Small satellites in Low Earth Orbit (LEO) attract much attention from both industry and academia. The latest production and launch technologies constantly drive the development of LEO constellations. However, the wideband signal, except text messages, cannot be transmitted directly from an LEO satellite to a standard mobile cellular phone due to the insufficient link budget. The current LEO constellation network has to use an extra ground device to receive the signal from the satellite first and then forward the signal to the User Equipment (UE). To achieve direct network communications between LEO satellites and UE, we propose a novel distributed beamforming technology based on the superposition of electromagnetic (EM) waves radiated from multiple satellites that can significantly enhance the link budget in this paper. EM full-wave simulation and Monte Carlo simulation results are provided to verify the effectiveness of the proposed method. The simulation results show a nearly 6 dB enhancement using two radiation sources and an almost 12 dB enhancement using four sources. The received power enhancement could be doubled compared to the diversity gain in Multiple-Input and Single-Output (MISO). Furthermore, other practical application challenges, such as the synchronization and Doppler effect, are also presented.

翻译：低地球轨道上的小卫星在工业界和学术界引起了广泛关注。最新的生产和发射技术不断推动低地球轨道星座的发展。然而，除短信外的宽带信号无法直接从低地球轨道卫星传输到标准的移动蜂窝手机，原因是链路预算不足。当前的低地球轨道星座网络必须使用额外地面设备首先接收卫星信号，然后将信号转发至用户设备。为了实现低地球轨道卫星与用户设备之间的直接网络通信，本文提出了一种基于多颗卫星辐射的电磁波叠加的新型分布式波束成形技术，该技术能够显著增强链路预算。本文提供了电磁全波仿真和蒙特卡洛仿真结果来验证所提出方法的有效性。仿真结果表明，使用两个辐射源时链路预算提升近6 dB，使用四个辐射源时提升近12 dB。与多输入单输出系统中的分集增益相比，接收功率增强效果可翻倍。此外，本文还探讨了其他实际应用挑战，如同步问题和多普勒效应。