Jamming emits white Gaussian noise that causes interference to both the legitimate receiver and eavesdropper. It has been an effective method for improving physical-layer security in wireless communication. In this paper, cautious jamming strategy based on optimal jammer selection method is proposed. More specifically, by using perfect channel state information, cautious jamming strategy selects an optimal jammer to improve the secrecy performance. For the purpose of comparison, we consider the direct jamming strategy and the adaptive jamming strategy as benchmark schemes. Closed-form expressions of the exact intercept probability for three jamming strategies are derived over Rayleigh fading channels and the theoretical analysis is validated by Monte-Carlo simulation. Both the analytical and the simulation results show that: 1) increasing the power of jammer is an effective approach to mitigate the intercept probability; 2) the intercept probability can be decreased and the wiretapped range of eavesdropper can be reduced by increasing the number of jammer; 3) by using perfect CSI and selecting optimal jammer, cautious jamming strategy outperforms direct jamming strategy and adaptive jamming strategy.
Jamming emits white Gaussian noise that causes interference to both the legitimate receiver and eavesdropper. It has been an effective method for improving physical-layer security in wireless communication. In this paper, cautious jamming strategy based on optimal jammer selection method is proposed. More specifically, by using perfect channel state information, cautious jamming strategy selects an optimal jammer to improve the secrecy performance. For the purpose of comparison, we consider the direct jamming strategy and the adaptive jamming strategy as benchmark schemes. Closed-form expressions of the exact intercept probability for three jamming strategies are derived over Rayleigh fading channels and the theoretical analysis is validated by Monte-Carlo simulation. Both the analytical and the simulation results show that: 1) increasing the power of jammer is an effective approach to mitigate the intercept probability; 2) the intercept probability can be decreased and the wiretapped range of eavesdropper can be reduced by increasing the number of jammer; 3) by using perfect CSI and selecting optimal jammer, cautious jamming strategy outperforms direct jamming strategy and adaptive jamming strategy.
In this article, we investigate the physical layer security for a wireless communication system consisting of a base station (BS) and a user (U) in the face of an eavesdropper (E). A friendly jammer is opportunistically selected from multiple jammers to create intentional interference upon E. However, the legitimate user U is not aware of the information transmitted by the jammer and thus cannot remove the interfering signal. In this context, we propose interference-limited opportunistic jammer selection (IL-OJS) scheme and interference-canceled opportunistic jammer selection (IC-OJS) scheme to reduce the damage of interference to U for improving physical layer security. Specifically, in the IL-OJS scheme, the selected jammer sets an interference threshold. When the interference to U is less than the threshold value, the selected jammer will work (i.e., emit artificial noise), and vice versa, it will stop jamming. By contrast, IC-OJS scheme utilizes a specially designed signal to eliminate interference received by U from the selected jammer. For comparison, we also present the conventional non-jammer (NJ) scheme as a benchmark. Exact and asymptotic closed-form secrecy outage probability expressions for NJ, IL-OJS, and IC-OJS schemes are derived over Nakagami-mfading channels. Numerical results show that the secrecy performance of proposed IL-OJS and IC-OJS schemes is better than that of NJ scheme. Additionally, the secrecy outage probability performance of IL-OJS and IC-OJS schemes can be improved by increasing the number of jammers.
In this paper, we investigate the physical-layer security for a wireless communications network comprised of multiple users and a common base station (BS) in the presence of an eavesdropper. We propose a joint user-jammer selection scheme for preventing the eavesdropper from intercepting the confidential user-BS transmission. Specifically, a user is first selected to transmit its message to the BS, while another user is chosen to act as a friendly jammer for emitting the artificial noise to interfere with the eavesdropper. We also consider the conventional multiuser scheduling as a benchmark. Closed-form intercept probability expressions are derived for the conventional multiuser scheduling and proposed joint user-jammer selection schemes over Rayleigh fading channels. Numerical results show that the proposed joint user-jammer selection significantly outperforms the conventional multiuser scheduling in terms of the intercept probability, especially with an increasing number of users.
