siscom chair inaugural lecture - imt...
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Optics Departmentpage 1
Can photonic network technology
bring broadband access to all and
help save the planet?
Outline
1. GHG Emissions & ICT
2. Energy consumption of ICT
3. Green Fixed Networks
4. Green Mobile Networks
5. Green Photonics
6. Conclusions
Optics Department
Climate Change
page 2 Source : IPCC Fourth Assessment Report, Climate Cha nge 2007
► 15-30% cut in GHG emissions
needed by 2020 to keep
temperature increase under 2°C
►60-80% reduction may
be needed by 2050
We have a problem !
Optics Department
World Energy Today
page 3
Electricity = 30% Primary Energy
CO2 emissions:
1W Electricity = 2.1 W Primary Energy
Source: Mario Pickavet, IBBT – Ghent University ECOC 2008 SymposiumNetwork Solutions to Reduce the Energy Footprint of ICT
Optics Department
ICT Supply Chain
page 4
Electrical Power Sources
Data & Network Centres
Service & Application Providers
Enterprises & Users
Optics Department
Can ICT save the planet?
Virtualisation & Dematerialisation
� SMART 2020 identified savings of 7.8 Gt CO2e that could be delivered by ICT solutions in 2020 : 5X the sector’s footprint, 15% of global emissions
page 5
Source: European Commission Joint Research Centre, “The Future Impact of ICTs on Environmental Sustainability”, August 2004
http://www.smart2020.org/
Optics Department
ICT Emissions
� ICT industry emissions of 830m tons CO2
in 2007 accounted for 2% of global
emissions and is comparable to the
aviation industry.
� ICT is 5th largest industry in terms of
electrical power consumption
• Telecom Italia is the second largest
consumer of electrical power in Italy
after the railway system
� ICT emissions growth is faster than any
other industry sector doubling every 4
years.
Source: An Inefficient Truth, 2007, Global Action Plan
http://www.globalactionplan.org.uk/green-it
page 6
Optics Department
Home networks
page 7Source : Deutsche Telekom
An extreme example of broadband multimedia home networks
Optics Department
Cautions
� Whole Lifecycle Emissions
• GHG emissions from manufacturing & disposal phases of ICT hardware comparable to the use phase
• Reduced “churn” necessary
� Rematerialisation
• Whatever happened to “the paperless office”?
• Paper consumption has increased with the introduction of ICT
� Jevon’s Paradox
page 8
Optics Department
Jevon’s Paradox
� Khazzoom-Brookes postulate: Increased
energy efficiency paradoxically tends to lead
to increased energy consumption.
page 9
Increased energy efficiency by itself is not enough.
Sustainability requires other forms of governmental/legal
intervention.
Source: http://en.wikipedia.org/wiki/Jevons_paradox
Optics Department
France Telecom Network Energy Consumption
page 10
Source : Laetitia Souchon Foll, PhD, Telecom & Management SudParis, 2008
Optics Department
Why does it take so much energy
to move mass-less information?
page 11
“This energy argument suggests that all except the shortest intrachip communications should be optical”
D A B Miller, ‘ Optics for low-energy communication within digital processors: quantum detectors, sources, and modulators as efficient impedance convertors’, Opt. Lett., 14(2), 1989, 146-148.
Optics Department
Retaining Data in the Optical Domain
� Transporting data in the optical domain
• Optical Networks- Replacing copper legacy networks (mainly access) by optical, i.e.
deploying FTTx (e.g. Fibre to the Home : FTTH)
• Optical Interconnections ?- O/E/O conversions are expensive
� Minimising O/E/O conversions
• A “green” optoelectronics challenge : making O/E/O conversions more efficient - Energy consumption of optoelectronic interfaces many orders of
magnitude greater than estimates of fundamental limits
page 12
Optics Department
Data Centres
page 13
Source: C. Randy Giles, ‘GreenTouch: Meeting the Challenge of Energy Usage in the ICT industry’, IWFIPT, Kyoto, 2010
Optics Department
A computer scientist’s dream
� Purchasing green power locally is expensive with high transmission line losses
• Demand for green power within cities expected to grow dramatically
� Data centers
• Cooling is also a major problem in cities
� Most renewable energy sites are very remote and impractical to connect to
electrical grid.
