A Dual Function Compromise for Uplink ISAC: Joint Spectrum and Power Management

The integrated sensing and communication (ISAC) has been identified as a crucial enabling technology for the development of the sixth-generation (6G). This paper specifically focuses on the uplink orthogonal frequency division multiplexing (OFDM) ISAC system. By utilizing uplink ISAC signals, the base station (BS) can obtain a comprehensive understanding of its surroundings. However, due to the rapid growth of the sensing and communication services, spectrum resources are becoming increasingly scarce, which consequently leads to the tradeoff between sensing and communication. To address this challenge, we employ subcarrier and power allocation techniques that minimize the Cramer-Rao lower bound (CRLB) while satisfying the requirements of peak-to-sidelobe level ratio (PSLR) and communication data rate (CDR). Through this approach, subcarriers exhibit exceptional sensing performance are screened out to create a wider virtual sensing bandwidth. The resulting optimization problem is formulated as a nonconvex one. By utilizing the convex relaxation and cyclic minimization algorithm (CMA), the resource allocation problems are solved iteratively. Numerical results prove that our proposed strategy outperforms the conventional methods in terms of sensing and communication tradeoffs.