerable. Thus any energy saving which can be
achieved becomes significant when the number of sites is taken into account. At the same time, it is likely that the
energy consumption of the customer-owned equipment connected to the access network is likely to have an energy
demand far in excess of that of the network equipment. This is completely outside the scope of any possible
standardization initiative and can only be influenced by manufacturers minimizing the power requirements of their
products, perhaps under a Code of Conduct.
In order to monitor the implementation and operation of energy efficient broadband deployment, the documents will
also discuss Key Performance Indicators (KPI) for energy efficiency and focus on the possible consequences of
standardization of installations, cabling techniques and equipment. In particular, the study will investigate possibilities
and suggest solutions for development of processes for optimization in installation techniques and energy consumption.
ETSI
7 ETSI TR 105 174-4 V1.1.1 (2009-10)
1 Scope
The present document details measures which may be taken to improve the energy efficiency the access networks for
broadband deployment. Clauses 2 and 3 contain references, definitions and abbreviations which relate to this part;
similar information will be included in the corresponding clauses of the other parts, thus ensuring that each document
can be used on a "stand-alone" basis.
Clause 4 of the present document:
• identifies the standardization bodies working on interfaces to, cabling within, installation of, and other aspects
of the communication infrastructures of, access networks;
• outlines some of the principal access network topographies and their differences in respect of energy
consumption;
• provides strategic analysis of energy consumption trends within access networks;
• develops the concept of Key Performance Indicators (KPI), introduced in Part 1 of this multi-part set of
documents, to enable consistent monitoring of energy efficiency;
• outlines further work needed to ensure the improvement of energy efficiency in communication networks.
This will enable the proper implementation of services, applications and content on an energy efficient infrastructure,
though it is not the goal of the present document to provide detailed standardized solutions for network architecture.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
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 indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
ETSI
8 ETSI TR 105 174-4 V1.1.1 (2009-10)
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] ETSI TR 102 530: "Environmental Engineering (EE); The reduction of energy consumption in
telecommunications equipment and related infrastructure".
[i.2] ETSI TS 102 533: "Environmental Engineering (EE); Measurement Methods and limits for Energy
Consumption in Broadband Telecommunication Networks Equipment".
[i.3] "EC Code of Conduct on Energy Consumption of Broadband Equipment".
[i.4] IEEE Standard 802.11: "IEEE Standard for Information technology - Telecommunications and
information exchange between systems - Local and metropolitan area networks - Specific
requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications".
[i.5] IEEE Standard 802.15.1: "IEEE Standard for Information technology - Telecommunications and
information exchange between systems - Local and metropolitan area networks - Specific
requirements - Part 15.1: Wireless Medium Access Control (MAC) and Physical Layer (PHY)
Specifications for Wireless Personal Area Networks (WPAN)".
[i.6] IEEE Standard 802.15.4: "IEEE Standard for Information technology - Telecommunications and
information exchange between systems - Local and metropolitan area networks - Specific
requirements - Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY)
Specifications for Low Rate Wireless Personal Area Networks (WPANs)".
[i.7] IEEE Standard 802.16: "IEEE Standard for Local and metropolitan area networks - Part 16: Air
Interface for Broadband Wireless Access Systems".
[i.8] ITU-T Recommendation G.983.1 (05/2005): "Broadband optical access systems based on Passive
Optical Networks (PON)".
[i.9] ITU-T Recommendation G.983.2 (01/2007): "ONT management and control interface
specification for B-PON".
[i.10] ITU-T Recommendation G.983.3 (07/2005): "A broadband optical access system with increased
service capability by wavelength allocation".
[i.11] ITU-T Recommendation G.983.4 (01/2005): "A broadband optical access system with increased
service capability using dynamic bandwidth assignment".
[i.12] ITU-T Recommendation G.983.5 (01/2002): "A broadband optical access system with enhanced
survivability".
[i.13] ITU-T Recommendation G.984.1 (03/2008): "Gigabit-capable passive optical networks (GPON):
General characteristics".
[i.14] ITU-T Recommendation G.984.2 (03/2008): "Gigabit-capable passive optical networks (GPON):
Physical Media Dependent (PMD) layer specification".
