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Mobile edge computing (MEC)-enabled satellite–terrestrial networks (STNs) can provide task computing services for Internet of Things (IoT) devices. However, since some applications’ tasks require huge amounts of computing resources, sometimes the computing resources of a local satellite’s MEC server are insufficient, but the computing resources of neighboring satellites’ MEC servers are redundant. Therefore, we investigated inter-satellite cooperation in MEC-enabled STNs. First, we designed a system model of the MEC-enabled STN architecture, where the local satellite and the neighboring satellites assist IoT devices in computing tasks through inter-satellite cooperation. The local satellite migrates some tasks to the neighboring satellites to utilize their idle resources. Next, the task completion delay minimization problem for all IoT devices is formulated and decomposed. Then, we propose an inter-satellite cooperative joint offloading decision and resource allocation optimization scheme, which consists of a task offloading decision algorithm based on the Grey Wolf Optimizer (GWO) algorithm and a computing resource allocation algorithm based on the Lagrange multiplier method. The optimal solution is obtained by continuous iterations. Finally, simulation results demonstrate that the proposed scheme achieves relatively better performance than other baseline schemes.

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.

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.

The use of satellites as an integrated part of larger deployed IP networks is today constrained by the fact that satellite networks need particular interface functions and careful management, due to the cost of space segment resources. This paper describes a new approach to the design of the satellite/terrestrial network interface that seeks to ease integration of satellite systems in IP-based network infrastructure. It proposes an evolution towards a common external interface and development of appropriate common satellite IP-layer protocol modules. This new design will demand new research and development and is expected to result in additional standardization actions.

In this paper, the main concepts of the Wireless Infrastructure over Satellite for Emergency COMmunications project (WISECOM) are presented. These concepts rely upon the idea of a light and rapidly deployable system that can be autonomously used in remote areas where telecommunication networks have broken down to provide access to emergency telecommunication services using a large set of wide-spread telecommunication technologies such as GSM, UMTS, WiFi, WiMAX, and TETRA and a satellite back-hauling link. In the paper, a detailed description of the whole WISECOM system is provided, with emphasis on the WISECOM Access Terminal, the unit deployed on the disaster area and interfacing the selected satellite system to different wireless local access technologies. Then, three relevant and realistic examples of configuration of the WISECOM system (GSM, UMTS and TETRA over satellite) are detailed.