  Eigenvalue-based detectors are considered as an important method of spectrum
sensing since they do not require the information about the primary user (PU)
signal. In this paper we propose a method to improve the performance of the
eigenvalue-based detector. The proposed method introduces a new test statistic
based on combinatorial matrix with components which are overlapping subgroups
extracted from the array of received signals. As a result, its covariance
matrix has a larger maximum eigenvalue and trace value than the one without
overlapping. Simulation results show that our proposed method can further
improve the detection performance of the optimal eigenvalue-based detector. The
paper also shows the effect of different overlapping methods on the receiver
operating characteristic curve.
