Accurate channel modeling has become critical for evaluating multiple-input multiple-output (MIMO) performance, especially as 5G standardization matures and efforts toward 6G begin. Recent studies within the 3rd Generation Partnership Project (3GPP) have shown that the tapped delay line (TDL) model, currently used for performance testing, fails to capture the spatial propagation characteristics required for realistic MIMO evaluation. To address this limitation, the reduced clustered delay line (rCDL) model has been introduced as a more accurate alternative with manageable computational complexity, thereby enabling practical implementation in test equipment. This work investigates the rCDL through a comparative analysis with the legacy TDL. First, the angular characteristics of both models are examined. Then, their spatial profiles are compared with real-world measurements from a typical commercial deployment. The results reveal clear deficiencies in the TDL and show that the rCDL better matches measured propagation behavior. As a case study, channel state information (CSI) reporting performance is evaluated in single-user MIMO scenarios. The results show that, with appropriate simulation parameter settings, the rCDL enables clear discrimination between low- and high-resolution CSI reporting schemes, unlike the TDL. These findings confirm the relevance of the rCDL model for MIMO performance evaluation and support its use in current and future standardization efforts.

翻译：精确的信道建模对于评估多输入多输出（MIMO）性能已变得至关重要，尤其是在5G标准化日趋成熟且6G研发启动之际。第三代合作伙伴计划（3GPP）内的近期研究表明，当前用于性能测试的抽头延迟线（TDL）模型无法捕捉现实MIMO评估所需的空间传播特性。为应对这一局限，简化簇延迟线（rCDL）模型被提出作为一种更精确且计算复杂度可控的替代方案，从而使其能够在测试设备中实际部署。本研究通过与传统的TDL模型进行对比分析，深入探讨了rCDL模型。首先，检验了两种模型的角域特性。随后，将它们的空间剖面与典型商业部署场景的实际测量数据进行了比较。结果揭示了TDL模型的明显缺陷，并表明rCDL模型能更好地匹配实测的传播行为。作为案例研究，在单用户MIMO场景下评估了信道状态信息（CSI）反馈性能。结果表明，通过适当的仿真参数设置，rCDL模型能够清晰区分低分辨率与高分辨率CSI反馈方案的性能差异，而TDL模型则无法做到这一点。这些发现证实了rCDL模型在MIMO性能评估中的适用性，并支持其在当前及未来标准化工作中的应用。