Energy efficient deployment of HetNets: Impact of power amplifier and delay

Exponential growth of capacity demand is making energy efficient cellular network densification an important issue. As a network is dimensioned based on the busy hour capacity demand, a large portion of network capacity remains idle for a big part of the day. Unfortunately, the power consumption of a base station does not scale down proportionally when load decreases. In this paper, a heterogeneous network (HetNet) consisting of macro and micro base station (BS) is considered. In order to save energy, we vary the density of micro BS based on the offered load and divide the load between the two layers in an energy efficient manner. With this scheme, 30% energy saving is achievable. In our analysis, we incorporate the efficiency characteristics of a realistic power amplifier (PA) and energy-delay trade-off. The analysis suggests that efficient power amplifiers and small additional flow transfer delay not only reduce the overall energy consumption but also impact the densification and load sharing in the cellular network. The results of this paper indicate that for energy efficient operation, the configuration of HetNet needs to be dynamic to cope with the temporal variation of capacity demands as well as the load needs to be shared between different layers properly.