Optimal energy and spectrum sharing for cooperative cellular systems

Powered by renewable energy sources, cellular communication systems usually have different traffic loads and resource availabilities over time. It is helpful for two neighbouring systems to cooperate in resource sharing when one is excessive in one resource (e.g., spectrum), while the other is sufficient in another resource (e.g., energy). In this paper, we propose a joint energy and spectrum sharing scheme between different cellular systems to save their operational costs. When the two systems are fully cooperative (e.g., belonging to the same entity), we formulate their cooperation problem to minimize the weighted sum cost as a convex optimization problem and obtain its closed-form optimal solution. We also study another partially cooperative scenario where the two systems have their own interests. We show that the two systems seek for partial cooperation when they find complementarity between the spectrum and energy resources. Under the partial cooperation conditions, we propose a distributed algorithm for the two systems to gradually and simultaneously reduce their costs from a non-cooperation benchmark to the Pareto optimum. This distributed algorithm also takes fairness into consideration, by reducing each system's cost proportionally. Finally, numerical results are presented to demonstrate the improvement made by our proposed schemes.