Two stage spectrum sensing for cognitive radio

Abstract

In past few decades the need for high data rate wireless communication has experienced a booming growth indicating a huge commercial potential. The growing demand of wireless devices is restricted by the spectrum access policy of radio regulatory regime. The commercial success of the unlicensed spectrum has encouraged FCC to frame policies towards more flexible and open spectrum access. Cognitive radio has emerged as a solution to the problem of low spectral occupancy and inefficient utilization of the licensed radio spectrum. It identifies the unused portions of the licensed spectrum known as spectrum holes and makes them available for unlicensed or secondary users. Spectrum sensing, an important part of cognitive radio sense the surrounding radio environment and determines the presence or absence of the licensed user in the licensed band. It helps to get an overview on the radio environment usage and in determining the spectrum holes. The two-stage spectrum sensing method utilizes the strength of both energy and cyclostationary schemes. In this the received signal first passes through the energy detection. If the signal is not detected in this stage it goes to the cyclostationary detection stage. It was observed that the two-stage spectrum sensing method outperforms both the energy detection and cyclostationary detection method. In this dissertation, two-stage detection scheme detects the presence of wireless microphone signals and a modified detection method for cyclostationary is proposed. The simulation results verify this.