Secrecy Rate Maximization for Hybrid Satellite-terrestrial Wireless Networks

‍ ‍This paper investigates the secrecy rate maximization （SRM） optimization problem in a hybrid satellite （SAT）-terrestrial wireless network， which SAT wireless network is regarded as the primary network and terrestrial cellular network is regarded as the secondary network. Under the perfect channel state information （CSI） model of the hybrid SAT-terrestrial wireless network， the primary SAT network shares the spectrum with the terrestrial network in the presence of a capable eavesdropper. Based on the SRM principle， the objective function of the optimization problem is to maximize the secrecy rate for the primary SAT network while satisfying the allowable signal-to-interference-plus-noise ratio （SINR） requirement of the secondary user （SU） and the transmit power limitations of the terrestrial base station （BS）. In order to deal with the intractable problem better， we consider an iterative algorithm with variables substitution and the Taylor approximation to convert the original optimization problem into a simple convex framework and obtain the optimal beamforming （BF） vector. Finally， numerical simulations are given to verify the feasibility and practicability of the proposed optimization algorithms.