This paper investigates the performance limits of cognitive uplink Fixed Satellite Service (FSS) and terrestrial Fixed Service (FS) operating in 27.5-29.5 GHz for Ka-band. In light of standard International Telecommunications Union (ITU) recommendations and a rain fading channel model, we analyze the interference level at the FS receiver by considering the channel statistical properties, propagation losses and antenna patterns. By employing the interference constraint criterion at the FS, an analytical expression for the capacity of the cognitive uplink FSS is derived, which is useful in understanding the performance limits and the potential application of the considered coexistence scenario. Simulation results are carried out to verify the theoretical derivations, and highlight the impact of key parameters on the performance limits.

Satellite communication networks are expected to be indispensable as part of an integrated complement for the upcoming 5G networks, since they can provide the most comprehensive coverage and reliable connection for areas where are economically unviable and/or difficult to deploy terrestrial infrastructures. Meanwhile, power-domain non-orthogonal multiple access (NOMA), which can serve multiple users simultaneously within the same time/frequency block, has been viewed as another promising strategy used in the 5G network to provide high spectral efficiency and resource utilization. In this article, we introduce a general overview of the application of NOMA to various satellite architectures for the benefits of meeting the availability, coverage, and efficiency requirements targeted by 5G. The fundamental and ubiquitous features of satellite link budget are first reviewed. Then, the advantage and benefit of introducing the NOMA scheme in various satellite architectures, such as conventional downlink/uplink satellite networks, cognitive satellite terrestrial networks, and cooperative satellite networks with satellite/terrestrial relays, are provided, along with the motivation and research methodology for each scenario. Finally, this article reviews the potential directions for future research Index Terms—Power-domain non-orthogonal multiple access, satellite networks, cognitive satellite terrestrial networks, cooperative satellite terrestrial networks, 5G.

Hybrid satellite-terrestrial relay network (HSTRN) has been viewed as a flexible and promising solution to be developed with heterogeneous devices and integrated infrastructures for improved coverage and reduced latency. Taking the requirements of overall spectral and power efficiency into account, we consider different adaptive transmission schemes for the hybrid architecture oriented to potential applications in practical scenarios, and obtain the analytical expressions for the achievable channel capacity with respect to different schemes, i.e., optimal power and rate adaptation, and truncated channel inversion and fixed rate. Numerical simulations confirm the validity of the derived theoretical results, and provide useful guidance for emerging applications in HSTRN that are under various fixed/adaptive transmit power or rate requirements.

In this paper, we investigate the secrecy performance against eavesdropping of a land mobile satellite (LMS) system, where the satellite employs the spot beam technique, and both the terrestrial user and eavesdropper are equipped with multiple antennas and utilize maximal ratio combining (MRC) to receive the confidential message. Specifically, in terms of the availability of the eavesdropper’s CSI at the satellite, we consider both passive (Scenario I) and active (Scenario II) eavesdropping. For Scenario I where the eavesdropper’s channel state information (CSI) is unknown to the satellite, closed-form expressions for the probability of non-zero secrecy capacity and secrecy outage probability are derived. Furthermore, expressions for the asymptotic secrecy outage probability are also presented to reveal the secrecy diversity order and array gain of the considered system. For Scenario II where the eavesdropper’s CSI is available at the satellite, novel expressions for the exact and asymptotic average secrecy capacity are obtained. Based on a simple asymptotic formula, we can characterize the high signalto- noise ratio (SNR) slope and high SNR power offset of the LMS systems. Finally, simulations are provided to validate our theoretical analysis and show the effect of different parameters on the system performance.