Fast and Efficient Phase-Only Beam Nulling for NGSO Satellite Communication Systems

To avoid the ground-based interference, this letter introduces a beam nulling approach for non-geostationary orbit (NGSO) satellites equipped with large-scale antenna arrays (LSAAs). Due to cost considerations, all antenna elements of LSAAs are typically connected to a few radio frequency chains, resulting in the beam pattern being formed through phase shifters exclusively. Additionally, the rapid change in the incident directions of interference, caused by the high mobility of NGSO satellites, necessitates a swift response to prevent the interference sources from deviating from the nulling regions of the beam pattern. However, the large-scale, phase-only and real-time requirements render most existing beam nulling approaches inapplicable. To address this challenge, we propose a fast phase-only beam nulling algorithm based on the framework of majorization minimization (MM). Furthermore, we derive the closed-form Karush-Kuhn-Tucker (KKT) point to solve the MM problem efficiently, and design a simple but effective bisection method to accelerate the convergence speed. Simulation results demonstrate that the proposed algorithm outperforms the state-of-the-art algorithms in terms of computational cost and convergence speed. IEEE