Reduce Instantaneous Power Variance in ISAC Waveform and Precoding Design

A trade-off between instantaneous power variance (IPV) and ranging sidelobe was found when choosing the orthogonal signal base for integrated sensing and communication (ISAC) waveform. Recent study shows that the orthogonal frequency division multiplexing (OFDM) waveform achieves a lowest ranging sidelobe while single-carrier (SC) waveform achieves the highest under orthogonal signal bases. In this paper, we use IPV as a substitute metric for peak-to-average ratio (PAPR) to measure nonlinear power amplifier distortion and prove that SC waveform has the lowest PAPR while OFDM has highest. We give an efficient trade-off design through partial DFT-spread OFDM and prove that the interleaved DFT-spread OFDM achieves the Pareto optimal of this kind. We also utilize the metric in multi-antenna precoding design in order to reduce the IPV in each antenna. Simulation results are given that verify our analysis.