This paper investigates the secrecy performance of a spectrum sharing network, whereNlegitimate source-destination pairs orderly access the shared spectrum for communication, while an eavesdropper (E) attempts to tap the legitimate information transmission. To improve the physical layer security, we propose two jamming strategies that can intelligently switch between jamming and non-jamming, namely, suboptimal jammer selection (SJS) scheme and optimal jammer selection (OJS) scheme. Specifically, when a user pair is assigned to access the shared spectrum, another source is chosen as a friendly jammer in order to create intentional interference at E. For the purpose of comparison, we present the non-jammer selection (NJS) scheme as a benchmark. Analytical closed-form secrecy outage probability expressions of NJS, SJS and OJS schemes are derived over Nakagami-mfading channels. We further present an asymptotic secrecy outage probability analysis to evaluate the secrecy diversity gain performance of NJS, SJS and OJS schemes. Numerical results show that the secrecy outage probability performance of OJS scheme is better than SJS and NJS schemes in the low average channel power gainΩDregion. Furthermore, the secrecy outage probabilities of NJS as well as SJS and OJS schemes converge to each other with the increase ofΩD, due to the fact that the OJS and SJS scheme will switch to NJS scheme whenΩDtends to infinity.
Physical layer security methods based on joint relay and jammer selection (JRJS) have been widely investigated in the study of secure wireless communications. Different from current works on JRJS schemes, which assumed that the global channel state information (CSI) of the eavesdroppers (Eves) was known beforehand, then the optimal relaying and jamming relays were determined. More importantly, the time complexity of selecting optimal jamming relay is O(N2), where N is the maximum number of relays/Eves. In this paper, for the scenario where the source wants to exchange the message with the destination, via relaying scheme due to longer communication distance and limited transmission power, in the presence of multiple Eves, with the assumption of Eves' perfect CSI and average CSI, we propose two kinds of JRJS methods. In particular, the time complexity of finding the optimal jammer can be reduced to O(N). Furthermore, we present a novel JRJS scheme for no CSI of Eves by minimizing the difference between expected signal and interfering signal at the destination. Finally, simulations show that the designed methods are more effective than JRJS and other existing strategies in terms of security performance.
In this paper, we explore the physical-layer security in a wireless network consisting of multiple user pairs in the face of multiple eavesdroppers, which are deployed by an adversary for tapping the confidential transmissions of the user pairs deliberately. We propose a friendly jammer-assisted user-pair selection (FJaUPS) scheme to improve the security-reliability tradeoff (SRT). Conventionally, a friendly jammer is used to transmit the artificial noise that is specially designed onto the null space of the main channel (spanning from the source to legitimate destination) for the sake of not interfering with the destination. However, due to the presence of the channel state information estimation error, it is impossible to guarantee that the artificial noise perfectly lies in the null space of the main channel, resulting in a certain interference received at the legitimate destination caused by the friendly jammer. Hence, the impacts of the friendly jammer on the legitimate user transmissions and eavesdroppers are taken into account for evaluating the wireless SRT performance, which are quantified by the so-called self-interfering factor and jamming factor, respectively. Moreover, we derive the SRT of the proposed FJaUPS, as well as the traditional round-robin schemes over Rayleigh fading channels. For comparison purposes, we also provide the SRT result of the conventional pure user-pair selection (PUPS) in computer simulations. In addition, it is shown that the proposed FJaUPS schemes outperform both the traditional round-robin and PUPS methods in terms of their SRT.
This paper studies a scheme of optimal relay selection with cooperative jamming and optimal power allocation factor between forwarding relay and jammer.The traditional optimal relay selection scheme selects an optimal relay node to assist forward source information.Based on legitimate user and eavesdropper instantaneous channel state information, the proposed scheme selects two relay nodes to increase security against eavesdropper.The first relays to forward source information as traditional scheme.The second relays to send artificial noise as a friendly jammer.The relay operates in Decode-and-Forward strategy.The closed form expression of secrecy outage probability is derived.In addition, the optimal power allocation factor is given when the total relay transmit power is constrained.The simulation results verify that the proposed scheme can significantly improve system security performance compared with the traditional scheme.,