Energy-efficient 5G cloud RAN with virtual BBU server consolidation and base station sleeping

Heterogeneous network (HetNet) deployment where macro cells are overlaid by small cells is considered a de-facto solution for meeting the ever increasing mobile traffic demand in fifth generation (5G) networks. However, deployment of a large number of small cell base stations (BSs) result in considerable increase in HetNet energy consumption. Cloud radio access networks (C-RAN) has been proposed as an energy-efficient architecture that leverages cloud computing technology where baseband processing is performed in virtual baseband units (vBBU) in the BS cloud. In this paper, we address the energy efficiency (EE) optimization problem in the downlink for two-tier heterogeneous C-RAN (H-CRAN) comprising of macro and pico-cells. At the radio side of H-CRAN, a dynamic pico BS switching OFF algorithm based on a utility function is proposed while maintaining coverage and quality of service (QoS). In the cloud side, heuristic approximation algorithms are proposed including simulated annealing (H-CRAN SA) and genetic algorithm (H-CRAN GA) to minimize energy consumption by reducing the number of BBU servers used through vBBU placement. The proposed scheme is compared with distributed long term evolution advanced (LTE-A) Hetnet system and simulation results show that the proposed H-CRAN SA and H-CRAN GA schemes save 48% and 45% of energy on a daily average, respectively while maintaining the required QoS.