Optimal CPU Frequency Scaling Policies for Sustainable Edge Computing

Sustainable edge computing (SEC) is a promising technology that can reduce energy consumption and computing latency for the mobile Internet of things (IoT). By collecting solar or wind energy from the environment, an SEC cloudlet outside the electric grid can provide powerful computing capabilities for resource-constrained mobile IoT devices. Considering significant density variation of sustainable energy over time, the SEC cloudlet needs to dynamically adjust the clock frequency of the central processing unit (CPU) to balance energy consumption and computing power. In this paper, we consider the limited energy storage of the cloudlet and develop an offline optimal CPU frequency scaling policy to maximize the overall computing power of the cloudlet within a certain period of time. The tightest string policy that gives a graphical viewpoint of the optimal CPU frequency scaling is found.