A weighted cooperative spectrum sensing method based on double-threshold credibility in DTMB systems

Digital Television (DTV) spectrum located in VHF and UHF bands has excellent transmission and indoor penetration characteristics, and sensing the existence of signals of DTMB, i.e. the digital terrestrial multimedia broadcasting standard of China, becomes a key problem of the utilization of DTV spectrum resources in Cognitive Radio (CR) systems. A kind of weighted cooperative spectrum sensing method for DTMB based CR systems is proposed. The method adopts decision and fusion rule based on double-threshold credibility. All the secondary users (SUs) sense the signal from the primary user (PU) using different-interval PN auto-correlation to obtain local decision statistics, and the credibilities are estimated. Only reliable individual decisions beyond double thresholds have positive and larger credibilities and unreliable decisions between double thresholds are set zero credibilities. All local decisions and credibilities are combined to make a global decision. Besides, thresholds of credibility will be adjusted adaptively, balancing the detection performance and efficiency. The analyses of the simulation results prove that the novel method has a significant improvement in different situations compared to typical cooperative sensing methods.