Space-Time Beamforming for LEO Satellite Communications

TL;DR

This paper introduces space-time beamforming techniques for LEO satellite communications that leverage the spacetime channel vector to improve spectral efficiency and mitigate interference, outperforming traditional methods.

Contribution

The paper proposes two novel space-time beamforming methods, ST-ZF and ST-SLNR, tailored for moving satellites to enhance interference management and spectral efficiency.

Findings

ST-ZF achieves 3dB SNR gain over conventional methods.

ST-SLNR significantly improves sum spectral efficiency.

Effective interference mitigation in dense LEO satellite networks.

Abstract

Inter-beam interference poses a significant challenge in low Earth orbit (LEO) satellite communications due to dense satellite constellations. To address this issue, we introduce spacetime beamforming, a novel paradigm that leverages the spacetime channel vector, uniquely determined by the angle of arrival (AoA) and relative Doppler shift, to optimize beamforming between a moving satellite transmitter and a ground station user. We propose two space-time beamforming techniques: spacetime zero-forcing (ST-ZF) and space-time signal-to-leakage-plus-noise ratio (ST-SLNR) maximization. In a partially connected interference channel, ST-ZF achieves a 3dB SNR gain over the conventional interference avoidance method using maximum ratio transmission beamforming. Moreover, in general interference networks, ST-SLNR beamforming significantly enhances sum spectral efficiency compared to conventional interference management approaches. These results demonstrate the effectiveness of space-time beamforming in improving spectral efficiency and interference mitigation for next-generation LEO satellite networks.