A Soft Decision Scheme against Intermittent SSDF Attack in Cooperative Spectrum Sensing

Cooperative spectrum sensing for vacant bands is one of the key techniques in cognitive radio networks. However, the existence of malicious secondary users could severely degrade the performance of cooperative spectrum sensing. Currently, sequential probability ratio test scheme (SPRT) is considered as a powerful approach to improve the sensing decision for cooperative spectrum sensing. Considering the binary sensing behaviors of secondary users (SUs), a novel trusted sequential probability ratio test scheme based on beta function (BSPRT) is proposed in this paper to avoid the intermittent spectrum sensing data falsification (ISSDF) attack. By evaluating the trust value of SUs dynamically, the additive punishment and multiplicative decay factors are introduced to mitigate the harmful effect of malicious SUs in the process of the soft-decision data fusion, and thus improving the accuracy of the final sensing decision. Simulation results show that the novel scheme outperforms the conventional SPRT schemes. The BSPRT scheme can work effectively in the scenario where a half of SUs are malicious.