| In recent years, the information and communications technologies obtained the swift and violent development. The newly development business has created some serious problems such as the lack of frequency resource. The shortages of wireless spectrum have become a bottleneck to their development. The paper focuses on the research of cooperative spectrum sensing in cognitive radio. From both known SNR and unknown SNR environment, it explored the new methods of cooperative spectrum sensing, and it also offered an intellectual rationale for the shortages of wireless spectrum.For the case of known SNR, the paper has analyzed and introduced the theory and application of exponential weighting data fusion and trustworthiness-based matrix data fusion. It presented a new trustworthiness fixed exponential weighting data fusion algorithm and taken good use of each features and advantages. When the number of users is too much,to solve this problem that the system needs a larger channel bandwidth to finish the located information transmission task, the paper introduced the cluster model to the system, and built a new trustworthiness fixed exponential weighting data fusion cooperative spectrum sensing algorithm which based on the cluster model. Theoretical analysis and simulation results demonstrate that the new algorithm has a better detection performance than the traditional algorithm. After introducing the cluster model to the system, the detection performance has been remarkable increased,the channel bandwidth was reduced apparently and the system resources were more effectively. For the case of unknown SNR,the paper introduces the D-S evidence theory to the cooperative spectrum sensing system. It focused on the data fusion algorithm based on the D-S evidence theory and applied the new algorithm to cluster cooperative spectrum sensing. In order to solve the large calculating pressure caused by increasing the number of cognitive radio users in cluster, this paper has proposed a optimization scheme of D-S evidence theory data fusion cooperative spectrum sensing based on cluster. It can use the trustworthiness to remove the cognitive radio users whose trustworthiness are very low and just let the left users take part in the cooperative spectrum sensing. Theoretical analysis and simulation results demonstrate that the new scheme reduce the number of cognitive radio users, system energy consumption and calculating pressure while keeping system detection performance unchanged. In conclusion, the two optimize systems proposed by this paper from two points can reduce the system energy consumption and calculation while keeping the detection performance in a high level, which has laid a solid theoretical foundation for the engineering practices. |
