Physical Layer Security of Hybrid Satellite-FSO Cooperative Systems
TL;DR: The physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system is studied and it is found that with the AF with fixed gain scheme, the secrecy diversity order of the investigated system is only dependent on the channel characteristics of the FSO link and theFSO detection type, whereas the secrecy Diversity is zero when the relay node employs DF or AF with variable-gain schemes.
Abstract: In this paper, we study the physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system. The satellite links are assumed to follow the shadowed-Rician fading distribution, and the channel of the terrestrial link between the relay and destination is assumed to experience the gamma-gamma fading. For the FSO communications, the effects of different types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection) as well as the pointing error are considered. We derive exact analytical expressions for the average secrecy capacity and secrecy outage probability (SOP) for both cases of amplify-and-forward (AF) and decode-and-forward (DF) relaying. The asymptotic analysis for the SOP is also conducted to provide more insights on the impact of FSO and satellite channels on secrecy performance. It is found that with the AF with fixed gain scheme, the secrecy diversity order of the investigated system is only dependent on the channel characteristics of the FSO link and the FSO detection type, whereas the secrecy diversity is zero when the relay node employs DF or AF with variable-gain schemes.
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TL;DR: An exhaustive review of state-of-the-art research activity on PLS in satellite communications, which is categorize by different architectures including land mobile satellite communication networks, hybrid satellite-terrestrial relay networks, and satellite- terrestrial integrated networks.
Abstract: Research and processing development on satellite communications has strongly re-emerged in recent years. Following the prosperity of various wireless services provided by satellite communications, the security issue has raised growing concerns since the space information network is susceptible to be eavesdropped by illegal adversaries in such a large-scale wireless network. Recently, the physical-layer security (PLS) has emerged as an alternative security paradigm that explores the randomness of the wireless channel to achieve confidentiality and authentication. The success story of the PLS technique now spans a decade and thrives to provide a layer of defense in satellite communications. With this position, a comprehensive survey of satellite communications is conducted in this article with an emphasis on PLS. We first briefly introduce essential background and the view of the satellite Internet of Things (IoT), as well as discuss related research challenges faced by the emerging integrated network architecture. Then, we revisit the most popular satellite channel model influenced by many factors and list the commonly used secrecy performance metrics. Also, we provide an exhaustive review of state-of-the-art research activity on PLS in satellite communications, which we categorize by different architectures including land mobile satellite communication networks, hybrid satellite-terrestrial relay networks, and satellite-terrestrial integrated networks. In addition, a number of open research problems are identified as possible future research directions.
139 citations
Cites methods from "Physical Layer Security of Hybrid S..."
...[126] carried out the secrecy performance analysis of a hybrid satellite and FSO cooperative system under AF and DF relay protocols....
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TL;DR: This paper proposes a threshold-based scheduling scheme, where the geographically clustered eavesdroppers with both the colluded and collaborated eavesdropping scenarios are assumed, and deduces that with the proposed scheme, a comparable system performance with regard to the maximal selection scheme can be achieved.
Abstract: 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.
64 citations
Cites background from "Physical Layer Security of Hybrid S..."
...In [25], the authors analyzed the secrecy performance for satellite communication systems with one user and one eavesdropper....
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TL;DR: This paper analyzes the secrecy outage performance of RIS-aided vehicular communications and demonstrates the potential of improving secrecy with the aid of RIS under both V2V and V2I communications.
Abstract: Reconfigurable intelligent surfaces (RIS) is considered as a revolutionary technique to improve the wireless system performance by reconfiguring the radio wave propagation environment artificially. Motivated by the potential of RIS in vehicular networks, we analyze the secrecy outage performance of RIS-aided vehicular communications in this paper. More specifically, two vehicular communication scenarios are considered, i.e., a vehicular-to-vehicular (V2V) communication where the RIS acts as a relay and a vehicular-to-infrastructure (V2I) scenario where the RIS functions as the receiver. In both scenarios, a passive eavesdropper is present attempting to retrieve the transmitted information. Closed-form expressions for the secrecy outage probability (SOP) are derived and verified. The results demonstrate the potential of improving secrecy with the aid of RIS under both V2V and V2I communications.
63 citations
Additional excerpts
...V2I Communications Under the V2I scenario and with the independence between the RVs γD and γE , the SOP can be evaluated as [17] Po = ∫ ∞ 0 FγD (Θx+Θ− 1) · fγE(x) dx....
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TL;DR: In this paper, the authors provide a roadmap of key milestones towards a complete, global quantum networked landscape and summarise important challenges in space quantum technologies that must be overcome and recent efforts to mitigate their effects.
