Intelligent Reflecting Surface Enhanced Secure Transmission Against Both Jamming and Eavesdropping Attacks

Both the jammer and the eavesdropper pose severe
threat to wireless communications due to the broadcast nature of
wireless channels. In this paper, an intelligent reflecting surface
(IRS) assisted secure communication system is considered, where
a base station (BS) wishes to reliably convey information to a
user, in the presence of both a jammer and an eavesdropper
whose channel state information (CSI) is not perfectly known.
Specifically, we aim to maximize the system achievable rate
by jointly designing the BS’s transmit beamforming and the
IRS’s reflect beamforming with imperfect CSI, while limiting
the information leakage to the potential eavesdropper. Due to the
non-convexity and intractability of the original problem induced
by the CSI uncertainty, we utilize the auxiliary variables and
General Sign-Definiteness transformation to convert the original
optimization problem into a tractable convex optimization problem,
and then obtain the high-quality optimal solution by using
the successive convex approximation and penalty convex concave
procedure. Numerical simulations demonstrate the superiority
of our proposed optimization algorithm compared with existing
approaches, and also reveal the impact of key parameters on the
achievable system performance.