Spectrum Sensing of OFDM Signals in the Presence of Carrier Frequency Offset

This paper addresses the important issue of detecting orthogonal frequency-division multiplexing (OFDM) signals in the presence of carrier frequency offset (CFO). The proposed algorithm utilizes the characteristics of the covariance matrix of the discrete Fourier transform of the input signal to the detector to determine the presence of the primary user's signal. This algorithm can be exploited to differentiate OFDM signals from the noise through the proposal of a new decision metric, which measures the off-diagonal elements of the input signal's covariance matrix. The decision threshold subject to a given probability of false alarm is derived, whereas performance analysis is carried out to demonstrate the potential of the proposed algorithm. Finally, simulation results are presented to validate the effectiveness of the proposed sensing method in comparison with other existing approaches.