Green telecom layered framework for calculating carbon footprint of telecom network

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 425
GREEN TELECOM LAYERED FRAMEWORK FOR CALCULATING
CARBON FOOTPRINT OF TELECOM NETWORK
Himanshu Makkar1
1
Managed Services Engineer – Service & Resource Fulfillment: Operations, Delhi, India, makkar.himanshu@gmail.com
Abstract
This paper presents the concept of green telecommunication network, and provides information about the carbon footprint within the
fixed-line and wireless communication network. A section is devoted to describe the method with an example to calculate the carbon
footprint of telecom network using Green Telecom Layered Framework. This framework aids in bridging the chasm between
managing and mitigating the concentration of Green House Gases (GHG). The aim is to introduce the reader to the present green
telecommunication, and outline the necessity of energy efficiency in Information and Communication Technology (ICT). This paper
provides a comprehensive reference for growing base of researchers who will work on the energy efficiency of telecom network in
near future.
Index Terms: Green Telecom, Carbon Footprint, Layered Framework, and Green Network
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1. INTRODUCTION
Of late, the rise in the world's surface temperature has become
a matter of global concern, and is now comprehended as one
of the vital challenges confronting humanity. Deteriorating
natural resources, environment and climate changes have
become an important concern to the world [1]. With
advancing technologies, the world's need for the energy based
solution increases, and due to the non -availability of efficient
alternatives to fossil fuel energy sources , global temperature
has risen and is expected to rise from 1.4 ̊ C to 5.8 ̊ C, with a
doubling of CO2 concentrations over next 40 to 100 years [2].
With far and wide acceptance of ICT in each and every aspect
of our society, it is believed to have an Eco-Friendly or Green
image. This stature emanates from the fact that the modern
telecom is transforming our society by providing travel and
transport substitution. For instance: video conferencing,
teleconferencing etc., on-line delivery, and other channels of
reducing the human impacts on the environment. Virtual
meeting that includes audio and video conferencing in lieu of
travel could reduce CO2 emission by around 24 million tonnes
per year [3].
ICT usage has grown at an almost exponential rate worldwide
[4]. By 2015, the down-link traffic from cellular handsets is
expected to grow more than eight folds, rising from 56
Megabytes per month to 455 Megabytes per month [6]. By the
year 2020, nearly 80 % are projected to own mobile phone,
and one in 20 households to have broadband connections [5].
In recent years, the ever-increasing demands for
telecommunication services, has not only grown the energy
consumption significantly and poses an environmental
challenge in terms of larger carbon emission footprint of the
telecommunication industry, but also presses telecom
operators and vendors to spend less on energy and extract
more efficiency out of their systems. Consequently, telecom
vendors will need to take subtle decision of investing millions
in new energy optimization technologies and offering enough
innovations to satisfy not only their customers, but also their
own bottom line [8].
From the global outlook, compared with coal, iron and steel,
non-ferrous metal industries, the telecommunication industry
is not the most prominent industry of energy consumption [1].
Albeit telecom is comparatively energy lean, the telecom
networks are still driven largely by fossil fuel energy;
therefore, the energy cost represents a significant Operating
Expenditure (OPEX) item. In some telecommunication
markets, energy costs account for as much as half of a mobile
operator operating expenses [9].
As of now, in telecommunication industry, technological
developments were acted predominantly on meeting Quality
of Service (QoS) and capacity demands of the customer.
Every year around 12,000 new base stations are deployed
serving approximately 400 million new mobile subscribers
around the world [7]. This growing infrastructure requires an
increasing amount of electricity to power it, which increases
the energy consumption base of the telecom industry. Hence,
energy consumption of telecom network calls into questions,
and it is indispensable to develop energy-efficient telecom
solution.

