Effect of RF Impairments on Spectrum Sensing Techniques

Spectrum sensing is the key element in the implementation of a cognitive radio equipment allowing the utilization of vacant bandwidth unused by the primary users such as broadcasting white spaces. To implement suitable spectrum sensing techniques, RF front end is mandatory at the secondary devices. However, these front-ends are usually low cost devices implying then some RF impairments which may affect the properties and characteristics of the received signal hence the performance of the spectrum sensing. In this paper, we analyze the effect of three main imperfections on the spectrum sensing capabilities of a CR receiver: the carrier frequency offset, the IQ mismatch and the phase noise. We show that the energy detector is not sensitive to any of these errors while the cyclostationnarity detector is only sensitive to the phase noise while its performance is independent of the carrier frequency offset and IQ mismatch values.