This paper considers the localization of a moving target using a forward scatter radar consisting of a transmitter and an array antenna receiver. A direct positioning method based on maximum likelihood (ML) estimation is proposed and compared with the conventional two-step method in which the primary parameters, including Doppler shift and angle of arrival, should be determined in the first step. Moreover, closed-form expressions for Cramer–Rao lower bound of both methods are derived. The aforementioned methods are comprehensively compared in terms of positioning accuracy and computational complexity. Theoretical performance study, including determining the minimum required observation time for achieving a certain positioning error level and analyzing the best possible positioning accuracy in extreme scenarios, is carried out. The results of numerical simulations demonstrate that the proposed direct approach is more precise compared to the two-step method and can achieve higher resolution levels.

中文翻译：

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双基地前向散射雷达中的移动目标定位：性能研究和有效估计器

本文考虑使用由发射器和阵列天线接收器组成的前向散射雷达定位运动目标。提出了一种基于最大似然（ML）估计的直接定位方法，并与传统的两步法进行了比较，传统的两步法首先确定主要参数，包括多普勒频移和到达角。此外，导出了两种方法的 Cramer-Rao 下界的闭式表达式。上述方法在定位精度和计算复杂度方面进行了综合比较。进行了理论性能研究，包括确定实现特定定位误差水平所需的最短观测时间，以及分析极端情况下可能的最佳定位精度。