Survey on signal processing for GNSS under ionospheric scintillation: Detection, monitoring, and mitigation

Abstract

Ionospheric scintillation is the physical phenomena affecting radio waves coming from the space through the ionosphere. Such disturbance is caused by ionospheric electron‐density irregularities and is a major threat in Global Navigation Satellite Systems (GNSS). From a signal‐processing perspective, scintillation is one of the most challenging propagation scenarios, particularly affecting high‐precision GNSS receivers and safety critical applications where accuracy, availability, continuity, and integrity are mandatory. Under scintillation, GNSS signals are affected by amplitude and phase variations, which mainly compromise the synchronization stage of the receiver. To counteract these effects, one must resort to advanced signal‐processing techniques such as adaptive/robust methods, machine learning, or parameter estimation. This contribution reviews the signal‐processing landscape in GNSS receivers, with emphasis on different detection, monitoring, and mitigation problems. New results using real data are provided to support the discussion. To conclude, future perspectives of interest to the GNSS community are discussed.

Performance Evaluation of Adaptive Tracking Techniques with Direct-State Kalman Filter

“…These changing effects challenge the synchronization capability of the tracking stage [1,7]. Since traditional tracking lacks resilience due to its fixed configuration, there has been significant research towards robust tracking solutions to solve this problem [8,9]. However, there is still ample investigation to find the optimal technique in terms of performance and complexity [7].…”

Evaluation of Adaptive Loop-Bandwidth Tracking Techniques in GNSS Receivers

“…The latter arises due to the thermal noise, the oscillator phase noise, quantization noise, signal interference, and other noise sources [ 8 ]. Multi-path, fading effects, and scintillation also shape the noise and introduce biases [ 9 ]. The loop bandwidth of conventional STLs presents a trade-off between the ability to stay locked in the presence of dynamics and the amount of filtered noise to achieve better precision [ 6 ].…”

Traditional and Kalman Filter-Based GNSS Receiver Structures for Ionospheric Scintillation Monitoring and Mitigation

“…in equatorial and high-latitude regions [1]. The equatorial region experiences the most significant activity, with severe scintillation resulting in rapid amplitude and phase variations with deep amplitude fades for short periods, depending on factors such as solar activity, geomagnetic activity, latitude, carrier frequency, and daytime [2].…”

“…The equatorial region experiences the most significant activity, with severe scintillation resulting in rapid amplitude and phase variations with deep amplitude fades for short periods, depending on factors such as solar activity, geomagnetic activity, latitude, carrier frequency, and daytime [2]. Thereby the detection, monitoring, and mitigation of ionospheric scintillation effects in a GNSS receiver are challenging from the signal processing perspective [1].…”

“…A Kalman filter PLL was employed with LOS and clock error state variables, and measurement noise adjusted as a function of the carrier-to-noise ratio C/N 0 , allowing better phase tracking during the power fades and phase dynamics induced by scintillation when compared to a constant bandwidth loop [12]. The introduction of models representing the scintillation dynamics in the received signal into the Kalman filter formulation enabled decoupling both scintillation and LOS contributions to overcome the limitations of techniques that only adjust the level of uncertainty in models accounting for states related to the LOS dynamics, e.g., based on an estimate of C/N 0 [1]. Ionospheric scintillation is typically modeled as an autoregressive (AR) process.…”