Satellite communication (SatCom) has attracted much attention due to its inherent characteristics. Security issues have gained severe concerns in SatCom since it is susceptible to be illegally eavesdropped by malicious ground stations within large-scale wireless coverage. In this paper, we investigate the physical layer security of a multiuser SatCom system in the presence of multiple eavesdroppers. Particularly, we propose a threshold-based scheduling scheme, where the geographically clustered eavesdroppers with both the colluded and collaborated eavesdropping scenarios are assumed. Specifically, closed-form expression for the secrecy outage probability (SOP) is derived for the passive eavesdropping scenario when the channel state information (CSI) of the eavesdroppers is unavailable. Moreover, we obtain a closed-form expression for the average secrecy capacity (ASC) of the considered system under the proposed user scheduling scheme. In order to get further insights of the proposed scheduling scheme at high signal-to-noise ratios (SNRs), the asymptotic analysis for the SOP and ASC is also demonstrated. Moreover, the reduced percentage with respect to number of user examination is also given, which validates the simplicity and efficiency of our proposed scheme compared to the traditional approaches. Numerical results deduce that with the proposed scheme, a comparable system performance with regard to the maximal selection (MS) scheme can be achieved.
Satellite communication (SatCom) has attracted much attention due to its inherent characteristics. Security issues have gained severe concerns in SatCom since it is susceptible to be illegally eavesdropped by malicious ground stations within large-scale wireless coverage. In this paper, we investigate the physical layer security of a multiuser SatCom system in the presence of multiple eavesdroppers. Particularly, we propose a threshold-based scheduling scheme, where the geographically clustered eavesdroppers with both the colluded and collaborated eavesdropping scenarios are assumed. Specifically, closed-form expression for the secrecy outage probability (SOP) is derived for the passive eavesdropping scenario when the channel state information (CSI) of the eavesdroppers is unavailable. Moreover, we obtain a closed-form expression for the average secrecy capacity (ASC) of the considered system under the proposed user scheduling scheme. In order to get further insights of the proposed scheduling scheme at high signal-to-noise ratios (SNRs), the asymptotic analysis for the SOP and ASC is also demonstrated. Moreover, the reduced percentage with respect to number of user examination is also given, which validates the simplicity and efficiency of our proposed scheme compared to the traditional approaches. Numerical results deduce that with the proposed scheme, a comparable system performance with regard to the maximal selection (MS) scheme can be achieved.
In this paper, we investigate the physical layer security of land mobile satellite (LMS) communication networks, where the multiple legitimate users and eavesdroppers are considered in the system. In order to obtain the best system performance, we propose the cooperating scheme for legitimate users to receive the main signal. Besides, we design two representative eavesdropping scenes for the eavesdroppers, namely, Scene I, colluding scene: the eavesdroppers cooperate with each other and wiretap the information of the main channel together, and the Scene II, non-colluding scene which is the best eavesdropping scene, namely, the most harmful eavesdropper will be selected to overhear the information channel. Furthermore, we obtain the closed-form expressions for the non-zero probability of secrecy capacity, the secrecy outage probability (SOP), and average secrecy capacity (ASC) based on the proposed user cooperation scheme in the presence of two eavesdropping scenes. In order to obtain more insights at the high signal-to-noise-ratios, the asymptotic expressions for the SOP and ASC are also derived under two scenes, from which we can derive the effect of different parameters on the system performance conveniently. Finally, some representative Monte Carlo simulation results are provided to verify the correctness of the obtained analytical results.
This paper investigates the physical layer security (PLS) for the transmission of confidential information over satellite communication systems under unified framework. The generalized shadowed-Rician (SR) fading is utilized to model the satellite channel, and multiple legitimate users are served to cooperatively receive the broadcast signal with a cluster of unauthorized eavesdroppers. In particular, the channel estimation error (CEE) is considered for both the legitimate user and eavesdropping links. Based on the practical channel modeling, we derive the closed-form expressions for the probability of strictly positive secrecy capacity (PSPSC), secrecy outage probability (SOP), and average secrecy capacity (ASC) of the considered satellite communication system in the presence of imperfect channel estimation (ICE), which can provide efficient methods to evaluate the impacts of various propagation parameters on the secrecy performance. In order to obtain further insights into the key parameters on the secrecy performance at high signal-to-noise ratios (SNRs), the asymptotic expressions of the SOP and ASC are also derived. Monte Carlo simulation results are provided to verify the correctness of our performance analysis.
In this paper, we investigate the impacts of joint relay selection and user scheduling scheme on the physical layer security for hybrid satellite-terrestrial relay systems, where multiple terrestrial relays, multiple terrestrial users, and multiple illegitimate eavesdroppers are considered in the network. To strengthen the system security against wiretapping attack, we present a joint opportunistic relay selection and the threshold based user scheduling scheme to balance the system performance and implementation complexity. Furthermore, two representative eavesdropping cases are considered, i.e., the Case I, colluding case: the eavesdroppers cooperate with each other and wiretap the information together, and the Case II, non-colluding case: the best eavesdropper will be chosen to wiretap the information channel. Besides, we derive the closed-form expressions for the average secrecy capacity based on the proposed relay selection and user scheduling scheme in the presence of two eavesdropping cases. To get more insights at high signal-to-noise ratios, the asymptotic expressions for the average secrecy capacity are also derived under two cases, from which we can get the effect of different parameters on the system performance conveniently. At last, analytical results are validated through comparison with the Monte Carlo simulations.
This paper investigates the physical layer security for a cognitive satellite-terrestrial Internet-of-Things (IoT) network where a secondary base station (BS) communicates with multiple secondary users (Us) in the presence of an adaptive eavesdropper, which performs eavesdropping when the channel quality of the eavesdropping link is good and performs jamming otherwise. We consider a real situation where mutual interference exists between primary and secondary networks. Considering multiple secondary users available, we propose suboptimal user scheduling and optimal scheduling schemes to improve the secure transmission of BS-Us. Specifically, a user that maximizes the secrecy capacity of the system will be selected in the optimal scheduling scheme, which assumes that the channel state information (CSI) of all links is available. By contrast, the suboptimal scheduling scheme only knows the main links’ CSI, so the user maximizing the CSI of the main links is chosen. We derive the exact and asymptotic closed-form secrecy outage probability expressions for suboptimal and optimal scheduling schemes. For comparison, we also obtain the exact and asymptotic closed-form secrecy outage probability expressions for round-robin scheme. Numerical results show that the suboptimal and optimal user scheduling schemes perform better than round-robin user scheduling scheme in terms of secrecy outage probability. In addition, the secrecy performance of proposed suboptimal and optimal schemes can be improved by increasing the number of secondary users.
This paper investigates the impact of opportunistic user scheduling scheme on the secure transmission for the integrated satellite terrestrial relay systems (ISTRS), where multiple legitimate terrestrial users and multiple eavesdroppers are concerned in the system. In order to obtain the best secrecy performance, the terrestrial user with the optimal signal-to-noise ratio (SNR) is selected by employing opportunistic scheduling scheme to receive the signal. In addition, this paper considers two representative eavesdropping cases, i.e., Case I which is shown as the colluding case; the eavesdroppers work together and overhear the main channel, and Case II, which is called by non-colluding case: the eavesdropper with the largest SNR will be selected to overhear the legitimate users' channel. Furthermore, we obtain the closed-form expression for the secrecy outage probability (SOP) relied on the given scheduling scheme between two representative wiretapping cases. In order to obtain further results in high SNR regime, approximate SOP expressions under both cases are also derived. At last, some meaningful Monte Carlo (MC) simulation results are given to show the correctness of the theoretical results.
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.