Abstract: Concerted efforts are underway to establish an infrastructure for a global quantum internet to realise a spectrum of quantum technologies. This will enable more precise sensors, secure communications, and faster data processing. Quantum communications are a front-runner with quantum networks already implemented in several metropolitan areas. A number of recent proposals have modelled the use of space segments to overcome range limitations of purely terrestrial networks. Rapid progress in the design of quantum devices have enabled their deployment in space for in-orbit demonstrations. We review developments in this emerging area of space-based quantum technologies and provide a roadmap of key milestones towards a complete, global quantum networked landscape. Small satellites hold increasing promise to provide a cost effective coverage required to realised the quantum internet. We review the state of art in small satellite missions and collate the most current in-field demonstrations of quantum cryptography. We summarise important challenges in space quantum technologies that must be overcome and recent efforts to mitigate their effects. A perspective on future developments that would improve the performance of space quantum communications is included. We conclude with a discussion on fundamental physics experiments that could take advantage of a global, space-based quantum network.
48 citations
TL;DR: The results show that when the eavesdropper is placed near the transmitter, atmospheric condition imposes a less significant impact on secrecy performance; certain level of correlation can potentially enhance the secrecy performance for FSO communications; and the correlation imposes opposite impacts on the ASC and SOP of FSOcommunications.
Abstract: In this article, we study the physical layer security of free-space optical (FSO) communications under different eavesdropping scenarios. More specifically, the secrecy performance of FSO communication employing intensity modulation/direct detection detection is analyzed for the well-established Malaga channels. Three different realistic scenarios of eavesdropping are considered by assuming different placement locations for the eavesdropper in the paper. Novel expressions for the average secrecy capacity (ASC) and secrecy outage probability (SOP) are derived for the considered scenarios, and useful insights are also provided through asymptotic analysis. The results show: (1) When the eavesdropper is placed near the transmitter, atmospheric condition imposes a less significant impact on secrecy performance; (2) Certain level of correlation can potentially enhance the secrecy performance for FSO communications; (3) The correlation imposes opposite impacts on the ASC and SOP of FSO communications; and the secrecy performance metrics exhibit a non-monotonic impact with the increase of correlation; (5) When the correlation of the FSO links is too small or too large (i.e., the correlation parameter around 0 or 1), the correlation plays a more significant impact on secrecy performance; and (6) The asymptotic slope of the SOP is 0.5 for all eavesdropping scenarios under practical FSO channels.
45 citations
Cites methods from "Physical Layer Security of Hybrid S..."
...In the context of PLS, the secrecy outage probability is a widely used secrecy performance metric in the scenario where the node S does not have E ’s CSI [33]....
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...The impact of spatial correlation on the average secrecy capacity (ASC) was investigated in [5] by assuming that the transmitter has full knowledge on the channel state information (CSI) of both the legitimate receiver and eavesdropper....
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...Under the active eavesdropping scenario, the node S has full CSI of both the main and wiretap channels, based on which S can adapt the achievable secrecy rate accordingly [28]....
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References
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TL;DR: This paper finds the trade-off curve between R and d, assuming essentially perfect (“error-free”) transmission, and implies that there exists a Cs > 0, such that reliable transmission at rates up to Cs is possible in approximately perfect secrecy.
Abstract: We consider the situation in which digital data is to be reliably transmitted over a discrete, memoryless channel (dmc) that is subjected to a wire-tap at the receiver. We assume that the wire-tapper views the channel output via a second dmc). Encoding by the transmitter and decoding by the receiver are permitted. However, the code books used in these operations are assumed to be known by the wire-tapper. The designer attempts to build the encoder-decoder in such a way as to maximize the transmission rate R, and the equivocation d of the data as seen by the wire-tapper. In this paper, we find the trade-off curve between R and d, assuming essentially perfect (“error-free”) transmission. In particular, if d is equal to Hs, the entropy of the data source, then we consider that the transmission is accomplished in perfect secrecy. Our results imply that there exists a C s > 0, such that reliable transmission at rates up to C s is possible in approximately perfect secrecy.
7,129 citations
"Physical Layer Security of Hybrid S..." refers background in this paper
...It is shown through the physical layer security (PLS) theory in [13] that secure information transmission can be achieved when the quality of the eavesdropper’s link is inferior to that of the legitimate link....
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TL;DR: End-to-end performance of two-hop wireless communication systems with nonregenerative relays over flat Rayleigh-fading channels is presented and average bit-error rate expressions for binary differential phase-shift keying, as well as outage probability formulas for noise limited systems are derived.
Abstract: End-to-end performance of two-hop wireless communication systems with nonregenerative relays over flat Rayleigh-fading channels is presented. This is accomplished by deriving and applying some new closed-form expressions for the statistics of the harmonic mean of two independent exponential variates. It is shown that the presented results can either be exact or tight lower bounds on the performance of these systems depending on the choice of the relay gain. More specifically, average bit-error rate expressions for binary differential phase-shift keying, as well as outage probability formulas for noise limited systems are derived. Finally, comparisons between regenerative and nonregenerative systems are presented. Numerical results show that the former systems clearly outperform the latter ones for low average signal-to-noise-ratio (SNR). They also show that the two systems have similar performance at high average SNR.
1,388 citations
"Physical Layer Security of Hybrid S..." refers methods in this paper
...Remark 2: It should be noted that when the AF protocol with variable-gain scheme is employed and full CSI is utilized at the node R to counteract the instantaneous fading effects, the end-to-end SNR γV eq at node D can be expressed as: γ V eq = γR γD γR +γD +1 ∼= min (γR , γD ) = γDF eq [28]....
