Interference in Spectrum-Sharing Integrated Terrestrial and Satellite Networks: Modeling, Approximation, and Robust Transmit Beamforming

TL;DR

This paper develops robust transmit beamforming strategies for satellite-to-terrestrial interference mitigation in spectrum-sharing networks, using statistical CSI and approximation methods to enhance performance and reduce complexity.

Contribution

It introduces a novel interference model and robust beamforming schemes that do not require shared CSI, along with a terrestrial base station position-aided approximation approach.

Findings

Iterative optimization improves sum rate performance.

Closed-form solution offers low complexity with some rate reduction.

Simulation confirms effectiveness of proposed schemes.

Abstract

This paper investigates robust transmit (TX) beamforming from the satellite to user terminals (UTs), based on statistical channel state information (CSI). The proposed design specifically targets the mitigation of satellite-to-terrestrial interference in spectrum-sharing integrated terrestrial and satellite networks. By leveraging the distribution information of terrestrial UTs, we first establish an interference model from the satellite to terrestrial systems without shared CSI. Based on this, robust TX beamforming schemes are developed under both the interference threshold and the power budget. Two optimization criteria are considered: satellite weighted sum rate maximization and mean square error minimization. The former achieves a superior achievable rate performance through an iterative optimization framework, whereas the latter enables a low-complexity closed-form solution at the expense of reduced rate, with interference constraints satisfied via a bisection method. To avoid complex integral calculations and the dependence on user distribution information in inter-system interference evaluations, we propose a terrestrial base station position-aided approximation method, and the approximation errors are subsequently analyzed. Numerical simulations validate the effectiveness of our proposed schemes.