Joint Attitude and Precoding Optimization for LEO Satellite MIMO Communication Systems

In this letter, we investigate the beamforming optimization for low Earth orbit (LEO) satellite multi-user communication, where the satellite attitude is regarded as an additional tuning variable to mitigate the performance degradation caused by the non-omnidirectional radiation pattern of the antenna. By revealing the relationship between the LEO satellite attitude rotation matrix and the satellite-user transceiving signal model, we propose a novel joint attitude and precoding optimization (JAPO) method to maximize the sum rate of the LEO satellite communication system. Specifically, by utilizing a zero-forcing precoder, we optimize the beam power allocation and the satellite’s attitude with alternating optimization. In the optimization of the satellite’s attitude, we simplify the intractable problem related to the complex rotation matrix and then apply manifold optimization to solve it. Simulation results demonstrate that, compared to the baseline method, the proposed JAPO method consistently achieves higher sum rates across varying transmit power budgets, user numbers, and antenna array sizes, while converging rapidly, thereby highlighting the benefits of jointly optimizing the satellite’s attitude and precoding.