Secrecy Rate Optimization for IRS Assisted Mobile VLC System
In order to solve the lighting and communication security problems in scenarios such as nighttime urban security and disaster recovery,the Physical Layer Security(PLS)of a mobile Visible Light Communication(VLC)system is studied.In the mobile VLC,the Light Emitting Diode(LED)is embedded into the Unmanned Aerial Vehicle(UAV)to achieve simultaneous lighting and communication,and can be flexibly configured on demand.Since the UAV is mobile and the line-of-sight communication link cannot exist all the time,the Intelligent Reflective Surface(IRS)technology is introduced into the mobile VLC system to reconstruct the optical wireless transmission link in real time to further improve the security performance of the system.For the PLS of the IRS-assisted mobile VLC system,the secrecy rate of the mobile VLC system is maximized by jointly optimizing the UAV position,the IRS distribution matrix and the system transmit power.Since the resulting optimization problem is a nonlinear mixed integer non-convex problem,a low-complexity iterative algorithm is proposed to decouple the original optimization problem into three subproblems,which are solved by introducing relaxation variables,first-order Taylor expansions and successive convex approximation.The numerical results show that the proposed scheme can improve the secrecy rate of the system compared with several benchmark schemes.