Time reversal can resolve multipath problems and increase the detection probability, but the detection performance decreases when the target is moving. Because of the change in the channel response due to target motion, the focusing effect of a time-reversal-transmitted signal is reduced. In this article, a novel method based on time reversal, which detects a moving target embedded in a multipath environment with channel variation, is proposed. We establish conventional and time-reversal signal models of a moving target in an indoor diffuse multipath environment and derive likelihood ratio tests under these two conditions. The channel parameters and the changes due to target motion are obtained by echo estimation and are exploited as useful information by the detectors. The channel changes are taken into account in the time-reversal detector to improve its robustness. The time-reversal detector proposed in this article possesses the constant-false-alarm-rate property with respect to the unknown background noise. Although Monte Carlo simulation analysis has illustrated the superior performance of both conventional and time-reversal detectors and proved that both methods can improve the detection probability by exploiting the multipath effect, the time-reversal method outperforms the conventional method due to the spatial and temporal focusing effect on the channel.

中文翻译：

---

多径环境下基于时间反转的运动目标检测

时间倒转可以解决多径问题，增加检测概率，但当目标移动时检测性能下降。由于目标运动引起的信道响应变化，时间反转传输信号的聚焦效应降低。在本文中，提出了一种基于时间反转的新方法，该方法检测嵌入在具有信道变化的多径环境中的运动目标。我们在室内扩散多径环境中建立移动目标的常规和时间反转信号模型，并在这两种条件下得出似然比测试。信道参数和由于目标运动引起的变化是通过回波估计获得的，并被检测器用作有用的信息。时间反转检测器考虑了信道变化以提高其鲁棒性。本文提出的时间反转检测器具有相对于未知背景噪声恒定误报率的特性。尽管蒙特卡罗模拟分析表明了传统和时间反转检测器的优越性能，并证明两种方法都可以通过利用多径效应来提高检测概率，但时间反转方法由于空间和时间聚焦而优于传统方法对频道的影响。