Performance Trade-off Analysis of ISAC Systems Using Kullback-Leibler Divergence

This paper delves into the achievable trade-off in the performance of sensing and communication subsystems in integrated sensing and communication (ISAC) setup using the Kullback-Leibler divergence (KLD) as an informationtheoretical tool. The system model under consideration consists of a multiple-input-multiple-output (MIMO) base-station (BS) that simultaneously serves communication user equipments (CUEs) and detects targets using the same resources. The KLD framework offers a unified performance measure that encapsulates both the error rate of CUEs and the detection capability of targets. Moreover, the interrelationship between target detection capability, CUE error rate, and the proposed KLD is thoroughly investigated and elucidated. Theoretical derivations, corroborated by simulations, validate the high accuracy of the derived KLD in characterizing the performance of both subsystems. The findings of this study facilitate a holistic design of ISAC systems for next-generation wireless networks by providing insights into the sensing-communication performance trade-off.