Full-Duplex-Enabled Joint Communications and Sensing with Reconfigurable Intelligent Surfaces

TL;DR

This paper introduces a joint communication and sensing system using full-duplex MIMO and reconfigurable intelligent surfaces, optimizing beamformers and RIS phases to enhance performance and reduce self-interference.

Contribution

It presents a novel joint optimization framework for FD MIMO systems with RIS, including a new target estimation bound considering RIS deployment, and demonstrates significant performance gains.

Findings

Enhanced communication and sensing performance in simulations.

Joint design reduces the need for additional self-interference cancellation.

Proposed method outperforms traditional approaches in key metrics.

Abstract

The full-duplex (FD) technology has the potential to radically evolve wireless systems, facilitating the integration of both communications and radar functionalities into a single device, thus, enabling joint communication and sensing (JCAS). In this paper, we present a novel approach for JCAS that incorporates a reconfigurable intelligent surface (RIS) in the near-field of an FD multiple-input multiple-output (MIMO) node, which is jointly optimized with the digital beamformers to enable JSAC and efficiently handle self-interference (SI). We propose a novel problem formulation for FD MIMO JCAS systems to jointly minimize the total received power at the FD node's radar receiver while maximizing the sum rate of downlink communications subject to a Cram\'{e}r-Rao bound (CRB) constraint. In contrast to the typically used CRB in the relevant literature, we derive a novel, more accurate, target estimation bound that fully takes into account the RIS deployment. The considered problem is solved using alternating optimization, which is guaranteed to converge to a local optimum. The simulation results demonstrate that the proposed scheme achieves significant performance improvement both for communications and sensing. It is showcased that, jointly designing the FD MIMO beamformers and the RIS phase configuration to be SI aware can significantly loosen the requirement for additional SI cancellation.