Abstract
Land mobile satellite communication and physical layer security are considered as the promising paradigms in beyond 5G networks. In this paper, we establish the multi-relay hybrid satellite-terrestrial systems (HSTSs) with artificial noise (AN) to investigate the reliability and security, in which the satellite sends signals to the terrestrial destination through multiple decode-and-forward relays and there exists an eavesdropper trying to overhear the useful information. In order to improve the overall system performance, two relay selection (RS) schemes: i) optimal relay-receiver pair selection (ORRPS) and ii) suboptimal relay selection (SRS) are considered. ORRPS selects an optimal relay-receiver pair and an AN signal to maximize the corresponding signal-to-interference-plus-noise ratios of ${R_{k}} \to D\left ({{R_{k} \to E} }\right)$ and the SRS refers to selecting a relay that optimize the instantaneous channel gain ${\left |{ {{h_{R_{k}D}}} }\right |^{2}}\left ({{{{\left |{ {{h_{R_{k}E}}} }\right |}^{2}}} }\right)$ among $K$ relays, with the traditional round-robin selection scheme as a benchmark for comparison. Furthermore, the exact closed-form analytical expressions of outage probability (OP) and intercept probability (IP) under different RS schemes are derived for AN and non-AN conditions. To obtain more insights, the asymptotic analysis for high signal-to-noise-ratio regime is carried out. Based on the asymptotic analysis of OP, the diversity orders of the HSTSs are obtained. The numerical results and theoretical analysis shown that: i) The reliability of TRRS scheme is the worst among the three RS schemes, and the reliability of ORRPS scheme is the best; ii) The AN technology can significantly improve the security of the system, although it has a little adverse affect on the reliability; iii) Infrequent light shadowing has the best reliability, frequent heavy shadowing has the worst outage performance, and the change of security is opposite; iv) The OP of SRS and ORRP schemes decreased with the increase of $K$ , while the IP changed on the contrary, and the reliability and security of TRRS scheme did not change obviously.
Highlights
Land mobile satellite (LMS) communication, as the core of the beyond 5G networks, has attracted a great deal of attention due to its promising characteristics of seamless coverage and high date capacity [1], [2], and it mainly solves the communication tasks of land, sea and between air and ground public networks [3]–[6]
LMS SYSTEM DESCRIPTION As depicted in Fig. 1, a multi-relay hybrid satellite-terrestrial system is established, which consists of a geostationary orbit regenerative satellite (S), K DF relays Rk (k ∈ {1, 2, · · ·, K }), a ground destination (D) and an eavesdropper (E) surrounding the D and it wants to overhear the information from S and Rk
Remark 2: We found from Theorem 2 and Corollary 3 that the reliability for suboptimal relay selection (SRS) scheme decreases as K increases
Summary
Land mobile satellite (LMS) communication, as the core of the beyond 5G networks, has attracted a great deal of attention due to its promising characteristics of seamless coverage and high date capacity [1], [2], and it mainly solves the communication tasks of land, sea and between air and ground public networks [3]–[6]. In some cases, it is hard to achieve direct links between the satellite and the terrestrial nodes due to so-called masking effects from atmospheric conditions (i.e., clouds, rain, etc.) and ground obstructions (i.e., receivers in tunnels, etc.) To combat these negative effects, the cooperative relay-based hybrid satellite-terrestrial systems (HSTSs) were investigated in literature [19]–[21]. By sharing the antennas with other mobile users, multiple virtual transmitting antennas can be generated to obtain corresponding diversity gains and improve the performance of the mobile cooperative communication system Whereas, it generated additional inter-relay interference and energy consumption. We establish a general PLS framework based on satellite-terrestrial systems in the presence of AN, in which the satellite sends signals to the terrestrial destination through multiple DF terrestrial relays, and there is an eavesdropper trying to intercept valid effective information from satellite and relays. The υp ∼ CN μp, σp is used to illustrate the complex additive white Gaussian noise (AWGN) of mean μp and variance σp
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