Joint Antenna Rotation and Polarforming for Satellite Communications

Overview & Synopsis

This paper investigates joint antenna rotation and polarforming for low-Earth-orbit (LEO) communications, where a satellite equipped with rotatable dual-polarized antenna elements receives uplink signals from ground terminals (GTs) distributed across multiple clusters. In particular, antenna rotation redistributes directional gains across angularly separated clusters, while polarforming improves the separability of spatially correlated GT channels within each cluster. We formulate a weighted sum-rate maximization problem that jointly optimizes rotatable antenna (RA) orientation trajectories, element-wise polarformers, and digital receive filters under steering-range and inter-epoch slew constraints. To solve the resulting nonconvex problem, we develop a weighted minimum mean-square error (WMMSE)-based alternating algorithm, in which the optimal polarformer for each element is derived in semi-closed form, while an exact boresight parameterization yields convex feasible sets for RA-trajectory optimization, enabling Armijo-based gradient updates. Simulation results demonstrate that the proposed joint design outperforms benchmark schemes and reveal the complementary roles of antenna rotation in directional-gain allocation and polarforming in improving channel separability.