AAalto UniversityComnet

Energy Efficiency Techniques amp Challenges for Mobile Access Networks

Maliha Urooj Jada

Supervisor Jyri Haumlmaumllaumlinen

Work carried out Aalto University Date 19-05-2011

AAalto UniversityComnet

Outline Motivation Research Question Power Efficiency Model for Mobile Access Networks

ndash Equations behind results

ndash Result Analysis

Impact of Femtocells to the WCDMA Network Energy Efficiencyndash Energy Model

ndash Comparison Scenarios

ndash Methodology

ndash Result Analysis

Case Study Idle Mode Feature Requirement in Femtocell Conclusion and Future work

AAalto UniversityComnet

MotivationIn last few years energy efficiency for mobile networks has become

important for both industry and academia Although Mobile networks do not have considerable share in the

overall energy consumption of ndash ICT Sector gtgt Responsible for 2 to 10 of the

world energy consumption However the cellular companies are looking for adequate alternatives that

can improve the energy efficiency reducing energy costs while also improving their corporate image (being environmentally conscious)

With the time new technologies (such as LTE) will be deployed Along with the enhancement in networkrsquos capacity the energy consumption will also increase

Hence there is a need to take an action from now to improve the energy efficiency of existing mobile networks otherwise energy consumption will keep growing in proportion to the increase in peak hour traffic

AAalto UniversityComnet

Energy Saving Aspects in Mobile Networks Research Questions There exists two approaches towards Energy Efficient Mobile Networks

ndash To find apropriate solutions to the energy efficiency challenges for already existing networks

ndash To design future networks from energy (and cost) efficient perspective (Greenfield perspective)

Estimations for the future Telecomrsquos energy consumption admit large variationsndash Also difficulties and uncertainties exist in estimating the potential

savings due to the different methodologies used The largest fraction of energy consumption and accordingly CO2

emmissions occurs in Base Stations The ways to minimize the BS energy consumption

ndash Improvement in BS energy efficiency

ndash Usage of system level and software features

ndash Usage of BS site solutions

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks This work presents a simple Radio Network Power Usage Model

BS Transmission power

ndash Based on the model two different network deployment scenarios have been compared from energy consumption perspective

Aim gtgt To make visible the impact of different link budget and network parameters to the network energy consumption

OtherUEUEBSBSTotal PPNPNP

outTx

OperinTxOperBS

PPPPP

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Outline Motivation Research Question Power Efficiency Model for Mobile Access Networks

ndash Equations behind results

ndash Result Analysis

Impact of Femtocells to the WCDMA Network Energy Efficiencyndash Energy Model

ndash Comparison Scenarios

ndash Methodology

ndash Result Analysis

Case Study Idle Mode Feature Requirement in Femtocell Conclusion and Future work

AAalto UniversityComnet

MotivationIn last few years energy efficiency for mobile networks has become

important for both industry and academia Although Mobile networks do not have considerable share in the

overall energy consumption of ndash ICT Sector gtgt Responsible for 2 to 10 of the

world energy consumption However the cellular companies are looking for adequate alternatives that

can improve the energy efficiency reducing energy costs while also improving their corporate image (being environmentally conscious)

With the time new technologies (such as LTE) will be deployed Along with the enhancement in networkrsquos capacity the energy consumption will also increase

Hence there is a need to take an action from now to improve the energy efficiency of existing mobile networks otherwise energy consumption will keep growing in proportion to the increase in peak hour traffic

AAalto UniversityComnet

Energy Saving Aspects in Mobile Networks Research Questions There exists two approaches towards Energy Efficient Mobile Networks

ndash To find apropriate solutions to the energy efficiency challenges for already existing networks

ndash To design future networks from energy (and cost) efficient perspective (Greenfield perspective)

Estimations for the future Telecomrsquos energy consumption admit large variationsndash Also difficulties and uncertainties exist in estimating the potential

savings due to the different methodologies used The largest fraction of energy consumption and accordingly CO2

emmissions occurs in Base Stations The ways to minimize the BS energy consumption

ndash Improvement in BS energy efficiency

ndash Usage of system level and software features

ndash Usage of BS site solutions

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks This work presents a simple Radio Network Power Usage Model