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Fig. 1 Represents carbon footprint of ICT (in million tonnes) from the year 2000 to year 2020, and expected carbon emission from the
different components of ICT for the year 2020 (in million tonnes)
The rest of the paper is organized as follows. Section II
outlines the carbon emission footprint and energy
consumption trend in ICT. Section III provides the detailed
description of Green Telecom Layered Framework for finding
the carbon footprint of telecom network. Last section
concludes the paper outlining the possible future research
topics.
2. CARBON EMISSION AND ENERGY
CONSUMPTION OF ICT
With emerging new applications and technologies, ICT can
enact both positive and negative roles. Thus, the relationship
between ICT and the environment is complex and
multifaceted [10]. The time, space, material, and energy
needed to provide ICT services have decreased by three orders
of magnitude since the first PC was sold [11]. However, to
cater the meteoric growth in voice and data communication
usage, large volume of telecom equipment will continue to be
deployed both in the access network and the core network.
It is believed that continued improvements in energy
efficiency technologies will reduce the energy consumption
and provide a competitive advantage [12]. But due to
increase in the stock of ICT appliances and network
infrastructure to provide the uninterrupted services 24*7, the
carbon emission footprint of telecom sector has risen
significantly and will rise despite the development of energy-
efficient technologies [13].
It is estimated that ICT sector worldwide is responsible for
around 1% of the global CO2 emission [14]. The growth in the
global telecommunication carbon emission has risen from 150
million tonnes of CO2 equivalents in 2002 to 300 million
tonnes of CO2 equivalents in 2007, and is expected to reach
349 million tonnes of CO2 equivalents by 2020 [15] as shown
in Fig. 1. This comprises the impact of personal computers,
servers, cooling equipment, fixed and mobile telephone
equipment, network infrastructure, LAN, and office
communications etc.
The aforementioned components of ICT and their contribution
of carbon footprint in ICT sector are shown in Fig 2. By 2020,
ICT is expected to account for around 2% of the global carbon
emission. According to the recent trends in up-and-coming
applications and technologies, the number of fixed-line,
narrowband, and voice telephony accounts is expected to
remain fairly constant overall, but the number of broadband as
well as mobile accounts is expected to grow more than double
during this period [15].
The foremost share of the CO2 emission in the ICT
infrastructure is during the actual use of the network
equipment and devices. In the telecommunication network, the
components that contribute to carbon emission footprint
includes the Radio Access Network (RAN), fixed-line
network, the Core network, aggregator, transmission system,
and Fiber to the network (mainly in Access network) etc.
The distribution of power consumption across the network
components is shown in Fig. 3. Among the components of

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mobile network, the Base Transceiver System (BTS) alone
consume around 59% of the power in the network, while the
Mobile Switching Center (MSC) constitute around 21% and
the core transmission around 18% [15].
Fig.2 Contribution of different components of ICT to the
carbon emission
Among the network components, in RAN: BTS alone
consumes around 59% of power, and in Core: around 21% of
power is consumed by MSC and around 18% by core
transmission.
The predominant reason for the increase in the carbon
footprint of the telecom infrastructure would be due to
increase in the number of BTS, Base Station Controller (BSC),
and MSC. The growth is not only due to the increase in the
telecom infrastructure or number of broadband and mobile
accounts, but also because of emerging new applications like
sharing of videos, gaming, and other peer to peer content
exchange [5]. Emerging markets offer vast growth potential
for the telecom industry. A large global mobile market means
more people connecting with each other, more base stations
for vendor to deploy and maintain [10].
Fig.3 Distribution of power consumption across different
components of telecommunication network
3. MEHOD TO CALCULATE CARBON
FOOTPRINT OF TELECOMMUNICATION
NETWORK
Green telecommunication is much discussed topic in the
telecom industry and beyond. But still there are not enough
definitions available that have made it difficult to gauge the
effectiveness or the extent of its implementation. Every now
and then, optimizing energy consumption in one part of a
network can increase the power consumption and degrade the
performance in another part of the network [16].
Managing a network effectively and operating it in a green
manner is a complex task to perform. Therefore, the telecom
industry has realized that the next phase of its growth is
dependent on innovation in green technologies, and they have
also recognized that, there is a very close proximity between
energy saving and money. The combination of rising energy
costs and our avid inclination for connectivity and data will
lead to significant environment impact unless addressed by a
unified strategy [17]. This is inspiring the network operators
and business entities to pay more attention to their energy
consumption and finally works towards its reduction.
3.1 Green Telecom Layered Framework
A Green Telecom Layered Framework takes a holistic view of
telecom network architecture. It is divided into three levels:
Network Component, Transmission Technology, and Network
Equipment as shown in Fig. 4.
The first level is the Network Component. It can be broadly
divided into two network domains: Core Network and Access
Network.
A Core Network is the central part of the telecommunication
network that provides various services to customers and end
users. The core network generally refers to the backbone
infrastructure of the telecom network which interconnects
larger cities, and spans nationwide, and even intercontinental
distances [18]. The core network is typically based on a mesh
topology and carries huge amount of traffic.
An Access Network is the part of a telecom network which
connects subscribers to their immediate service providers and
to the core network. The access network is the “Last Mile” of
a telecom network connecting the telecom Central Office
(CO) with the end users [18]. It comprises the major part of
the telecommunication network. It is also a major consumer of
energy due to the presence of a huge number of active
elements [19].
The second level is the Transmission Technology. The
transmission technologies in core as well as access network
are widely used to support the basic physical infrastructure. It

