Flexible Duplexing Mode Selection Optimization for Network-Assisted Full-Duplex Cell-Free Massive MIMO Systems

Abstract

Network-assisted full-duplex enables simultaneous uplink (UL) and downlink (DL) communications by allocating remote antenna units (RAUs) to perform either UL reception of DL transmission at each time slot, which improve the spectral efficiency (SE) of cell-free massive multiple-input multiple-output (MIMO) systems. However, the previous studies usually fix the duplex mode of RAUs to analyze the system performance. A more flexible duplex technology concerning mode selection of RAUs is introduced to solve the resource allocation problem of CF MIMO systems. RAUs can flexibly adapt UL or DL working mode to utilize the UL/DL resource efficiently. This letter proposed a duplex mode selection algorithm based on parallel successive convex approximation and mathematical transformation skills. Simulation results show that the proposed algorithm achieves a higher SE gain than other traditional schemes with lower complexity.