Abstract
Cognitive radio is a revolutionary paradigm to migrate the spectrum scarcity problem in wireless networks. In cognitive radio networks, collaborative spectrum sensing is considered as an effective method to improve the performance of primary user detection. For current collaborative spectrum sensing schemes, secondary users are usually assumed to report their sensing information honestly. However, compromised nodes can send false sensing information to mislead the system. In this paper, we study the detection of untrustworthy secondary users in cognitive radio networks. We first analyze the case when there is only one compromised node in collaborative spectrum sensing schemes. Then we investigate the scenario that there are multiple compromised nodes. Defense schemes are proposed to detect malicious nodes according to their reporting histories.We calculate the suspicious level of all nodes based on their reports. The reports from nodes with high suspicious levels will be excluded in decision-making. Compared with existing defense methods, the proposed scheme can effectively differentiate malicious nodes and honest nodes. As a result, it can significantly improve the performance of collaborative sensing. For example, when there are 10 secondary users, with the primary user detection rate being equal to 0.99, one malicious user can make the false alarm rate (Pf ) increase to 72%. The proposed scheme can reduce it to 5%. Two malicious users can make Pf increase to 85% and the proposed scheme reduces it to 8%.
Highlights
Nowadays the available wireless spectrum becomes more and more scarce due to increasing spectrum demand for new wireless applications
Two malicious users can make P f increase to 85%, the simple defense scheme can reduce P f to 23%, the proposed scheme reduces it to 8%
By calculating the suspicious level, we propose a scheme to detect malicious user according to their report histories
Summary
Nowadays the available wireless spectrum becomes more and more scarce due to increasing spectrum demand for new wireless applications. Secondary users are allowed to opportunistically access spectrums which have already been allocated to primary users, given that they do not cause harmful interference to the operation of primary users. In order to access available spectrums, secondary users have to detect the vacant spectrum resources by themselves without changing the operations of primary users. Existing detection schemes include matched filter, energy detection, cyclostationary detection, and wavelet detection [2,3,4,5,6]. Among these schemes, energy detection is commonly adopted because it does not require a priori information of primary users
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