User association based on Cobb-Douglas function in HetNets with hybrid energy sources

In the wireless cellular networks, energy harvesting is a promising green technology to utilize the renewable energy obtained from the environment. Terminals can utilize the renewable energy to save on-grid power and reduce carbon emissions. This paper investigates the user association problem in heterogeneous networks with hybrid energy sources, where all the BSs are powered by on-grid power and renewable energy. The Cobb-Douglas production function is first introduced to formulate a user association problem under a flow-level traffic model, where the weight can be changed to achieve different tradeoffs. Then a low complexity distributed algorithm implemented by user and base station side is proposed, which can converge to the global optimal solution. Simulation results demonstrate that the proposed algorithm can utilize the renewable energy efficiently, and enable flexible tradeoffs by adjusting the weight value.