Joint Beamforming and Illumination Pattern Design for Beam-Hopping LEO Satellite Communications

TL;DR

This paper proposes joint beamforming and illumination pattern design methods for beam-hopping LEO satellite communications, achieving high sum-rate performance with reduced hardware complexity through hybrid beamforming techniques.

Contribution

It introduces novel optimization schemes for hybrid beamforming and illumination patterns in beam-hopping LEO SatComs, addressing non-convex constraints with efficient algorithms.

Findings

Proposed schemes achieve satisfactory sum-rate performance.

Hybrid beamforming approaches reduce hardware complexity.

Optimization algorithms effectively handle non-convex constraints.

Abstract

Since hybrid beamforming (HBF) can approach the performance of fully-digital beamforming (FDBF) with much lower hardware complexity, we investigate the HBF design for beam-hopping (BH) low earth orbit (LEO) satellite communications (SatComs). Aiming at maximizing the sum-rate of totally illuminated beam positions during the whole BH period, we consider joint beamforming and illumination pattern design subject to the HBF constraints and sum-rate requirements. To address the non-convexity of the HBF constraints, we temporarily replace the HBF constraints with the FDBF constraints. Then we propose an FDBF and illumination pattern random search (FDBF-IPRS) scheme to optimize illumination patterns and fully-digital beamformers using constrained random search and fractional programming methods. To further reduce the computational complexity, we propose an FDBF and illumination pattern alternating optimization (FDBF-IPAO) scheme, where we relax the integer illumination pattern to continuous variables and after finishing all the iterations we quantize the continuous variables into integer ones. Based on the fully-digital beamformers designed by the FDBF-IPRS or FDBF-IPAO scheme, we propose an HBF alternating minimization algorithm to design the hybrid beamformers. Simulation results show that the proposed schemes can achieve satisfactory sum-rate performance for BH LEO SatComs.