Adaptive Cell Range Expansion for Energy Cost Saving in Heterogeneous Cellular Networks with Hybrid Energy Supplies

The exponential growth of wireless service has led to a great amount of energy consumption on base stations. In this paper, we envision that base stations of future cellular networks are heterogenous and can be powered by hybrid energy supplies: on-grid energy and green energy. And the unit cost of green energy can be much less than that of on-grid energy. We study the energy cost saving problem and propose an adaptive range expansion algorithm in such a green heterogeneous network. The key idea of our proposed algorithm is to adaptively set the biasing factor for each pico BS according to the estimated energy drain ratio to make more utilization of the green energy for energy cost saving. We compare the proposed algorithm with the max-RSRP algorithm and the conventional range expansion algorithm with an identical biasing factor for all pico BSs. Simulation results demonstrate that our proposed algorithm can significantly reduce the total energy cost.