Network-controlled repeaters (NCRs) are a low-cost means to extend coverage and strengthen macro diversity in wireless networks. They operate in real time by amplifying and re-transmitting the incoming signal with only hardware-level delays, without requiring any channel state information (CSI) at the repeater itself. However, their power amplifiers (PAs) generate non-linear distortion that is jointly forwarded with the desired signal and can undermine multiuser performance unless the distortion statistics are exploited. This paper develops a distortion-aware (DA) uplink framework for repeater-assisted massive MIMO (RA-MIMO) under PA non-linearities. We adopt a memoryless third-order polynomial model for the repeater PA and characterize the achievable spectral efficiency (SE) using the Bussgang decomposition. Closed-form expressions are derived for the Bussgang gain matrix and the distortion covariance. We also design a DA combining vector that maximizes the effective signal-to-interference-plus-distortion ratio.

翻译：网络控制中继器（NCR）是一种低成本手段，用于扩展无线网络的覆盖范围并增强宏分集。它们通过实时放大并重传输入信号来工作，仅引入硬件级延迟，无需中继器本身获取任何信道状态信息（CSI）。然而，中继器的功率放大器（PA）会产生非线性失真，该失真与期望信号共同转发，若未利用失真统计特性，可能损害多用户性能。本文针对PA非线性下的中继器辅助大规模MIMO（RA-MIMO）系统，提出了一种失真感知（DA）上行链路框架。我们采用无记忆三阶多项式模型描述中继器PA，并基于Bussgang分解刻画可达频谱效率（SE）。推导得到了Bussgang增益矩阵和失真协方差的闭式表达式，同时设计了最大化有效信号-干扰-失真比（SIDR）的DA合并向量。