Defense Against Primary User Emulation Attack Based On Channel Characteristics In Cognitive Radio Networks

Cognitive radio is an effective technology of communication to relief the scarcity of the spectrum and to solve the underutilization of spectrum. When people focus on the algorithm of spectrum sensing, they should pay more attention to the precondition of cognitive radio and cognitive radio networks, that is, the security. The features of cognitive radio lead to some special threats existing in cognitive radio networks, such as primary user emulation attack and spectrum sensing data falsification attack. By emulating the characteristics of primary user's signal, attacker could cheat normal secondary users and achieve its own purpose. To research on the problem of primary user emulation attack in cognitive radio, this thesis indicates the potential form of primary user emulation attack, and explores different strategies of defense in corresponding conditions of networks.When the physical locations of nodes in cognitive radio networks are fixed, we indicate that a cooperative attack exists in CRN taking advantage of moment estimation based on wireless channel characteristics. After that, we propose a defense, that is, multiple normal secondary users extract the channel characteristics parameter independently and determine the identity of transmitter cooperatively based on hard decision. The results of simulation show this strategy can distinguish primary user from attacker, and defeat PUEA effectively.Considering the mobility of primary user, we propose a scheme that is multiple secondary users acquire observations of the locations of primary user cooperatively by received signal strength (RSS) algorithm and track the mobile primary user using Kalman filter. Guaranteed secure precision of tracking and locating, we shorten the time for completing the algorithm in order to make attacker can not have enough time to attack. So this scheme can solve the problem when the primary user is mobile.