Full-Duplex meets Reconfigurable Surfaces: RIS-assisted SIC for Full-Duplex Radios

Reconfigurable intelligent surfaces (RIS) are a key enabler of various new applications in sixth generation (6G) smart radio environments. By utilizing an RIS prototype system, this paper aims to enhance self-interference cancellation (SIC) for in-band full-duplex (FD) communication systems. SI suppression is a crucial requirement for FD communication as the SI severely limits the performance of a node by shadowing the received signal from a distant node with its own transmit signal. To this end, we propose to assist SI cancellation by exploiting an RIS to form a suitable cancellation signal in the analog domain.Building upon a 256-element RIS prototype, we present results of RIS-assisted SIC from a practical testbed. Given an initial analog isolation of 44dB provided by the antenna design, we are able to cancel the leaked signal by an additional 59dB in the narrowband case, resulting in an overall SI suppression of 103dB without additional digital cancellation. The presented case study shows promising performance to build an FD communication system on this foundation.