Security Cooperation In Cognitive Radio Networks Using Game Theory

Nowadays,with the rapid improvement of economic level and the rapid development of technology,mobile intelligent terminals become more popular.More and more people communicate,socialize and shop via the wireless network,which brings great convenience to our life,but raises a security issue leading to personal privacy exposed to all.The traditional security communication builds upon cryptographic techniques and is applied at the network layer.This causes problems such as key management and key distribution which is unsuited to centerless dynamic wireless networks.With the emergence of new calculation modes,the eavesdroppers decipher encryption keys easily.So more and more researchers study the security problem at the physical layer and focus on cooperation among nodes utilized the broadcast and superposition nature of the wireless channel to improve the system security performance.In the real wireless networks,each node has its own aim,and it's reluctant to help other nodes in the case they don't benefit.Currently,the wireless spectrum resource becomes scarce thanks to the rapid development of wireless communication.In the cognitive radio network(CRN),the secondary users(SU)are willing to cooperate with the primary user(PU)to enhance the security of the primary link for the usage of the authorized spectrum.To tackle this problem,in this paper,some game theory approaches are employed to study the security cooperation among the CRN nodes,i.e.,analyze their interaction and design the fair and efficient cooperation schemes to make the system stable.The major contributions are as follows:1.Considering the scenario that a trusted SU acts as a cooperative relay to enhance the security of the primary link in CRN,a security scheme based on stackelberg game is presented,and the corresponding stackelberg equilibrium is obtained.The stackelberg scheme is then extended into a two-layer game scheme in which the outer framework and the inner one are respectively the original stackelberg game and a second-price sealed-bid auction.The auction may be seen as the sub-game of the original stackelberg game.The corresponding dominant strategy equilibrium and the stackelberg one are derived.Numerical results show that both the schemes can improve the performance of the two parties.Compared with the original stackelberg scheme,the two-layer game scheme not only facilitates the competition among the SUs but also enhances the predominance of PU,so it increases the cooperation chances between the PU and SUs and better improves the profits of both parties.Numerical results also show that in a real application,the cooperative jamming strategy is complementary to the cooperative relaying strategy.2.Considering the scenario that two SUs act as a cooperative relay and a cooperative jammer respectively to enhance the security of the primary link in CRN,a two-layer game scheme is proposed to model the security cooperation between the PU and multiple SUs.The outer framework of the two-layer game is the stackelberg game with the PU and all the SUs as the leader and the followers respectively,in which the PU selects the best relay and jammer with the exhaustive method,while the inner one is a power control game the selected SUs play.In order to reduce the computational complexity,a sub-optimal scheme based on the two-layer game is put forward.The PU firstly selects the cooperative relay and jammer according to the instantaneous channel state information,then plays the two-layer game with the selected SUs.Numerical results show that,compared with the original stackelberg scheme considering a single relay,the two-layer game scheme considers multiple cooperative SUs and provides more SUs with the access opportunities,improves the SUs' overall profits,so it promotes the cooperation between the PU and SUs and further improves the system security performance.3.A security cooperation scheme based on a second-price sealed-bid auction is proposed to solve the problem that some SUs wish to access the authorized spectrum by “threaten-to-access” in CRNs and to transform these SUs from potential eavesdroppers into potential friendly jammers.Next,the rule of the traditional second-price sealed-bid auction is slightly modified to obtain the optimal strategy of the SU who wins the bid and to improve the performance of both the seller and the bidder.Numerical results show that the proposed scheme not only converts the hostile relation between the PU and the SUs into a cooperative one but also gives them considerable autonomy,so it facilitates the competition among the SUs,increases the access opportunity of the SUs and further improves the security rate of the primary link.Numerical results also show that the proposed scheme can still improve the performance of the PU and the SUs when the cost per unit transmission power,the wire-tap channel gain or the interference channel gain from the SUs to the PU is large.In summary,several schemes based on Stackelberg game,the second-price sealed-bid auction and the two-layer game are proposed to study the security cooperation between the PU and SUs,and these schemes benefit every participator.