Spectrum Sensing of MIMO SC-FDMA Signals in Cognitive Radio Networks: UMP-Invariant Test

Key role in cognitive radio (CR) process play the spectrum sensing techniques which are employed by the unlicensed secondary users in order to detect the spectrum holes. It is, therefore, very important to do this with an optimal method. This inspire us to consider a Uniformly Most Powerful Invariant (UMPI) test as an optimum invariant test for the spectrum sensing problem. To this end, we develop UMPI -based spectrum sensing scheme for multiple-input multipleoutput (MIMO) single carrier frequency division multiple access (SC-FDMA) cognitive radio networks. In [1], authors have solved this detection problem via the widely known generalized likelihood ratio test (GLRT) with no optimality property for a finite number of observations, whereas the derived UMPI test is the optimum invariant test. Interestingly, we find that the UMPI test is equivalent to the GLRT obtained in [1]. Hence, we show that the GLRT is an optimal test for a finite number of observations in the above spectrum sensing problem.