Cooperative Jamming Aided Secure Communication with Intelligent Reflecting Surface

In this paper, we study the jamming aided physical layer security of the intelligent reflecting surface (IRS) assisted communication system in the presence of an eavesdropper. We aim to prove that the optimally designed jamming strategy is beneficial for the IRS assisted secure transmission. Specifically, we first derive the successful and secret transmission probability (SSP) in the closed form. Then we maximize the SSP by optimizing the jamming power allocation. When the number of the IRS elements or the total transmit power increases, less jamming power is required. It is also found that the jamming location and its corresponding optimal jamming power follow a certain quantitative relation, especially when the number of the IRS elements or the total transmit power is large. Finally, simulations are provided to validate our analytical derivations.