Performance Evaluation of Spectrum Sensing Using Welch Periodogram for OFDM Signals

Reliable spectrum sensing is one of the key technologies for enabling spectrum coexistence. In this paper, co operative spectrum sensing based on the Welch periodogram is studied in frequency selective fading environment for quadrature phase shift keying (QPSK) and orthogonal frequency division multiplexing (OFDM) signals. Parameter selection for sensing OFDM signal is discussed, and near-optimal values for frequency averaging for QPSK and OFDM signals are derived. The results, given as receiver operating characteristic (ROC) curves, indicate that the frequency-selective fading degrades the performance of the sensing. This could be compensated by co-operation of several sensing nodes. Both analytical and simulation results indicate that best performance of spectrum sensing is achieved with different combining rules in the case of signal passing through additive white Gaussian noise (AWGN) or fading channels.