In this paper, we suggest a physical layer security transmission scheme which can be employed when an eavesdropper is located near a receiver and channels are correlated. When the receiver-eavesdropper distance is short, it is difficult to obtain a security gain because the eavesdropper can have a similar channel compared to the receiver. To mitigate this problem, the receiver may transmit a jamming signal to prevent data acquisition from the eavesdropper. On this occasion to lessen the outgoing interference caused by the jamming signal to external communication networks, we assume that the sum of the transmission power of the transmitter and the jamming power of the receiver is kept constant. Under this restricted power consumption condition, we evaluate the security performance of our proposed transmission scheme using two metrics, such as threshold outage probability and secrecy capacity. By simulation, we find the optimal power consumption ratio between transmission power and jamming power which maximizes the threshold outage probability. We also analyze the secrecy capacity by simulation and numerical results.
In this paper, we suggest a physical layer security transmission scheme which can be employed when an eavesdropper is located near a receiver and channels are correlated. When the receiver-eavesdropper distance is short, it is difficult to obtain a security gain because the eavesdropper can have a similar channel compared to the receiver. To mitigate this problem, the receiver may transmit a jamming signal to prevent data acquisition from the eavesdropper. On this occasion to lessen the outgoing interference caused by the jamming signal to external communication networks, we assume that the sum of the transmission power of the transmitter and the jamming power of the receiver is kept constant. Under this restricted power consumption condition, we evaluate the security performance of our proposed transmission scheme using two metrics, such as threshold outage probability and secrecy capacity. By simulation, we find the optimal power consumption ratio between transmission power and jamming power which maximizes the threshold outage probability. We also analyze the secrecy capacity by simulation and numerical results.
This letter studies a challenging physical layer security problem for downlink transmissions when facing a randomly located active eavesdropper. Artificial noise (AN) is transmitted in conjunction with a confidential signal to defend against the eavesdropper. However, the active eavesdropper with changeable location can perform both eavesdropping and malicious jamming simultaneously, which yields the secrecy outage probability as an unsuitable performance metric. In this case, a more appropriate metric, the hybrid outage probability which takes both the transmission outage probability and secrecy outage probability into consideration, is derived to evaluate the security performance. Based on the hybrid outage probability, we can optimize the power allocation to the confidential and AN signals. Furthermore, an insecure region is defined to restrict the location of the eavesdropper. Additionally, the insecure range is defined as a valuable indicator of a circular insecure region. Simulation results are provided to depict the region around receiver is insecure.
The inherent openness of wireless medium makes information security one of the most important and difficult problems in wireless networks.Physical layer security, which achieves the information-theoretic security by exploiting the differences between the physical properties of signal channels such that a degraded signal at an eavesdropper is always ensured and thus the original data can be hardly recovered regardless of how the signal is processed at the eavesdropper, has been studied as a promising approach to providing a strong form of security.By now, many research works have been devoted to understand the fundamental performance limits of physical layer security under different wire-tap channel models.It is notable that among different wire-tap channel models, the fading channel model has been an important model to efficiently capture the basic time-varying properties of wireless channels.Available works related to physical layer security study of the fading wire-tap channel are mainly based on the assumption that the channel from a transmitter to a legitimate receiver is independent of the one from the transmitter to an eavesdropper.In practice, however, the correlation among channels from a transmitter to different receivers has been frequently observed.Therefore, understanding the performance of physical layer security under the more practical correlated fading channels is of great importance for practical applications of physical layer security in wireless networks.In this thesis, we aim to provide a comprehensive study on the fundamental performance limits of physical layer security under a fading wire-tap channel, where the channel from transmitter to legitimate receiver is correlated with the one from transmitter to eavesdropper.We start the study from the scenario when the transmission power is asymptotically infinite.In particular, we first provide an informationtheoretic formulation of secure transmission over wireless fading channels at one realization of coherence interval in the high transmission power regime and show that the secrecy capacity is limited by the channel gain ratio of the main and eavesdropper channels rather than the transmission power, which is different from the Shannon's capacity that increases with transmission power.We next characterize the asymptotic outage probability and also asymptotic outage secrecy capacity for the correlated fading wire-tap channel as the transmission power goes to infinity.We then analyze the performance of physical layer security under correlated fading wire-tap channel with a limited transmission power, a more complicate scenario compared with the one with asymptotic-infinite power.Specifically, we provide theoretical modeling for the secrecy capacity, transmission outage probability and secrecy outage probability of such systems.In particular, we first derive a simple closedform expression of secrecy capacity based on the typical Marcum Q function.This is achieved by exploring the symmetry property between the main channel and eavesdropper channel such that some complicated integration operations involved in the secrecy capacity analysis can be significantly simplified.We then derive the transmission outage probability and secrecy outage probability to depict the reliability and security performances of the concerned wire-tap channel.Finally, extensive numerical results are provided to illustrate the inherent performance tradeoffs under i I am truly and deeply indebted to so many people that there is no way to acknowledge them all, or even any of them properly.Without their support, help and encouragement, this work would not and could not haven been done.I extend my deepest gratitude to all.
