Robust Resource Allocation for Secure Multiple Active RIS-Aided Full Duplex Communications

In this work, we investigate the performance of a multi active reconfigurable intelligent surface (ARIS)-aided full duplex (FD) secure network with an imperfect channel state information (iCSI) in the presence of an eavesdropper (Eve). We aim to minimize the total power while ensuring the desired quality of service (QoS) of uplink and downlink users within available resource constraints considering the norm-bounded iCSI at each receiving node. To tackle the non-convex nature of the formulated problem, we propose an alternating optimization (AO) based algorithm that jointly optimizes the combining vector and transmit beamforming at Alice, power allocation at each uplink user, and active beamforming at ARIS. The efficacy and convergence of the proposed algorithm are validated via extensive numerical simulation. The potential of ARISs, compared to its passive RIS (PRIS) counterpart, towards a robust FD secure system is demonstrated. Finally, we discuss the impact of key parameters such as maximum amplification factor, and RIS, and CSI error on the performance of the considered system.