The demands of 5G mobile communications, such as higher throughput and lower latency in future communications, has promoted more advanced communication technologies and heterogeneous network integration. Satellite communication has been recently considered as a key part of 5G for the benefits of meeting the availability and ubiquitous coverage requirements targeted by 5G. As a potential 5G technology, multi-satellite cooperative transmission systems have been studied, as they can provide the high throughput brought by virtual multiple-input multiple-output structures. In this article, we briefly review the concepts and techniques of multi-satellite cooperative transmission systems in 5G. Moreover, the architectures of two multi-satellite relay transmission systems based on TDMA and NOMA are introduced. In particular, we focus more on the performance evaluation and research challenges of the TDMAbased architecture to explore its system optimizing approach. Finally, to exploit the full potential of multi-satellite systems in 5G networks, future trends and challenges are discussed.

中文翻译：

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5G中的多卫星中继传输：概念，技术和挑战

5G移动通信的需求，例如未来通信中更高的吞吐量和更低的等待时间，促进了更先进的通信技术和异构网络集成。卫星通信最近被视为5G的关键部分，其好处是可以满足5G的可用性和无处不在的覆盖范围要求。作为一种潜在的5G技术，已经研究了多卫星协作传输系统，因为它们可以提供虚拟多输入多输出结构带来的高吞吐量。在本文中，我们简要回顾了5G中多卫星协作传输系统的概念和技术。此外，介绍了两个基于TDMA和NOMA的多卫星中继传输系统的体系结构。尤其是，我们将重点放在基于TDMA的体系结构的性能评估和研究挑战上，以探索其系统优化方法。最后，为了充分利用5G网络中多卫星系统的潜力，讨论了未来的趋势和挑战。