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The explosive growth of various services boosts the innovation and development in terrestrial communication systems for the implementation of the next generation mobile communication networks. However, simply utilizing limited resources in terrestrial communication networks is difficult to support the massive quality of service (QoS) aware requirements and it is hard to guarantee seamless coverage in far remote regions. Leveraging the intrinsic merits of high altitude and the ability of multicasting or broadcasting, satellite communication systems provide an opportunity for novel mobile communication networks with its tight interaction and complementary characteristics to traditional terrestrial networks. It is believed that the convergence of satellite and terrestrial networks can solve the problems existing in current mobile communication systems and make a profound effect on global information dissemination. In this paper, we make a comprehensive survey on the convergence of satellite and terrestrial networks. First, motivations and requirements of satellite-terrestrial network convergence are identified. Then, we summarize related architectures of existing literature, classify the taxonomy of researches on satellite-terrestrial networks, and present the performance evaluation works in different satellite-terrestrial networks. After that, the state-of-the-art of standardization, projects and the key application areas of satellite-terrestrial networks are also reviewed. Finally, we conclude the survey by highlighting the open issues and future directions.

This paper investigates a novel architecture of coordinated multi-point (CoMP) transmission in the cognitive satellite-terrestrial network associated with an unmanned aerial vehicle (UAV). We consider the downlink communication where the UAV and base station (BS) cooperatively serve the terrestrial user by sharing the licensed satellite network spectrum. The goal of this paper is to maximize the achievable rate of the terrestrial user by jointly optimizing BS/UAV transmit power allocation and UAV trajectory, subjecting to the interference temperature threshold imposed on satellite network as well as UAV mobility constraint. The formulated problem is shown in a complicated non-convex form, which is hard to tackle. To this end, we decompose the original problem into two sub-problems, and the block coordinate descent method is employed to solve the two sub-problems alternately. Specifically, for the first sub-problem, the optimal BS/UAV transmit power is obtained with a given UAV trajectory by using the Lagrangian dual method. For the second sub-problem, the UAV trajectory is attained with a given BS/UAV power allocation by using the successive convex approximation technique. Simulation results show that our proposed joint CoMP transmission scheme significantly improves the terrestrial network throughput compared with other benchmark schemes.

The integration of satellite and terrestrial networks is a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure, as also demonstrated by recent commercial and standardisation endeavours. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to traditional terrestrial systems, as LTE or 5G. In this paper, two architectures are proposed for a LEO mega-constellation realising a satellite-enabled LTE system, in which the on- ground LTE entity is either an eNB (Sat-eNB) or a Relay Node (Sat-RN). The impact of satellite channel impairments as large delays and Doppler shifts on LTE PHY/MAC procedures is discussed and assessed. The proposed analysis shows that, while carrier spacings, Random Access, and RN attach procedures do not pose specific issues, HARQ requires substantial modifications. Moreover, advanced handover procedures will be also required due to the satellites' movement., Comment: Submitted to IJSCN Special Issue on SatNEx IV

An unprecedented exploding demand for broadband high-speed, heterogeneous, ultra-reliable, secure, and low latency communications is motivating and leading the definition of new standards and technologies for wireless communications, known as 5G. The massive scientific and industrial interest in 5G communications is motivated by the key role that 5G systems can play in the worldwide economic and societal processes to support next generation vertical services, e.g., Internet of Things, Industry 4.0, automotive and transportation sectors, e-Health, factories of the future, etc. The integration of satellite and terrestrial networks can be a cornerstone to the realisation of the foreseen heterogeneous global system. Due to their inherent large footprint, satellites can efficiently complement and extend dense terrestrial networks, both in densely populated areas and in rural zones, as well as provide reliable Mission Critical services. While in the past terrestrial and satellite networks have evolved almost independently from each other, leading to a difficult a posteriori integration, the definition of the future 5G paradigm provides the unique chance for a fully-fledged architecture. This Special Issue aims at collecting the latest progresses in scientific, industrial, regulatory, and standardisation analyses, as well as sharing novel concepts and ideas, for a fully integrated satellite-terrestrial network. Potential topics include, but are not limited to: • System architecture: challenges and solutions • Impact of satellite channel impairments on the system physical layer • Integration with low altitude drones • Scheduling • Higher layers design • Regulatory aspects • Standards evolution • Coexistence with Advanced LTE and IoT networks • Application to 5G verticals • Cognitive radio techniques

SHINE is a European Space Agency funded project focusing on the secure distribution of multimedia contents in the presence of hybrid satellite-terrestrial networks equipped with in-network caching capabilities. We describe the SHINE testbed, from both the design and the implementation perspectives. We also identify the set of procedures that need to be adopted when deploying the SHINE components in the form of containerized micro-services on top of the SHINE infrastructure.

In this paper, we investigate the performance of a two-way hybrid satellite multi-terrestrial cooperative network with hardware impairments (HIs). Particularly, opportunistic relay selection scheme is employed in the considered network, which can substantially enhance the spectral efficiency and spatial diversity gain. By considering both the amplify-and-forward (AF) and decode-and-forward (DF) relay protocols, the closed-form expressions of the outage probability (OP) and throughput for the system are derived. Furthermore, in order to observe the effects of HIs level and the number of terrestrial relays on the system performance at high signal-to-noise ratios (SNRs), the asymptotic expressions of the system performance are also derived. Finally, computer results are presented to reveal the correctness of the analytical results.