Cooperative Wideband Spectrum Sensing Over Fading Channels

Abstract

In cognitive radio (CR) systems, it is crucial for secondary users to reliably detect spectral opportunities across a wide frequency range. This paper studies a novel multi-rate sub- Nyquist spectrum sensing (MS3) system capable of performing wideband spectrum sensing in a cooperative CR network over fading channels. The aliasing effects of sub-Nyquist sampling are modelled. To mitigate such effects, different sub-Nyquist sampling rates are applied such that the numbers of samples at different CRs are consecutive prime numbers. Moreover, the performance of MS3 over fading channels (Rayleigh fading and log-normal fading) is analysed in the form of bounds on the probabilities of detection and false alarm. The key finding is that the wideband spectrum can be sensed using sub-Nyquist sampling rates in MS3 over fading channels, without the need of spectral recovery. In addition, the aliasing effects can be mitigated by the use of different sub-Nyquist sampling rates in a multi-rate sub-Nyquist sampling system.