LAUSR

Efficient energy utilization to reduce carbon footprint has become a great concern in diverse domains. In cellular mobile communications, using green energy and adopting heterogeneous networks have been recently promoted as a strategic shift for reducing greenhouse gas emission. Considering a green heterogeneous cellular network, this paper studies how to design user association (UA) algorithms for efficient utilization of green energy. We first formulate a constrained total energy cost minimization (ECM) problem and decompose the problem into two components: the UA problem and optimal bandwidth allocation (OBA) problem, which are complementary to each other. Then, an OBA algorithm is proposed to minimize the power consumption of each base station under a given UA scheme. For the UA problem, we propose both a centralized and a distributed UA algorithm to find feasible and near-optimal solutions based on the OBA algorithm, making the efficient utilization of the green energy storage for ECM. Simulations are used to compare our algorithms with the maximum channel gain algorithm and the maximum reference signal received power algorithm that also apply the OBA. Results demonstrate that our algorithms can significantly reduce the total energy cost and improve the efficiency of green energy utilization.