Massive multiple-input multiple-output (MIMO) has enabled substantial spatial multiplexing and array gains in real-world systems, while distributed MIMO (D-MIMO) improves macro-diversity over wide areas at the cost of deployment complexity. Repeater-assisted massive MIMO (RA-MIMO) is a lower-cost alternative that can recover key distributed-MIMO advantages. This paper asks whether repeater assistance can also enhance frequency diversity. We study an uncoded discrete Fourier transform-spread orthogonal frequency-division multiplexing (DFT-s-OFDM) uplink with one-tap single-carrier frequency-domain equalization (SC-FDE) based on minimum mean-square error (MMSE) and derive a receiver-matched semi-analytic bit-error rate (BER) expression by averaging over channel and interference realizations, without Gaussian approximation of residual despreading interference. The analysis clarifies how repeater delay reshapes frequency correlation, and waveform simulations confirm tight agreement with the derived expression together with improved high-signal-to-noise ratio (SNR) BER decay, highlighting delay as a practical tuning knob.

翻译：大规模多输入多输出（MIMO）已在真实系统中实现了显著的空间复用和阵列增益，而分布式MIMO（D-MIMO）通过增加部署复杂度提升了广域宏分集性能。中继辅助大规模MIMO（RA-MIMO）作为一种低成本替代方案，可恢复分布式MIMO的关键优势。本文探究中继辅助能否增强频率分集。我们研究采用基于最小均方误差（MMSE）单抽头单载波频域均衡（SC-FDE）的非编码离散傅里叶变换扩展正交频分复用（DFT-s-OFDM）上行链路，通过对信道和干扰实现进行平均（无需对残余解扩干扰进行高斯近似），推导出与接收机匹配的半解析误码率（BER）表达式。该分析阐明了中继延迟如何重塑频率相关性，波形仿真验证了推导表达式的紧密吻合性，并展示了高信噪比（SNR）下BER衰减特性的改善，凸显了延迟作为实用调谐参数的价值。