Experimental studies on energy and eigenvalue based Spectrum sensing algorithms using USRP devices in OFDM systems

In this paper, first, energy detection (ED) based spectrum sensing inorthogonal frequency division multiplexing (OFDM) system using National Instrument (NI) Universal Software Radio Peripheral (USRP) 2942R software defined radio platform has been implemented. It is observed that in practical scenario ED scheme gives poor performance at low gain (G) values. To overcome the shortcomings of energy detection, we propose eigenvalue based detection of the primary user (PU) signal, where the ratio of the maximum eigenvalue to the average eigenvalue is used to detect the PU signal in both the single and multiple antenna systems/SISO and multiple-input and multiple-output (MIMO) based CR user. The analytical expression of the performance metric (probability of detection [Pd]) has been derived. Further, the experimental studies show that proposed technique gives optimum (Pd) in both SISO and MIMO case. It has been observed that the proposed technique outperforms the ED based detection even if the Tx-Rx separation increases.