IRS‐Aided Secure Communication in Multiuser MISO System With Hardware Impairments

Unavoidable hardware impairments (HIs) in practical systems can significantly impact system performance. This study explores the security design of an IRS‐assisted multiuser MISO eavesdropping network, focusing on robust secrecy rate optimization considering residual transceiver HIs. We aim to maximize the worst‐case minimum secrecy rate, subject to the IRS phase‐shift unit modulus constraint and single‐user transmit power constraint. A dynamic bandwidth allocation strategy is proposed to mitigate security performance degradation caused by HIs. Using the block coordinate descent (BCD) method, we iteratively optimize variables, transforming the nonconvex optimization problem into manageable subproblems via successive convex approximation (SCA) and semidefinite relaxation (SDR) algorithms. The simulation results show that dynamic bandwidth allocation significantly improves performance and reduces the impact of HIs on the system’s secrecy rate by 10%. The simulation results also show that the use of IRS‐assisted communication can reduce the transmit power by ~20%. This highlights the effectiveness of our proposed strategy in enhancing the security of IRS‐assisted wireless networks.