A novel two stage improved spectrum sensing for cognitive radio systems

In this paper, we present a novel two stage detector for spectrum sensing using fuzzy logic. The first stage consists of classical Energy detector which is preferred approach because of its simplicity. However its performance decreases at low SNR. Hence, second stage consisting of Fuzzy logic Detectoris invoked, if detection is failed by first stage. Implementation of Fuzzy logic helps in taking rational decision in uncertain conditions and improves the performance and accuracy. Fuzzy logic detector takes decision based on two new parameters which are calculated from estimated energy and estimated PSD of received signal. Numerical results show that proposed scheme improves performance by 20% at −9 dB when compared with two stage sensing using ED and cyclostationary based detection. Moreover, applicability of proposed scheme is independent of format or structure detection of Primary user signal whereas priori information about primary user signal is required for cyclostatonary based detection. Proposed scheme also gives comparable performance with MED and ADT based detector where multiple energy detectors were used at first stage. Thus our scheme gives the benefit of low complexity and cost since single and simple classical Energy detector is used a first stage.