• But can be easily reached by an optical network
• May also meet some of government’s objectives of extending broadband to
rural/remote areas
Data Centres do not need to be located in cities
� Eliminate enterprise servers and move existing business and consumer
applications to clouds and virtual servers at zero carbon data centres
� Eliminate consumer PC and use hand held devices or solar powered devices to
access applications over Internet
• RIM Blackberry or Apple iPhone
page 14
Optics Departmentpage 16
Virtual Relocation : Follow the Sun / Wind
� Opportunistically relocate infrastructure without interrupting user services
� Data is relocated
� Network is automatically
reconfigured to direct traffic
to the new data centre
� Servers and end users keep
the same IP addresses
Virtual Network & Compute
Infrastructure
Optics Department
Packet Switched Networks
page 18
A
B
C
R1
R2
R3
R4 D
E
FR5
Source: Nick McKeown http://yuba.stanford.edu/~nickm/
Optics Departmentpage 19
Router Power Consumption
0
2
4
6
8
10
12
14
16
1990 1993 1996 1999 2002 2003 2004
Pow
er (
kW)
Power Consumption per chassisSource: Nick McKeown 2006
Cisco CRS-1 Router
92 Tbps on 80 Racks
Energy consumption :
Powering ~ 1 MW
Air-conditioning ~ 1MW
Optics Departmentpage 20
Utilisation: capacity dimensioned for peak load
Source : Laetitia Souchon Foll, PhD, Telecom & Management SudParis, 2008
Mean Power
Traffic
Optics Departmentpage 21
Big Routers
Switch Core Linecards
1 2 3 4 5 6 7 8 9 10111213141516
17181920212223242526272829303132
131415161718
192021222324
252627282930
3132
1 2 3 4 5 6
7 8 9 101112
1 2 3 4 5 6 7 8 9 10111213141516
17181920212223242526272829303132
Up to 1000ft
Source: Nick McKeown http://yuba.stanford.edu/~nickm/
Optics Departmentpage 24
Circuit switches control the topology SONET/SDH, DWDM
© Nick McKeown 2006
� Circuit switches are simple- “Start with a packet switch and throw 90% of it away”
� Circuit switches are well-suited to optics
But…
� Circuit switches are unfashionable
Optics Departmentpage 25
Conventional Wisdom
© Nick McKeown 2006
Circuit switching finally eliminated?
Optics Departmentpage 26
Dynamic Circuit Switches
© Nick McKeown 2006
Capacity on demand between edge routers
S. A. Paredes, T. J. Hall, ‘Flexible bandwidth allocation and scheduling in a packet switch with an optical core’, J. Optical Networks. 4 (5), 260-270 (2005), http://www.osa-jon.org/abstract.cfm?URI=JON-4-5-260/
Wei Yang, Sofia A. Paredes, Henry Schriemer, Trevor J. Hall, ‘Protection of Dynamic and Flexible Bandwidth on Demand in Metro Agile All-Optical Ring Networks’, J. Opt. Commun. Netw. 1, 2009, pp. A160-A169
Optics Departmentpage 28
Ubiquitous Wireless Access (Computer Scientist’s Dream)
Source: Vodefone Group PlC
Handsets
►Energy consumption of handsets
negligible in comparison to BS
consumption
► High churn may make manufacturing
/ disposal phase emissions significant?
Base Stations
► Only 5-10% of BS power is useful RF
emission.
► RF Power Amplifier ~ 45% efficient
► Cooling
Fans ~ 10-15% of BS power
Air Conditioning ~ 50% of BS power
Optics Departmentpage 29
Wireless Networks
Cellular Radio
� Provide mobile access to fixed network; backhauling
� Degrees of mobility
� Cellular Networks : handover
� …
Optics Department
Single or multiple antenna coverage ?
