Research On Fractal Dimension-Based Cooperative Spectrum Sensing Technology

In recent years,with the rapid development of communication technology and a large number of new communication services put into operation,the consequent shortage of spectrum resources has become a major bottleneck in the progress of communication technology.Then Cognitive Radio arises as one of the effective means for solving the problem of spectrum resource scarcity and improving channel capacity.In this paper,we focus on cooperative spectrum sensing and its optimization algorithm based on fractal dimension in cognitive radio.Current spectrum sensing methods are sensitive to noise uncertain,inaccurate in low signal-to-noise Ratio(SNR).To solve these issues,a double threshold cooperative spectrum sensing method based on fractal dimension is proposed.It senses the presence of primary users according to different characteristics of fractal dimension between signals and noise.Set the double threshold to improve the detection accuracy.The cognitive user sends local detect results to the fusion center for reliability integration and make a final judgment.The simulation results demonstrate the proposed method has good detection performance at low SNR,and it is insensitive to noise uncertainty.Then on this basis of above algorithms,different cognitive radios have different geographic locations and channel environment,which cause that the local decisions have different influence to the final decision at the fusion center in cooperative detection.For solving these problems,the weighting algorithm based on probability accumulation is analyzed in this paper.By introducing the fractal difference factor,we proposed the Fractal Difference-Based cooperative spectrum sensing optimization algorithm.Simulation results show the sensing method proposed in this paper achieves higher detection probability,reduces the number of cognitive nodes in cooperative detection and saves the channel resources,while ensuring better protection of the primary user.At last,this paper studies the security problems in spectrum sensing,extends fractal dimension-based cooperative spectrum sensing to PUEA detection problems,a novel cooperative detection algorithm for primary user emulation based on two-dimensional features is proposed.Analyzing the PUEA detection algorithm based on one-dimensionalfeature and discusses the limitations of one-dimensional feature parameter identification.The problem is that some types of signals can not be identified,and the detection performance is poor under low-noise environment.Consist a two-dimensional feature vector,by combining the fractal dimension and the characteristic parameters of the instantaneous energy,and the PUEA signal is recognized,which overcomes the limitation of one-dimensional feature recognition for some types Signal "blind zone",and improve the low SNR under the conditions of identification probability.Compared with the traditional PUEA detection method,the proposed PUEA detection algorithm based on two-dimensional feature can get a higher overall system detection probability.