Research Of Cooperative Spectrum Sensing Algorithm In Cognitive Radio Based On Particle Swarm Optimization

As the basis technology for the realization of cognitive radio,spectrum sensing technology need to quickly and accurately detect spectrum hole.Cooperative spectrum sensing could solve the hidden terminal problem and multipath fading in single-user sensing,many scholars proposes algorithms about cooperative spectrum,but the existing detection performance can’t achieve the need of practical application.so this thesis mainly researches how to further improve the spectrum sensing performance and reduce the system bandwidth consumption increased in cooperative spectrum sensing. So,cooperative spectrum sensing in cognitive radio based on particle swarm optimization is proposed in the thesis.Energy detection is introduced in this thesis,single-user spectrum and cooperative spectrum is simulated and analysed.Cooperative spectrum sensing based on particle swarm optimization and clustering is introduced in the thesis.Particle swarm optimization is used to assign the weights for each cognitive user.It is simulated in Gauss channel,the simulation results show that the algorithm can achieve better performance than EGC(Equal Gain Combination) and weighted by signal-to-nosie ratio.Second,In order to reduce the system bandwidth consumption while the cognitive user send information to the fusion center in soft decision.Cluster-based cooperative spectrum sensing model is first introduced in this thesis.Cooperative spectrum sensing based on particle swarm optimization is used in the cluster,the fusion center makes a final decision according each cluster’s decision information. The simulation results show that this method can improve the accuracy of spectrum sensing and reduce the system bandwidth consumption.Energy detection in low SNR has poor performance,In order to solve this problem, The thesis combined energy detection and SLRT, it can be referred to as ED-SLRT.This new algorithm could explained that for better SNR energy detection is used in spectrum sensing,for poor SNR SLRT is used in spectrum sensing. It is simulated in Gauss channel,the simulation results show that the algorithm can achieve better performance than energy detection.Second,On the basis of the new algorithm, Particle swarm optimization is proposed to optimize the threshold in cooperative spectrum sensing.This algorithm takes the error detection probability in cooperative spectrum sensing as the target function,In order to get the minimum value of the target function,Particle swarm optimization is used to optimize the target function.The simulation results show that the error detection probability using particle swarm optimization to optimize the threshold is smaller than all cognitive users using the same threshold.