This paper considers the uplink of user-centric cell-free massive MIMO (multiple-input multiple-output) systems. We utilize the user-centric dynamic cooperation clustering (DCC) framework and derive the achievable spectral efficiency with two-layer decoding that is divided between the access points and the central processing unit (CPU). This decoding method is also known as large-scale fading decoding (LSFD). The fronthaul signaling load is analyzed and a nearly optimal second-layer decoding scheme at the CPU is proposed to reduce the fronthaul requirements compared to the optimal scheme. We also revisit the joint optimization of LSFD weights and uplink power control and show that the corresponding max-min fair optimization problem can be solved optimally via an efficient fixed-point algorithm. We provide simulations that bring new insights into the cell-free massive MIMO implementation.

翻译：本文审视了无用户中心细胞的大型大型MIMO(多投入多输出产出)系统的上链。 我们使用以用户为中心的动态合作集群框架(DCC),通过在入口点和中央处理单位(CPU)之间划分的两层解码得出可实现的光谱效率。 这种解码方法也被称为大规模脱码(LSFD ) 。 我们分析了前门信号负荷,并提议在CPU实行近乎最佳的二层解码计划,以减少前门需求与最佳计划相比。 我们还重新审视了LSFD重量和上链功率控制的联合优化,并表明相应的最大限度公平优化问题可以通过高效的固定点算法得到最佳的解决。 我们提供模拟,为无细胞大型IMIM的大规模实施带来新的洞察力。