The future 5G networks are expected to use millimeter wave (mmWave) frequency bands to take advantage of the large unused spectrum. However, due to the high path loss at mmWave frequencies, coverage of mmWave signals can get severely reduced, especially for non-line-of-sight (NLOS) scenarios as mmWave signals are severely attenuated when going through obstructions. In this work, we study the use of passive metallic reflectors of different shapes/sizes to improve 28 GHz mmWave signal coverage for both indoor and outdoor NLOS scenarios. We quantify the gains that can be achieved in the link quality with metallic reflectors using measurements, analytical expressions, and ray tracing simulations. In particular, we provide an analytical model for the end-to-end received power in an NLOS scenario using reflectors of different shapes and sizes. For a given size of the flat metallic sheet reflector approaching to the size of the incident beam, we show that the reflected received power for the NLOS link is the same as line-of-sight (LOS) free space received power of the same link distance. Extensive results are provided to study the impact of environmental features and reflector characteristics on NLOS link quality.

中文翻译：

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使用无源反射镜增强NLOS mmWave链接的覆盖范围

预计未来的5G网络将使用毫米波（mmWave）频带来利用大量未使用的频谱。但是，由于毫米波频率处的高路径损耗，毫米波信号的覆盖范围会大大减少，尤其是对于非视线（NLOS）场景，因为毫米波信号在穿过障碍物时会严重衰减。在这项工作中，我们研究了使用不同形状/尺寸的无源金属反射器来改善室内和室外NLOS场景的28 GHz mmWave信号覆盖率。我们使用测量，解析表达式和光线跟踪模拟，对使用金属反射器的链路质量可以实现的增益进行量化。特别是，我们提供了使用不同形状和大小的反射器的NLOS情况下端到端接收功率的分析模型。对于给定尺寸的接近入射光束尺寸的平面金属薄板反射器，我们表明NLOS链路的反射接收功率与同一链路的视线（LOS）自由空间接收功率相同距离。提供了广泛的结果来研究环境特征和反射器特性对NLOS链路质量的影响。