Hybrid Satellite-terrestrial System Research Articles

Capacity Analysis of Hybrid Satellite-Terrestrial Systems with Selection Relaying.

A hybrid satellite-terrestrial relay network is a simple and flexible solution that can be used to improve the performance of land mobile satellite systems, where the communication links between satellite and mobile terrestrial users can be unstable due to the multipath effect, obstacles, as well as the additional atmospheric losses. Motivated by these facts, in this paper, we analyze a system where the satellite-terrestrial links undergo shadowed Rice fading, and, following this, terrestrial relay applies the selection relaying protocol and forwards the information to the final destination using the communication link subjected to Nakagami-m fading. For the considered relaying protocol, we derive the exact closed-form expressions for the outage probability, outage capacity, and ergodic capacity, presented in polynomial-exponential form for the integer-valued fading parameters. The presented numerical results illustrate the usefulness of the selection relaying for various propagation scenarios and system geometry parameters. The obtained analytical results are corroborated by an independent simulation method, based on the originally developed fading simulator.

Performance Analysis of HSTC Network with Non-Static Terrestrial Nodes in a Fading Environment

In this paper, Hybrid satellite-terrestrial systems (HSTC) are preferred in dynamic type environments with high mobility of nodes due to the performance enhancement features in multiple relay-based selective decode-and-forward (DF) approach. Because of the satellite link, aerial satellite to destination and satellite to relay links, are not the same due to time-selective shadowed Rician fading. Time-selective Rician fading depends on parameters like the angle of elevation of the satellite, the terrestrial relay node, and the node destination links, considered to be distinctively time-selective Nakagami faded. Here, per-frame average symbol error rate (SER) and outage probability are derived in a closed-form expression with consideration of M-ary PSK modulated symbols transmission. After evaluation, it was detected that the system performance is significantly degraded due to the time-varying nature of the links (dynamic environment). After various simulations and calculations, it was established that the error rate of the HSTC is significantly low by increasing the elevation angle of the satellite on the relay point. The performance enhancement can be observed by enhancing the satellite angle at the destination node of user equipment.

Enabling NOMA in Overlay Spectrum Sharing in Hybrid Satellite-Terrestrial Systems

In this paper, a hybrid satellite-terrestrial spectrum sharing system allows terrestrial secondary network to cooperate with a primary satellite network and to further provide higher spectrum efficiency. For massive connections design, we implement non-orthogonal multiple access (NOMA) technique to form cognitive radio based satellite-terrestrial (CR-NSHT) system relying on NOMA and further achieve more benefits compared with traditional schemes. The secondary network only remains its stable operation when the outage probability of such system is guaranteed, and thereby, to explore advantages of spectrum sharing opportunities. Considering Shadowed-Rician fading for satellite links, and Nakagami- $m$ as well as Rician fading for terrestrial links, we derive the closed-form expressions of the outage probability to evaluate the performance of secondary network. We consider further system performance metrics including ergodic capacity, energy efficiency and multi-user scenarios. We also demonstrate the impacts of power allocation factors, transmit signal-to-noise ratio (SNR) at the source, parameters of satellite links, target rates, and fading severity parameters on the system performance. Numerical and simulation results validate our analysis and highlight the performance gains of the proposed schemes for CR-NSHT with relay link serving secondary network and direct link serving the primary network.

Reliability and Security Performance Analysis of Hybrid Satellite-Terrestrial Multi-Relay Systems With Artificial Noise

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.

Performance Analysis of Overlay Spectrum Sharing in Hybrid Satellite-Terrestrial Systems With Secondary Network Selection

In this paper, we study a hybrid satellite-terrestrial spectrum sharing system (HSTSSS) in which multiple terrestrial secondary networks cooperate with a primary satellite network for dynamic spectrum access. For complexity-aware HSTSSS design, we propose an amplify-and-forward-based overlay spectrum sharing protocol using partial and opportunistic secondary network selection schemes. The secondary network selection aims to minimize the outage probability of the primary satellite system and, thereby, to explore spectrum sharing opportunities. With the overlay approach, the selected secondary network allocates part of its power to relay the satellite signal and utilizes the remaining power to transmit its own signal. Considering Shadowed-Rician fading for satellite links, and Nakagami- ${m}$ as well as Rician fading for terrestrial links, we derive closed-form expressions for the outage probability of both primary and secondary networks, and examine their achievable diversity orders. Numerical and simulation results validate our analysis and highlight the performance gains of the proposed schemes for an HSTSSS with and without a direct satellite primary communication link.

Performance Characterization of a Hybrid Satellite-Terrestrial System with Co-Channel Interference over Generalized Fading Channels.

The transmission of signals in a hybrid satellite-terrestrial system (HSTS) in the presence of co-channel interference (CCI) is considered in this study. Specifically, we examine the problem of amplify-and-forward (AF)-based relaying in a hybrid satellite-terrestrial link, where the relay node is operating in the presence of a dominant co-channel interferer. It is assumed that direct connection between a source node (satellite) and a destination node (terrestrial receiver) is not available due to masking by obstacles in the surrounding. The destination node is only able to receive signals from the satellite with the help of a relay node located at the ground. In the proposed HSTS, the satellite-relay channel follows the shadowed Rice fading; and the channels of interferer-relay and relay-destination links experience generalized Nakagami-m fading. For the considered AF-based HSTS, we first develop the analytical expression for the moment generating function (MGF) of the overall output signal-to-interference-plus-noise ratio (SINR). Then, based on the derived exact MGF, we derive novel expressions for the average symbol error rate (SER) of the considered HSTS for the following digital modulation techniques: M-ary phase shift keying (M-PSK), M-ary quadrature amplitude modulation (M-QAM) and M-ary pulse amplitude modulation (M-PAM). To significantly reduce the computational complexity for utility in system-level simulations, simple analytical approximation for the exact SER in the high signal-to-noise ratio (SNR) regime is presented to provide key insights. Finally, numerical results and the corresponding analysis are presented to demonstrate the effectiveness of the developed performance evaluation framework and to view the impact of CCI on the considered HSTS under varying channel conditions and with different modulation schemes.

Impact of MIMO enabled relay on the performance of a hybrid satellite-terrestrial system

In this paper, we investigate a hybrid satellite terrestrial system with multiple input and multiple output enabled fixed relay, which is more reliable than the conventional dual-hop multiple single input and single output relaying network. Providing a small number of antennas on a fixed relay is easier to undertake than setting up on a mobile terminal due to the size limitation. In this study, we consider the impact of cooperating fixed relay with multiple transmitting and receiving antennas on the hybrid satellite-terrestrial system. Amplify-and-forward cooperative protocol is used at the relay node while for signal combining at the relay node, maximum ratio combining and maximum ratio transmission techniques are used. Independent and non-identically distributed fading channels, shadowed Rician, and Nakagami-$$m$$m, are assumed between the source-relay and relay-destination links respectively. An analytical approach is derived to evaluate the performance of the system in terms of outage probability, symbol error rate (SER) and ergodic capacity. The closed form expressions for the probability density function, cumulative distribution function, moment generating function, average SER of the total end-to-end signal-to-noise ratio are derived. We further derive the approximate closed form expression of ergodic capacity. These derived analytical expressions are applied to the general operating conditions together with available satellite channel data of various degrees of shadowing. The analytical results are compared with Monte Carlo simulations. The results show the improvement in the performance of the hybrid satellite-terrestrial system under various antenna arrangements at the relay node.