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© 2012 Mobile VCE

Green Radio:

Research Advances

Overview

Prof. John S. Thompson and Dr Chadi Khirallah

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© 2012 Mobile VCE

Presentation Overview

Traffic Growth Trends and Energy Challenge

Mobile VCE - Green Radio Project

Green Radio Techniques and Architectures

Green Radio Techniques Integration

Conclusions

Future Work

2

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© 2012 Mobile VCE

13/09/10

Green Radio – (ww.mobilevce.com/green-radio)

3

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© 2012 Mobile VCE

Green Radio

A global industrial perspective on achieving access

network efficiency for wireless communications

Research monitored and steered, and publications

reviewed by industrialists at quarterly progress meetings

4

Program driven by the INDUSTRIAL requirement

$3M – three years (1st June 2009 - )

Funded by 12 companies and government (EPSRC)

Research program defined by industry and academia

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© 2012 Mobile VCE

Green Radio – Goal and Members

By 2012, deliver Energy-Efficient Architectures & Techniques

that achieve a10 to 100-fold reduction in power consumption.

Energy

(Joule/bit)

2009 2010 2011 2012

Target

State-of-the-art

10-100x drop

GR Project

Year

5

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© 2012 Mobile VCE

Research Objectives

6 Architectures: Assess the most energy efficient base

station deployments

Heterogeneous Networks

Relays and Multi-hop

Traffic offload to femto cell or WiFi

Techniques: Develop Innovative Concepts for Energy

Savings in base stations

Improved Amplifier Designs

New Cross-layer protocols

Efficient Scheduling Algorithms

Integration of investigated approaches to provide a

holistic overall view of potential energy savings

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© 2012 Mobile VCE

13/09/10

1. Conventional

Cellular

WLAN

Fixed

Relay

Femto

Cell

Node BContent

Server

Mobile

Relay

2. In-Building

Relay

3. Multi-hop

Relay

4. Heterogeneous

Relay

GR - Optimum Architectures

7

Find the most energy-efficient base station deployments

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© 2012 Mobile VCE

GR Techniques: Power Efficient Hardware

PA & Cooling dominated

overall consumption

Integration PA & Antenna

reduce Feeder losses

Power Efficient

Signal Processing Appropriate

Backhaul

Hardware Integration & Advanced PA Techniques

8

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© 2012 Mobile VCE

Base station – Operational Power Models 9

Need to consider energy-efficiency under: Low Traffic Load: Switch–OFF unused equipment (PA, transceivers, network

connections)

High Traffic Load: Improve energy-efficiency of equipment & advanced traffic

management

Linear BS

models are

good

approximation

but may not

match reality

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© 2012 Mobile VCE

Embodied Energy – Need to Consider It

9kg CO2

4.3kg

CO2

2.6kg

CO2

8.1kg

CO2

Mobile

CO2 emissions per subscriber per year

Operation

Embodied

energy

Base station

Base station:

u Digital, RF hardware

u Feeders, antennas, tower

u Climate control, backhaul

u Installation, delivery, reclamation, packaging

Mobile:

u Semiconductors, PCB

u Plastic housing

u Charger

u Installation, delivery, reclamation, packaging

Embodied energy:

Zero

load RF loading

To

tal

po

we

r

0%

100%

Rated

RF

output

Base station operating power:

Depends on traffic and zero-load power

Operational electricity use

considers traffic-related power and

zero-load power

Embodied energy is a significant

part of total energy use, especially

at the mobile

10

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© 2012 Mobile VCE

Status of Green Radio Project

11 Green Radio project has studied benefits of many

techniques and architectures

Results are measured using Energy Reduction Gains

(ERG) metric:

The percentage of energy saved by the test system,

when compared to a baseline system

ERG = 0% → no energy saving

ERG = 100% → no energy consumption!

Practical → 0%<ERG >100%

ERG = 90% → 10x times reduction

ERG = 99% → 100x times reduction

Green Radio individual techniques ERG = 25 - 60%

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© 2012 Mobile VCE

Register of Technologies (Individual Tech.) 12

GR project :

Studied many

individual concepts

Promising energy

gains (RF and Op)

Methods to assess

techniques

integration 18

60

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© 2012 Mobile VCE

Integration of Techniques

13 GR techniques and architectures and their Individual

Energy Reduction Gains (ERG)

Introduce some promising individual energy-efficient

techniques:

High Traffic load: Antenna, PA and CoMP

Discuss two Integration approaches in GR project

Register of Technology (RF/Operational Energy gains)

13

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Class J Power Amplifiers

Class J Amplifier relies on fundamental and 2nd

harmonic tuning to achieve high efficiency

Two Class - J prototypes are experimentally verified

Narrowband – Efficiency > 70%

Extended bandwidth – Efficiency > 50%

Energy gain ~ 33%

Key Advantages:

Simplified design process

Multiple channels/ standards

supported

Efficiency/linearity maintained

14

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© 2012 Mobile VCE

Efficient Antenna 15

Dielectric power loss is a

dominant factor

Antenna Efficiency -

the ratio of the radiated power to the input power of the antenna

Pradiated

Pdissipated

Pinput

High efficiency - most of the

input power is radiated

Air-substrate

• 95% (narrow- band), 90% (250 MHz LTE),

• energy save 18%

(a) Duroid: high–cost

energy loss (40-50%)

(b) Arlon (c) FR4: low-cost

energy-loss (50-70%)

Dielectric – substrate

simplicity and direct integration with RF

circuits

3-D radiation patterns of co-polarisation measured at 2.4GHz.

