Ziv-Zakai Bound Empowering Guaranteed-asymptotic-sensing Integrated Sensing and Communication

Although the state-of-the-art (SOTA) Integrated Sensing and Communication (ISAC) system design aims to optimize the overall performance by balancing sensing and communication, it inherently overlooks the risk of sporadic large sensing errors bringing fatal results and making the system unstable. To address this issue, this project introduces Ziv-Zakai Bound (ZZB) to empower the guaranteed-asymptotic-sensing ISAC system design. For the first time, this project incorporates the ZZB methodology into typical Multi-Input Multi-Output (MIMO) ISAC system equipped with beamformers and intelligent reflective surfaces (IRS), to thoroughly avoid large sensing errors by guaranteeing the sensing performance into the asymptotic region. To achieve this goal, the existing ZZB derivation framework will be extended to accommodate a typical MIMO ISAC model. This extension will consider the parameter space with nuisance and the MIMO array beampatterns into the ZZB derivation for the first time. After deriving an analytical ZZB that accurately indicates the threshold of entering the asymptotic sensing region, beamformers in the MIMO ISAC system will be co-designed to ensure the sensing performance beyond the threshold by dynamically allocating beams for sensing side, while also meeting communication performance constraints.Furthermore, in scenarios where the asymptotic sensing cannot be guaranteed solely through beamformers design, an ZZB-based IRS configuration method will be proposed. The IRS will be configured according to the threshold indicated by ZZB to guarantee asymptotic sensing first, and the remaining IRS resources will be allocated to communication side to enhance Channel State Information. Beyond the SOTA ISAC system design methodology, the proposed ISAC system design leverages the advantage of ZZB that accurately indicates the asymptotic sensing threshold, to thoroughly eliminate the risk of large sensing errors appearing in the ISAC system and enhance its robustness.