Active RIS‐Aided Wideband Self‐Interference Cancellation Method for Full‐Duplex and ISAC Systems

ABSTRACT

This letter proposes a broadband self‐interference cancellation (SIC) method based on a 4 × 4 active reconfigurable intelligent surface (RIS) array for full‐duplex (FD) and integrated sensing and communication (ISAC) systems. Each 2 × 2 RIS sub‐array constitutes a unit cell, in which one channel receives the incident signal, while the remaining three channels reradiate the amplified and phase‐shifted signals to achieve SIC. The phase values of the digital phase shifters (DPS) are optimised using random‐max sampling (RMS) combined with the greedy search (GS) algorithm to maximise the SIC performance. To validate the proposed method, a prototype system operating at 6.5 GHz was designed, fabricated, and experimentally evaluated. Measurement results demonstrate that the proposed active RIS‐aided SIC method provides an additional 20 dB of SIC over a 200 MHz bandwidth and outperforms its passive RIS counterpart.