Enhancing Ranging Precision in OFDM-Based LEO Navigation: Signal Design and Receiver Implementation

Abstract Emerging low Earth orbit (LEO) satellites offer new opportunities for navigation augmentation. This paper investigates the potential of orthogonal frequency division multiplexing (OFDM) signals for LEO satellite navigation, focusing on challenges arising from carrier frequency offsets (CFOs) in low signal-to-noise ratio (SNR) environments. We comprehensively analyze the navigation properties of OFDM signals, assessing two synchronization sequence (SS) candidates for their resilience against CFOs. Our findings suggest that the m-sequence effectively mitigates integer CFOs while minimally impacting the receiver’s ranging estimation in the presence of fractional CFOs. Additionally, we introduce an SS detection architecture that integrates differential coherent accumulation (DCA) with a near-optimal likelihood ratio test (NOLRT). This DCA-NOLRT-based LEO receiver enhances detection reliability and sensitivity, effectively managing residual fractional CFOs and improving detection probabilities in low-SNR scenarios. Numerical simulations and terrestrial experiments validate the proposed framework’s capability to minimize CFO-induced ranging errors, even under demanding conditions in LEO navigation scenarios.