An Interference Mitigation Strategy for LEO Satellite Systems based on Adaptive Beamforming with Sidelobe Suppression

In this paper, we propose an interference mitigation strategy for low Earth orbit (LEO) satellite systems based on adaptive beamforming that incorporates both sidelobe level (SLL) control and dynamic adaptation to reduce co-frequency interference by analyzing the real-time positions of interfering satellites and serving satellite relative to the user terminal. In this study, we consider a uniform rectangular array (URA) as the user terminal antenna configuration in the LEO satellite system. The adaptive beamforming technique based on the Taylor weighting algorithm is applied for sidelobe suppression by generating a beam pattern with the desired SLL. The real-time positions of interfering satellites and serving satellite relative to the user terminal are computed by solving the orbital parameters. Based on real-time position information, the adaptive beamforming technique is utilized to dynamically adjust the beam pattern and generate an appropriate SLL, thereby minimizing the impact of co-frequency interference to its maximum extent. The simulation results demonstrate that the proposed strategy achieves a user terminal received carrier-to-interference ratio (C/I) exceeding 27dB for 95% of the simulation time, representing a significant improvement of 47.5% compared to conventional methods. Moreover, the upper limit of C/I has also significantly escalated from 40dB to 80dB. These findings strongly validate the effectiveness of the proposed strategy in mitigating interference and enhancing overall system performance.