Energy efficiency gains through data offloading in heterogeneous small cell networks

The deployment of so-called small cells is considered to be a prominent solution to the ever increasing mobile data traffic demand and to provide capacity at traffic hot spots effectively. However, overlaying macro base stations will still consume the highest fraction of the network power. In this paper, we study the power consumption and energy efficiency of heterogeneous networks, when large macro base stations offload traffic to more energy-efficient small cells and, thereby, lower their power consumed. In order to evaluate the potential energy efficiency gains utilizing different types of small cells, namely mi-cro, pico, and femto cells, we use a powerful network evaluation framework, which is based on the modeling of flow dynamics of mobile traffic and inter-cell interference conditions. We apply an existing data offloading algorithm to the model of a real deployed Long Term Evolution network and find that utilizing micro, pico, and femto base stations to offload traffic yield similar results with respect to the overall network power consumption. During the course of a day, the power consumption can be reduced by 23.6 % 28.8 % and 24.2 % respectively. However, we observed that micro base stations are much more suitable to serve additional offloaded traffic due to their larger coverage areas, which makes them superior to pico and femto base stations, in particular in terms of total network energy efficiency.