Robust secure transmission design for spectral coexistence in satellite and terrestrial network

A robust secure beamforming (BF) algorithm based on imperfect channel state information of eavesdroppers was proposed to improve the secrecy performance for satellite-terrestrial integrated network (STIN), in which satellite network organically coexisted with the terrestrial network. Firstly, for the scenario in which satellite and terrestrial networks shared the spectral resources and adopted BF to serve Earth stations (ESs) and terrestrial users, respectively, a joint optimization problem was formulated to maximize the achievable secrecy rate threshold of the ES, whereas satisfying the quality of service (QoS) requirements, the secrecy outage probability and the transmit power budgets. To tackle this mathematically intractable problem, the zero-forcing criterion was employed to reduce complexity, and then an iterative algorithm based on the Bernstein inequality and the Dinkelbach method was proposed to obtain satisfactory solutions. Finally, computer simulation results confirm that the proposed algorithm achieves superior performance with a fast convergence rate, and can strike a favorable balance between secrecy performance and computational complexity.