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.
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.
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 explore the physical-layer security of a multi-user wireless system that consists of multiple users intending to transmit to a base station (BS), while multiple eavesdroppers attempt to tap the user transmissions. We examine the employment of multi-user scheduling for improving the transmission security against eavesdropping and propose a multiuser scheduling scheme, which only requires the channel state information (CSI) of BS without the need of the passive eavesdroppers' CSI. We also consider the round-robin scheduling for comparison purposes. The closed-form secrecy outage probability expressions of the round-robin scheduling and proposed multiuser scheduling are derived over Rayleigh fading channels. Numerical results demonstrate that the proposed multi-user scheduling outperforms the round-robin scheduling in terms of the secrecy outage probability. As the number of users increases, the secrecy outage probability of round-robin scheduling keeps unchanged. By contrast, the secrecy outage performance of the proposed multi-user scheduling improves significantly with an increasing number of users.
In this paper, we study a multiuser uplink network consisting of one base station (BS), multiple users and one eavesdropper (E), where the users are intended to transmit their confidential messages to BS, while the eavesdropper attempts to tap their transmissions. To improve the transmission secrecy, we propose two friendly jammer selection-aided multiuser scheduling schemes, namely, the random jammer selection-aided multiuser scheduling (RJS-MUS) without knowing the eavesdropper's channel state information (CSI) and the optimal jammer selection-aided multiuser scheduling (OJS-MUS), where the CSIs of eavesdropper are available. For comparison purposes, the conventional non-jammer selection-aided multiuser scheduling (NJS-MUS) scheme is considered as a benchmark. We derive exact and asymptotic closed-form secrecy outage probability expressions for the conventional NJS-MUS as well as proposed RJS-MUS and OJS-MUS schemes. The numerical results show that the proposed RJS-MUS and OJS-MUS schemes with equal power allocation between the selected friendly jammer and scheduled user perform worse than the conventional NJS-MUS approach in terms of the secrecy outage probability in the low signal-to-noise ratio (SNR) region. As the SNR increases, the secrecy outage performance of RJS-MUS and OJS-MUS schemes substantially improves, which is, in turn, better than that of conventional NJS-MUS approach. Moreover, the secrecy advantage of RJS-MUS and OJS-MUS over NJS-MUS becomes more significant with an increasing SNR. Also, it is shown that for both the RJS-MUS and OJS-MUS schemes, a better secrecy performance can be achieved through an optimal power allocation (OPA) between the scheduled user and friendly jammer. In addition, the proposed RJS-MUS and OJS-MUS schemes with OPA strictly outperform the conventional NJS-MUS approach in terms of the secrecy outage probability.
Abstract This paper examines a wireless communication network comprised of a source and multiple relay‐user pairs in face of multiple malicious eavesdroppers. In order to improve the physical layer security of cooperative communication networks, a joint relay‐user pair and friendly jammer selection (JRUPaFJS) scheme is proposed. Apart from the impacts of friendly jammers on the eavesdroppers, that on the legitimate users is also taken into account due to the presence of channel state information estimation errors. The traditional round‐robin (TRR) scheme and traditional pure relay‐user pair selection (TPRUPS) scheme are considered as benchmark schemes. The exact closed‐form expressions of outage probability and intercept probability for the TRR and TPRUPS schemes as well as JRUPaFJS scheme over Rayleigh fading channels are derived. It is verified that the proposed JRUPaFJS scheme outperforms both the TRR and TPRUPS schemes in terms of their SRT, which demonstrates the wireless security and reliability benefits of exploiting JRUPaFJS scheme. Moreover, as the number of relay‐user pairs increases, the SRT of the TPRUPS and JRUPaFJS schemes improve notably, while as the number of eavesdroppers increases, the SRT of all the three schemes become worse.
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 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.