Low-Complexity LRT-Based Passive Radar Target Detection Algorithm in Interfering Conditions

This article addresses the problem of target detection in a two-channel distributed multiple-input-multiple-output (MIMO) passive radar (PR). In this scenario, multiple distributed transmitters emit signals received by two-channel distributed receivers, with one channel for surveillance and the other for reference. To address this PR detection problem, we propose two detectors based on the likelihood ratio test (LRT) principle. One is a subspace-based detector, where the unknown interference subspace is estimated. In this detector, only surveillance channels (SCs) are used to formulate the detection problem as a binary composite hypothesis-testing problem. However, reference channels (RCs) are employed to estimate the unknown interference subspace, resulting in a two-step detection method with a single-channel formulation. The second detector is an eigenvalue-based detector that utilizes both SCs and RCs to formulate the target detection problem. In addition, we present a low-complexity implementation of the eigenvalue-based detector, making it suitable for short- to long-range PR scenarios. Simulation results demonstrate the effectiveness of the proposed detector in target detection and interference cancellation capabilities.