[i.15] ITU-T Recommendation G.984.3 (01/2002): "Gigabit-capable passive optical networks (GPON):
Transmission convergence layer specification".
[i.16] ITU-T Recommendation G.984.4 (01/2002): "Gigabit-capable passive optical networks (GPON):
ONT management and control interface specification".
[i.17] ITU-T Recommendation G.984.5 (01/2002): "Enhancement band for gigabit capable optical access
networks".
[i.18] ITU-T Recommendation G.984.6 (01/2002): "Gigabit-capable passive optical networks (GPON):
Reach extension".
ETSI
9 ETSI TR 105 174-4 V1.1.1 (2009-10)
[i.19] ITU-T Recommendation G.992.1 (03/2003): "Asymmetric digital subscriber line (ADSL)
transceivers - Annex A: Specific requirements for an ADSL system operating in the frequency
band above POTS".
[i.20] ITU-T Recommendation G.992.3 (06/2008): "Asymmetric digital subscriber line transceivers 2
(ADSL2) - Annex J: All digital mode ADSL with improved spectral compatibility with ADSL
over ISDN".
[i.21] ITU-T Recommendation G.992.5 (01/2009): "Asymmetric digital subscriber line (ADSL)
transceivers - Extended bandwidth ADSL2 (ADSL2plus)".
[i.22] ETSI TS 105 174-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Broadband
Deployment - Energy Efficiency and Key Performance Indicators; Part 1: Overview, common and
generic aspects".
[i.23] ETSI TR 105 174-5-1: "Access, Terminals, Transmission and Multiplexing (ATTM); Broadband
Deployment - Energy Efficiency and Key Performance Indicators; Part 5: Customer network
infrastructures; Sub-part 1: Homes (single-tenant)".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
access circuit: telecommunications circuit connecting the operator site to the subscriber's premises
access network: part of the network that is deemed to include the last active component at the relevant operator site and
the first active element at the subscriber's premises
access point: termination point on a telecommunications network allowing access by nomadic devices to obtain
telecommunications services to which they have subscribed elsewhere
active element: network component that requires externally supplied electric power to enable it to perform its network
function
Bluetooth: short range wireless network defined by IEEE Standard 802.15 and usually considered to be part of a
Personal Area Network (PAN)
community network: communications network, usually wireless, established by and for a local community often to
compensate for lack of publicly available access to relevant facilities
customer: person or entity using a telecommunications service and who may or may not be the subscriber
Digital Access Carrier System (DACS): 0+2 pair gain system providing two separate telephone lines over one copper
pair using digital technology
digital radio: any wireless link system in which the information carried is encoded in any one of a variety of digital
formats
Digital Subscribers Line (xDSL): access circuit over which information is carried in a digital format and where the
upstream and downstream transmission rates may be the symmetrical (SDSL) or asymmetrical (ADSL)
energy consumption: measure of the energy consumed by the operation of the electronic devices necessary to provide
a specific communications service
enterprise network: network established by a large company or similar enterprise to serve its internal
telecommunications needs with connectivity to one or more public networks
Ethernet: frame-based local area networking technology standardized as IEEE 802.3
fibre to the cabinet: optical fibre distribution network providing connectivity from the network operator's site to a
shared distribution node close to the end-user's premises
ETSI
10 ETSI TR 105 174-4 V1.1.1 (2009-10)
firewall: security measure designed to prevent unauthorized electronic access to a networked computer system
flexibility point: device in the access network where access circuits can be configured to their intended destination by
cross connecting metallic pairs
games console: electronic device on which one or more games may be played and which is often capable of being
connected to a communications network
home network: network that supports and distributes within the home, those services to which a customer subscribes
hotspot: location that offers publicly accessible internet access over a wireless connection
Industrial, Scientific and Medical (ISM) band: band of radio frequencies allocated for use for industrial, scientific
and medical purposes
intrusion detection system: mechanism by which any attempt by an unauthorized user or terminal to gain access to a
communications network is detected
