In this study, we provide a detailed analysis of the frequency division duplex long term evolution downlink (FDD LTE DL) signal for passive bistatic radars that use the signal as an illuminator of opportunity. In particular, we analyze the cross-ambiguity function and illustrate its undesired deterministic peaks in the Doppler dimension due to the specific structure of the FDD LTE DL signal. A new adaptive mismatched filtering method is proposed for pre-processing the original reference signal to suppress these undesired deterministic peaks in the range-Doppler processing. The effectiveness of our proposed method is demonstrated via simulations following robustness analysis, showing that all undesired peaks are suppressed below −40 dB, with only 1.7 dB reduction in the main peak.

在本研究中，我们详细分析了无源双基地雷达的频分双工长期演进下行链路 (FDD LTE DL) 信号，这些雷达将信号用作机会照明器。特别是，我们分析了交叉模糊度函数，并说明了由于 FDD LTE DL 信号的特定结构，它在多普勒维度上的不希望有的确定性峰值。提出了一种新的自适应失配滤波方法对原始参考信号进行预处理，以抑制距离多普勒处理中这些不想要的确定性峰值。我们提出的方法的有效性通过稳健性分析后的模拟得到证明，表明所有不需要的峰值都被抑制在 -40 dB 以下，主峰值仅降低 1.7 dB。