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..., fixed-gain and variable-gain cooperative relaying, respectively [28]....
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TL;DR: This paper proposes to employ a multi-antenna base station (BS) as a source of green interference to enhance secure transmission in the satellite network and presents two beamforming schemes, namely, hybrid zero- forcing and partial zero-forcing to solve the optimization problem and obtain the BF weight vectors in a closed form.
Abstract: This paper investigates the physical layer security of a satellite network, whose downlink spectral resource is shared with a terrestrial cellular network. We propose to employ a multi-antenna base station (BS) as a source of green interference to enhance secure transmission in the satellite network. By taking the mutual interference between these two networks into account, we first formulate a constrained optimization problem to maximize the instantaneous rate of the terrestrial user while satisfying the interference probability constraint of the satellite user. Then, with the assumption that imperfect channel state information (CSI) and statistical CSI of the link between the BS and satellite user are available at the BS, we present two beamforming (BF) schemes, namely, hybrid zero-forcing and partial zero-forcing to solve the optimization problem and obtain the BF weight vectors in a closed form. Moreover, we analyze the secrecy performance of primary satellite network by considering two practical scenarios, namely: Scenario I, the eavesdroppers CSI is unknown at the satellite and Scenario II, the eavesdroppers CSI is known at the satellite. Specifically, we derive the analytical expressions for the secrecy outage probability for Scenario I and the average secrecy rate for Scenario II. Finally, numerical results are provided to confirm the superiority of the proposed BF schemes and the validity of the performance analysis, as well as demonstrate the impacts of various parameters on the secrecy performance of the satellite network.
255 citations
TL;DR: A unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency and unified free-space optical links under the effect of pointing errors is carried out.
Abstract: In this paper, we carry out a unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency (RF) and unified free-space optical (FSO) links under the effect of pointing errors. Both fixed and variable gain relay systems are studied. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection). In particular, we derive new unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability (OP), the higher order amount of fading, and the average bit error rate (BER) of a variety of binary modulations in terms of the Meijer's G function. Furthermore, an exact closed-form expression of the end-to-end ergodic capacity is derived in terms of the bivariate G function. Additionally, by using the asymptotic expansion of the Meijer's G function at the high-SNR regime, we derive new asymptotic results for the OP, the MGF, and the average BER in terms of simple elementary functions.
253 citations
"Physical Layer Security of Hybrid S..." refers background or methods in this paper
..., r = 1 denotes heterodyne detection (HD) and r = 2 implies intensity modulation with direct detection (IM/DD)), the parameter ξ is the ratio of the equivalent beam radius to the standard deviation of the pointing error displacement (jitter) at the FSO receiver [6], the parameters α and β are used to represent the severity of fading/scintillation due to the atmospheric turbulence conditions [24], h = ξ2 ξ2+1 , and, μr denotes the average electrical SNR of the FSO link under the HD or IM/DD detections (for HD detection, μ1 = E [γD ] = γ̄D , and for IM/DD detection, μ2 = γ̄D αβξ2(ξ2+2) (α+1)(β+1)(ξ2+1)2 ) [4]....
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..., free-space optical (FSO) communication, has gained increasing attention due to its potential as a cost-effective and wide bandwidth solution operating within the unlicensed optical frequency band, relative to the conventional radio frequency (RF) transmission systems [2], [4]–[7]....
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...The PDF fγD (x) of the instantaneous SNR γD is given as [4] fγD (x) = ξ2 r (α) (β)x G 3,0 1,3 ( hαβ ( x μr ) 1 r ∣∣∣∣ ξ2 + 1 ξ2, α, β )...
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TL;DR: In this letter, efficient performance bounds for multihop wireless communications systems with non-regenerative blind relays over non-identical Nakagami-n (Rice), Nakagama-m and NakagAMI-q (Hoyt) generalized fading channels, are presented.
Abstract: In this letter, efficient performance bounds for multihop wireless communications systems with non-regenerative blind relays over non-identical Nakagami-n (Rice), Nakagami-m and Nakagami-q (Hoyt) generalized fading channels, are presented. More specifically, the end-to-end signal-to-noise ratio (SNR) is formulated and upper bounded by using the well-known inequality between harmonic and geometric mean of positive random variables. This bound is used to study important system's performance metrics: i) the moments of the end-to-end SNR which are obtained in closed-forms, and ii) the outage probability and the average error probability for coherent and non-coherent modulations, which are accurately approximated using the moments-based approach. Furthermore, new analytical formulae are derived for the gain of previously proposed semi-blind relays in generalized fading environments. These kind of relays are used in numerical examples and computer simulations to verify the accuracy and to show the tightness of the proposed bounds.
237 citations
"Physical Layer Security of Hybrid S..." refers background in this paper
...where C is a constant for a fixed-gain relaying [31]....
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...The corresponding end-to-end SNR γAF eq at node D can be expressed as [31] γ eq = γR γD γD + C , (8)...
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