Secrecy Energy Efficient Beamforming for Satellite-Terrestrial Coordinated Communication Systems

This paper investigates the secrecy energy efficiency maximization (SEEM) problem in a satellite-terrestrial coordinated communication systems. First, we formulate a coordinated transmission optimization problem by using the secrecy energy efficiency (SEE) as optimization criterion and meanwhile the transmission quality of the terrestrial link and the transmission power of the satellite and ground base station as constraints. Due to the fractional form of SEE, the formulated optimization problem is nonconvex and mathematically intractable. Then, we transform the original fractional problem into an equivalent subtractive problem, and employ the difference of two-convex functions (D.C.) approximation method to arrive at an approximate convex problem. Finally, we propose a convergence proven iterative algorithm to solve the modified maximization problem. Simulation results are presented to illustrate the effectiveness of our proposed algorithm.