NETWORK COOPERATION FOR ENERGY SAVING IN GREEN RADIO COMMUNICATIONS - - PowerPoint PPT Presentation

NETWORK COOPERATION FOR ENERGY SAVING IN GREEN RADIO COMMUNICATIONS

Muhammad Ismail and Weihua Zhuang IEEE Wireless Communications – Oct. 2011

Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

2

Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

3

Introduction

• Green Communications Network Design Objectives:
• 1. Reduce the amount of energy consumption by

the networks’ BSs

• 2. Maintain a satisfactory QoS for the users

4

Introduction Cont.

Motivations for Green Radio Communications

Service Provider’s Financial Considerations Environmental Considerations

• Half of annual operating

expenses are energy costs

• Currently, 2% of CO2

emissions from telecom.

• By 2020, 4% of CO2

emissions

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Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

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Energy Saving at Network Level

Solutions for Energy Aware Infrastructure

Renewable Energy Sources Heterogeneous Cell Sizes Dynamic Planning

• Reduce CO2

emissions by using renewable energy

• Reliability issues
• Macro-cells 

Femto-cells

• Balance of

different cell sizes is required

• Exploit traffic

load fluctuations

• Switch off

available resources at light traffic load

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Dynamic Planning

• Temporal fluctuations in traffic load

Resources on-off Switching

Radio transceivers of active BSs Entire BS switch-off

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Dynamic Planning Cont.

• Dynamic planning challenges

Service Provision Guarantee Increase cell radii Relaying mechanism Network cooperation

• Increase

transmission power

• Unreliable for

delay sensitive applications

• Alternately

switch on-off resources

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Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

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Heterogeneous Medium

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Heterogeneous wireless communication network

Heterogeneous Medium Cont.

Potential Benefits of Cooperative Networking

Mobile Users Networks

• Always best

connection

• Multi-homing
• Relaying
• Load balance
• Energy saving

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Proposal

• In this article:
• Employ cooperative networking to achieve energy

saving and avoid dynamic planning shortcomings

• Networks with overlapped coverage alternately

switch on-off: 1. BSs, 2. radio transceivers of active BSs according to call traffic load conditions

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Proposal Cont.

• Develop an optimal resource on-off switching

framework:

• 1. Captures the stochastic nature of call traffic load
• 2. Adapts to temporal fluctuations in the call traffic

load

• 3. Maximize the amount of energy saving under

service quality constraints in a cooperative networking environment

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Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

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System Model

• Cellular/ WiMAX system
• cellular network cells

covered by WiMAX BS

N

• Vector of BSs working modes

in the overlapped coverage area

1 2 1

[ , ,..., , ]

N N

X x x x x





• channels available in

cellular network BS  active channels

C

cn

k

• channels available in

WiMAX network BS  active channels

M

wn

k

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System Model Cont.

• Power Consumption model

Total power consumption of WiMAX(Cellular) BS

( )

w c

P P ( )

wo co

P P

Fixed component

( )

wv cv

P P

Variable component

( )

wf cf

P P

Power consumption of inactive BS

( )

wo co

P P  

Switching cost

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System Model Cont.

• Call traffic and mobility

Assumptions:

• A1. New call arrivals to cell 

Poisson process with mean arrival rate

n

n



• A2. Handoff call arrivals to cell

 Poisson process with mean arrival rate

n

n



• A3. MT dwell time  exponential

distribution with mean

1/

• A4. Call duration  exponential

distribution with mean 1/ 

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The Proposed Energy Saving Strategy

Call Traffic Load Fluctuations

Large Scale Fluctuations Small Scale Fluctuations

{ 1,2,.., } T   24/ T   D { 1,2,.., } D  / D   

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The Proposed Energy Saving Strategy

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The Proposed Energy Saving Strategy

• Decision on BS Working Mode:
• Maximize energy saving
• Minimize the frequency at which BS changes its

working mode from inactive to active

• Achieve acceptable service quality (call blocking

probability)

• Ensure radio coverage in the overlapped area

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1 1 0, , 1 1 1 1 1 1

max ( ) ( ) (1 ) ( / ) / ! . . (( / ) / !) 1, , = 0,

• therwise

, =

n n n

N N c n w N n N S J X n n S n u n S S n u s n N N N n n

P P P P P P S s t n N S S C n N x N x x       

        

                                   

   

1 1

, 1,

N N n n

J x S M JC

 

       



The Proposed Energy Saving Strategy

• Large Scale Optimization Problem:

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The Proposed Energy Saving Strategy

   

 

1 1

max . ( ) . ( ) ( / ) / ! . . (( / ) / !)

n n n

n c co cn cv N w wo wn wv S S n u n S S n u s

x P P k P x P P k P S s t n N S     

  

       



• Small Scale Optimization Problem:

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Performance Evaluation

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Performance Evaluation Cont.

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Performance Evaluation Cont.

WiMAX Cellular 3 Cellular 2 Cellular 1 BS 24.5% 73.13% 48.75% 44.68% % Saving

Table 3. Percentage energy saving without small scale optimization

WiMAX Cellular 3 Cellular 2 Cellular 1 BS 34.45% 74.06% 50.31% 46.33% % Saving

Table 4. Percentage energy saving with small scale optimization

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Performance Evaluation Cont.

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Outline

Introduction Energy Saving at the Network Level The Potentials of Network Cooperation Network Cooperation for Energy Saving System Model The Proposed Strategy Performance Evaluation Conclusion

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Conclusion

• Network cooperation for energy saving on two scales:
• Large scale: networks with overlapped coverage alternately

switch their BSs according to long-term traffic load fluctuations

• Small scale: active BSs switches its channels according to short-

term traffic load fluctuations

• Satisfactory service quality in terms of call blocking and large

percentage of energy saving, ensure radio coverage

• Service quality constraints can be extended to: minimum

achieved throughput for data applications and delay and delay- jitter for video streaming applications

• Incurred cost: synchronization overhead required

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THANK YOU !

For more information please refer to: M.Ismail and W.Zhuang, “Network cooperation for energy saving in green radio communications,” IEEE Wireless Communications, Vol. 18, No. 5, Oct. 2011.