OS-CFAR thresholding in decentralized radar systems

In a decentralized detection scheme, several sensors perform a binary ( hard) decision and send the resulting data to a fusion center for the final decision If each local decision has a constant false alarm rate (CFAR), the final decision is ensnred to be CFAR. We consider the case that ea"h local decision is a threshold decision, and the threshold is proportional, through a suitable multiplier, to a linear coniJination of order statistics (OS) from a reference set (a generalization of the concept of OS thresholding). We address the following problem: given the fusion rule and the relevant system parameters, select each threshold multiplier and the coefficients of each linear combination so as to maximize the overall probability of detection for constrained probability of false alarm. By a Lagrangian maximization approach, we obtain a general solution to this problem and closed-form solutions for the AND and OR fusion logics. A performance assessment is carried on, showing a global superiority of the OR fusion rule in tel111S of detection probability (for operating couditions matching the design assumptions) and of robustness (when these do not match). We also investigate Ilhe effect of the hard quantization performed at the local sensors, by comparing the said performance to those achievable by the same fusion rule in the limiting case of no quantization