The GNSS performance is significantly degraded in urban canyons because of the signal interferences caused by buildings. Besides the multipath and non-line-of-sight (NLOS) receptions, the diffraction effect frequently occurs in urban canyons, which will severely attenuate the signal strength when the satellite line-of-sight (LOS) transmitting path is close to the building edge. It is essential to evaluate the performance of current diffraction models for GNSS before applying mitigation. The detailed steps of applying the knife-edge model and the uniform geometrical theory of diffraction (UTD) model on GNSS are given, including the and pseudorange simulation of the diffracted signal. The performances of both models are assessed using real data from two typical urban scenarios. The result shows the UTD can adequately model the GNSS diffraction effect even in a complicated urban area. Compared with the knife-edge model, the UTD achieves better modeling accuracy, whereas it requires higher computational loads.

中文翻译：

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城市地区 GNSS 衍射模型的性能评估

由于建筑物引起的信号干扰，城市峡谷中的 GNSS 性能显着下降。除了多径和非视距（NLOS）接收外，城市峡谷中经常出现绕射效应，当卫星视距（LOS）发射路径靠近建筑物时，会严重衰减信号强度边缘。在应用缓解措施之前，必须评估当前 GNSS 衍射模型的性能。给出了刀刃模型和均匀衍射几何理论（UTD）模型在 GNSS 上应用的详细步骤，包括和衍射信号的伪距模拟。两种模型的性能均使用来自两个典型城市场景的真实数据进行评估。结果表明，即使在复杂的城市地区，UTD 也可以充分模拟 GNSS 衍射效应。与刀刃模型相比，UTD 实现了更好的建模精度，但需要更高的计算量。