Low Earth orbit (LEO) satellite networks (SatNets) are envisioned to play a crucial role in providing global and ubiquitous connectivity efficiently. Accordingly, in the coming years, thousands of LEO satellites will be launched to create ultradense LEO mega-constellations, and the Third Generation Partnership Project (3GPP) is working on evolving fifth-generation (5G) systems to support such non-terrestrial networks (NTN). However, many challenges are associated with the deployment of LEOs from communications and networking perspectives. In this paper, we propose a novel cell-free massive multiple-input multiple-output (CF-mMIMO) based architecture for future ultra-dense LEO SatNets. We discuss various aspects of network design, such as duplexing mode, pilot assignment, beamforming, and handover management. In addition, we propose a joint optimization framework for the power allocation and handover management processes to maximize the network throughput and minimize the handover rate while ensuring quality-of-service (QoS) satisfaction for users. To the best of our knowledge, this is the first work to introduce and study CF-mMIMO-based LEO SatNets. Extensive simulation results demonstrate the superior performance of the proposed architecture and solutions compared to those of conventional single-satellite connectivity and handover techniques from the literature.

中文翻译：

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未来超密集低轨卫星网络：无蜂窝大规模 MIMO 方法

低地球轨道 (LEO) 卫星网络 (SatNets) 被设想在有效提供全球和无处不在的连接方面发挥关键作用。因此，在未来几年内，将发射数以千计的 LEO 卫星以创建超密集 LEO 巨型星座，而第三代合作伙伴计划 (3GPP) 正致力于发展第五代 (5G) 系统以支持此类非地面网络（ NTN）。然而，从通信和网络的角度来看，许多挑战与 LEO 的部署有关。在本文中，我们为未来的超密集 LEO 卫星网络提出了一种新型的基于无细胞大规模多输入多输出 (CF-mMIMO) 的架构。我们讨论了网络设计的各个方面，例如双工模式、导频分配、波束成形和切换管理。此外，我们为功率分配和切换管理过程提出了一个联合优化框架，以最大化网络吞吐量并最小化切换率，同时确保用户的服务质量（QoS）满意度。据我们所知，这是第一项介绍和研究基于 CF-mMIMO 的 LEO SatNets 的工作。广泛的仿真结果表明，与文献中的传统单卫星连接和切换技术相比，所提出的架构和解决方案具有卓越的性能。