Joint AP Mode Selection and Power Control for Network-Assisted Full-Duplex Cell-Free Massive MIMO

This study examines a network-assisted full-duplex (NAFD) cell-free massive MIMO (CF-mMIMO) system, in which half-duplex access points (APs) simultaneously serve multiple uplink and downlink user equipment (UEs) using the same frequency resources. NAFD technology facilitates full-duplex transmission over existing half-duplex hardware through dynamic scheduling of AP operating modes, resulting in significant improvements in system spectral efficiency (SE). To ensure fairness among all UEs, we aim to maximize the minimum SE across UEs by jointly optimizing the AP operation modes and the uplink and downlink power control of the UEs, which helps mitigate severe cross-link interference for UEs with the lowest SE. We propose a novel joint optimization scheme based on integer linearization techniques to address this strongly coupled mixed-integer non-convex problem and achieve a near-optimal solution. Simulation results demonstrate that our proposed scheme outperforms the benchmark approach, providing a more equitable quality of service throughout the coverage area.