The energy cost of cellular networks is ever increasing to match the surge of wireless data traffic, and savings in this cost is important to reduce the operational expenditure of wireless operators in the future. Recent advancements in renewable energy integration and two-way energy flow in smart grid provide potential new solutions to save cost. However, they also impose challenges, especially on how to use the stochastically and spatially distributed renewable energy harvested at cellular BSs to reliably supply time- and space-varying wireless traffic over cellular networks.
To overcome these challenges, in this article we present three approaches, energy cooperation, communication cooperation, and joint energy and communication cooperation, in which different BSs bidirectionally trade or share energy via the aggregator in smart grid, and/or share wireless resources and shift loads with each other to reduce the total energy cost.