Energy-Efficient User Association and Beamforming for 5G Fog Radio Access Networks
Résumé
Recently, Fog-RANs have been introduced as the evolution of Cloud Radio Access Networks (CRAN) for enabling edge computing in 5G systems. By alleviating the fronthaul burden for data transfer, transport delays are expected to be greatly reduced. However, in order to support envisioned 5G real-time and delay-sensitive applications, tailored radio resource and interference management schemes become necessary. Therefore, this paper investigates the issues of user scheduling and beamforming for energy efficient Fog-RAN. We formulate the energy efficiency maximization problem, taking into account the local user clustering constraint specific to Fog-RANs. Given the difficulty of this non-convex optimization problem, we propose a strategy where the energy efficient user scheduling is split in two parts: first, we solve an equivalent sum-rate maximization problem, then, the most energy-efficient FogAPs are activated in a greedy manner. To meet the requirement of low computational complexity of FogAPs, local beamforming is performed given fixed user scheduling. Simulation results show that the proposed scheme not only provides similar levels of user rates and fairness, but also largely outperforms the system energy efficiency in comparison with the baseline scheme.