标题： GNSS直接定位估计中的多路径误差传播几何图谱 显示英文标题

标题： Geometrical portrait of Multipath error propagation in GNSS Direct Position Estimation

摘要： 直接定位估计（DPE）是一种从全球导航卫星系统（GNSS）信号的交叉模糊函数（CAF）中直接估计位置、速度和时间（PVT）信息的方法，在城市环境中显著增强了接收机的鲁棒性。然而，在DPE理论背景下，对多路径误差的理论表征仍然不足。几何观测表明，DPE误差在多路径和热噪声作用下分别表现出估计偏差和方差的特性。通过几何分析扩展DPE噪声方差的理论框架，本文重点通过量化由于相对于方位角和仰角的偏心偏差引起的CAF和PVT解的偏差，来建立多路径误差的几何表示。引入了一个卫星圆周多路径偏差（SCMB）模型，融合了多个卫星信道的CAF和PVT误差。通过讨论各种多路径条件，建立了最大或最小PVT偏差的边界。通过蒙特卡洛仿真和城市峡谷测试验证了多路径几何图景的正确性。研究结果表明，最大PVT偏差取决于各个卫星信道中观察到的最大多路径误差。此外，PVT偏差随着卫星仰角增加，受CAF多路径偏差投影的影响。这为从几何角度选择DPE卫星提供了参考，强调了选择高仰角和低仰角的平衡组合以实现最佳卫星几何配置的重要性。 显示英文摘要

摘要： Direct Position Estimation (DPE) is a method that directly estimate position, velocity, and time (PVT) information from cross ambiguity function (CAF) of the GNSS signals, significantly enhancing receiver robustness in urban environments. However, there is still a lack of theoretical characterization on multipath errors in the context of DPE theory. Geometric observations highlight the unique characteristics of DPE errors stemming from multipath and thermal noise as estimation bias and variance respectively. Expanding upon the theoretical framework of DPE noise variance through geometric analysis, this paper focuses on a geometric representation of multipath errors by quantifying the deviations in CAF and PVT solutions caused by off-centering bias relative to the azimuth and elevation angles. A satellite circular multipath bias (SCMB) model is introduced, amalgamating CAF and PVT errors from multiple satellite channels. The boundaries for maximum or minimum PVT bias are established through discussions encompassing various multipath conditions. The correctness of the multipath geometrical portrait is confirmed through both Monte Carlo simulations and urban canyon tests. The findings indicate that the maximum PVT bias depends on the largest multipath errors observed across various satellite channels. Additionally, the PVT bias increases with satellite elevation angles, influenced by the CAF multipath bias projection. This serves as a reference for selecting DPE satellites from a geometric standpoint, underscoring the importance of choosing a balanced combination of high and low elevation angles to achieve an optimal satellite geometry configuration.