Spectrum Sensing in OFDM using Energy Detection: A Comparative Study in AWGN and Rayleigh Channels

Orthogonal Frequency Division Multiplexing based modulation schemes has the advantage of reducing ISI in Cognitive Radios (CR). An OFDM modulation scheme for CR, with QAM and PSK symbol mapping techniques, is implemented. Spectrum sensing is carried out for this ISI free system using Energy Detection method, both in AWGN and Rayleigh fading channels. The performance of these systems is compared using ROC curves and Area under ROC's. Results of the analysis showed that QAM-OFDM in AWGN channel conditions yielded better performance for energy detection based spectrum sensing.