Rank Sum Nonparametric CFAR Detector in Nonhomogeneous Background

The parametric CFAR detectors maintain a constant false alarm rate (CFAR) with an assumption of a known clutter distribution form. The representative ones of them are the cell-averaging (CA) CFAR, the greatest-of (GO) CFAR, and the ordered statistic (OS) CFAR, etc. In this work, we consider the rank sum (RS) nonparametric CFAR, which has an advantage that it can maintain CFAR even the distribution form of clutter becomes a different one. A closed form of the false alarm rate for the RS detector at clutter edges is derived, and a comparison of the performance of the RS detector in multiple targets situation and at clutter edges to that of the CA-CFAR, the GO-CFAR, and the OS-CFAR with noncoherent integration is made.