2. CONTENTS
• Introduction
• Why do we care about energy efficiency?
• Network Architectures
• Access Network Architecture
• Analysis of Optical and DSL technologies
• Customer Premises Equipment
• Core network architecture
• Quantification of power consumption
• Optimization of power consumption
• Conclusion
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3. PREFACE
OBJECTIVES
• To give an idea about energy efficiency in communication
networks.
• To examine different network’s power consumption.
• To discuss power quantification and optimization methods in
various networks.
APPROACH
• Discussion on various network architectures and its power
consumption.
• Effects of power consumption on energy efficiency.
• Quantification and optimization of power consumption.
• Conclusion
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4. INTRODUCTION
• Every emerging technology is mainly evaluated on its carbon
footprint.
• Information and Communication Technology (ICT) is
accountable for 2-4 % of worldwide carbon emissions.
• One sixth of these emissions is contributed by
telecommunication networks.
Figure 1: Electricity consumption per year by various fields
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5. INTRODUCTION(CONTD...)
• ICT is being regarded as a solution with the potential to
eliminate about 15 % of the global carbon footprint.
• Sleep mode, component optimization and power management
are the already suggested power saving strategies.
• Different network architectures, its design parameters defining
power consumption, methods for quantification and the
reduction techniques are discussed here.
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6. WHY DO WE CARE ABOUT ENERGY EFFICIENCY?
• From a simple transistor to environment, thermal energy is
increasing.
• ICT alone is responsible of a percentage which vary from 2 −
4% of the world power consumption.
• Pressure to reduce network power consumption while still
growing network capacity and functionality.
• Scalability
• Power density in racks of communication equipments is
reaching practical limits.
• Makes cost-efficient scaling of telecommunication networks
difficult.
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7. NETWORK ARCHITECTURES
• ACCESS NETWORKS
• CORE NETWORKS
• Access Networks can be again classified as:
• FIXED LINE ACCESS NETWORKS
• WIRELESS ACCESS NETWORKS
Figure 2: Network Overview
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8. ACCESS NETWORK ARCHITECTURE
Fixed line access networks
• Users are connected through physical wires.
• 3 main types of technologies are in use :-
• DSL(Digital Subscriber Line)-Asymmetric DSL , Very high bit
rate DSL
• Coax cable technology-uses Data Over Cable Service
Interface Specification Standard.
• Optical technology-point- point , active star or Passive
Optical Network (PON).
• Cable access networks are constructed with an optical
backhaul-HFC
• Optical access networks can be terminated with VDSL
node-FTTB ,FTTC , FTTx
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9. ANALYSIS OF OPTICAL AND DSL TECHNOLOGIES
• Traffic in access network is bursty and highly variable.
• Power consumption per subscriber is considered as a metric.
ADSL
• Downstream speeds: 8 Mbps(ADSL) to 24 Mbps(ADSL2+)
• Upstream speed : 1 Mbps
• Maximum range : 1.5 km to 5.5 km
• Range allows large user aggregation-hence power consumption
is negligible
VDSL
• Uses an extended frequency spectrum compared to ADSL.
• Aggregation is closer to the user- so significant power
consumption.
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10. ANALYSIS OF OPTICAL AND DSL
TECHNOLOGIES(contd...)
Optical fiber technology
• Allows both high bit rates( upto 10Gbps) and range
(10-20km).
• P2P connections are used in backhaul network to aggregate
large traffic.
• In active star and PON ,bit rate capacity is distributed over
large number of users.
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11. WIRELESS ACCESS NETWORKS
• Different technologies provides different access bit rates to the
user.
• 3 main emerging wireless technologies are:-
• WiMAX( Worldwide Interoperability for Microwave
Access)-IEEE802.16 std.
• HSPA (High- Speed Packet Access)-successor of UMTS
• LTE (Long Term Evolution)-4G technology
• The factor under consideration for determining power in a
wireless access network is the area covered by the base
stations.
• The covered area is related to the input power of the base
station antenna and the bit rate.
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12. CUSTOMER PREMISES EQUIPMENT
• At the customer premises, access networks will be connected
to the customer premises equipment.
• For fixed line networks it will be a home gateway.
• For wireless networks, it can be any equipment-like mobile
phone,home gateway, wireless network interface card in a
computer etc.
• Hence wireless technologies are generally called as mobile
stations.
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13. CORE NETWORK ARCHITECTURE
• Current core networks are mix of several layers like IP-over-
ATM - over- SDH.
Figure 3: Core network architecture
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14. QUANTIFICATION OF POWER CONSUMPTION
FIXED LINE ACCESS NETWORKS
• Each subscriber has a dedicated connection.
• ADSL equipment consumes 1-2W/sub and VDSL consumes
3-5W/sub.
• Optical network consumes 10-20W/port which can be further
reduced if GPON is used.
• OLT-Optical Line Terminal-using for connection consumes
0.2-0.8W/sub.
• VDSL DSLAM with 16 connections use only 0.01-0.05W/sub.
• Power Usage Effectiveness (PUE) - typically a factor of 2
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15. QUANTIFICATION OF POWER CONSUMPTION
(contd...)
WIRELESS ACCESS NETWORKS
• Highest power consumer is the base station.
• Power per subscriber is dependant on the subscriber density in
the area covered by the base station.
• For comparison a bit rate / active user is taken as 3Mbps for
all technologies.
