Doppler Shift Compensation Methods for High-Dynamic Low-Earth-Orbit Satellites

Low-Earth-orbit (LEO) satellites provide key technical advantages, including low latency, wide coverage, and high data rates. Large-scale constellation deployment can accelerate global communication infrastructure development, enabling seamless connectivity and enhanced emergency response. However, inter-orbital-plane communication links are challenged by rapidly changing topologies, producing severe Doppler frequency shifts, characterized by large dynamic ranges and fast variations, which disrupt carrier recovery and degrade demodulation performance. This paper presents an orbital modeling and analysis of Doppler frequency shift variations in LEO satellites, demonstrating frequency offsets up to 340 kHz and variation rates surpassing 2 kHz/s. Based on this analysis, the performances of closedloop and feedforward tracking algorithms are evaluated. To accommodate both co-orbital and cross-orbital scenarios, a dual-mode Doppler compensation strategy is proposed, guided by an adaptive threshold update mechanism based on acceleration estimation. Specifically, a phase-locked loop (PLL) is employed under low-dynamic conditions, while a feedforward Fast Fourier Transform-Viterbi Viterbi (FFT-VV) algorithm is adopted in high-dynamic environments. A sliding window weighted update mechanism is introduced to enable smooth threshold adjustment, ensuring robust Doppler acquisition, precise phase compensation, and seamless switching between compensation modes. Simulation results demonstrate that the proposed strategy maintains a normalized root mean square error (NRMSE) below 2×10⁻⁴ in lowacceleration cases and stabilizes at 5.48×10⁻⁴ under high dynamics, with phase variations within ±0.04 radians. This study further verifies the proposed adaptive strategy, indicating that it can dynamically adapt to real-time link conditions and significantly enhance the robustness of LEO satellite receivers in both co-orbital and cross-orbital environments.