ISAC Rate Region of Pinching-Antenna Systems

The aim of this article is to analyze the performance limits of employing Pinching-Antenna SyStem (PASS) in integrated sensing and communications (ISAC). Specifically, a PASS-assisted ISAC system is considered, where a pinched waveguide is utilized to simultaneously communicate with a user and sense a target. Closed-form expressions for the achievable communication rate (CR) and sensing rate (SR) are derived to characterize the information-theoretic limits of this dual-functional operation. Inner and outer bounds on the achievable CR-SR region are derived using an element-wise alternating optimization technique and by invoking Cauchy-Schwarz and Karamata's inequalities, respectively. Numerical results demonstrate that the derived bounds closely approximate the true CR-SR region; and ii) PASS can achieve a significantly larger rate region than conventional fixed-antenna systems.