BS Transmission power

ndash Based on the model two different network deployment scenarios have been compared from energy consumption perspective

Aim gtgt To make visible the impact of different link budget and network parameters to the network energy consumption

OtherUEUEBSBSTotal PPNPNP

outTx

OperinTxOperBS

PPPPP

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

MotivationIn last few years energy efficiency for mobile networks has become

important for both industry and academia Although Mobile networks do not have considerable share in the

overall energy consumption of ndash ICT Sector gtgt Responsible for 2 to 10 of the

world energy consumption However the cellular companies are looking for adequate alternatives that

can improve the energy efficiency reducing energy costs while also improving their corporate image (being environmentally conscious)

With the time new technologies (such as LTE) will be deployed Along with the enhancement in networkrsquos capacity the energy consumption will also increase

Hence there is a need to take an action from now to improve the energy efficiency of existing mobile networks otherwise energy consumption will keep growing in proportion to the increase in peak hour traffic

AAalto UniversityComnet

Energy Saving Aspects in Mobile Networks Research Questions There exists two approaches towards Energy Efficient Mobile Networks

ndash To find apropriate solutions to the energy efficiency challenges for already existing networks

ndash To design future networks from energy (and cost) efficient perspective (Greenfield perspective)

Estimations for the future Telecomrsquos energy consumption admit large variationsndash Also difficulties and uncertainties exist in estimating the potential

savings due to the different methodologies used The largest fraction of energy consumption and accordingly CO2

emmissions occurs in Base Stations The ways to minimize the BS energy consumption

ndash Improvement in BS energy efficiency

ndash Usage of system level and software features

ndash Usage of BS site solutions

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks This work presents a simple Radio Network Power Usage Model

BS Transmission power

ndash Based on the model two different network deployment scenarios have been compared from energy consumption perspective

Aim gtgt To make visible the impact of different link budget and network parameters to the network energy consumption

OtherUEUEBSBSTotal PPNPNP

outTx

OperinTxOperBS

PPPPP

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Energy Saving Aspects in Mobile Networks Research Questions There exists two approaches towards Energy Efficient Mobile Networks

ndash To find apropriate solutions to the energy efficiency challenges for already existing networks

ndash To design future networks from energy (and cost) efficient perspective (Greenfield perspective)

Estimations for the future Telecomrsquos energy consumption admit large variationsndash Also difficulties and uncertainties exist in estimating the potential

savings due to the different methodologies used The largest fraction of energy consumption and accordingly CO2

emmissions occurs in Base Stations The ways to minimize the BS energy consumption

ndash Improvement in BS energy efficiency

ndash Usage of system level and software features

ndash Usage of BS site solutions

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks This work presents a simple Radio Network Power Usage Model

BS Transmission power

ndash Based on the model two different network deployment scenarios have been compared from energy consumption perspective

Aim gtgt To make visible the impact of different link budget and network parameters to the network energy consumption

OtherUEUEBSBSTotal PPNPNP

outTx

OperinTxOperBS

PPPPP

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks This work presents a simple Radio Network Power Usage Model

BS Transmission power

ndash Based on the model two different network deployment scenarios have been compared from energy consumption perspective

Aim gtgt To make visible the impact of different link budget and network parameters to the network energy consumption

OtherUEUEBSBSTotal PPNPNP

outTx

OperinTxOperBS

PPPPP

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Power Efficiency Model for Mobile Access Networks Two comparison scenarios

ndash First scenario The inter-site distance (ISD) is fixed and focus is on power consumption

ndash Second scenario In second scenario the BS transmission power is constant but the ISD is scaled which reflects to the number of BS sites

First scenario is related to the case where operator is updating BSs in an existing deployment while second scenario considers Greenfield operator that is building a new network

