Green communications is a very hot topic. As mobile networks evolve in terms of higher rates/throughput, a consequent impact on operating costs is due to (aggregate) network energy consumption. As such, design on 4G networks and beyond have increasingly started to focus on `energy efficiency' or so-called 'green' networks. Many techniques and solutions have been proposed to enhance the energy efficiency of mobile networks, yet no book has provided an in-depth analysis of the energy consumption issues in mobile networks nor has detailed theories, tools and solutions for solving the energy efficiency problems.

This book presents the techniques and solutions for enhancing energy efficiency of future mobile networks, and consists of three major parts. The first part presents a general description of mobile network evolution in terms of both capacity and energy efficiency. The second part discusses the advanced techniques to green mobile networks. The third part discusses the solutions that enhance mobile network energy efficiency as well as provides future directions. Whilst the reader is expected to have basic knowledge of wireless communications, the authors present a brief introduction of the evolution of mobile networks, providing the knowledge base for understanding the content of the book. In addition, complicated network problems are illustrated using simple examples. This will help the reader understand the concept and intuition of various techniques and solutions.

• Incorporates the latest research results from both academia and industry, providing an up-to-date overview of existing technologies and solutions on making mobile networks greener

• Consists of three sections with a gradually increasing technical depth on green mobile networks, providing the reader with a systematic view of the research area, and helping those with different technical backgrounds to better understand the content
• Covers existing enabling technologies for green mobile networking, including an innovative discussion of state-of-the-art solutions and algorithms

Nirwan Ansari, New Jersey Institute of Technology, USA

Tao Han, University of North Carolina at Charlotte, USA

Preface ix

List of Abbreviations xi

Part I Green Mobile Networking Technologies 1

1. Fundamental Green Networking Technologies 3

1.1 Energy Efficient Multi-cell Cooperation 3

1.2 Heterogeneous Networking 4

1.3 Mobile Traffic Offloading 6

1.3.1 Infrastructure Based Mobile Traffic Offloading 7

1.3.2 Ad-hoc Based Mobile Traffic Offloading 7

1.3.3 User-BS Associations in Heterogeneous Mobile Networks 7

1.4 Device-to-Device Communications and Proximity Services 8

1.5 Powering Mobile Networks With Renewable Energy 9

1.6 Green Communications via Cognitive Radio Communications 9

1.7 Green Communications via Optimizing Mobile Content Delivery 11

2. Multi-cell Cooperation Communications 15

2.1 Traffic Intensity Aware Multi-cell Cooperation 15

2.1.1 Cooperation to Estimate Traffic Demands 17

2.1.2 Cooperation to Optimize Switching Off Strategy 18

2.2 Energy Aware Multi-cell Cooperation 19

2.3 Energy Efficient CoMP Transmission 19

2.3.1 Increasing Energy Efficiency for Cell Edge Communications 19

2.3.2 Enabling More BSs Into Sleep Mode 22

2.4 Summary and Future Research 22

2.4.1 Coalition Formation 23

2.4.2 Green Energy Utilization 24

2.4.3 Incentive Mechanism 24

2.5 Questions 24

3. Powering Mobile Networks with Green Energy 25

3.1 Green Energy Models: Generation and Consumption 25

3.1.1 Green Power Generation 25

3.1.2 Mobile Network Energy Consumption 25

3.2 Green Energy Powered Mobile Base Stations 26

3.2.1 Green Energy Provisioning 26

3.2.2 Base Station Resource Management 27

3.3 Green Energy Powered Mobile Networks 28

3.3.1 Off-Grid Green Mobile Networks 29

3.3.2 On-Grid Green Mobile Networks 30

3.3.3 Mixture of Green Base Stations and Grid Powered Base Stations 31

3.4 Summary 32

3.5 Questions 32

4. Spectrum and Energy Harvesting Wireless Networks 33

4.1 Spectrum Harvesting Techniques 33

4.1.1 Energy Efficiency in Spectrum Harvesting Networks 34

4.1.2 Enhancing Energy Efficiency Through Spectrum Harvesting 39

4.2 Energy Harvesting Techniques 44

4.2.1 Green Energy Harvesting Models 44

4.2.2 Green Energy Utilization and Optimization 46

4.2.3 Cognitive Functionalities in Energy Harvesting 47

4.3 FreeNet: Spectrum and Energy Harvesting Wireless Networks 50

4.3.1 FreeNet Application Scenarios 51

4.3.2 Dynamic Network Architecture Optimization 53

4.3.3 Communication Protocol Suite Design 57

4.4 Summary 58

4.5 Questions 58

Part II Green Mobile Networking Solutions 59

5. Energy and Spectrum Efficient Mobile Traffic Offloading 61

5.1 Centralized Energy Spectrum Trading Algorithm 63

5.1.1 System Model and Problem Formulation 64

5.1.2 A Heuristic Power Consumption Minimization Algorithm 67

5.2 Auction-Based Decentralized Algorithm 70

5.2.1 An Auction-Based EST Scheme 72

5.3 Performance Evaluation 81

5.3.1 Centralized Energy Spectrum Trading Algorithm 81

5.3.2 Auction-Based Decentralized Algorithm 87

5.4 Summary 90

5.5 Questions 90

6. Optimizing Green Energy Utilization for Mobile Networks with Hybrid Energy Supplies 91

6.1 Green Energy Optimization Scheme for Mobile Networks With Hybrid Energy Supplies 91

6.1.1 System Model and Problem Formulation 93

6.1.2 Problem Formulation 95

6.1.3 The GEO Algorithm 99

6.1.4 Performance Evaluation 106

6.2 Optimal Renewable Energy Provisioning for BSs 110

6.2.1 Related Work on Provisioning the Green Power System 111

6.2.2 System Model and Problem Formulation 112

6.2.3 The Green Energy Provisioning Solution 116

6.2.4 Performance Evaluation 123

6.3 Summary 128

6.4 Questions 128

7. Energy Aware Traffic Load Balancing in Mobile Networks 129

7.1 Traffic Load Balancing in Mobile Networks 129

7.2 ICE: Intelligent Cell brEathing to Optimize the Utilization of Green Energy 131

7.2.1 Problem Formulation 132

7.2.2 The ICE Algorithm 133

7.2.3 ICE Algorithm Performance 135

7.3 Energy- and QoS-Aware Traffic Load Balancing 138

7.3.1 System Model and Problem Formulation 139

7.3.2 vGALA: A Green Energy and Latency Aware Load Balancing Scheme 144

7.3.3 Properties of vGALA 147

7.3.4 The Practicality of the vGALA Scheme 152

7.3.5 The Admission Control Mechanism 154

7.3.6 Performance Evaluation 155

7.4 Energy Efficient Traffic Load Balancing in Backhaul Constrained Small Cell Networks 165

7.4.1 System Model and Problem Formulation 166

7.4.2 Network Utility Aware Traffic Load Balancing 171

7.4.3 Performance Evaluation 176

7.5 Traffic Load Balancing in Smart Grid Enabled Mobile Networks 185

7.5.1 System Model and Problem Formulation 189

7.5.2 An Approximation Solution 191

7.5.3 Performance Evaluation 197

7.6 Summary 200

7.7 Questions 201

8. Enhancing Energy Efficiency via Device-to-Device Proximity Services 203

8.1 Energy Efficient Cooperative Wireless Multicasting 205

8.1.1 System Model and Problem Formulation 205

8.1.2 Gradient Guided Algorithm 206

8.1.3 Performance Evaluation 207

8.2 Green Relay Assisted D2D Communications 212

8.…