A framework for energy efficient control in heterogeneous cloud radio access networks

The exponential growth in the mobile data traffic promotes the evolution of the infrastructure, while takes grate challenges for designing 5G network, such as significant amount of energy consumption and expenses, huge complexity on operation and lack of flexibility on management. Software defined network (SDN) and cloud computing are the two promising technologies for the future network due to their advantages in simplicity and efficiency in operation. Heterogeneous cloud radio access network (H-CRAN) architecture is characterized by the attributes of both SDN and cloud computing, which brings significant improvements on system performance. while the intra-tier interference among remote radio units (RRHs) especially the inter-tier interference between RRHs and high power node (HPN) affect the spectral efficiency (SE) and energy efficiency (EE) performance. To mitigate the inter-tier interference and improve system performance of H-CRANs, the interference coordination technology is considered. In this paper, the transmit power for RRHs and HPNs are optimized to maximize system EE. The optimization problem with total allowed power constrains is developed. To deal with the non-convexity, based on the Dinkelbach method and the duality gap theorem, an equivalent convex problem is transformed. Through the dual decomposition method, the optimal power allocation for RRH and HPN are derived. Numerical results show that the proposed scheme can improve the EE of H-CRANs compared with the comparison scheme.