Spectrum sensing methods in cognitive radio network

Abstract

Cognitive radio is a capable technology, which has provided a different way to increase the efficiency of the electromagnetic spectrum utilization. CR allows unlicensed users or secondary users (SUs) to use the licensed spectrum through dynamic channel assignment strategies or spectrum access when the primary users (PUs) are in a dormant state to improve the spectrum utilization and hence avoid spectrum scarcity. For this we need intelligent spectrum sensing techniques which can detect the presence of spectrum holes and allocate them to the secondary users without interfering with the activities of the primary users. This thesis specifically investigates the Cyclo-stationary detector, the energy detector and their simulation in MATLAB to know the presence of licensed users. Energy detector is a semi blind spectrum sensing technique, which do not need any prior information about the signal to know the presence of primary users. It is simple and easy to implement, but requires high SNR conditions for optimal performance, which is in accordance with our simulation results. The poor performance of ED in low SNR conditions provides option for new spectrum sensing techniques which performs better in LOW SNR conditions. In that Sense the Cyclo-stationary detector overcomes the problem as it gives optimal performance even at low SNR conditions. The wireless microphone signal which is specified in IEEE 802.22 standard (first standard based on cognitive radio) is used as the test signal for the performance evaluation of the energy detector as well as the cyclo-stationary detector.