Cyclostationarity Based Signal Detection in Cognitive Radio Networks

The inefficient usage of the existing frequency spectrum and the ever increasing need for spectrum for communication has demanded means of opportunistic access to the licensed bands without interfering with the licensed primary users. Cognitive radio nodes have the capability of dynamic spectrum access and can provide a solution for the increasing spectral demand. Several spectrum sensing techniques can be employed to identify the presence of the primary signal. This paper focuses on the technique of utilizing the cyclostationary properties present in the primary user signal. The Spectral Correlation Function (SCF) of the signal received from the spectrum is used to make a decision regarding the presence of the signal. The signal detection can be reduced to a simple identification problem where the cognitive radio node just needs to identify the SCF pattern to identify the presence of the corresponding signal. Study is done to detect a QPSK modulated primary user signal and the results show that the signal presence can be detected even under very low SNR conditions.