An OFDM Compatible Sensing Waveform Design for 6G ISAC System

Integrated sensing and communication (ISAC) is an important new research topic for sixth-generation (6 G), where the waveform design should be studied. The chirp-based waveform is widely used in radar systems due to its low peak-to-average power ratio (PAPR) and good autocorrelation properties and is a candidate waveform for ISAC systems. To realize the chirpbased waveform in ISAC systems without additional hardware cost, an orthogonal frequency division multiplexing (OFDM) compatible sensing waveform is proposed in this paper. Firstly, a frequency domain processing (FDP) module is proposed to realize chirp signal under the OFDM transmitter structure. Then, to satisfy different communication requirements, the sensing symbol pattern is designed on top of the FDP module to realize multiple orthogonal chirps with flexible patterns. Evaluation results demonstrate that the proposed chirp-based waveform based on the unified waveform structure can achieve 4 dB and 13 dB signal-to-noise ratio (SNR) gain over traditional OFDM waveform with Zadoff-Chu (ZC) sequence or random payloads under the same range and velocity estimation accuracy.