Robust Secure Beamforming for Spectral Coexistence of UAV and Satellite Systems

In this paper, we investigate the secrecy and reliable transmission for a spectral coexistence of unmanned aerial vehicle (UAV) and satellite system, where the UAV is equipped with the uniform circular array (UCA). Specifically, considering the imperfect channel state information (CSI) of the UAV downlinks, we formulate a constrained optimization problem to minimize the transmission power of UAV while satisfying the requirements of UAV user's achievable secrecy rate (ASR) and the satellite users' interference level. Since the optimization problem is intractable and nonconvex, we adopt discretization method and semidefinite programming (SDP) to transform the original problem into solvable one, and then use standard software package to get the optimal beamforming weight vector. Finally, simulation results are given to illustrate the superiority of the proposed BF scheme.