User Association for Energy Balancing in HetNets with Hybrid Energy Sources

Driven by the energy consumption concerns, renewable energy harvesting is introduced to reduce the energy demand from the traditional power grid. As a key technology of wireless communications, heterogeneous networks can achieve the spectrum and energy efficiency by deploying various low transmit power base stations, which provide an ideal scenario to utilize the renewable energy harvesting to supply power for the base stations. This paper investigates the user association problem in the heterogeneous networks with hybrid energy sources, where all the base stations are powered by grid and renewable energy. The user association problem is first formulated for utility proportional fairness, aiming to achieve the energy balancing. Then an iterative algorithm operated by the users and base stations is proposed, which can converge to the global optimal solution. Simulation results demonstrate that the proposed algorithm can reduce the on-grid power consumption and achieve a flexible energy balancing.