Energy Savings in 3G Using Dynamic Spectrum Accessand Base Station Sleep Modes

Tiago Gouveia e Cunha

Thesis to obtain the Master of Science Degree in

Electrical and Computer Engineering

Supervisors:

Prof. Antnio Jos Castelo Branco Rodrigues

Prof. Pedro Manuel de Almeida Carvalho Vieira

Examination CommitteeChairperson: Prof. Fernando Duarte Nunes

Supervisor: Prof. Antnio Jos Castelo Branco RodriguesMembers of the Committee: Prof. Antnio Joo Nunes Serrador

Eng. Nuno Oliveira e Silva

October 2014

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To my Parents

"Chose a job you love, and you will never have to work a day in your life."

- Confucius

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Acknowledgments

Finishing this work marks a very important chapter of my life and is the culmination of years

of work and devotion. Surely that I couldnt get here alone and you have contributed for the

success over the course and this particular work. It is now time to give the proper tribute that

you deserve.

A friend once told me that for the success of a work like this, you must have a supervisor

whose way of work combines with your own. Not only I had the luck to develop a work on a

subject that I find extremely interesting (Mobile Communications) as I had a word to say in

which direction to go (Energy Savings). That liberty and autonomy that was given to me made

the global work extremely motivating. Therefore, for all of this, as well as for all the support

and feedback given, I would like to express my gratitude to my supervisor, Professor Antnio

Rodrigues and to my co-supervisor Professor Pedro Vieira.

Meanwhile, the interest demonstrated by CELFINET in this subject, specifically by the Eng.

Luis Varela and by the Eng. Nuno Oliveira e Silva gave me the opportunity to integrate a highly

dynamic team and to continue developing the work in a casual an pleasant environment with

all the help and support from a highly skilled set of people, which proved to be priceless for the

success of the work. I also would like to thank to Eng. Andr Martins for all the assistance

and encouragement during all the work stages and to Eng. Nuno Fernandes for providing all the

network statistics.

To all my friends from Setbal, from Tcnico and from the TEIA whose company and moti-

vation made me get here and provided me all the support and strength to successfully achieve

another goal in my life. As one of my favorite poet/composer, Vinicius de Moraes would say:

"Eu poderia suportar, embora no sem dor, que tivessem morrido todos os meus amores, mas

enlouqueceria se morressem todos os meus amigos!"

Finally my most sincere gratitude goes to my family. If today I am in this position is

undoubtedly because of you. An huge thank you for the premium education that you provided

me. All that I am today, that I will achieve, and all that I will ever be I owe that to you.

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Resumo

O consumo energtico e a eficincia energtica so factores cruciais para a sustentabilidade

da indstria de telecomunicaes mveis. Esta Dissertao de Mestrado pretende avaliar a pos-

sibilidade de reduo do consumo energtico nas Estaes Base atravs da adoo de modos

de suspenso destas durante perodos do dia de baixa utilizao de recursos, recorrendo com-

pensao de cobertura e capacidade assegurada pela co-localizao de banda(s) de frequncia

adicionais. O mtodo proposto recorre Alocao Dinmica de Espetro (DSA) como forma de

realocar os utilizadores durantes os perodos de baixo trfego, mantendo a Qualidade de Servio

(QoS). Como dados de entrada para o algoritmos desenvolvido, usaram-se estatsticas de rede

reais, de uma Operadora de Telecomunicaes Mveis Portuguesa. Ficou provado que, utilizando

o mtodo proposto, possvel obter poupanas energticas na ordem dos 43%, o que corresponde

a uma reduo anual de e600 em custos energticos, por cada site, o que se traduziria numa

poupana de mais de 1.25 milhes de euros, considerando uma topologia de rede semelhante

da operadora mvel nacional analisada.

Palavras-chave: Poupana Energtica, Modo de Suspenso de Estaes Base, AcessoDinmico de Espetro, Green Communications.

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Abstract

The energy consumption and energy efficiency of mobile telecommunication networks are

crucial factors for the sustainability of this industry. This paper targets the reduction of the

energy consumption at a Base Station level through the adoption of sleep modes during the off-

peak periods of the day and relying in the existence of co-located and overlaid frequency bands

to provide the coverage and capacity backup for the switched-off cells. It relies on the Dynamic

Spectrum Allocation (DSA) method to opportunely relocate users during the low-load periods

while maintaining the service quality of service (QoS). For the input data, real traffic statistics

were used. Using this strategy and the proposed algorithm it was possible to achieve savings

of about 43% corresponding to a reduction of over e600 of yearly energy costs per-site. The

results were furthered to the study of a Portuguese mobile operator case and it was concluded

that savings of more than 1.25 million euros were easily achieved.

Keywords: Energy Saving; Base Station sleep modes; green communications, cognitivemulti-band operation, dynamic spectrum access.

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Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Resumo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvi

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii

List of Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii

1 Introduction 1

1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 Work Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 Further Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Basic Concepts 5

2.1 WCDMA - UMTS Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.1 System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.2 Radio Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.3 Handover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1.4 Frequency Bands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.1.5 Performance Analysis & QOS . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Key Performance Indicators (KPI) . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.2.1 KPI Categories in a UTRAN network . . . . . . . . . . . . . . . . . . . . 13

2.3 Channel Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.3.1 CE in HSDPA and EUL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.3.2 Traffic Mix Handing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.3.3 CE Dimensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.4 Energy Saving in Mobile Networks . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.4.1 Power Saving Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

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2.5 Mobile Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.1 Daily Traffic Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.6 Base Station Power Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.7 State-of-the-Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3 Energy Saving Algorithm 37

3.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.1.1 The Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

3.1.2 Simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2 Input Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2.1 NodeB Mapping File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.2.2 KPIs File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

3.2.3 Power Statistics File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.2.4 Baseband Pool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

3.3 Parameters Import . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.3.1 Data Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.4 Data Consolidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.4.1 Eligibility Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.4.2 Data Parsing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

3.5 Preliminary Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . .