Cognitive radio is an emerging trend to solve the problem of scarce spectrum resources in the prosperous area of wireless communication. By dynamically utilizing unoccupied spectrums of primary (licensed) users, secondary (unlicensed) users can meet their own communication requirements. While traditional security attacks on wireless networks still exist, the cognitive radio technologies bring unique security challenges. Current literature on solving these problems assume a central authority, which, for example, assumes the role of a fusion centre. Dynamic wireless environments are composed of users from different competing wireless operators, and assuming the existence of a central authority is a major restriction. We propose approaches that do not rely on these centralized assumptions, and are thus more applicable to practical cognitive radio networks.
Cooperative sensing is an effective solution to improve sensing accuracy and robustness in the presence of fading and shadowing that make individual sensing less reliable. However, when an adversary can corrupt some nodes in the network, the effectiveness of cooperative sensing may degrade dramatically. We design the first fully distributed security scheme, ReDiSen, to defend such attacks in cooperative sensing. We apply reputation generated from exchanged sensing results as an aid to restrict the impact of malicious behaviours. Both theoretical analysis and simulation results indicate that ReDiSen provides an effective countermeasure against security attacks by enabling secondary users to obtain more accurate cooperative sensing results in an adversarial environment. ReDiSen does not rely on a central authority, and is therefore more applicable in dynamic cognitive radio networks.
In a cognitive radio network, selfish secondary users may not voluntarily contribute to the desired cooperative sensing process. We design the first fully distributed scheme to incentivize node participation in cooperative sensing, by connecting sensing and spectrum allocation, and offering incentive from the latter to the former. Secondary users who are more active and report more accurate sensing values are given higher reputation values, which in turn lead to lower prices in the spectrum allocation phase. Theoretical analysis and simulation results indicate that the proposed method effectively incentivizes sensing participation, and rewards truthful and accurate reporting. Our proposed system is fully distributed and does not rely on a central authority, and so is more applicable in dynamic cognitive radio networks in practice. We also show how to improve the robustness of reputation when malicious nodes report spurious reputation.
VCG (Vickrey-Clarke-Groves) spectrum auctions represent a classic type of truthful spectrum allocation method in cognitive radio networks. While security and privacy issues recently start to draw attention in such spectrum auctions, there exists little work that examines the scenario where the auctioneer is not fully trustworthy. We present the first verifiable VCG spectrum auction that allows verification of the winner determination and pricing phases of the VCG auction. We use maximal independent set enumeration and secure multiparty computation to solve the verification problem, while protecting privacy of wireless users. We propose different methods in different steps of the verification scheme, and analyze the effectiveness, information leakage, and efficiency. Our scheme does not rely on a third party, does not alter the auction process, and by using an offline verification process, does not introduce extra delay to the auction process.