Cooperative spectrum sensing study using Welch periodogram

Spectrum sensing is one of the crucial tasks for enabling the use of the cognitive radios. In this paper, we study cooperative spectrum sensing using the Welch periodogram in different fading channel environments. We consider the performance of the Welch periodogram using receiver operating characteristic curves for single- and multicarrier signals. In the cooperative sensing, we study how the number of the cooperative users affects the selection of the reasonable combining rules. In addition, we present the idea of the simultaneous sensing of several sub bands. Finally, we discuss the implementation aspects of the Welch periodogram. In particular, we study the complexity reduction by shortening the length of Fast Fourier Transform (FFT) used in the Welch periodogram. Our theoretical and simulation results indicate that the parameters for the Welch periodogram should be carefully selected to achieve the best performance. In addition, by using smaller FFT sizes, we are able to reduce the complexity of the Welch periodogram without any degradation on the performance. We show that its practical implementation is possible with any existing baseband processor. Finally, we show that the sensing performance can be significantly improved by increasing the number of the cooperative users at the cost of the signalling overhead over the network. (11 refs.)