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is deployed for achieving high speed, high capacity, and
scalability etc. [18]. For instance: Synchronous Optical
Network (SONET)/ Synchronous Digital Hierarchy (SDH),
Wavelength Division Multiplexing (WDM), Time Division
Multiplexing (TDM) or Asynchronous Transmission Mode
(ATM) etc. The aforementioned transmission technologies
have been deployed over the past two decades [21].
Fig.4 Green Telecom Layered Framework: three layer
architecture namely Network Component, Transmission
Technology and Network Equipment
The final level of Green Telecom Layered Framework is
defined by the term Network Equipment. The network
equipment level i.e. the telecom infrastructure level, consists
of both hardware and software elements, and it is the main
level at which the energy consumption of telecommunication
network is investigated.
Consider an IP over WDM as an example as shown in Fig. 5.
The WDM is the transport technology which multiplexes
optical carrier signals onto single optical cable. A WDM
transport system uses a multiplexer at the transmitter end for
combining several optical carrier signals on one channel and
de-multiplexer at the receiver end for separating them apart.
The preamplifier and the power booster are used for
amplifying the power of the optical signals so as to increase
the sensitivity of the receiver and to compensate the power
loss respectively.
Energy consumption of WDM transport network components
can be found in switching level and also in transmission level.
In switching level, the principal components that consume
energy are Digital Cross Connect (DXC), routers or switches,
and Optical Cross Connect (OXC). In transmission level, the
components which are the main consumer of energy consist of
multiplexer, de-multiplexer, transponder, pre-amplifier, and
power boosters [18].
3.2 Carbon Footprint Calculation for
Telecommunication Network
The measurement is the only step that bridges the chasm
between manage and mitigation. But the problem with this
first step is that, in many cases proper method to calculate the
carbon emission from telecom network does not exists.
Even if organizations are unable to directly measure their
telecom carbon emission and power consumption, they are
often aware that it is too high and should be lowered if
possible [22]. Therefore, choosing the right methodology to
measure the carbon footprint of the telecom network is critical
in ensuring that green telecom projects are successful over
time.
The carbon footprint of the network equipment, that is, the
telecom infrastructure is calculated based on the energy
consumption at both, the network component layer and the
transmission technology layer. The carbon footprint
calculation can be divided into two parts depending upon the
operation of the telecom network equipment: using Grid
Power and using Diesel Generator (DG) Set.
3.2.1 Using Grid Power
PTE is the total power consumption of the network element
including the power required for fan and other cooling
equipment etc. (in kilowatt). PCO is the power needed for
compensating the heat produced during the actual operation of
the network equipment (in kilowatt) and PNE is the operating
power of the network equipment (in kilowatt) given by the
formula [23].
[23]
Where PMAX is the maximum power of the equipment (in
kilowatt), PAVG is its average operating power (in kilowatt)
and PSLEEP is its power rating when operating in sleep mode
(in kilowatt). The operation of the ICT equipment is at room
temperature (via forced cooling).
The carbon emission EG (in tonnes per year) during the
operation of network element using the power generated from
the grid is given by
(1)
Where ECO2 is the carbon emission factor (in kilogram per
kilowatt hour) and HG is the average number of hour’s
network element is operated using grid power per day.

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Fig. 5 Telecom network hierarchy
3.2.2 Using Diesel Generator Set
In remote regions, where grid power is available only for few
hours in a day, vendors often rely on inefficient diesel
generators, which will significantly grow the carbon footprint
of telecommunication sector.
The energy density of diesel is 45.64 Megajoules per kilogram
or 38.6 Megajoules per liter [24], which means 10.7 kilowatt
hour of power is generated per liter of diesel. One liter of
diesel produces 2.629 kilogram of CO2 [24], therefore, 0.2457
kilogram of CO2 is produced per kilowatt hour in one liter.
Let PDG be the capacity of DG set (in kilovolt ampere) having
the power factor of used for HDG average numbers of hours
network element is operated using DG set per day. The carbon
emission EDG (in tonnes per year) during the operation of
network element using the power generated from the DG sets
is given by
(2)
Where N is amount of diesel (in liter) consumed by DG set in
one hour and η is the efficiency of the DG set.
Carbon emission ET (in tonnes per year) of the
telecommunication network equipment can be calculated by
adding (1) and (2),
Table 1 & 2 represent carbon emission calculation for core
network in rural and urban area using method described
above.
Table-1 Carbon emission calculation for core network in rural
area
RURAL
Carbon Emission Calculation (GRID Power)
Total
Carbon
Emission
(in
tonnes)
Avg. Power
Consumption
of Network
Element
(KW)
Avg.
Grid
Power
Supply
(hours)
Carbon
Emission
Factor
(Kg/KWH)
Emission
(in
tonnes)
1.76 13 0.523 4.3677
Carbon Emission Calculation (DG Set Power)
DG Set
Capacity
(KVA)
Avg.
DG
Set
Power
Supply
(hours)
Liters of
Diesel
Consumed
(per hour)
Emission
(in
tonnes)
15 11 2.5 29.634 34.0017

