Survey on energy harvesting wireless communications: Challenges and opportunities for radio resource allocation

Green radio communications has received a lot of attention in recent years due to its impact on telecom business, technology and environment. On the other hand, energy harvesting communication has emerged as a potential candidate to reduce the communication cost by tackling the problem in a contrasting fashion. While green communication techniques focus on minimizing the use of radio resources, energy harvesting communication relies on environment friendly techniques to generate energy from renewable resources and on effective use of the stored energy under the condition that there is always energy available when required. Thus, the focus migrates from minimization of energy to optimal time domain ‘distribution’ of energy, which causes a paradigm shift in radio resource allocation research. This survey summarizes major research work in the area of energy harvesting resource allocation. Instead of just focusing on the power allocation based on average and maximum power constraints, the random energy arrival process and packet/energy buffering interact in a challenging way to open new research problems. First, we present the fundamental concepts in energy harvesting communications and review recent research work in different wireless network applications. We discuss some quantitative results from the existing literature to explain the state of the art work. The energy cooperation aspect of energy harvesting is addressed in detail which has emerged as an interesting area of research recently. Finally, we conclude by summarizing some open challenges for future research and scope for innovation in this emerging area.