RIS-Empowered Jamming for Protected Zone Formation in In-Band Full Duplex Systems

The rapid proliferation of mobile technologies introduces substantial security vulnerabilities, with conventional cryptographic approaches increasingly inadequate. Physical layer security (PLS) approaches, especially when paired with advanced methods like full-duplex (FD) communication and reconfigurable intelligent surfaces (RISs), offer substantial potential for enhanced security. This work proposes a novel RIS-aided inband FD (IBFD) framework that employs artificial noise (AN) to establish a protected zone (PZ) around the legitimate user, operating independently of any a priori knowledge regarding the number, positions, or channels of potential eavesdroppers. To achieve this, the RIS is functionally partitioned into two distinct segments: one enhances the legitimate user's data rate, while the other simultaneously intensifies AN to jam any unauthorized users within the PZ. We formulate a secrecy capacity (SC) maximization problem that optimizes both the legitimate user's transmission power and the RIS configuration, while meeting quality-of-service (QoS) requirements. Simulation results indicate the superior efficacy of the proposed technique in enhancing SC compared to benchmarks that employ RIS and AN independently. In particular, the proposed approach achieves an approximate SC improvement of 80% and 49% over the “RISonly” and “AN-only” approaches, respectively, underscoring its significant potential to enable robust PLS in next-generation communication networks.