Suppressing RF front-end nonlinearities in wideband spectrum sensing

As a result of wideband analog front-end, wideband spectrum sensing techniques are prone to suffer from RF non-linearities. Intermodulation products due to strong subbands or carriers stemming from low noise amplifier nonlinearities, can easily degrade the spectrum sensing performance by causing false alarms and degrading the detection probability. We analyze the effects of third-order nonlinearities on both energy detectors and cyclostationary detectors under front-end nonlinearities. We show that the presence of strong blockers in the wideband channel can substantially degrade the sensing performance of both detectors, and energy detectors loose their advantage over cyclostationary detectors. Then, we propose an adaptive interference cancellation algorithm to compensate for the effect of the blockers at any subband of interest. The obtained results also show that when compensation is enabled, cyclostationary detector is more robust to moderate blocker signal levels than the corresponding energy detector.