Robust Beamforming Avoiding Satellite Interference in Integrated Terrestrial and Satellite Networks

This paper investigates robust transmit beamforming based on statistical channel state information (CSI), against satellite-to-terrestrial user terminal (UT) interference arising from spectrum sharing in the integrated terrestrial and satellite network. First, we develop an integral-form interference model free of shared CSI to characterize the interference from satellite to terrestrial UTs. Then, we propose a robust interference-avoidance transmit beamforming scheme under the interference threshold and power budget. We derive a closed-form solution based on the minimum mean square error criterion and apply a bisection method to satisfy interference thresholds. Furthermore, we introduce a base station position-aided approximation scheme to eliminate the complex integral calculations. Numerical simulations validate the proposed schemes.