Comparison Casesndash Comparing power usage in two different networks (network 1 and network 2) by computing

the ratio between powers that are needed in all BSs in the networks

11

22

BSBS

BSBS

PN

PNR

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

First Scenario Result Analysis The impact of cell edge rate

requirement (TPmin)and outage probability (Prout)are large

Cases 1 (Diamond) amp 2 (Triangle)

ndash TPmin has been doubled wrt reference nw gtgtPower difference is large in case 2 than in 1 because Pout has been decreased in case 2

Cases 3 (Square) amp 4 (Circle)

ndash Improvement in (Weff) BW efficiency and (Γeff) SINR efficiency (reflecting use of multiple antenna)will reduce the effect of Increased rate requirement and decreased outage probability

0 02 04 06 08 1 12 14 16 18 2-1

0

1

2

3

4

5

Ratio between transmission power and power on other operations

Pow

er d

iffer

ence

in c

ompa

red

netw

orks

[dB

]

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Equations behind results

We can compute ע and ratio D1D2

Where PN is the noise power

IM is the interference margin

G is the BS antenna gain

α is parameter that includes impact from carrier freq amp antenna height

β is path loss exponent

σSF is standard deviation for shadow fading

Weff is BW efficiency amp Γeff is SINR efficiency

TP min is the minimum throughput amp Prout is Outage probability

1

10)(Pr1min

10)(Pr1min

1012

1012

1

outQSFeffWW

TP

outQSFeffWW

TP

effMN

outTx

effMN

outTx

IP

GPD

DG

IPP

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Second Scenario Result Analysis Changes in rate and outage

requirement have crucial impact to coverage

Doubling rate requirement on cell edge will lead to approximately one a half fold increase in BS density

If also Pout is halved then two fold increase in BS density is needed

This huge cost source can be reduced by introducing multi-antenna sites

Reference parameters (0562005010)

New parameters Value of R

Case 1 (0562010010) 147 (168dB)

Case 2 (0562010005) 210 (322dB)

Case 3 (0661110010) 097 (-010dB)

Case 4 (0661110005) 139 (144dB)

(Weff Γeff TPmin Prout)

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Impact of Femtocells to the WCDMA Network Energy Efficiency Investigated the potential energy savings by deploying femtocells into a

macrocellular WCDMA network Study utilized WCDMA Downlink load equations Determined gtgt How load sharing between femtocells and macrocells will

contribute to the overall energy consumption of the network by exploiting the Cell Breathing phenomenon

Introduced two comparison scenarios gtgt To estimate how the change in network configurations will effect the energy consumption in the modified network wrt the reference network

Cell Size Breathing At BS noise floor is proportional to load To maintain specific SINR in case of increased noise floor mobile terminals have to move closer to the BS site due to their limited power which effectively shrinks the size of the cell Similarly when load decreases the cell expands outwards

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Energy Model

Dimension gtgt kWhkm2

Area covered by a three sector site A=94R2=ISD2

For accurate calculations we adopt UMTS macrocell BS specific values Poper=137W and PTX=57W (Ref )

For femto BS input power we use two values 2W and 5W (Ref )gtgt To show the difference in energy savings between both ip power cases

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxNew

OperCellNewSite

Ntw

24

24

The daily energy consumption per square kilometer in the network

G Micallef P Mogensen H O Scheck ldquoCell Size Breathing and Possibilities to Introduce Cell Sleep Moderdquo European Wireless Conference p 111-115 2010

Press Release on NEC FP 810 femtocell product 2010 httpwwwslashgearcomnec-fp810-femtocell-tiny-but-14-45-7mbps-data-rates-1073529

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Comparison Scenarios

First Scenario Macrocell ISD is fixed the change in nw energy consumption is estimated when femtocell penetration rate is increasing Addition of femtocells is only visible in macrocell load factor

h

A

PNPPNAE

Site

FFTxNew

OperCellNtw 24

Second Scenario Macrocell ISD is not fixed the addition of femtocells to macrocellular system decreases the macrocell BS density due to cell breathing and thus reduces the energy consumption

hA

PNN

hAN

PPNNAE

Site

FFCell

SiteSite

TxOperCellNewSite

Ntw

24

24

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Methodology To Calculate the daily energy consumption without femtocells