Method to

determine

antenna

efficiency

vs.

dielectric

material

Energy

efficiency

depends on

material

and

frequency

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© 2012 Mobile VCE

Coordinated Multi-Point Tx/Rx (CoMP) 16

LTE-A: Rel. 11

Distributed User-location aware MIMO

CoMP yields 60% energy gain (cell-edge)

Multi-cell JT- CoMP → ERG = 0- 80% (%) Baseline Single-cell energy consumption

(mJoule/bit)

• Joint base station transmission

improves cell-edge rates

• CoMP mitigates mutual interference

and uses cooperative diversity gain

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© 2012 Mobile VCE

GR - Integration Approach (I): “Combining Matrix” 17

Simple approach to

analyse existing energy

saving results

Assess which

techniques can be

successfully combined

Yields an estimate of

the potential overall

energy savings

→ Now discuss structure of combining matrix in detail

GR

Techniques

Combining Matrix

Overall Energy

Reduction Gain

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© 2012 Mobile VCE

Techniques Clustering – Combining Matrix High Traffic Load Techniques

Less than Cumulative Benefit

Full Cumulative Benefit

18

Identify techniques that combines

successfully (Cumulative benefit)

Ignore combinations with reduce benefit

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© 2012 Mobile VCE

Techniques Clustering – Combining Matrix

Low Traffic Load Techniques

Techniques Interactions

The Integration of SM and BM or SB techniques yields less

than the cumulative ERGs

Increase in traffic load in active cells that have to handle any

remaining traffic from switch-off cells

In other words SM changes traffic condition from low to high

in active cells

19

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© 2012 Mobile VCE

Estimated Combined ERG - High and Low Traffic Load

Combined ERG

translates to

power reduction

factor of 5-10

fold for high

traffic load and

only 4 fold for

low traffic load

20

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© 2012 Mobile VCE

Macro-only Network Re-deployment - Heterogeneous Networks (LTE-A)

21

Base station (eNB) oHigh pathloss

oHigh Tx Power

(40 W/sector)

Relay Nodes (RN) o Lower pathloss

o Lower Tx Power

(0.2 - 7 W)

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© 2012 Mobile VCE

Techniques Integration + HetNet

High Traffic Load - Combined ERG translates to power

reduction factor up to 12 fold

Low Traffic Load – two bounds • Pessimistic - no techniques Integration power reduction

only 3-4 fold

• Optimistic - with Integration power reduction up to 8-12

fold

22

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© 2012 Mobile VCE

GR Integration Approach (II):

“VCEsim Simulation”

23

Simulation Model

(VCEsim)

GR Techniques

Analytical Model

Overall Energy

Reduction Gain

Simulator allows different concepts to be studied, varying

the cell type, traffic models, user distributions, etc.

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© 2012 Mobile VCE

Results – VCESim Simulator

Re-deployment of macro

eNB energy saving 92%

Fixed deployment macro

eNBs energy saving 75% 24

Energy Gain =

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© 2012 Mobile VCE

Integration Outcomes

25 Both combining matrix and VCEsim approaches

yield similar ERG results

Achieving further energy improvements is very

challenging!

Combined energy gain is very sensitive to

modelling and traffic load assumptions

Different approaches for high load vs. low load

traffic conditions

Energy efficiency gains of 5- 10x are feasible with

current and near future technologies

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© 2012 Mobile VCE

Technology Platforms & Industrial Briefs

Tech Demos: Fibre2Air, PA, Antenna,

Videos: PA, scheduling, Fibre2Air, MechRelay

IBs: PA, Antenna, R-NC, Fibre2Air, WiFi/3G

Platforms: VCEsim, …

Available from: www.mobilevce.com

26 Industry Briefs

Strategic Industry Relevance & Key R&D Advances

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© 2012 Mobile VCE

Conclusions

27

Green Radio project has studied techniques and

architecture concepts

Gains of individual approaches yield typically

25-60% energy reduction gain

Pressing demand for more energy efficient

networks in future

Presented integration solutions to assess overall

improvements – these suggest up to 90-95%

energy reduction gain by combining techniques

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© 2012 Mobile VCE

Challenges and Future Work

Fragmented Not enough! Spectrum Allocation

HetNets Deployments

28

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© 2012 Mobile VCE

29

Flexible Spectrum and High Performance RF

Multi-Radio/Multi-Band

– How many can we juggle?

Multi-Radio –

ONLY a matter of Co-existence!

5 band/ 2 standard 850, 900, 1800, 1900, 2100 MHz GSM /3G

Lots of new bands 33 bands in 3GPP LTE Spec.

GPS, WiFi, Bluetooth, …

Cross-band spectrum

aggregation

Significant RF design issue

Antenna: -Multi-band tuning

-Size (MIMO) at lower frequency

Power amplifier - Broadband power match

RF filter/duplexer - Adjacent channel rejection/

suppression in Tx and Rx

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© 2012 Mobile VCE

Thank you

Further information contact:

Dr Chadi Khirallah

E-mail: c.khirallah@ed.ac.uk

WWW: www.mobilevce.com

www.mobilevce.com

© 2012 Mobile VCE

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31

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