Metro is important public transportation in reducing traffic congestion, protecting the environment, and moving more people efficiently. Due to ever-increasing demands on high data rate, and seamless connections of the onboard passengers, millimeter-wave (mmWave) wideband communications are considered as potential options. Therefore, realistic mmWave channel characterization, and modeling are important for the system design, network planning, and performance prediction in metro. In this work, mmWave propagation channel is analyzed, and a hybrid channel model is proposed for inside metro environment. By conducting channel measurement at 26.5-40 GHz, and calibrating ray-tracing (RT) simulations, the propagation mechanisms are revealed, the influence of the objects is found, and principal specular reflected rays are traced. A hybrid ray, and graph channel model is proposed to effectively model the diffuse scattering components by adding scattered points around principle paths traced by RT. The proposed model is validated by measurements at different receiving positions. The analysis of the channel characteristics in power, delay, and angular domains indicates that the hybrid model is appropriate to model multipath propagation in the confined metro train environment, where many objects exist, and reverberation is important.

中文翻译：

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地铁列车毫米波通信的信道表征和混合建模


地铁是减少交通拥堵、保护环境、高效运送更多人的重要公共交通。由于对高数据速率和机上乘客无缝连接的需求不断增长，毫米波 (mmWave) 宽带通信被认为是潜在的选择。因此，真实的毫米波信道表征和建模对于城域系统设计、网络规划和性能预测非常重要。在这项工作中，分析了毫米波传播信道，并提出了适用于地铁内部环境的混合信道模型。通过在 26.5-40 GHz 进行信道测量并校准射线追踪 (RT) 模拟，揭示传播机制，发现物体的影响，并追踪主要镜面反射射线。提出了一种混合射线和图形通道模型，通过在 RT 追踪的主路径周围添加散射点来有效地模拟漫散射分量。所提出的模型通过不同接收位置的测量进行了验证。对功率、延迟和角度域中信道特性的分析表明，混合模型适用于对受限地铁列车环境中的多径传播进行建模，该环境中存在许多物体，并且混响很重要。