Battery aging-aware energy management of green small cells powered by the smart grid

Abstract

Mobile operators are deploying energy-harvesting heterogeneous networks due to their foreseen advantages such as self-sustainable capability and reduced operating expenditure, which cannot be offered by conventional grid powered communications. However, the used energy storage is subject to irreversible aging mechanisms, requiring intelligent management that considers both the energy cost and battery life cycle. In this paper, we propose a cognitive energy management strategy for small cell base stations powered by local renewable energy, a battery, and the smart grid to simultaneously minimize electricity expenditures of the mobile operators and enhance the life span of the storage device. Non-linear battery models and aging processes are considered to formulate the energy cost optimization problem. Simulation results in different configurations show that a degradation-aware policy significantly improves the battery lifetime, while achieving considerable cost savings.

Battery Aging-Aware Green Cellular Networks with Hybrid Energy Supplies

“…Other degradations occur when the battery is at rest, and they are known as calendar aging [8]. Among the few studies that consider the aging of batteries while studying cellular networks powered by RE is [9]. This study shows that by respecting some battery aging constraints, the battery life span can enhance up to 50% of its initial state of health per year.…”

“…cycling), denoted by cycle aging and at rest, denoted by calendar aging [8]. Even though in this paper we do not focus on calculating the battery capacity degradation, we translate the constraints imposed on the battery in [9] to fit our model, in order to minimize the above mentioned degradations. In the following, we summarize the battery constraints used in our work.…”

“…As a result, the lithium battery usage is restricted on a specific range of: 2) Calendar aging: The battery calendar life is the time elapsed until the battery becomes unusable. It is influenced by the battery temperature and time [9]. Thus, in order to operate the lithium battery in a safe operating area restricted to temperature, high (dis)charge currents should be avoided.…”

“…The latter results in a decrease in the operational cost of about 4% compared to BAPA algorithm, after one year. The details of estimating the battery capacity degradations are derived in [9] and are omitted here for brevity. Even though these degradations are pessimistic, they serve as a benchmark to compare the different algorithms.…”

“…In contrast to [9], in this paper we study the case of cellular network where BSs can cooperate under RE and smart grid (SG) environment, while respecting the constraints imposed on the battery that expand its life span. We consider a large-scale cellular network where a percentage of its sites is equipped with local RE and battery storages.…”