Bidirectional Restricted AP Selection for Cell-Free Massive MIMO Systems

Cell-free massive MIMO systems serve users through geographically distributed access points (APs). However, if all APs provide services to each user, it will result in high power consumption and low energy efficiency. To solve this problem, we propose a user equipment (UE) priority criterion and an AP selection scheme. The criterion requires the system to prioritize serving more important UEs in order of priority. Moreover, a bidirectional restricted method was employed in the AP selection scheme. The outcomes of simulations indicate that the proposed scheme outperforms related works in both spectral efficiency and energy efficiency.