In this paper our goal is to optimize the energy efficiency (EE) of massive multi-input multi-output (MU-MIMO) systems through Cloud Radio Access Network (C-RAN). First we obtain the maximum energy efficiency with four user association algorithms, named nearest-based user association (NBUA), full user association, multi-candidate RRHs user association (MCRUA), and improved (MCRUA), respectively. Then we consider a multiple-objective optimization approach (MOOP) which is non -convex. Pareto solution using weighted Tchebycheff method is proposed to convert MOOP into equivalent single-objective optimization problem (SOOP). The simulation results show comparisons of the four user association algorithms in which the improved MCRUA achieves higher performance.
This research was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2016R1A2B4012752).