meshed network: communications network, usually wireless, in which every node has connectivity with a number of
other nodes thus enabling a variety of possible communication paths between nodes
mobile phone: terminal device capable of voice (and often data) communications which operates using one or more
types of publicly available wireless communications systems
network gateway: device which will enable the interconnecting of two networks which inherently use different and
incompatible protocols
packet: information block identified by a label at layer 3 of the OSI reference model
peripheral: peripheral is a device attached to a host computer whose primary functionality is dependent upon the host,
and which expands the host's capabilities, but is not part of the core architecture of the system
point-to-multi-point: communications link operating between a network operator's site and a number of other locations
point-to-point: communications link operating between two, usually fixed, locations
service: provision of a defined functionality in a computer systems or telecommunications environment
sub-loop: secondary access circuit from a street cabinet or similar access node used to deliver one or more services to a
customer
subscriber: person or entity responsible for paying for a telecommunications service
Subscribers Loop Carrier (SLC): equipment providing multiple telephone circuits over one or two standard
subscriber's telephone lines (see also DACS)
triple play (telecommunications): provision of cable TV, telephony and broadband data as a combined service
offering, possibly using a single bearer medium
Watt (W): unit of power, the rate at which work is done; in electrical terms it is the product of the supply voltage
(volts) and the current passed (amps)
Watt-hour (Wh): unit of energy used or work done; the product of the rate at which work is done and the time for
which it done
NOTE: The terms "Watt" and "Watt-hour" are frequently confused.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
3G 3rd Generation (mobile networks)
3GPP 3G (mobile) Partnership Project
4G 4th Generation (mobile networks)
ETSI
11 ETSI TR 105 174-4 V1.1.1 (2009-10)
ADSL Asymmetrical Digital Subscribers Line
NOTE: See ITU-T Recommendation G.992.1 [i.19].
ADSL2 Second generation ADSL with extended upstream bandwidth
NOTE: See ITU-T Recommendation G.992.3 [i.20].
ADSL2+ Second generation ADSL with extended downstream bandwidth
NOTE: See ITU-T Recommendation G.992.5 [i.21].
BBF Broadband Forum
BEF Building Entrance Facility
BSC Base Station Control site
BSS (Mobile) Base Station
CATV Cable Television
CMTS Cable modem termination system
CoC Code of Conduct
CPE Customer Premises Equipment
DACS Digital Access Carrier System - see also SLC
DECT Digital Enhanced Cordless Telecommunications
DHCP Dynamic Host Configuration Protocol
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Multiplexer
EC European Commission
EE Environmental Engineering
EEF (broadband service) Energy Efficiency Factor
ENTI External Network Test Interface
FDM Frequency Division Multiplex
FSO Free Space Optics
FTTB Fibre To The Building
FTTC Fibre to the Cabinet
FTTH Fibre To The Home
GPON Gigabit Passive Optical Network
GPRS General Packet Radio Service
GSM General System for Mobile communication/Global Mobile System
HEF Home Entrance Facility
HFC Hybrid Fibre Coaxial
HGI Home Gateway Initiative
IEEE Institution of Electrical and Electronics Engineers (USA)
ISDN Integrated Services Digital Network
ISM Industrial, Scientific and Medical (frequency band)
ISP Internet Service Provider
ITU International Telecommunications Union
KPI Key Performance Indicator
LAN Local Area Network
LBL Lawrence Berkley Laboratories
NGN Next Generation Network
NPC Normalized Power Consumption (per line)
NTP Network Termination Point
OIE Operator Independent Equipment
OLT Optical Line Terminal
ONT Optical Network Termination
ONU Optical Network Unit
OSE Operator Specific Equipment
PAN Personal Area Network
PC Personal Computer
PLC Power Line Carrier
PON Passive Optical Network
POTS Plain Old Telephone Service
PSTN Public Switched Telephone Network
QAM Quadrature Amplitude Modulation
ETSI
Distribution Distribution
12 ETSI TR 105 174-4 V1.1.1 (2009-10)
RF Radio Frequency
SDSL Symmetric Digital Subscriber Line
SLC Subscribers Line Carrier (system)
NOTE: See also DACS.
TDM Time Division Multiplex
UMTS Universal Mobile Telecommunication System
USB Universal Serial Bus
VDSL Very high-speed Digital Subscriber Line
VoIP Voice over Internet Protocol
W Watt
WAN Wide Area Network
WDM Wavelength Division Multiplex
Wh Watt hour
WiFi Wireless Fidelity
NOTE: Technology using IEEE 802.11 standards.