NF Femtocell addition gtgt Femtocells take certain portion of users (Rfx100)

ndash Rf=ratio between femtocell and macrocell connection

ndash Number of macrocell sites decreasinggtgt reducing energy consumption of network

Assumptions gtgt Femto BSs are turned on only when there is traffic

gtgt Each femtocell serves single user Service rate=64kbps Initial system load=09

h

A

PPNAE

Site

TxOperCellNtw 24

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

First Scenario Result Analysis

100Rfemto 0 25 50 75

(EA)M [kWhkm2] 2435 2288 2140 1993

(EA)Total [kWhkm2] PF = 5W 2435 2577 2718 2859

(EA)Total [kWhkm2] PF = 2W 2435 2403 2371 2339

EA decreases in Macrocells when Rf increases

5W femto BS power gtgt Total energy consumption in the network is growing 2W femto BS power gtgt Total energy consumption is slightly decreasing with

additional femtocells

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Second Scenario Result Analysis

Energy consumption by macrocells is rapidly decreasing since lower load allows less dense macrocell grid

Decrease in macro BS density is limited by the non-femtocell users

ndash If network is to be build from scratch then second scenario would be beneficial from energy efficiency perspective

50 femtocell (2W) penetrationgtgt 63 of energy would be saved

50 femtocell (5W) penetrationgtgt 49 of energy would be saved

0 01 02 03 04 05 06 07 08 09 10

5

10

15

20

25

Ene

rgy

cons

umpt

ion

per s

quar

e ki

lom

eter

[kW

h]

Ratio between femtocell and macrocell connections

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Case Study Idle Mode Feature in Femtocell

In second comparison scenario case significant amount of energy savings was observedndash Thus we continued with this case to discuss the importance of designing

a special feature in femtocells gtgt Power Save Feature (Idle Mode) to achieve significant amount of energy savings in network

If femto BSs are activated all the time gtgt Femto BS energy consumption easily overtake the achieved savings on the macrocell sidendash So femto BS should not remain activated if indoor traffic is non-existent

rather should enter sleep modendash Femto BS should have the traffic sensing ability

Addition in Previous methodology gtgt Assume that when femtocell utilized with PS feature any fixed NF remain active throughout Rf scale

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Results Analysis

Energy savings for both types of femtocells (with and without power save feature) having input powers 2W and 5W

Energy Saving is more when deployed femtocell possess power save feature

When Rf ~1 almost same energy is saved in both types of femtocellsThis explains

ndash Femtocells without PS feature are more unfavourable when there is not much indoor traffic

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Case 1 NF=Nusers

ndash With ip power of 2W gtgt Network with femtocells that do not possess PS Feature consumes extra energy (No Energy Saving) until Rf reaches 005

ndash With ip power of 5W gtgt Extra Energy consumed until Rf reaches 02 However this extra energy is more than the extra energy consumed in case of 2W Femto BS

In case of 5W input power this femtocell PS feature is necessarily required

Case 2 NF= 23 x Nusers

ndash Energy Saving gets reduced

Number of Femtocells should be limited

NF(upper bound)=Nusers gtgt Maximum gain in energy saving

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

Conclusions amp Future work

This work discusses the importance of reduction in energy consumption to achieve economic and environmental benefits

It has addressed the possible ways to minimize the energy consumption on the BS sites

Power consumption model is developedgtgt comparisons have been made to show the impact of different link budget and network parameters

Impact of femtocells to WCDMA Network energy efficiency has been discussed along with the importance of idle mode feature in femtocell

Future work To take into account the impact of daily traffic variations in previous work For that

purpose a new performance metrics will be needed To see how the co-ordinated and planned microcellularpicocellularfemtocellular

network extensions would effect the energy efficiency

AAalto UniversityComnet

THANK YOU

AAalto UniversityComnet

THANK YOU