Rotatable Antenna-Enabled Satellite Communication: Joint Design of Boresight Alignment and Beam Tracking
This work addresses beam misalignment in LEO satellite links for mobile satellite communication systems, offering a practical solution with low complexity.
The paper proposes a rotatable antenna (RA)-enabled LEO satellite communication framework that jointly designs beamforming and antenna boresight directions to mitigate beam misalignment caused by high orbital velocities. Simulations show significant improvements in achievable rate and robustness over fixed and random boresight baselines.
Low Earth orbit (LEO) satellite links experience rapid angular variation due to high orbital velocities, which causes severe beam misalignment and array gain degradation under conventional fixed-antenna architectures. In this letter, we propose a rotatable antenna (RA)-enabled LEO communication framework, where RA arrays are deployed at both the satellite and the ground node (GN) to exploit antenna boresight reconfiguration as an additional spatial degree-of-freedom (DoF) for maintaining directional alignment under high mobility. By leveraging the rank-one line-of-sight (LoS) channel structure inherent to satellite links, we derive closed-form solutions for the joint design of the transmit/receive beamforming and antenna boresight directions, revealing that optimal performance can be achieved via decoupled alignment across antennas with low computational complexity. To enable practical operation under dynamic conditions, we further develop a channel estimation and beam tracking protocol that exploits the predictable satellite orbit to continuously update boresight directions with low training overhead. Simulation results demonstrate that the proposed RA-enabled design significantly outperforms fixed and random boresight baselines in terms of achievable rate and robustness to angular variations, highlighting the effectiveness of rotational spatial reconfiguration in high-mobility satellite communications.