Unmanned aerial vehicle intelligent metasurface assisted satellite-ground physical layer secure transmission method and system

Abstract

The invention discloses an unmanned aerial vehicle intelligent metasurface-assisted satellite-ground physical layer secure transmission method and system, and the method comprises the steps: constructing a signal transmission model based on a communication system, and obtaining the instantaneous signal to interference plus noise ratio of a communication terminal and the instantaneous and secure rate of the system; forming a transmission optimization problem model which jointly optimizes a satellite base station transmitting precoding matrix, a satellite-borne passive intelligent metasurface phase shift matrix, an airborne active intelligent metasurface diagonal reflection matrix and an unmanned aerial vehicle track and takes maximization of the average and safety rate of the system as a target; through analysis of a problem structure, a solution framework of hierarchical processing is provided, and a transmission signal and intelligent metasurface reflection are respectively processed by using successive convex approximation, penalty-based manifold optimization and a positive semidefinite programming algorithm in an inner layer; an unmanned aerial vehicle flight path algorithm based on depth deterministic strategy gradient is adopted at the outer layer to obtain the optimal flight path design, and the eavesdropping is effectively inhibited and the safety performance of the satellite-ground communication system is improved by cooperating with the optimization solution of the inner and outer layer problems.

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