The envisioned 5G ecosystem will be composed of heterogeneous networks based on different technologies and communication means, including satellite communication networks. The latter can help increase the capabilities of terrestrial networks, especially in terms of higher coverage, reliability, and availability, contributing to the achievement of some of the 5G KPIs. However, technological changes are not immediate. Many current satellite communication networks are based on proprietary hardware, which hinders the integration with future 5G terrestrial networks as well as the adoption of new protocols and algorithms. On the other hand, the two main paradigms that are emerging in the networking scenario -- software defined networking (SDN) and network functions virtualization -- can change this perspective. In this respect, this article presents first an overview of the main research works in the field of SDN satellite networks in order to understand the already proposed solutions. Then some open challenges are described in light of the network slicing concept by 5G virtualization, along with a possible roadmap including different network virtualization levels. The remaining unsolved problems are related to the development and deployment of a complete integration of satellite components in the 5G ecosystem.

中文翻译：

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5G生态系统中的卫星网络集成：研究趋势和开放挑战

设想的5G生态系统将由基于不同技术和通信手段的异构网络组成，包括卫星通信网络。后者可以帮助提高地面网络的功能，尤其是在更高的覆盖范围，可靠性和可用性方面，从而有助于实现某些5G KPI。但是，技术变革不是立即的。当前许多卫星通信网络都基于专有硬件，这阻碍了与未来5G地面网络的集成以及新协议和算法的采用。另一方面，网络场景中出现的两个主要范例-软件定义网络（SDN）和网络功能虚拟化-可以改变这种观点。在这方面，本文首先概述了SDN卫星网络领域的主要研究工作，以了解已经提出的解决方案。然后根据5G虚拟化的网络切片概念以及可能的路线图（包括不同的网络虚拟化级别）描述了一些开放的挑战。其余未解决的问题与5G生态系统中卫星组件的完整集成的开发和部署有关。