Mitigation of Multi-Carrier Intermodulation Interference in Communication Satellites with the Cooperation of the Ground System

Multi-beam communication systems are increasingly adopted in satellite communications because they optimize limited on-board resources, serve more users, and enhance communication capacity. To optimize the utilization of on-board equipment resources, an integrated design approach is commonly employed, in which a single power amplifier is utilized to simultaneously amplify multiple carrier signals across various beams. Due to the non-linear characteristics of power amplifiers, intermodulation interference generated between multi-path signals falls within the communication frequency band and interferes with the communication signal. This interference is particularly severe for low-power signals when there are significant differences in signal power among multiple channels. This paper proposes a satellite-ground cooperative power control method. Without adding extra on-board channelization processing equipment, the ground system analyzes the terminal signal characteristics and uploads corresponding power control instructions to the satellite. By adjusting the gain levels of different transponder channels, the nonlinear intermodulation interference is mitigated so that the signal-to-noise ratio (SNR) degradation is limited to 0.34dB. Simulation analysis demonstrates that the method proposed in this paper can effectively mitigate the impact of intermodulation interference caused by terminal power differences on the signal-to-noise ratio of communication, thereby verifying the effectiveness of the proposed method.