ABSTRACT
Traditional efforts for saving energy in cellular networks focus on reducing the transmit powers of base stations (BSs) and mobile devices. However, when a BS is in its working mode, studies show that more than 50% of the energy consumed is due to circuit processing, air conditioning, and other factors [1]. In addition to the growing awareness of energy-efficient wireless networks and their environmental benefits, electricity bills have become a significant cost factor for mobile
7.1 Introduction .......................................................................................................................... 143 7.2 Background/Related Work ................................................................................................... 145
7.2.1 Overview of Cooperative P2P Communications ...................................................... 145 7.2.2 Overview of Green Cellular Communications ......................................................... 146 7.2.3 Chapter Novelty ........................................................................................................ 147
7.3 System Model ....................................................................................................................... 148 7.3.1 Rate Calculations and Channel Model ..................................................................... 148
7.4 Energy-Efficient Clustering Approach for D2D Communications ....................................... 150 7.4.1 Single-Cell System Model with D2D Communications ........................................... 150 7.4.2 Energy Calculations .................................................................................................. 151 7.4.3 Cooperative Cluster Formation Method ................................................................... 152
7.5 Green Approach for LTE Cellular Networks ....................................................................... 153 7.5.1 Multicell System Model for Green LTE Networks ................................................... 153 7.5.2 Admission Control and Resource Allocation ........................................................... 154 7.5.3 Utility Calculation .................................................................................................... 154 7.5.4 Green Communication Method ................................................................................ 154
7.6 Joint Approach: Interplay between D2D Collaboration and Green Cellular Networks ....... 155 7.7 Results and Discussion ......................................................................................................... 157 7.8 Future Research Directions .................................................................................................. 159 7.9 Conclusion ............................................................................................................................ 161 Acknowledgment ........................................................................................................................... 161 Author Biographies ........................................................................................................................ 161 References ...................................................................................................................................... 162
operators [2]. This trend in reducing energy consumption and ensuring green wireless networks is supported by political and national initiatives, which are beginning to put requirements on lowering the CO2 emissions. For example, the European Commission research project EARTH concentrates on energy efficiency in radio access networks with the goal of finding solutions and concepts that can reduce energy consumption of mobile broadband systems by 50% [3]. An effective approach to save energy in wireless networks is to completely turn off selected BSs when the traffic load becomes light (e.g., see Refs. [4-7]).
