Full-Duplex Operation of ISAC: Self-Interference Reduction from the Lens of IRS

Integrated sensing and communication (ISAC) has recently emerged as a key paradigm for future wireless networks. In ISAC, sensing and communication functionalities are jointly optimized, and the same communication infrastructure is used to provide various communication and sensing services. In ISAC, some form of full-duplex operation is necessary to support monostatic sensing applications, where the transmission of the sensing signal and reception of the reflected signal are performed by the same node. Thereby, a key challenge is the issue of self-interference, which, if not handled properly, may severely limit the sensing performance. This paper addresses the self-interference problem in full duplex operation by leveraging an intelligent reflecting surface (IRS) to provide spatial separation of the transmitted and the received (i.e. reflected) signal in a monostatic sensing setting. By strategically deploying an IRS in the system, we demonstrate its effectiveness in mitigating self-interference and enabling simultaneous sensing and communication operations. Specifically, we present numerical results that showcase the potential of IRS-assisted sensing to extend the sensing range or, alternatively, to reduce the hardware requirements for self-interference suppression in certain scenarios.