Fundamental and Practical Performance Assessment in Monostatic ISAC: From Sub-6GHz to Sub-THz

In the evolving landscape of 6G cellular standards, integrated sensing and communications (ISAC) is gaining traction, building upon advancements in 5G. This paper addresses ISAC's foundational aspects, exploring limits and showcasing prototypes, signaling readiness for its integration into cellular standards. By providing an analytical framework for modeling cellular system sensing performance, we anticipate 6G features and outline feasible sensing key performance indicators (KPIs) across frequency bands, including the current 5G main band frequency range one (FR1), the emerging FR3, lower mmWave at FR2 and the sub-THz D band. Simulation examples validate our framework, enhancing our understanding of ISAC trade-offs, feasibility, and practical constraints across diverse frequency ranges for practical ISAC usage.