Multi-Constellation GNSS Multipath Mitigation Using Consistency Checking
Multi-Constellation GNSS Multipath Mitigation Using Consistency Checking
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发表时间：
2011-09
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通讯作者：
Ziyi Jiang;P. Groves;W. Ochieng;S. Feng;C. Milner;P. Mattos
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作者：
Ziyi Jiang;P. Groves;W. Ochieng;S. Feng;C. Milner;P. Mattos
在典型的城市环境中，接收到无多径、多径污染和非视线（NLOS）传播的GNSS信号的混合。由多径污染和NLOS接收引起的误差是城市环境中降低消费级定位精度的主要来源。已经开发了许多传统的基于接收机和基于天线的技术来减轻多径或NLOS接收，取得了混合的成功。然而，定位精度可以基于仅选择那些最少被多径和NLOS传播污染的信号以形成导航解决方案的简单原理而最大化。多星座GNSS的出现提供了实现这种技术的机会，这种技术对于消费级设备来说可能是低成本和有效的。它也可以被实现为对其他多径缓解技术的增强。本文的重点是信号选择的一致性检查，从而从不同的卫星测量相互比较，以确定NLOS和最多的多径污染的信号。一致性检查的原则是，多径污染和NLOS测量产生一个不太一致的导航解决方案比多径自由测量。基于RAIM的故障检测基于相同的原理操作。三个一致性检查计划的基础上单历元最小二乘残差进行评估：单扫描，递归检查和前两个的混合版本。两种类型的加权方案也被认为是：卫星仰角为基础的和信号C/N 0为基础的加权。本文还讨论了不同的观测量，可能会使用的一致性检查算法的不同应用和检测灵敏度的影响。所提出的算法的测试结果使用静态定位和独立的动态定位实验的数据。静态数据是在开阔天空和城市峡谷位置使用一对测量级多星座全球导航卫星系统接收器同时使用全球定位系统和全球轨道导航卫星系统信号收集的，而动态数据是在混合城市环境中使用汽车上的消费级全球定位系统/全球轨道导航卫星系统接收器收集的。在开放环境中，使用加权递归方法在位置域中表现出显着的改进。然而，在城市环境中，对于传统的基于RAIM的信号选择来说，没有足够的直接接收信号始终有效。这两个定位的改进和风险离群值的证明。更先进的技术已被确定为在未来的研究调查。
In a typical urban environment, a mixture of multipath-free, multipath-contaminated and non-line-of-sight (NLOS) propagated GNSS signals are received. The errors caused by multipath-contaminated and NLOS reception are the dominant source of reduced consumer-grade positioning accuracy in the urban environment. Many conventional receiver-based and antenna-based techniques have been developed to mitigate either multipath or NLOS reception with mixed success. Nevertheless, the positioning accuracy can be maximised based on the simple principle of selecting only those signals least contaminated by multipath and NLOS propagation to form the navigation solution. The advent of multi-constellation GNSS provides the opportunity to realise this technique that is potentially low-cost and effective for consumer-grade devices. It may also be implemented as an augmentation to other multipath mitigation techniques. The focus of this paper is signal selection by consistency checking, whereby measurements from different satellites are compared with each other to identify the NLOS and most multipath-contaminated signals. The principle of consistency checking is that multipath-contaminated and NLOS measurements produce a less consistent navigation solution than multipath-free measurements. RAIM-based fault detection operates on the same principle. Three consistency-checking schemes based on single-epoch least-squares residuals are assessed: single sweep, recursive checking and a hybrid version of the first two. Two types of weighting schemes are also considered: satellite elevation-based and signal C/N0-based weighting. The paper also discussed the different observables that may be used by a consistency-checking algorithm for different applications and their effect on detection sensitivity. Test results for the proposed algorithms are presented using data from both static positioning and stand-alone dynamic positioning experiments. The static data was collected using a pair of survey-grade multi-constellation GNSS receivers using both GPS and GLONASS signals at open sky and urban canyon locations, while the dynamic data was collected using a consumer-grade GPS/GLONASS receiver on a car in a mixed urban environment. Significant improvements in position domain are demonstrated using the weighted recursive methods in the open environments. However in the urban environments, there are insufficient directly received signals for the conventional RAIM-based signal selection to be effective all the time. Both positioning improvements and risky outliers are demonstrated. More advanced techniques have been identified for investigation in future research.