Downlink Power Control for Cell-Free Massive MIMO System With Radio Stripes

Radio stripes present a promising fronthaul topology for cell-free massive multiple-input multiple-output systems, enabling seamless connections between the access points (APs) and central processing unit through a single shared cable. In contrast to the traditional star topology, the stripes structure offers a substantial reduction in deployment and maintenance costs, thereby emerging as a more cost-effective and practical solution. However, the distributed arrangement of APs within the radio stripes potentially poses a threat to the overall system performance, particularly if some APs are situated far away from users. To address this issue, we introduce an AP switching technique aimed at enhancing the spectral efficiency of the system. To further improve the system performance, we have formulated a weighted sum-rate maximization problem that takes into account the quality of service of users, the transmit power of APs, and the interference among users. To tackle this problem, a power control algorithm that optimizes the transmit power vector of the active APs has been proposed. Simulation results demonstrate that our proposed method not only enhances the system throughput but also improves the energy efficiency.