High-Sensitivity Carrier Sensing Using Overlapped FFT for Cognitive Radio Transceivers

Abstract

A noise suppression technique using overlapped FFT for carrier sensing of cognitive radio is proposed. The energy detection method is modified. A broadband signal is FFTed and the averaged power of each bin throughout the carrier-sensing period is calculated and judged against a threshold. At the process, adjacent FFT frames are overlapped greatly but with sufficiently large interval compared to the sample-by-sample sliding window. As a result, the averaging effect of noise increases and false alarm (FA) and misdetection (MD) probabilities are improved with much smaller computation amount than the sample-by-sample sliding window case. Simulations on FA and MD probabilities are performed and the effectiveness is confirmed. A model to explain the phenomenon using oversampling was introduced.