基于ADC精度与AP选择的去蜂窝系统能效均衡方法

去蜂窝大规模多输入多输出（MIMO）系统通过部署大规模接入点（AP），获得宏分集增益和较低的路径损耗，但产生的大量功耗损失使得系统能效质量失衡。针对去蜂窝大规模MIMO系统与多AP联合协作的能效质量失衡问题，提出一种基于模数转换器（ADC）精度和AP选择的能效均衡方法。利用泊松过程对用户分布进行建模，推导出激活所有AP时频谱效率及能量效率的闭式解，将有效信道与干扰信道增益的占比作为排序指标，通过降序排序的方法获得相应信道方差矩阵索引，按索引对AP集进行逐层筛选，当AP联合服务用户获得频谱效率的变化差值小于阈值时，停止筛选并确定用户间干扰低的AP组合。通过ADC精度与AP选择的联合优化获取最优量化位数，实现系统频谱效率与能效的均衡。仿真结果表明，与全AP选择、基于大尺度衰落的AP选择方法相比，该方法能达到较优的能效质量均衡，尤其在用户密集区域，可提升约20%能效，同时利用最大最小功率控制可保证系统区域一致良好的用户服务质量。

Energy Efficiency Equalization Method of Cell-Free System Based on ADC Precision and AP Selection

Cell-free massive Multiple Input Multiple Output (MIMO) systems achieve macro diversity gain and low path loss owing to the large-scale deployment of Access Points (AP), but the resulting large power loss also leads to an imbalance with respect to system energy efficiency.To address the energy efficiency quality imbalance problem of multi-AP joint cooperation in cell-free massive MIMO systems, this paper proposes an energy efficiency equalization method based on Analog-to-Digital Converter (ADC) precision and AP selection.First, the Poisson process is used to model the user distribution, and the closed-form solutions of spectral efficiency and energy efficiency are derived when all AP are activated.Then, the effective channel and interference channel gain are considered as a kind of indicator to obtain the corresponding channel covariance matrix by using the method of descending order index, step-by-step according to the index of AP set selection. When using the AP service users to determine whether the change in the spectral efficiency difference is less than the threshold, stop filter and determine the AP combination of low interference between users.Finally, through the joint optimization of ADC precision and AP selection, the optimal quantization number is obtained to achieve a balance in terms of the system spectral efficiency and energy efficiency. Simulation results show that compared with the AP selection method based on full AP selection and large-scale fading, the proposed method can achieve a better energy efficiency balance, especially in the user intensive area, which can improve energy efficiency by about 20%.Moreover, the use of max-min power control can further realize good regional consistent user service quality.