Renewable energy-enabled wireless networks

The introduction of renewable energy sources (RESs) as power supply for communication systems and, for wireless cellular networks in particular, is becoming more and more attractive for a number of reasons. First, the need to reduce network operation costs through energy saving. Second, the interest in bringing cellular communications to areas of the world where the power grid is not developed and/or reliable, or in emergency situations, generates a great interest in off-grid base stations (BSs) that are energy self-sufficient. Finally, the introduction of RES as power supply is a promising way to start responding to the timely issue of Information and Telecommunication Technology (ICT) sustainability. In this chapter, we discuss the technological challenges associated with the introduction of RES-based power supply for wireless networks. Sources like photovoltaic (PV) panels and small wind turbines are the most suited ones for powering cellular access networks, due to their limited size and relatively ease of deployment. However, these sources are intermittent and generate variable amounts of energy not always easy to predict. Network operations require mechanisms and algorithms for deciding the optimal configuration that depends also on consumption and energy availability. Optimality of network operation is not simply performance maximization but becomes also consumption reduction, cost minimization, and emission reduction, through the optimal usage of the locally produced energy. In addition, considerations on the power supply dimensioning will also be presented in this chapter.