全球导航卫星系统（GNSS）向多星座组合应用方向蓬勃发展。双模甚至多模组合定位将成为卫星导航接收机中的主要定位模式。定位算法中利用来自多个卫星导航系统的卫星信号可以获得数目倍增的测距资源和更优的星座分布几何结构，既有利于提升定位精度，也为完好性性能的提高带来了契机。但可见测距资源的倍增客观上也增大了测距出现故障偏差的概率，因此组合定位算法的完好性也更加重要。为了充分利用多星座带来的优势，以提升组合定位故障检测和排除性能，并增强定位解的置信度，本文重点研究了多模接收机自主完好性监测（RAIM）方法。主要完成工作如下：（1）比较分析单模与双模、三模卫星导航系统RAIM技术性能。仿真分析了组合导航系统在故障检测和排除率、虚警率、保护级别及系统可用性相比单模系统带来的提升作用。指出多模组合系统与传统单模RAIM方法的主要区别，并给出了组合星座各系统卫星数量的限制条件。（2）提出了一种支持多测距故障假设的RAIM方法。该方法建立了卫星分布几何结构与定位估计、故障检测关系模型，研究了各模型卫星分布几何结构对故障测距引起的定位误差与检测统计值间耦合性的影响，利用分组间残差矢量建立新型检测统计量与门限值，通过检验子集一致性来检测和排除含有偏差的测距。在给定虚警要求条件下，利用几何优选分组能够有效提升较小故障的故障检测和排除率，并支持多测距故障假设。（3）提出了一种基于信号体制优化的接收机伪距误差热噪声模型。根据不同信号调制方式在接收机码跟踪延迟锁相环路中码跟踪精度的差异性，建立了基于码跟踪误差的热噪声模型，并推导了各频点测距加权因子的产生方式，结合传统双频组合噪声方差估计，进而细化完善了传统双频模型。将该模型应用于双频加权RAIM方法，能够提升各频点测距准确度，并有效保证定位精度。随着信号体制向多样化发展趋势，该模型能够适用于未来多信号体制的多模多频RAIM场景。
Multi-constellation combined application is the trends of Global Navigation Satellite Systems (GNSS). Integrated positioning by dual-mode even multi-constellation are the main applications of navigation receivers. Signals from constellations can be acquired, and the receivers can gain the redouble of satellites and a significant improvement in the constellation geometric distribution. Therefore, the higher positioning accuracy can be obtained, and the good opportunities for reliability can be provided, however, the probability of the fault measurements is increased objectively due to the redouble of available measurements. Consequently, the integrity of integrated positioning algorithm becomes increasingly important. In order to take the full advantages from multi-constellations improve the performance of faults detection and exclusion, and enhance the confidence of positioning solution, this dissertation around integrity gives deep studies on Receiver Autonomous Integrity Monitoring（RAIM） for multi-constellation system. The main contributions are as follows:(1) The performances of RAIM in single mode, dual-mode and three-model system are Compared and analyzed. And the improvement in fault detection rate, fault exclusion rate, false alarm rate, protection lever and system availability are Analyzed through simulation. The differences between multi-constellation and single mode system are pointed out, then the limiting conditions for satellites of systems in multi-constellation are presented. (2) A novel RAIM algorithm for multi-faulty measurements is proposed. This algorithm presents typical models for relational model among constellation geometry distribution, position estimation and fault detection rate. Then the impacts on coupling between positioning error by faulted measurements of the models and detection statistics are studied. The novel algorithm establishes new detection statistics and thresholds by using the residual vector of groups, detects and excludes the ranging errors by testing the consistency of subsets. The proposed algorithm can achieve a higher detection and exclusion rate for the small faults by optimal geometry grouping under a given false alarm rate, and apply to multi-faulty measurements scenarios.（3）A based signal structures receiver thermal noise model for code tracking errors is proposed. Through analyzing the code tracking accuracy diversity for several typical signal modulation types in delay-locked Loop of receivers, a thermal noise model considering signal structures receiver for code tracking errors is established. And the formulas of calculated weighted values are derived, combined with noise variance estimate of traditional dual-frequency model, and then traditional dual-frequency model. The proposed model can promote optimal fault detection rate, and guarantee the positioning solution accuracy. In addition, the novel model can also be implemented in the receiver design for the future GNSS systems, where various services from multi-constellation and multi-frequency are available.
