Dynamic Trust Threshold Value Based on Market Theory in Cognitive Radio Networks

In Cognitive radio networks (CRNs) the primary users(PUs) and secondary users(SUs) share the spectrum resource, which can be an effective solution to the problem that the existing network spectrum utilization is not high. Therefore, to correctly sense whether the spectrum is idle or not is an important prerequisite for spectrum sharing. Spectrum sensing requires the secondary users to cooperate in sensing and report the sensed data. Therefore the CRN is subject to sensed data tampering and primary user emulation. The trustiness of the SUs is, therefore, very important. In this paper, the trust management is introduced to solve the problem of the trustiness of the SUs. A method of trust threshold value judgment is proposed for selecting the trust threshold in trust management. And the threshold will be a standard of the trustiness of SUs. Market equilibrium in the market theory is adopted. The demand function and supply function are built to find the trust value at the market equilibrium point. With the Beta distribution, the ultimate threshold will be given so that it can ensure the fairness of the SUs.