As Internet of Things (IoT) has boomed in recent years, many security issues have also been exposed. Focusing on physical layer security in wireless Internet of Things network communication, a series of security methods have been widely studied. Nevertheless, cooperative jamming methods in physical layer security to fight against collusive eavesdroppers have not been thoroughly studied yet. In this article, we study a cooperative-jamming-based physical layer secure transmission scheme for Internet of Things wireless networks in the presence of collusive eavesdroppers. We design a cooperative jamming strategy without knowing the channel state information of eavesdroppers. Considering the cooperation of multiple nodes with multiple antennas, this strategy can maximize the signal-to-interference-plus-noise ratio at an actuator (legitimate receiver). Meanwhile, the generated cooperative jamming signals can reduce the signal-to-interference-plus-noise ratio at eavesdroppers. To explore the theoretical security performance of our strategy, we perform a secrecy outage probability analysis and an asymptotic analysis. In the cases of cooperative jamming and without cooperative jamming, the closed-form expressions of the secrecy outage probability are deduced, and the influence of system parameters on the secrecy outage probability becomes more intuitive through a strict mathematical asymptotic behavior analysis. In addition, considering the energy limitation of Internet of Things devices, we propose a power allocation algorithm to minimize the total transmission power given the security requirements. The numerical results show the effectiveness of our schemes and are consistent with the theoretical analysis.
Security has become an increasingly important issue in wireless communications for the IoT (Internet of Things) environments, to which physical layer approaches can contribute by differentiating desired transceiver and wiretap channels for security of confidential data. In this paper, we propose an optimal power allocation strategy for practical physical-layer security, based on friendly jamming with cancellation for anti-eavesdropping. In particular, secrecy outage probability is evaluated in scenarios involving a pair of transmitter-receiver and a passive eavesdropper near the receiver. We derive the optimal power allocation strategy and the required cancellation capability to enhance secrecy performance. Numerical results verify the tradeoff between jamming power ratio and cancellation capability. Furthermore, our proposed scheme can achieve the improved secrecy rate regardless of availability of eavesdropper channel information.
We propose a secure transmission scheme for a wiretap channel, where a source transmits to a legitimate destination in the presence of a full- duplex eavesdropper. We assume that the full- duplex eavesdropper performs both eavesdropping and malicious jamming simultaneously. In order to combat the full-duplex active eavesdropper, the source transmits artificial noise (AN) signals, apart from information signals, to confuse the eavesdropper. We adopt the hybrid outage probability as the performance metric, which takes both the transmission outage probability and the secrecy outage probability into consideration. We derive a compact expression for the hybrid outage probability. Utilizing the derived expression, we determine the optimal power allocation factor between information signals and AN signals that minimizes the hybrid outage probability. We also examine the asymptotic hybrid outage probability in the high signal-to-noise ratio regime. Furthermore, we compare the secrecy performance achieved by a full-duplex active eavesdropper with that achieved by a passive eavesdropper, showing that active eavesdropping can be more harmful to the legitimate system.
In the research of physical layer security, cooperative jamming has recently drawn considerable attention. Jammer plays a friendly role to transmit jamming signal to create interference at the eavesdroppers. However, few literatures consider the scenario in which jammer plays a hostile role to interfere legitimate users. In this paper, we study an ad hoc network where legitimate users transmit with the ALOHA protocol in the presence of hostile users. Each hostile user acts as a jammer or eavesdropper with probability q or 1 - q, respectively. We assess the network performance from both sides of the legitimate user and the hostile user. Particularly, from the perspective of the legitimate user, we evaluate how the connection outage and secrecy outage affect the secrecy transmission capacity, and then derive the optimal ALOHA transmission probability that maximizes the capacity. In view of the hostile user, we obtain the optimal jamming probability that can lead to the largest connection outage probability of legitimate users subject to a given successful eavesdropping probability constraint.