Ambiguity Function Based Filter Designs for OFDM ISAC Systems

Filtering techniques are commonly applied to orthogonal frequency division multiplexing (OFDM) signals to suppress out-of-band emissions and manage power allocation. In integrated sensing and communication (ISAC) systems, these filters can impact overall sensing performance. This letter investigates the effect of filtering on sensing capabilities in terms of the ambiguity function (AF). To address the non-convex nature of the AF, we first derive a truncated approximation of AF and obtain the corresponding filter through convex optimization. We then use a nonlinear optimizer that iteratively refines the filter to maximize the AF performance. Numerical simulations demonstrate the effectiveness of the proposed solution for ISAC systems.