Cooperative Spectrum Sensing Over Imperfect Reporting Channels In Cognitive Radio Networks

With the rapid development of wireless communication technology, the scarcity of spectrum resource is getting more and more attention, therefore cognitive radio technology is put forward. The advantage of cognitive radio is that it is able to utilize the spectrum resource dynamically, so that spectrum resource can be used effectively. Spectrum sensing is the key to the cognitive radio technology, and it is also the precondition of cognitive radio cycle. Cooperative spectrum sensing over imperfect reporting channels is researched in this paper so as to improve the detection performance of cooperative spectrum sensing over imperfect reporting channels.Firstly, the present situation of cognitive radio is introduced and the problem of cooperative spectrum sensing in cognitive radio is analyzed. The shortcoming of local spectrum sensing is also discussed. What’s more, we give a brief introduction of spectrum sensing based on energy detection, the model of cooperative spectrum sensing and the data fusion technology which is commonly used.Secondly, as single threshold energy detection is easily affected by noise uncertainty, the basic model of double threshold energy detection is introduced in order to solve this problem. On the basis of the existing double threshold energy detection, the performance of hierarchical cooperative spectrum sensing is discussed. Through theoretical analysis, the performance parameters of hierarchical cooperative spectrum sensing over imperfect channels are obtained. In order to reduce the performance loss caused by non-ideal channel, MDA weighting rule is introduced. Simulation results show that MDA weighting rule used in this paper can effectively improve the performance of hierarchical cooperative spectrum sensing over imperfect channels.Finally, the problem of data falsification attack in cooperative spectrum sensing is studied. With the goal of maximizing the spectrum efficiency, authentication codes are attached to each of the local spectrum information to filter out the incorrect information caused by malicious users. And the authentication code length is optimized using steepest descent method. The simulation results demonstrate that this method improves the spectrum effectively in the presence of malicious users and achieves a good tradeoff between detection performance and system overhead.