User association for green heterogeneous cellular networks with hybrid energy supplies

The exponential increase of wireless services has led to a great amount of energy consumption of base stations (BSs). In this paper, we envision that BSs of future cellular networks are heterogeneous and can be powered by hybrid energy supplies. We study the user association problem for minimizing energy cost in such a green heterogeneous network. The key idea of our proposed algorithm is to reassign users originally associated with on-grid energy powered BSs to green pico BSs or macro BSs to make the best of green energy for energy cost saving. We compare this algorithm with the nearest association scheme, in which users are assigned to their nearest BSs. Simulation results demonstrate that our proposed algorithm can significantly reduce the total energy cost, and maximize the utilization of green energy.