We investigate the physical layer (PHY) security of a system with a base-station (BS), a legitimate user, and an eavesdropper, whose exact location is unknown but within a ring-shaped area around the BS. To this end, we present novel closed-form expressions for the secrecy outage probability, which take into consideration both the impact of fading, as well as the eavesdropper's location uncertainty. The derived expressions are validated through simulations, which reveal that the level of uncertainty should be seriously taken into account in the design and deployment of a wireless system with PHY security.
We investigate the physical layer (PHY) security of a system with a base-station (BS), a legitimate user, and an eavesdropper, whose exact location is unknown but within a ring-shaped area around the BS. To this end, we present novel closed-form expressions for the secrecy outage probability, which take into consideration both the impact of fading, as well as the eavesdropper's location uncertainty. The derived expressions are validated through simulations, which reveal that the level of uncertainty should be seriously taken into account in the design and deployment of a wireless system with PHY security.
We evaluate and quantify the joint effect of fading and multiple interferers on the physical-layer (PHY) security of a system consisting of a base-station (BS), a legitimate user, and an eavesdropper. To this end, we present a novel closed-form expression for the secrecy outage probability, which takes into account the fading characteristics of the wireless environment, the location and the number of interferers, as well as the transmission power of the BS and the interference. The results reveal that the impact of interference should be seriously taken into account in the design and deployment of a wireless system with PHY security.
Wireless physical layer security has attracted great attention in recent years. Although mobility is an intrinsic property of wireless networks, most of the existing works only consider static scenarios and the impact of mobility on wireless physical layer security is not well understood. To fill this gap, in this paper, we investigate physical layer security in the scenario with a random mobile receiver under Rayleigh fading channel. We consider a common scenario where a base station or access point communicates to a random mobile receiver with a passive eavesdropper in a circular region. The secrecy performances under three typical random mobility models are studied: random waypoint model (RWP); random direction model (RD); and border move model. We investigate the secrecy characteristics of the mobile user under steady-state running and provide a general analytical framework for computing the ergodic secrecy capacity. We derive tractable closed-form expressions of positive secrecy capacity probability and secrecy outage probability for RWP and RD mobility users, respectively. By comparing the secrecy performance of mobility with static case, we find that the RWP mobile user can achieve much better secrecy performance than the others. We then investigate the secrecy performance of RWP mobile user with pause time. Furthermore, the two types of secrecy improvement strategies for random mobile users are proposed. In the first strategy, a transmit subcell for RWP users is bounded. We allow the transmitter to communicate with the mobile user only when he is moving within the subcell. In the other strategy, the transmitter is turned on only when the evaluated secrecy performance reaches to a required level. We strike a good trade-off between the secrecy improvements and transmit outage probability. Extensive simulation results validate our theoretical analysis. Finally, we extend our framework to other realistic scenarios, including nodes moving in other shapes of areas, and multiple non-cooperative and cooperative eavesdroppers.
In this article, the physical layer security (PLS) is investigated for reconfigurable intelligent surface (RIS)-aided wireless communication systems, where one RIS is deployed to assist the communications between a pair of transmitter (Alice) and receiver (Bob), under a passive eavesdropper (Eve) attack. For the Eve, different from the bounded channel state information uncertainty model, the distribution of the Eve’s location is introduced into the wiretap link. In the proposed system, considering that the Eve can overhear signals transmitted from Alice or reflected by the RIS, two scenarios are studied for RIS-aided secure communication systems: one is that the Eve distributes close to Alice without the RIS orientation, and the other is that the Eve locates close to Bob and in the presence of the RIS. After investigating the probability distribution functions of the Eve’s location and the wiretap link, the novel cumulative density functions (CDFs) of the received signal-to-noise ratios (SNRs) at the Eves are, respectively, derived for the two considered scenarios, taking into account the effects of RIS reflection coefficients, pathloss, and Eve’s location distribution. The closed-form expressions for the probability of the nonzero secrecy capacity and the ergodic secrecy capacity are obtained, providing insights into the impact of the Eve’s location uncertainty and the RIS design on the secrecy performance. Moreover, based on the derived CDFs for received SNRs at Eves, the secrecy outage probabilities are, respectively, analyzed. Specifically, under the constraint of the secrecy outage probability, the closed forms of the minimum required SNRs at Bob and the number of RIS elements are also obtained. Simulation and analytical results corroborate the derived expressions and reveal the tradeoff between the system’s energy efficiency and the number of RIS elements.
In this paper, the physical layer security of a multi-user jamming-assisted broadcast network in the presence of multiple eavesdroppers. Specifically, a base station (BS) is broadcasting data to multiple end-users via direct links in the presence of multiple passive wiretappers, while both the legitimate users and the eavesdroppers use a maximal-ratio combining scheme to achieve high spatial diversity gain. Furthermore, the BS is broadcasting a jamming signal that can not be canceled by the eavesdroppers to increase their decoding failure rates. All links are subject to Nakagami-m fading models. Relying on the upper incomplete moment-generating function of the combined Signal-to-interference-plus-noise ratio (SINR) at each wiretapper’s MRC output, tight approximate and asymptotic expressions for the secrecy outage probability (SOP) are derived considering two different scenarios, i.e., (i) absence and (ii) presence of the broadcasted artificial noise. The impact of the jamming signal level, severity fading parameter, and the number of MRC branches are examined, while the most influential parameter on the system’s security is retrieved. Numerical results and simulations reveal the accuracy of the obtained analytical expressions and gain more useful insights into the system’s secrecy.
The wiretap channel model in a wireless scenario is analyzed where there is a transmitter, multiple legitimate receivers, non-colluding and colluding eavesdroppers; each of them is equipped with one antenna. Furthermore, all the channels are mutually independent and experiencing quasi-static Nakagami-m fading. We derive closed-form expressions for the exact secrecy outage probability as well as the average secrecy capacity with both non-colluding and colluding eavesdroppers. Such performance metrics are used to analyze the impacts of the number of receivers and eavesdroppers on the system. Remarkably, our results reveal that, for non-colluding eavesdroppers, increasing the number of users will cause greater secrecy degradation than the number of eavesdroppers, especially when the main channel is far superior to the wiretap channel or the value of the fading parameter is high. And for the colluding case, it turns out to be the opposite.
In this paper, the performance for physical-layer (PHY) security of a wireless communication system in mixed α-μ and κ-μ fading channels is analyzed. The system under consideration consists of a transmitter and a legitimate receiver in the presence of an eavesdropper, wherein the main channel is subject to α -μ fading while the wiretap channel undergoes κ-μ fading. We assume that the legitimate users and the eavesdropper are equipped with a single antenna. We derive a novel analytical expression for the lower bound of secure outage probability (SOP). Next, we investigate the asymptotic behavior of the SOP for high signal-to-noise ratio (SNR) of the main channel. Finally, we provide Monte-Carlo simulations to verify our proposed analytical framework.