Rotatable Antenna-Enabled Satellite Communication: Joint Design of Boresight Alignment and Beam Tracking

2026-06-01

AI Summary

This work addresses the beam misalignment and array gain degradation caused by the high-speed motion of low Earth orbit (LEO) satellites with fixed antenna beams. To mitigate these issues, the paper proposes a rotatable antenna architecture that deploys directionally adjustable beamforming arrays at both the satellite and ground terminals. Leveraging the rank-one property of line-of-sight (LoS) channels, the mainlobe orientation is treated as an additional spatial degree of freedom and jointly optimized with beamforming weights. An efficient, low-complexity alignment strategy—decoupling beam steering from weight optimization—and orbit-prediction-driven channel estimation enable low-overhead beam tracking. Simulation results demonstrate that the proposed scheme significantly outperforms baseline approaches with fixed or randomly oriented mainlobes in terms of achievable rate and robustness against angular perturbations.

Abstract

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.

Problem

• LEO satellite communication
• beam misalignment
• rotatable antenna
• angular variation
• array gain degradation

Innovation

• Rotatable Antenna
• Boresight Alignment
• Beam Tracking
• LEO Satellite Communication
• Spatial Reconfiguration