Energy efficiency in 5G access networks: Small cell densification and high order sectorisation

In this paper we evaluate the energy efficiency of a 5G radio access network (RAN) based on LTE technology when comparing two small cell deployment strategies to enhance the RAN capacity. Specifically, we compare densifying a 3-sector macrocell RAN with small cells against first upgrading to a 6-sector macrocell RAN before densifying with small cells. The latter strategy has been used in urban areas by 4G network operators. The energy consumption gain (ECG) is used as a figure of merit in this paper. The radio base station power consumption is estimated by using a realistic power consumption model. Our results show that deploying a small cell overlay in a 3-sector macrocell RAN is more energy efficient than deploying a small cell overlay in a 6-sector macrocell RAN even though the latter uses fewer small cells. Further energy savings can be achieved by implementing an adaptive sectorisation technique. An energy saving of 25% is achieved for 6-sectors when progressively decreasing the number of active sectors from 6 to 1 in accordance with the temporal average traffic load. Irrespective, the 3-sector option with or without incorporating the adaptive sectorisation technique is always more energy efficient.