Low Density
of High Power transmitters
High Density
of Low Power transmitters
page 30
Multiple antennas offer lower total power for same coverage :
• if greater than 1/R² fall-off in radiated intensity (cluttered environments)
vs
Optics Departmentpage 31
Simulation Results: DAS vs Mono Antenna
•page 31
•Mono-Antenna SystemPropagation Model : DP ; Transmit Power : Pt = 10 dBm (Pout=100%); Antenna: EIRP=-2 dBm ; Channel : 1
•Maximum received Power (dBm) •Maximum Bit-rate (Mbit/s) •DAS
Propagation Model : DP ; Transmit Power : Pt = 1 dBm (Pout=25%) ; Antenna: EIRP=-17 dBm; Channel : 1, 6, 11
•Maximum received Power (dBm) •Maximum Bit-rate (Mbit/s)
Optics Departmentpage 32
Measurement results: DAS vs Mono Antenna
•page 32
•Mono-Antenna SystemPropagation Model : DP ; Transmit Power : Pt = 10 dBm (Pout=100%); Antenna: EIRP=-2 dBm ; Channel : 1
•Maximum received Power (dBm) •Maximum Bit-rate (Mbit/s) •DAS
Propagation Model : DP ; Transmit Power : Pt = 1 dBm (Pout=25%) ; Antenna: EIRP=-17 dBm; Channel : 1, 6, 11
•Maximum received Power (dBm) •Maximum Bit-rate (Mbit/s)
Optics Departmentpage 34
Directional links
� Sending power only where and when needed
• Increased power efficiency
• Increased complexity :- Multiple Target Pointing Acquisition and Tracking needed
Optics Department
Phased Array Radar
Electronic Beam Forming & MIMO
page 35
http://www.microwaves101.com/encyclopedia/phasedarrays.cfm
MIMO : Multiple Input Multiple Output
Optics Department
Two-dimensional optical phased array antenna
on silicon-on-insulator
page 36
Karel Van Acoleyen, Hendrik Rogier & Roel Baets, Optics Express, 18(13), 21 June 2010, pp. 13655-13660
Optics Department
Putting it together
� Broadband Services
• Higher frequency carriers (shorter wavelengths)
� Sophisticated antennas (MIMO)
• Shorter wavelengths for compactness (especially handsets)
� High density of antennas
• Simple remote stations (for low cost)
• Distribute signals from base stations / central stations via a network
• Keep data in the optical domain
� Energy Harvesting
⇒⇒⇒⇒
� Optical feeder network
• Remote powering and/or solar powered remote stations
• Solar powered handsets?
page 37
Optics Department
Radio-over-Fibre Technologies for Wireless Access
page 38 http://departements.telecom-bretagne.eu/optique/research/capilr/
Optical link
Picocell
◄ Pico-cellular wireless coverage with
optimized distribution of RF power in
indoor environments
▲Intelligent Light Poles for the distribution of
wireless services in outdoor environments
Optics Department
Numerous Architectural Options
page 39
• {Analog, Digital}, {BB, IF, RF} transmissions
• Local Oscillator signal distribution
E/O O/E
Central Station Access Point
Mobilef0
Optical fibre
Wireless Path
fRFRF RF
f0
f0
fc=fIF
fc=fRF
fc
BB
data
carrierRF
Baseband-over-Fibre
IF-over-Fibre
RF-over-Fibre Frequency up-down
conversion not required
Frequency up-down
conversion required
(de)modulation
required
Optics Department
Narrow line-width single & multiple frequency
lasers as sources of mm wave carriers
page 40
0.06 nm/°C
Optics Department
Thermoelectric Cooler (TEC)
� Operating frequency of optical devices is
sensitive to temperature.
� A TEC is commonly used to stabilise the
temperature of an optical component.
� A TEC is 5-10% efficient compared to an
ideal reversible heat engine.
� Several Watts of electricity is consumed to
cool devices that inherently dissipate
minimal power in comparison.
page 41
�Share TEC among many devices
�No integratable isolator
� Reference slave to master oscillators
� Locking techniques complex & expensive
�Athermal Design
� Challenging
http://en.wikipedia.org/wiki/Thermoelectric_cooling
Optics Departmentpage 42
Conclusions
� Business as usual in ICT is unsustainable
• Improved energy efficiency is necessary but not enough
• Need zero carbon solutions
� Power resources on demand
� Keep data in the optical domain
� Use (optical) circuit switching in the core banish IP to the edge
� Use optical backhaul for mobile access
� Deploy Radio-over-Fibre for mobile access
� Harvest renewable energy
� Grand challenges
• Directional rather than broadcast (optical) wireless
- Pointing acquisition and tracking?
• Green Optoelectronics
- Eliminate thermoelectric cooling & heating
- Nano-photonics to approach fundamental o-e-o conversion energy
consumption limits?
Optics Department
Can photonic network technology bring broadband
access to all and help save the planet?
� Yes, but paradigm-shifting solutions will be required.
Thank you!
page 43
Optics Departmentpage 44
SISCOM Chair Programme
� Missions & Events
• UK & Scandinavian Mission
• Green Radio over Fibre Workshops
� Joint supervision of students
• PhD student at Telecom Bretagne recruited
� Development of Laser Sources of mm-waves
• Canadian funding approved
� Progress CapilR Radio over Fibre Demonstrator
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