Network Cooperation for energy saving in green radio

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




System Model



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

5

Outline

Introduction




System Model



Conclusion

6

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

7

Dynamic Planning

• Temporal fluctuations in traffic load

Resources on-off Switching

Radio transceivers of

active BSs Entire BS switch-off

8

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

9

Outline

Introduction




System Model



Conclusion

10

Heterogeneous Medium 11

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

12

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

13

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

14

Outline

Introduction




System Model



Conclusion

15

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 NX x x x x

- channels available in

cellular network BS

active channels

C

cnk

- channels available in

WiMAX network BS

active channels

M

wnk

16

System Model Cont.

• Power Consumption model

Total power consumption of

WiMAX(Cellular) BS

( )w cP P

( )wo coP P

Fixed

component

( )wv cvP P

Variable

component

( )wf cfP P Power consumption of

inactive BS ( )wo coP P Switching cost

17

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/

18

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

19

The Proposed Energy Saving Strategy 20


• 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

21

1 10, ,

1 1

1

1

1

1

max ( ) ( ) (1 )

( / ) / !. .

(( / ) / !)

1, , =

0, otherwise

, 0

=

n

n

n

N N

c n w N n NS J X

n n

S

n u n

SS

n u

s

n

N

NN

n

n

P P P P P P

Ss t n N

S

S C n Nx

N x

x

1

1

, 1,

N

N n

n

J x S M JC


• Large Scale Optimization Problem:

22


10

1

max . ( ) . ( )

( / ) / !. .

(( / ) / !)

n

n

n

n c co cn cv N w wo wn wvS

S

n u n

SS

n u

s

x P P k P x P P k P

Ss t n N

S

• Small Scale Optimization Problem:

23

Performance Evaluation 24

Performance Evaluation Cont. 25

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

26

Performance Evaluation Cont. 27

Outline

Introduction




System Model



Conclusion

28

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

29

30

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.

Documents

Network Cooperation for energy saving in green radio