WiMax Worldwide Interoperability for Microwave Access
xDSL Digital Subscriber Line (generic title)
4 Overview of access network solutions
4.1 Customer access point
For the purposes of the present document, the access network is deemed to include the last active component at the
relevant operator site and the first active element at the subscriber's premises. The connection between the operator's
access network and the home distributor as shown in figure 1 (or the equivalent in non-generic cabling) is provided by
network access cabling and some type of network telecommunication equipment as shown.
Network access cabling
in EN 50173-x standards
Access network
OIE ENTI
Service interface
OSE ENTI
Service
interface
Figure 1: Network access cabling and equipment
ETSI
13 ETSI TR 105 174-4 V1.1.1 (2009-10)
The access network normally includes a Network Termination Point (NTP) at the customer's premises. In the case of a
broadband connection this typically comprises a passive interface (ENTI) and an optional item of apparatus. The
apparatus may either be specific to the network operator (OSE) or may be operator independent (OIE) as described in
the following examples:
• OSE: CATV modem, FTTH modem (if no standardization is achieved);
• OIE: DSL modem, FTTH modem (if standardization is achieved).
The OSE is regarded as part of the access network whereas the OIE is part of the customer premises infrastructure.
In some cases the OIE, or some part of it, may be powered from the access network and the OSE may be powered from
the customer premises. For this reason, calculations of the energy efficiency of the access network should take into
account any energy required to maintain the functionality at the service interface, irrespective of the source of that
energy.
Some OIE or OSE may have functionality beyond that which is strictly necessary to provide adequate service
termination. For example, a DSL or cable modem may have an inbuilt router or WiFi terminal. When determining the
energy efficiency in these cases, a judgement should be made as to what proportion of the total power requirement of
the device should be taken into account for the purposes of the calculation.
This clause will examine the principal access network topographies used for the delivery of NGN services and describe
them in sufficient detail to define their typical power requirements. It should be appreciated that each of the
topographies to be described will have a number of variants; no attempt will be made to describe all of these or their
implications on energy consumption.
In some cases, proprietary systems or those having a specific application may be described. It is not intended that these
are definitive but only that they serve to describe an access network mechanism. Legacy applications will only be
described insofar as is necessary to present a substantially complete picture.
4.2 Principal access technologies
4.2.1 Metallic Loop
The traditional access network or local distribution network has comprised a copper based network with each subscriber
or in some cases, each service, having a dedicated copper twisted pair from the operator site ("telephone exchange") to
the customer's premises. Such connections are normally made via a number of "flexibility points" in the external
distribution network allowing the pairs to be routed appropriately; discussion of this is outside the scope of the present
document. Some networks incorporate conductors made from other metals (typically aluminium or bronze) but these
are very much in the minority.
This network technology was originally conceived for voice telephony and has remained virtually unchanged for more
than a hundred years apart from improvements having been made in its physical construction and the materials used.
The network is essentially passive, no power normally being required between the operator site and the customer
premises. Its application has been extended to include multiple channel telephony (for example, ISDN2 and DACS
based services); although these are not seen as core services, they are expected to exist for a considerable time, thus
necessitating the continued existence of the metallic network.
These networks have been and will continue to be used for broadband services using xDSL in support of the NGN.
These have typically operated up to approximately 8 Mbit/s using older DSL technology, this being principally
dependent upon the line length, but up to a few tens of Mbit/s using ADSL2+ and VDSL, though only relatively short
subscriber lines can support the download speeds recommended by ITU-T as the equipment capability, thus limiting the
usefulness of the more advanced DSL technologies. Lines carrying xDSL services usually serve a single terminal, or a
small home or enterprise network for a single subscriber.
4.2.2 Other metallic-based solutions
There are several variants of the copper based local access network, some based on similar copper pairs to those
described above and others on co-axial cable. These are mostly suited to short access circuits and are more frequently
used in customer networks.
ETSI
14 ETSI TR 105 174-4 V1.1.1 (2009-10)
Coaxial copper cables are sometimes been used in the access network for circuits serving business premises requiring
substantial communications capacity and/or a resilient network connection. Such connections have typically carried
multi-channel TDM or FDM systems or Ethernet-based services and were usually arranged on a "point-to-point" basis,
duplicated when resilience was required. Ethernet services were normally carried on ring-configured circuits,
sometimes extending into the customer premises network.
