Performance of Downlink and Uplink Integrated Sensing and Communications (ISAC) Systems

TL;DR

This paper analyzes the fundamental performance limits of integrated sensing and communications (ISAC) systems in downlink and uplink scenarios, revealing their advantages over traditional isolated systems in terms of degrees of freedom.

Contribution

It provides a theoretical analysis of diversity orders, high SNR slopes, and achievable rate regions for ISAC systems, highlighting their improved performance over conventional methods.

Findings

ISAC offers higher degrees of freedom for CR and SR.

Diversity orders and high SNR slopes are characterized.

CR-SR regions for ISAC are explicitly derived.

Abstract

This letter analyzes the fundamental performance of integrated sensing and communications (ISAC) systems. For downlink and uplink ISAC, the diversity orders are analyzed to evaluate the communication rate (CR) and the high signal-to-noise ratio (SNR) slopes are unveiled for the CR as well as the sensing rate (SR). Furthermore, the achievable downlink and uplink CR-SR regions are characterized. It is shown that ISAC can provide more degrees of freedom for both the CR and the SR than conventional frequency-division sensing and communications systems where isolated frequency bands are used for sensing and communications, respectively.