A cell-free Massive multiple-input multiple-output (MIMO) system is considered, where the access points (APs) are linked to a central processing unit (CPU) via the limited-capacity fronthaul links. It is assumed that only the quantized version of the weighted signals are available at the CPU. The achievable rate of a limited fronthaul cell-free massive MIMO with local minimum mean square error (MMSE) detection is studied. We study the assumption of uncorrelated quantization distortion, which is commonly used in literature. We show that this assumption will not affect the validity of the insights obtained in our work. To investigate this, we compare the uplink per-user rate with different system parameters for two different scenarios; 1) the exact uplink per-user rate and 2) the uplink per-user rate while ignoring the correlation between the inputs of the quantizers. Finally, we present the conditions which imply that the quantization distortions across APs can be assumed to be uncorrelated.

中文翻译：

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莱斯衰落和相移下具有本地 MMSE 接收器的有限前传无小区大规模 MIMO


考虑无小区大规模多输入多输出 (MIMO) 系统，其中接入点 (AP) 通过有限容量的前传链路链接到中央处理单元 (CPU)。假设 CPU 处仅提供加权信号的量化版本。研究了具有局部最小均方误差 (MMSE) 检测的有限前传无小区大规模 MIMO 的可实现速率。我们研究了文献中常用的不相关量化失真的假设。我们表明，这种假设不会影响我们工作中获得的见解的有效性。为了研究这一点，我们比较了两种不同场景下不同系统参数的上行每用户速率； 1) 精确的上行链路每用户速率和 2) 上行链路每用户速率，同时忽略量化器输入之间的相关性。最后，我们提出了一些条件，这意味着可以假设 AP 之间的量化失真是不相关的。