Such solutions are now considered to be obsolescent and not expected to play a part in NGN access networks, except
possibly as subscriber drop circuits from street-located facilities. For example, coaxial cables are frequently used for
this application in CATV networks using a variety of Hybrid Fibre Coaxial (HFC) architectures.
4.2.3 Wireless access
4.2.3.1 General
A number of wireless systems have been proposed for NGN access networks, some providing network connections for
fixed users and others for roaming and nomadic users. The crossover point between systems intended for use in home or
enterprise and those intended for access networks is not clear-cut, some products being appropriate in both applications.
These systems are summarized in the following clauses but none can be regarded as a broadband access solution, either
because of their limited range or bandwidth or both.
4.2.3.2 Bluetooth
Bluetooth is a wireless protocol which facilitates data transmission over short distances from fixed, portable and mobile
devices. The protocol is standardized in IEEE 802.15.1[i.5] and it was originally intended for creating wireless Personal
Area Networks (PANs) to provide secure connectivity between devices such as telephones, personal computers, digital
cameras, game consoles, etc. using unlicensed radio frequencies in the industrial, scientific and medical (ISM) bands.
Bluetooth technology has been used for access network applications, most commonly in customer networks over very
short distances. The technology was designed for, and is more suited to, "in-house" and PAN applications. It is not
generally regarded as a commercial access product, therefore will not be discussed further in the present document.
4.2.3.3 ZigBee
ZigBee is a low-power digital radio standard (IEEE 802.15.4 [i.6]) for wireless PANs as a simpler and less expensive
alternative to Bluetooth. ZigBee is targeted at Radio-Frequency (RF) applications requiring a low data rate, long battery
life and secure networking, more suited to "in-house" applications such as building automation ("domotics"). Thus, it is
more commonly found in customer network applications than in access networks. It is not regarded as a commercial
access product, therefore will not be discussed further in the present document.
4.2.3.4 WiFi
WiFi is a popular wireless technology standardized in IEEE 802.11 [i.4], originally intended to be used in home
networks, mobile phones, video games and other electronic devices requiring some form of in-house wireless
networking capability but now partially superseded in these applications by the Bluetooth and ZigBee technologies.
WiFi technology is supported by most modern PC operating systems, game consoles and computer peripherals, thus
providing point to multi-point wireless internet connectivity for such devices. It is also widely used for in-house
distribution of audio and video media or other data. WiFi has found many applications in home and enterprise networks
and has become widespread in corporate infrastructures.
The latest draft of the WiFi specification allows for operation at 2,4 GHz or 5 GHz, with network data rates of up to
108 Mbits/s with a potential for further increases up to several hundred Mbit/s using frame aggregation and
sophisticated modulation techniques. Channel bonding may also be used to increase data rates, though it application in
the 2,4 GHz band is limited due to overlapping channel allocations. At 5 GHz, the range of WiFi is reduced due to
increase atmospheric attenuation.
It should be noted, however, that the available bandwidth is shared between all devices connected to the wireless access
point and that the use of channel bonding will usually block a substantial proportion of the available RF channels. The
available external bandwidth is dependent on the access technology employed to connect the local access point to the
access network operator's site and this may in itself limit the user experience.
ETSI
15 ETSI TR 105 174-4 V1.1.1 (2009-10)
More recent developments have enabled the interconnection of WiFi access points to form meshed networks, thus
providing seamless access across large areas, potentially ranging up to many square kilometres. Both the point to multi-
point and meshed topologies can operate together in such community networks, providing wide-area network access for
both fixed and nomadic users.
WiFi is thus both an access network and customer premises network technology. As well as providing "permanent"
access connectivity, WiFi systems can also support publicly available hotspots, either without charge or on a
subscription basis. Businesses, hotels and restaurants may provide free WiFi access to hotspots to attract customers.
Such "public" networks require the addition of a secure network gateway, firewall, DHCP server, intrusion detection
system, accounting and other functions thus increasing their overall energy consumption.
4.2.3.5 WiMax
WiMax (an abbreviation of Worldwide Interoperability for Microwave Ac
...