Detection of intelligent malicious user in cognitive radio network by using friend or foe (FoF) detection technique

In a cognitive radio network, dynamic spectrum must be shared with an unlicensed user because of the limited bandwidth of the wireless spectrum. As a regulation of cognitive radio networks, a secondary user is allowed to utilize the unoccupied spectrum when it is not being used by the primary user. However, an intelligent malicious user can attack a cognitive radio network and block the permitted channel for the secondary user. The invasion of an intelligent malicious user is a serious problem in the deployment of such networks. In this paper, we introduce a novel scheme based on friend or foe (FoF) detection with physical-layer network coding to detect a secondary user and an intelligent malicious user. The entire cognitive radio network is protected while the secondary user and intelligent malicious user are accurately detected. The effectiveness of the proposed approach is analyzed theoretically and by MATLAB simulation. It is shown that with the FoF detection technique and the proposed algorithm, the base station can detect the secondary user and intelligent malicious user with high accuracy. Computer simulations show that the probability of detection is almost 100% and that the probability of the false alarm is almost 0% for a low Eb/N0. Consequently, the proposed technique can be applied to a cognitive radio network to protect the entire network and ensure appropriate channel utilization by the secondary user.