Constraint-Aware Power Allocation for OFDM-ISAC: A Joint PSL–CRB Optimization Approach

This paper presents a novel power allocation strategy, referred to as Joint Sensing-Constrained Optimization for Dynamic Allocation (JSCO-DA), designed for orthogonal frequency-division multiplexing (OFDM) systems operating in integrated sensing and communication (ISAC) environments. Unlike traditional water-filling methods that prioritize communication performance alone, JSCO-DA incorporates critical sensing constraints namely, Peak Sidelobe Level (PSL) and Cramer-Rao Bound (CRB) into the optimization framework. The algorithm dynamically fuses the classical water-filling approach with sensing-aware power profiles to ensure compliance with both communication and sensing objectives, while keeping the resulting capacity loss within an acceptable bound. Simulation results reveal that JSCO-DA consistently outperforms conventional dynamic allocation techniques by delivering enhanced capacity, energy efficiency, and spectral efficiency under joint PSL–CRB constraints. These results highlight the potential of JSCO-DA as a practical and efficient solution for emerging ISAC-enabled OFDM systems.