Joint User Scheduling and Two Stage Beamforming for LEO Satellite Networks

Future wireless communication systems demand seamless global coverage and large-scale connectivity. Low Earth Orbit (LEO) satellites present a promising solution owing to their wider field of view and lower deployment costs. This article proposes a two-stage beamforming (TSB) scheme for massive multiple-input multiple-output (MIMO) LEO satellite networks, leveraging slowly varying statistical channel state information at the transmitter. Specifically, to optimize the limited satellite resources, a low-complexity graph-based user clustering algorithm is designed prior to implementing the beamforming stage. The proposed TSB scheme involves employing codebook- based analog beamforming at each satellite access point, followed by fractional programming for digital multi-user precoding design on the Central Processing Unit. Simulation results demonstrate the good performance of the scheme, underscoring its potential in future LEO giant constellations.