Energy detection and eigenvalue based detection: An experimental study using GNU radio

Spectrum sensing plays a key role in enabling the cognitive radios access to vacant spectrum, since it helps avoid interference with the incumbent users. However there are not many studies that show the feasibility of the detectors and analyze their performance under real noise and interference conditions. In this work we developed an energy detector to be used on a USRP2 with GNU Radio. We analyzed the detector performance by measuring probabilities of detection and false alarm and how these are influenced by the sensing time and threshold selection. To verify the validity of theoretical expressions comparisons with theoretical values were made. In this paper we also present an initial study of an eigenvalue detector. It is shown that the filtering done during the decimation of the signal, alters the shape of the noise spectrum and how this consequently degrades the performance of the eigenvalue detector.