• WiMAX - Lowest- 2.9kW/BS - Range of 340 m
• LTE - Highest - 3.7kW/BS - Range of 470 m
• HSPA - Intermediate - 3.7kW/BS - Range of 240 m
• If subscriber density is considered as 300users/sq.km in urban
and sub urban areas:
• LTE-18W/Subs
• WiMAX-27W/Subs
• HSPA-68W/Subs
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16. QUANTIFICATION OF POWER
CONSUMPTION(contd...)
CUSTOMER PREMISES EQUIPMENT
• The home gateway consumes about 5-10 W for fixed line
technologies.
• Home gateways for optical networks also have larger energy
consumption compared to its DSL counterparts.
• In wireless networks, the power consumption of mobile stations
is much lower since these are designed for mobile applications.
CORE NETWORKS
• 90% of power consumption is concentrated in the nodes.
• WDM links via optical amplifiers make up only 10% of power
consumption.
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17. QUANTIFICATION OF POWER CONSUMPTION
(contd...)
Figure 4: Generalized core network power consumption distribution
• Layer 1 and 2-provides framing, physical connection to a
specific network(ATM. SONET , Ethernet or SDH) etc.
• Currently the power consumption in core networks is less
compared to access networks.
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18. QUANTIFICATION OF POWER CONSUMPTION
(contd...)
Figure 5: Properties of different access network technologies
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19. QUANTIFICATION OF POWER CONSUMPTION
(contd...)
Figure 6: Power consumption/subscriber of different network technologies
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20. POWER CONSUMPTION OPTIMIZATION
• SWITCHING OFF COMPONENTS
• REDUCING LOAD
• OPTIMIZING POWER CONSUMPTION OF THE
REMAINING COMPONENTS
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21. POWER CONSUMPTION OPTIMIZATION (contd...)
SWITCHING OFF COMPONENTS
• Switch off elements when demand is lower.
• Dynamic topology optimization -used in core networks
• Dynamic Bandwidth Allocation -used in fixed line access
networks.
• Hybrid hierarchical base station deployment -used in
wireless access networks.
• Optimization of power in home gateway is important.
• These are individual devices that needs to be activated only
when the user is active.
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22. POWER CONSUMPTION OPTIMIZATION (contd...)
REDUCING LOAD
• Adaptive link rate (ALR) -Used in access networks.
• Link rates are adapted on the basis of factors such as mean
packet delay and packet loss based on a handshake
mechanism.
• An ethernet link with ALR can operate at a lower data rate
for over 80 percent of the time, yielding significant energy
savings with only a very small increase in packet delay
• The algorithms for adaptive link rate use large packet buffers
which require hardware that needs to be powered.
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23. POWER CONSUMPTION OPTIMIZATION (contd...)
REDUCING LOAD
• A non bypass scenario: all the traffics in a node will be
processed by the IP router
• Optical bypass - used in core networks.
• As IP routers consumes the most power,optical bypassing is a
promising option to decrease power consumption.
• Optical bypasses uses the same infrastructure as the original
opaque network hence no additional capacity is added to the
network.
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24. POWER CONSUMPTION OPTIMIZATION (contd...)
Table 1: Reduction of total PC for different traffic loads using optical
bypass - standby PC: 0.81678 MW
Network load(E) PC with 0 bypass with 10 bypasses reduction
140 1.2751 1.18696 6.91
280 1.7457 1.57327 9.88
420 2.2793 2.00099 12.21
560 2.7719 2.46233 13.17
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25. POWER CONSUMPTION OPTIMIZATION (contd...)
OPTIMIZING THE POWER CONSUMPTION OF
REMAINING COMPONENTS
• Increasing the ranges of base stations using MIMO - in
wireless access networks.
• Optical packet switching and Optical burst switching -
Used in core networks.
• A hybrid approach in which optical switches using electronic
buffering is a more feasible low-power approach for the future.
• For continent - sized core networks , increasing the
maximum optical path length can reduce power
consumption.
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26. CONCLUSION
• The number of internet users is fast increasing hence the
power consumption also.
• Saving power in telecommunication networks is becoming an
important challenge.
• For reducing power; switching off components , reducing the
loads on the networks and optimizing the power consumption
of the network elements can be adopted.
• In fixed line access networks power consumption optimization
is focused on the technology shift towards full optical
networks.
• In wireless access networks many optimizations can still be
implemented.
• In core networks the power consumption is relatively low.
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27. REFERENCES
• [1].Vereecken, W.; Van Heddeghem, W.; Deruyck, M.; Puype,
B.; Lannoo, B.; Joseph, W.; Colle, D.; Martens, L.;
Demeester, P., ”Power consumption in telecommunication
networks: overview and reduction strategies,”
Communications Magazine, IEEE , vol.49, no.6, pp.62-69,
June 2011
• [2].S. Aleksic, Analysis of Power Consumption in Future
High-Capacity Network Nodes, IEEE/OSA J. Opt.
Commun.and Net., vol. 1, no. 3, Aug. 2009, pp. 24558.
• [3].K. Christensen and B. Nordman, Reducing the Energy
Consumption of Networked Devices, IEEE 802.3 tutorial,2005.
• [4]. M. Gupta and S. Singh, Greening of the Internet,
SIGCOMM03: Proc. 2003 Conf. Apps.,
Technologies,Architectures, and Protocols for Computer
Commun.,New York, NY, USA: ACM, 2003, pp. 1926.
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