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Table-2 Carbon emission calculation for core network in
urban area
URBAN
Carbon Emission Calculation (GRID Power)
Total
Carbon
Emission
(in
tonnes)
Avg. Power
Consumption
of Network
Element
(KW)
Avg.
Grid
Power
Supply
(hours)
Carbon
Emission
Factor
(Kg/KWH)
Emission
(in
tonnes)
3.125 21 0.84 20.12
Carbon Emission Calculation (DG Set Power)
DG Set
Capacity
(KVA)
Avg.
DG
Set
Power
Supply
(hours)
Liters of
Diesel
Consumed
(per hour)
Emission
(in
tonnes)
15 3 2.5 8.082 28.202
CONCLUSIONS
The contemporary scenario is exceedingly demanding and
challenging, and the world's increasing need for the
computation, data storage, and communication is maneuvering
the rapid growth in the telecommunication, and intensifying
the emission associated with enhancing technologies.
As mobile operators and vendors are making every effort to
extend their network beyond the reach of power grids, they
need to find the alternatives to non-renewable energy sources
such as diesel, which is widely used today to power the
telecommunication network. However, due to lack of enough
definitions it seems to be difficult for translating this progress
into the progress of sustainable development.
The Green Telecom Layered Framework gives insight into
different layers of telecom network for calculating the carbon
footprint emission depending upon the energy consumption at
the telecom infrastructure level. Measuring the carbon
footprint effectively should be the first priority for business
entities, which paves way for managing the network by
reducing the amount of energy required for system to operate
without compromising the capabilities. And then think about
the alternative energy options to minimize the overall carbon
footprint of the system.
REFERENCES
[1] Huawei, “Improving energy efficiency, Lower CO2
emission and TCO,” White Paper, Huawei energy
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[2] IPCC, “Intergovernmental Panel on Climate Change:
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007.
[3] Labelle, Richard, “ICTs for e-Environment: Guideline
for Developing Countries, with a Focus on Climate
Change”, ITU-2008.
[4] ITU, “International Telecommunication Union: World
Telecom /ICT Indicator Database”, ITU-2008.
[5] TRAI, “Telecom Regulatory Authority of India:
Recommendations on approach towards Green
Telecommunications”, Apr. 2011.
[6] Singh, R. "Wireless Technology: To Connect the
Unconnected." World Bank.
[7] Sistek, H. "Green-tech base stations cut diesel usage by
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[13] Bio Intelligence Service, “Impacts of Information and
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[14] The Economist, “How green is your network”,
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[15] The Climate Group GeSI, “SMART2020: Enabling the
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[20] Ghani, Nasir, Sudhir Dixit, and Ti-Shiang Wang. "On
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Magazine, IEEE 38, no. 3 (2000): 72-84.

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[21] Manchester, James, Jon Anderson, Bharat Doshi, and
Subra Dravida. "IP over SONET." Communications
Magazine, IEEE 36, no. 5 (1998): 136-142.
[22] Connection Research, “A Green ICT Framework:
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[23] Parker, Michael C., and Stuart D. Walker. "Road
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no. 8 (2011): A49-A58.
[24] DEFRA, “Act on CO2 Calculator: Data, Methodology
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BIOGRAPHIES
Himanshu Makkar received B.Tech degree in Electronics and
Communication Engineering from Guru Gobind Singh
Indraprastha University, Delhi, India in 2009. Currently work
as Managed Services Engineer – Service & Resource
Fulfillment: Operations.
Research Interests: advanced wireless networks, routing
protocols, green networking, core network performance
analysis and QoS in telecommunication network.

Green telecom layered framework for calculating carbon footprint of telecom network

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