Radar Target Detection and Localization Aided by an Active Reconfigurable Intelligent Surface

In this letter, we consider a monostatic radar and study the joint detection and localization of a prospective target when the receiver is assisted by a reconfigurable intelligent surface (RIS). To mitigate the multiplicative path loss in the target-RIS-radar hops, we resort to an active RIS, which allows both redirecting and amplifying the incident signal. Upon choosing the array gain factor of the radar transmitter and the RIS to uniformly cover the inspected region, the joint target detection and localization is formulated as a composite hypothesis testing problem, which is solved via a generalized likelihood ratio test (GLRT). Numerical examples are provided to show the merits of the proposed architecture.