Adaptive Ultra-Tight Integration Architecture for Robust GNSS Tracking

Time-varying scenarios challenge the synchronization capability of global navigation satellite system (GNSS) receivers with incoming GNSS signals. Aiding the line-of-sight (LOS) dynamics from the navigation engine into the tracking channels, also known as ultra-tight integration, significantly benefits synchronization. However, ensuring effective coordination between tracking channels and the navigation engine is crucial to optimize the system performance. This paper introduces an adaptive ultra-tight integration architecture using the normalized bandwidth control algorithm (NBCA) to enhance the synergy between tracking channels and the navigation engine. The NBCA is an adaptive tracking technique that adjusts the response time of a tracking channel based on the discriminator’s output statistics. This adaptive technique is used to coordinate various stages of the ultra-tight integration architecture, aiming for improved synergy. The proposed method is implemented in an open software interface GNSS hardware receiver. The NBCA-based ultra-tight integration architecture is evaluated under simulated static and dynamic scenarios with different carrier-to-noise density ratio (C/N₀) levels. The results confirm the functionality and stability of the adaptive ultra-tight integration and the robustness under signal blockages. The NBCA successfully manages the hot-start functionality, reducing power consumption by eliminating the need for reacquisition.