Quasi-Deep Integration for DPE/INS in GNSS Navigation Domain: Framework Design and Optimization

Abstract

Direct position estimation (DPE) represents a pioneering technique empowering global navigation satellite system (GNSS) receivers to directly estimate position, velocity, and time (PVT) from correlation values. Despite its promise, DPE encounters formidable GNSS challenges, including multipath interference, signal fading, and interference, leading to performance degradation. Integrating an inertial navigation system (INS) with DPE receivers emerges as a viable solution. However, traditional GNSS/INS integration frameworks, such as loose, tight, or deep integration, may not seamlessly apply to DPE receivers due to their distinct signal processing procedures. Hence, this study endeavors to formulate a conceptual integration framework tailored to DPE/INS fusion, emphasizing the intrinsic connection and projection relationship between the correlation domain and the navigation domain. Within this framework, a preliminary design termed quasi-deep DPE/INS integration in the navigation domain is proposed, where the INS furnishes prior information crucial for determining the PVT solution and delineating the candidate search space for DPE receivers. This approach aims to strike a balance between system noise performance and dynamic capabilities, while reducing the computational load during the search process. Furthermore, a theoretical analysis of the quasi-deep integration performance is conducted, offering insights into optimizing the fusion weights for PVT and the search parameters for DPE receivers. Simulation results underscore the efficacy of the proposed integration framework, the analytical process, and the fusion optimization strategy. The urban experiment shows that DPE/INS quasi-deep integration offers more stable and accurate positioning results compared to both GNSS/INS loose and tight integrations. Moreover, the maximum position and velocity errors of the quasi-deep integration can be reduced up to 80% compared to pure DPE receivers, underscoring its potential applicability in challenging urban environments.