Integrated Sensing and Communication (ISAC) is one of the key pillars envisioned for 6G wireless systems. ISAC systems combine communication and sensing functionalities over a single waveform, with full resource sharing. In particular, waveform design for legacy Orthogonal Frequency Division Multiplexing (OFDM) systems consists of a suitable time-frequency resource allocation policy balancing between communication and sensing performance. Over time and/or frequency, having unused resources leads to an ambiguity function with high sidelobes that significantly affect the performance of ISAC for OFDM waveforms. This paper proposes an OFDM-based ISAC waveform design that takes into account communication and resource occupancy constraints. The proposed method minimizes the Cram\'er-Rao Bound (CRB) on delay and Doppler estimation for two closely spaced targets. Moreover, the paper addresses the under-sampling issue by interpolating the estimated sensing channel based on matrix completion via Schatten p-norm approximation. Numerical results show that the proposed waveform outperforms the state-of-the-art methods.
@article{arxiv.2312.12298,
title = {Waveform Design for OFDM-based ISAC Systems Under Resource Occupancy Constraint},
author = {Silvia Mura and Dario Tagliaferri and Marouan Mizmizi and Umberto Spagnolini and Athina Petropulu},
journal= {arXiv preprint arXiv:2312.12298},
year = {2023}
}