PAPR Reduction of OFDM Waveform in Integrated Passive Radar and Communication Systems

For the dual-function radar and communication (DFRC) system based on the orthogonal frequency division multiplexing (OFDM) signal, low peak-to-average power ratio (PAPR) design of the waveform is very important to improve the transmitting efficiency and overall performance. In this paper we consider this problem in the context of the integrated passive radar and communication (IPRC) system in which the channel state information (CSI) and transmitting waveform are unknown to the passive radar. In this context, the traditional constellation extension method is applicable but the effect of PAPR reduction is limited by the constellation size. To solve this problem, we propose a low PAPR waveform design method suitable for a large constellation size. The new method makes two improvements to significantly reduce the PAPR by increasing the constellation point participating in the extension and expanding the extension regions, which is independent of the CSI. Specifically, we adjust the extension regions by the scaling factor to obtain different PAPR, while remaining the pilot data unchanged. Furthermore, the communication performance is semi-analytically analyzed, and the consistency of semi-analytical results and simulation results verifies the effectiveness of the proposed method. Analysis and numerical results demonstrate that the proposed method can achieve good comprehensive performance of communication and passive radar detection compared with other methods in the case of large constellation size.