Stochastic queue modeling and key design metrics analysis for solar energy powered cellular networks

There is a growing interest around the world in supplying cellular networks with renewable energy, e.g., solar, wind, and hydro, to reduce carbon footprints. One of the most challenging topics is how to design a reliable and efficient renewable energy powered cellular system, which consists of the energy harvesting part, the energy buffer part and the energy consumption part. Motivated by the open issue, we provide a theoretical basis for modeling and key design metrics definition and analysis of the solar energy powered small cells in Hetnet, which will be widely deployed in LTE(-A) networks. Firstly, the energy flow behavior of solar powered small cells is modeled by using the stochastic queue model, and then dynamics of the constructed model is analyzed mathematically. Secondly, three key design metrics, service outage probability (SOP), renewable energy utilization efficiency (REUE) and Mean depth of discharge (MDoD), are defined, and then closed-form expressions of them are derived. Through numerical analysis with measured data of the solar radiation and temperature, the design metrics under different conditions are illustrated vividly, and the optimal design limit is provided. The proposed modeling method and key design metrics provide a theoretical basis for actual designs of solar energy powered small cells, which also can be further applied to the scenario of other forms of renewable energy powered small cells.