IRS-Assisted Secret Key Generation With Transceiver Hardware Impairments

This letter investigates an intelligent reflective surface (IRS)-aided physical-layer key generation (PKG) system under the residual transceiver hardware impairments (THI). We derive the closed-form expression of key generation rate (KGR) as the performance metric and formulate a KGR maximization problem under the constraints of the transmit power at the base station and the unit-modulus phase shift of IRS. To tackle this issue, we propose an alternating optimization (AO) algorithm involving successive convex approximation (SCA), semi-definite relaxation (SDR) and penalty methods to iteratively optimize transmit beamforming and phase shift of IRS. Numerical results demonstrate that the proposed beamforming scheme exhibits greater robustness to hardware impairments compared to the conventional non-robust scheme.