Beam Update Rate Analysis for Low-Complexity Hybrid Beamforming in LEO Satellites

Massive antenna arrays with hybrid beamforming offer enhanced antenna gain and beam steering flexibility for low Earth orbit (LEO) satellite communications, balancing flexibility, complexity and power consumption. However, efficient beamforming implementation is challenging due to satellites’ high velocity, limited power and computational constraints. In this paper, we investigate the update rate requirements of the analog and digital beamforming coefficients for various LEO altitudes and antenna array sizes, using a low-complexity discrete Fourier transform (DFT) codebook for analog beam steering and zero-forcing (ZF) digital precoding to minimize inter-beam interference. Simulation results show that analog beam steering updates are generally manageable—requiring realignment in the range of seconds—even for lower orbits and larger arrays. In contrast, digital precoding updates are more stringent, requiring updates in the order of tens of milliseconds to prevent a significant decline in performance. Moreover, we demonstrate the need to optimize analog beam steering codebooks to adapt to the satellite’s service area. Finally, we propose a digital precoding update algorithm to optimize the trade-off between update rate and system performance.